Biological evolution is the general form of the exam. Hypotheses of the origin of life on Earth. Evidence for the evolution of wildlife. Evolutionary results: adaptability of organisms to their environment, diversity of species

Evolutionary teaching

Evolutionary doctrine (theory of evolution) - a science that studies the historical development of life: causes, patterns and mechanisms. Distinguish between micro- and macroevolution.

Microevolution - evolutionary processes at the level of populations, leading to the formation of new species.

Macroevolution - the evolution of supraspecific taxa, as a result of which larger systematic groups are formed. They are based on the same principles and mechanisms.

Development of evolutionary ideas

Heraclitus, Empidocles, Democritus, Lucretius, Hippocrates, Aristotle and other ancient philosophers formulated the first ideas about the development of living nature.
Carl Linnaeus believed in the creation of nature by God and the constancy of species, but admitted the possibility of the emergence of new species by crossing or under the influence of environmental conditions. In the book "The System of Nature" K. Linnaeus substantiated the species as a universal unit and the main form of existence of living things; each species of animals and plants has assigned a double designation, where the noun is the name of the genus, the adjective is the name of the species (for example, Homo sapiens); described a huge number of plants and animals; developed the basic principles of taxonomy of plants and animals and created their first classification.
Jean Baptiste Lamarck created the first holistic evolutionary teaching. In the work "Philosophy of Zoology" (1809), he identified the main direction of the evolutionary process - the gradual complication of organization from lower to higher forms. He also developed a hypothesis about the natural origin of man from ape-like ancestors who switched to a terrestrial lifestyle. Lamarck considered the striving of organisms for perfection as the driving force of evolution and asserted the inheritance of acquired traits. That is, the organs necessary in the new conditions develop as a result of exercise (the neck of a giraffe), and unnecessary organs atrophy as a result of non-exercise (the eyes of a mole). However, Lamarck was unable to reveal the mechanisms of the evolutionary process. His hypothesis about the inheritance of acquired traits turned out to be untenable, and his statement about the internal striving of organisms for improvement was unscientific.
Charles Darwin created an evolutionary theory based on the concepts of the struggle for existence and natural selection. The preconditions for the emergence of Charles Darwin's doctrine were the following: accumulation by that time of rich material on paleontology, geography, geology, biology; development of selection; advances in taxonomy; the emergence of cell theory; the scientist's own observations during a voyage around the world aboard the Beagle. Charles Darwin outlined his evolutionary ideas in a number of works: "The origin of species by natural selection", "Change of domestic animals and cultivated plants under the influence of domestication", "The origin of man and sexual selection", etc.

Darwin's teachings boil down to the following:

• each individual of a particular species has individuality (variability);
• personality traits (although not all) can be inherited (heredity);
• individuals produce a greater number of offspring than they survive to puberty and the beginning of reproduction, that is, there is a struggle for existence in nature;
• the advantage in the struggle for existence remains with the most adapted individuals, which have a greater chance of leaving behind offspring (natural selection);
• as a result of natural selection, there is a gradual complication of the levels of organization of life and the emergence of species.

Evolutionary factors according to Charles Darwin - this is

• heredity,
• variability,
• struggle for existence,
• natural selection.

Heredity - the ability of organisms to transmit from generation to generation their characteristics (features of structure, development, function).
Variability - the ability of organisms to acquire new characteristics.
Struggle for existence - the whole complex of relationships between organisms and environmental conditions: with inanimate nature (abiotic factors) and with other organisms (biotic factors). The struggle for existence is not a "struggle" in the literal sense of the word; in fact, it is a survival strategy and a way of the organism's existence. Distinguish between intraspecific struggle, interspecific struggle and struggle with unfavorable environmental factors. Intraspecific struggle - struggle between individuals of the same population. It is always very stressful, as individuals of the same species need the same resources. Interspecies struggle - struggle between individuals of populations of different species. It occurs when species compete for the same resources or when they are linked by a predator-prey relationship. Wrestling with unfavorable abiotic environmental factors especially manifests itself when environmental conditions deteriorate; enhances intraspecific struggle. In the struggle for existence, the individuals most adapted to the given habitat conditions are revealed. The struggle for existence leads to natural selection.
Natural selection - a process as a result of which predominantly individuals with hereditary changes that are useful in these conditions survive and leave behind offspring.

All biological and many other natural sciences were rebuilt on the basis of Darwinism.
Currently, the most widely accepted is synthetic theory of evolution (STE)... Comparative characteristics of the main provisions of the evolutionary teachings of Charles Darwin and STE are given in the table.

Comparative characteristics of the main provisions of the evolutionary doctrine of Charles Darwin and the synthetic theory of evolution (STE)

Signs	Evolutionary theory of Charles Darwin	Synthetic theory of evolution (STE)
The main results of evolution	1) Increasing the adaptability of organisms to environmental conditions; 2) increasing the level of organization of living beings; 3) an increase in the diversity of organisms
Unit of evolution	View	Population
Evolution factors	Heredity, variability, struggle for existence, natural selection	Mutational and combinative variability, population waves and gene drift, isolation, natural selection
Driving factor	Natural selection
Interpretation of the term natural selection	Survival of the fittest and death of the less fit	Selective reproduction of genotypes
Forms of natural selection	Motive (and sexual, as its variety)	Motive, stabilizing, disruptive

The emergence of devices. Each adaptation is developed on the basis of hereditary variability in the process of struggle for existence and selection over a number of generations. Natural selection supports only appropriate adaptations that help the body survive and reproduce.
The adaptability of organisms to the environment is not absolute, but relative, since environmental conditions can change. Many facts prove this. For example, fish are perfectly adapted to aquatic habitats, but all these adaptations are completely unsuitable for other habitats. Moths collect nectar from light-colored flowers, which are clearly visible at night, but often fly into the fire and die.

Elementary factors of evolution - factors that change the frequency of alleles and genotypes in the population (genetic structure of the population).

There are several basic elementary factors of evolution:
mutation process;
population waves and gene drift;
insulation;
natural selection.

Mutational and combinative variability.

Mutation process leads to the emergence of new alleles (or genes) and their combinations as a result of mutations. As a result of mutation, the transition of a gene from one allelic state to another (A → a) or a change in the gene in general (A → C) is possible. The mutational process, due to the randomness of mutations, does not have directionality and, without the participation of other evolutionary factors, cannot direct the change in the natural population. It only supplies the elementary evolutionary material for natural selection. Recessive mutations in a heterozygous state constitute a hidden reserve of variability that can be used by natural selection when conditions of existence change.
Combinative variability arises as a result of the formation in descendants of new combinations of already existing genes inherited from their parents. The sources of combinative variability are the crossing of chromosomes (recombination), the random divergence of homologous chromosomes in meiosis, and the random combination of gametes during fertilization.

Population waves and gene drift.

Population waves (life waves) - periodic and non-periodic fluctuations in the population size both upward and downward. The reasons for population waves can be periodic changes in environmental factors of the environment (seasonal fluctuations in temperature, humidity, etc.), non-periodic changes (natural disasters), colonization of new territories by species (accompanied by a sharp outbreak of numbers).
Population waves act as an evolutionary factor in small populations where gene drift is possible. Gene drift - random undirected change in the frequencies of alleles and genotypes in populations. In small populations, the action of random processes leads to noticeable consequences. If the population is small in number, then as a result of random events, some individuals, regardless of their genetic constitution, may or may not leave offspring, as a result of which the frequencies of some alleles may change dramatically in one or several generations. So, with a sharp decline in the population size (for example, due to seasonal fluctuations, reduced food resources, fire, etc.), rare genotypes may be among the few surviving individuals. If in the future the number is restored at the expense of these individuals, then this will lead to a random change in the frequencies of alleles in the gene pool of the population. Thus, population waves are the supplier of evolutionary material.
Insulation due to the emergence of a variety of factors that impede free crossing. The exchange of genetic information between the formed populations stops, as a result of which the initial differences in the gene pools of these populations increase and become fixed. Isolated populations can undergo various evolutionary changes, gradually transform into different species.
Distinguish between spatial and biological isolation. Spatial (geographic) isolation associated with geographical obstacles (water barriers, mountains, deserts, etc.), and for sedentary populations, and simply with large distances. Biological isolation due to the impossibility of mating and fertilization (due to a change in the timing of reproduction, structure or other factors that prevent crossing), the death of zygotes (due to biochemical differences in gametes), sterility of the offspring (as a result of a violation of chromosome conjugation during gametogenesis).
The evolutionary significance of isolation is that it reinforces and enhances genetic differences between populations.
Natural selection. Changes in the frequencies of genes and genotypes caused by the evolutionary factors discussed above are random, undirected. Natural selection is the driving force behind evolution.

Natural selection - a process as a result of which predominantly individuals with useful properties for the population survive and leave behind their offspring.

Selection operates in populations; its objects are the phenotypes of individual individuals. However, selection for phenotypes is selection of genotypes, since not traits, but genes are transmitted to offspring. As a result, there is an increase in the relative number of individuals in the population with a certain property or quality. Thus, natural selection is a process of differential (selective) reproduction of genotypes.
Selection affects not only properties that increase the likelihood of leaving offspring, but also traits that are not directly related to reproduction. In some cases, selection can be aimed at creating mutual adaptations of species to each other (plant flowers and insects visiting them). Traits can also be created that are harmful to an individual individual, but ensure the survival of the species as a whole (a stung bee dies, but, attacking the enemy, it keeps the family). In general, selection plays a creative role in nature, since from undirected hereditary changes are fixed those that can lead to the formation of new groups of individuals, more perfect in the given conditions of existence.
There are three main forms of natural selection: stabilizing, driving, and disruptive (disruptive) (Table).

Forms of natural selection

The form	Characteristic	Examples of
Stabilizing	Aimed at preserving mutations leading to less variability in the average value of the trait. It acts under relatively constant environmental conditions, that is, as long as the conditions that led to the formation of one or another sign or property persist.	Preservation of the size and shape of the flower in insect pollinated plants, since the flowers must correspond to the size of the body of the pollinating insect. Preservation of relict species.
Moving	Aimed at preserving mutations that change the average value of the trait. Occurs when environmental conditions change. Individuals of the population have some differences in genotype and phenotype, and with a prolonged change in the external environment, a part of the individuals of the species with some deviations from the average norm can gain an advantage in life and reproduction. The variation curve shifts in the direction of adaptation to new conditions of existence.	The emergence in insects and rodents of resistance to pesticides, in microorganisms - to antibiotics. Darkening of the color of the birch moth (butterflies) in the developed industrial regions of England (industrial melanism). In these areas, the bark of trees becomes dark due to the disappearance of lichens sensitive to atmospheric pollution, and dark butterflies are less visible on tree trunks.
Disruptive (disruptive)	Aimed at preserving mutations leading to the greatest deviation from the average value of the trait. Bursting selection is manifested when environmental conditions change in such a way that individuals with extreme deviations from the average gain take advantage. As a result of disruptive selection, population polymorphism is formed, that is, the presence of several groups that differ in some way.	With frequent strong winds, insects with well-developed wings or with rudimentary ones remain on the oceanic islands.

A brief history of the evolution of the organic world

The age of the Earth is about 4.6 billion years. Life on Earth originated in the ocean over 3.5 billion years ago.
Short story development of the organic world is presented in the table. The phylogenesis of the main groups of organisms is shown in the figure.
The history of the development of life on Earth is studied on the basis of the fossil remains of organisms or traces of their vital activity. They are found in rocks of different ages.
The geochronological scale of the Earth's history is divided into eras and periods.

Geochronological scale and history of the development of living organisms

Era, age (in million years)	Period, duration (in million years)	Animal world	Plant world	The most important aromorphoses
Cenozoic, 62–70	Anthropogen, 1.5	The modern animal world. Evolution and human domination	Modern flora	Intensive development of the cerebral cortex; upright posture
	Neogene, 23.0 Paleogene, 41 ± 2	Mammals, birds, insects dominate. The first primates (lemurs, tarsiers) appear, later parapithecus and dryopithecus. Many groups of reptiles, cephalopods are disappearing	Flowering plants, especially herbaceous plants, are widespread; the flora of gymnosperms is decreasing
Mesozoic, 240	Chalk, 70	Bony fishes, first birds, small mammals predominate; placental mammals and modern birds appear and spread; giant reptiles are dying out	Angiosperms appear and begin to dominate; ferns and gymnosperms are decreasing	The emergence of a flower and a fruit. The appearance of the uterus
	Yura, 60	Giant reptiles, bony fish, insects, and cephalopods dominate; Archeopteryx appears; ancient cartilaginous fish are dying out	Modern gymnosperms dominate; ancient gymnosperms are dying out
	Trias, 35 ± 5	Amphibians, cephalopods, herbivores and carnivorous reptiles predominate; bony fishes, oviparous and marsupial mammals appear	Ancient gymnosperms predominate; modern gymnosperms appear; seed ferns are dying out	The appearance of a four-chambered heart; complete separation of arterial and venous blood flow; the appearance of warm-bloodedness; the appearance of mammary glands
Paleozoic, 570
	Perm, 50 ± 10	Marine invertebrates and sharks dominate; reptiles and insects develop rapidly; animal-toothed and herbivorous reptiles appear; stegocephalus and trilobites are dying out	Rich flora of seed and herbaceous ferns; ancient gymnosperms appear; treelike horsetails, lyes and ferns are dying out	Pollen tube and seed formation
	Carbon, 65 ± 10	Dominated by amphibians, molluscs, sharks, lungfish; winged forms of insects, spiders, scorpions appear and rapidly develop; the first reptiles appear; trilobites and stegocephals are markedly reduced	Abundance of arboreal ferns, forming "coal forests"; seed ferns appear; psilophytes disappear	The appearance of internal fertilization; the appearance of dense egg shells; keratinization of the skin
	Devon, 55	Shellfish, molluscs, trilobites, corals predominate; cross-finned, lung-finned and ray-finned fishes, stegocephaly appear	Rich flora of psilophytes; mosses, ferns, mushrooms appear	Dismemberment of the plant body into organs; conversion of fins to ground limbs; the appearance of respiratory organs
	Silurian, 35	Rich fauna of trilobites, molluscs, crustaceans, corals; shell fishes appear, the first terrestrial invertebrates (millipedes, scorpions, wingless insects)	Abundance of algae; plants come out onto dry land - psilophytes appear	Differentiation of the plant body into tissue; dividing the body of animals into sections; formation of jaws and girdles of limbs in vertebrates
Ordovician, 55 ± 10 Cambrian, 80 ± 20	Sponges, coelenterates, worms, echinoderms, trilobites predominate; jawless vertebrates (corymbs), molluscs appear	The prosperity of all departments of algae
Proterozoic, 2600		Protozoa are widespread; all types of invertebrates, echinoderms appear; primary chordates appear - subtype Cranial	Blue-green and green algae and bacteria are widespread; red algae appear	The emergence of bilateral symmetry
Archeyskaya, 3500		The emergence of life: prokaryotes (bacteria, blue-green algae), eukaryotes (protozoa), primitive multicellular		The emergence of photosynthesis; the appearance of aerobic respiration; the appearance of eukaryotic cells; the appearance of the sexual process; the emergence of multicellularity

View, its criteria. A population is a structural unit of a species and an elementary unit of evolution. Microevolution. Formation of new species. Speciation methods. Preservation of species diversity as the basis for the sustainability of the biosphere

View, its criteria

The founder of modern taxonomy, C. Linnaeus, considered the species as a group of organisms similar in morphological characteristics, which freely interbreed with each other. As biology has advanced, evidence has emerged that the differences between species are much deeper, and affect the chemical composition and concentration of substances in tissues, direction and speed. chemical reactions, the nature and intensity of vital processes, the number and shape of chromosomes, that is, the species is the smallest group of organisms reflecting their close relationship. In addition, species do not exist forever - they arise, develop, give rise to new species and disappear.

View is a set of individuals, similar in structure and characteristics of vital processes, having a common origin, freely interbreeding with each other in nature and giving fertile offspring.

All individuals of the same species have the same karyotype and occupy a certain geographical area in nature - area.

Signs of similarity between individuals of the same species are called criteria of the form... Since none of the criteria is absolute, a set of criteria must be used to correctly determine the species.

The main species criteria are morphological, physiological, biochemical, ecological, geographic, ethological (behavioral) and genetic.

1. Morphological - a set of external and internal signs of organisms of the same species. While some species have unique traits, it is often very difficult to distinguish closely related species using morphological traits alone. So, recently, a number of sibling species have been discovered that live on the same territory, for example, house and barrow mice, therefore, it is unacceptable to use exclusively the morphological criterion to determine the species.
2. Physiological - the similarity of the processes of vital activity in organisms, first of all, of reproduction. It is also not universal, since some species interbreed in nature and give fertile offspring.
3. Biochemical - the similarity of the chemical composition and the course of metabolic processes. Despite the fact that these indicators can vary significantly in different individuals of the same species, much attention is currently paid to them, since the features of the structure and composition of biopolymers help to identify species even at the molecular level and establish the degree of their relationship.
4. Ecological - the difference in species according to their belonging to certain ecosystems and ecological niches that they occupy. However, many unrelated species occupy similar ecological niches, so this criterion can be used to distinguish a species only in conjunction with other characters.
5. Geographical - the existence of a population of each species in a certain part of the biosphere - an area that differs from the areas of all other species. Due to the fact that for many species the boundaries of ranges coincide, and there are also a number of cosmopolitan species, the range of which covers vast areas, the geographical criterion also cannot serve as a marker "specific" feature.
6. Genetic - the constancy of the characteristics of the chromosomal set - the karyotype - and the nucleotide composition of DNA in individuals of the same species. Due to the fact that non-homologous chromosomes cannot conjugate during meiosis, the offspring from the crossing of individuals of different species with an unequal set of chromosomes either do not appear at all or are not fertile. This creates reproductive isolation of the species, maintains its integrity and ensures the reality of existence in nature. This rule can be violated in the case of crossing of closely related species with the same karyotype or the occurrence of different mutations, but the exception only confirms the general rule, and the species should be considered as stable genetic systems. The genetic criterion is the main one in the system of species criteria, but it is also not exhaustive.

For all the complexity of the system of criteria, a species cannot be represented as a group of organisms absolutely identical in all parameters, that is, clones. On the contrary, many species are characterized by a significant variety of even external signs, as, for example, for some populations of ladybirds, the predominance of red in color is characteristic, and for others - black.

Population is a structural unit of a species and an elementary unit of evolution

It is difficult to imagine that in reality individuals of the same species were evenly distributed over the earth's surface within the range, since, for example, the lake frog lives mainly in rather rare stagnant fresh water bodies, and it is unlikely that it can be found in fields and forests. Species in nature most often fall into separate groups, depending on the conditions suitable for the habitat - the population.

Population - a group of individuals of the same species, occupying part of its range, freely interbreeding with each other and relatively isolated from other populations of individuals of the same species for a more or less long time.

Populations can be divided not only spatially, they can even live in the same territory, but have differences in food preferences, breeding dates, etc.

Thus, a species is a set of populations of individuals with a number of common morphological, physiological, biochemical traits and types of relationships with the environment, inhabiting a certain area, and also capable of interbreeding with each other to form fertile offspring, but almost or not at all interbreeding with other groups. individuals of the same species.

Within species with large ranges, covering territories with different living conditions, sometimes they also differ subspecies - large populations or groups of neighboring populations with persistent morphological differences from other populations.

Populations are not scattered on the earth's surface randomly, they are tied to specific areas. The combination of all factors of inanimate nature necessary for the residence of individuals of this species is called habitat... However, these factors alone may not be enough to occupy this site by a population, since it must still be involved in close interaction with populations of other species, that is, take a certain place in the community of living organisms - ecological niche... So, the Australian marsupial koala bear, all other things being equal, cannot exist without its main food source - eucalyptus.

Populations of various species that form an inseparable unity in the same habitats usually provide a more or less closed cycle of substances and are elementary ecological systems (ecosystems) - biogeocenoses.

For all their exactingness to environmental conditions, populations of one species are heterogeneous in terms of area occupied, number, density and spatial distribution of individuals, often forming smaller groups (families, flocks, herds, etc.), gender, age, gene pool, etc. , therefore, distinguish between their size, age, sex, spatial, genetic, ethological and other structures, as well as dynamics.

Important characteristics of the population are gene pool - a set of genes characteristic of individuals of a given population or species, as well as the frequencies of certain alleles and genotypes. Different populations of the same species initially have a different gene pool, since new territories are being developed by individuals with random, rather than specially selected genes. Under the influence of internal and external factors, the gene pool undergoes even more significant changes: it is enriched due to the occurrence of mutations and a new combination of traits and is depleted as a result of the loss of individual alleles during the death or migration of a certain number of individuals.

New traits and their combinations can be useful, neutral or harmful, therefore, only individuals adapted to the given environmental conditions survive and reproduce in the population. However, at two different points on the earth's surface, environmental conditions are never completely identical, therefore, the direction of changes, even in two neighboring populations, can be completely opposite, or they will proceed at different rates. The result of changes in the gene pool is the divergence of populations by morphological, physiological, biochemical and other characteristics. If the populations are also isolated from each other, then they can give rise to new species.

So, the occurrence of any obstacles in the crossing of individuals of different populations of the same species, for example, due to the formation of mountain ranges, changes in river channels, differences in the timing of reproduction, etc., leads to the fact that the populations gradually acquire more and more differences and, in eventually become different species. For some time, at the boundaries of these populations, individuals are crossed and hybrids appear, but over time, these contacts disappear, that is, populations from open genetic systems become closed.

Despite the fact that the action of environmental factors is primarily exposed to individual individuals, the change in the genetic composition of a single organism is insignificant and will manifest itself, at best, only in its descendants. Subspecies, species and larger taxa are also not suitable for the role of elementary units of evolution, since they do not differ in morphological, physiological, biochemical, ecological, geographical and genetic unity, while populations, as the smallest structural units of a species, accumulating a variety of random changes, the worst of which will be eliminated, meet this condition and are the elementary units of evolution.

Microevolution

A change in the genetic structure of populations does not always lead to the formation of a new species, but can only improve the adaptation of the population to specific environmental conditions, however, species are not eternal and unchanged - they are capable of developing. This process of irreversible historical change of living things is called evolution. Primary evolutionary transformations occur within the species at the population level. They are based, first of all, on the mutational process and natural selection, leading to a change in the gene pool of populations and the species as a whole, or even to the formation of new species. The combination of these elementary evolutionary events is called microevolution.

Populations are characterized by enormous genetic diversity, which often does not manifest phenotypically. Genetic diversity arises from spontaneous mutagenesis that occurs continuously. Most mutations are unfavorable for the organism and reduce the viability of the population as a whole, but if they are recessive, they can persist in a heterozygote for a long time. Some mutations that do not have an adaptive value in the given conditions of existence are able to acquire such a value in the future or during the development of new ecological niches, thus creating a reserve of hereditary variability.

Fluctuations in the number of individuals in populations, migration and catastrophes, as well as the isolation of populations and species, have a significant impact on microevolutionary processes.

A new species is an intermediate result of evolution, but in no way its result, since this does not interrupt microevolution - it continues further. The emerging new species, in the case of a successful combination of traits, populate new habitats, and, in turn, give rise to new species. Such groups of closely related species are combined into genera, families, etc. Evolutionary processes occurring in supraspecific groups are already called macroevolution. Unlike macroevolution, microevolution takes place in a much shorter time frame, while the first one takes tens and hundreds of thousands and millions of years, as, for example, human evolution.

As a result of microevolution, the whole variety of species of living organisms is formed that have ever existed and are now living on Earth.

However, evolution is irreversible, and species that have already disappeared never reappear. The emerging species consolidate everything achieved in the process of evolution, but this does not guarantee that new species will not appear in the future, which will have better adaptations to environmental conditions.

Formation of new species

In a broad sense, the formation of new species is understood not only as the splitting off of a new species from the main stem or the decay of the parent species into several daughter species, but also the general development of the species as an integral system, leading to significant changes in its morphostructural organization. However, more often all the same speciation considered as a process of formation of new species through the branching of the “family tree” of the species.

A fundamental solution to the problem of speciation was proposed by Ch. Darwin. According to his theory, the dispersal of individuals of one species leads to the formation of populations, which, due to differences in environmental conditions, are forced to adapt to them. This, in turn, entails an exacerbation of the intraspecific struggle for existence, directed by natural selection. At present, it is believed that the struggle for existence is not at all an obligatory factor in speciation; on the contrary, the selection pressure in a number of populations may decrease. The difference in the conditions of existence contributes to the emergence of unequal adaptive changes in the populations of the species, the consequence of which is the divergence of the characteristics and properties of the populations - divergence.

However, the accumulation of differences, even at the genetic level, is by no means sufficient for the emergence of a new species. As long as populations differing in any way not only contact, but are also capable of interbreeding with the formation of fertile offspring, they belong to the same species. Only the impossibility of the flow of genes from one group of individuals to another, even in the event of the destruction of the barriers separating them, that is, crossing, means the completion of the most complex evolutionary process of the formation of a new species.

Speciation is a continuation of microevolutionary processes. There is a point of view that speciation cannot be reduced to microevolution, it represents a qualitative stage of evolution and is carried out through other mechanisms.

Speciation methods

There are two main ways of speciation: allopatric and sympatric.

Allopatric, or geographic speciation is a consequence of the spatial division of populations by physical barriers (mountain ranges, seas and rivers) due to their emergence or resettlement in new habitats (geographic isolation). Since in this case the gene pool of the separated population differs significantly from the maternal one, and the conditions in its habitat will not coincide with the initial ones, over time this will lead to divergence and the formation of a new species. A striking example of geographic speciation is the variety of finch species discovered by Charles Darwin while traveling on the Beagle ship on the Galapagos Islands off the coast of Ecuador. Apparently, individual individuals of the only finch inhabiting the South American continent somehow got to the islands, and, due to the difference in conditions (primarily food availability) and geographical isolation, they gradually evolved, forming a group of related species.

At the heart of sympatric, or biological speciation some form of reproductive isolation lies, with new species emerging within the range of the original species. A prerequisite for sympatric speciation is the rapid isolation of the formed forms. This is a faster process than allopatric speciation, and the new forms are similar to their original ancestors.

Sympatric speciation can be caused by rapid changes in the chromosome set (polyploidization) or chromosomal rearrangements. Sometimes new species arise from the hybridization of two original species, such as the domestic plum, which is a hybrid of blackthorn and cherry plum. In some cases, sympatric speciation is associated with the separation of ecological niches in populations of the same species within a single area or seasonal isolation - the discrepancy between the timing of reproduction in plants (different species of pine in California dust in February and April) and the timing of reproduction in animals.

Of all the variety of newly emerging species, only a few, the most adapted, can exist for a long time and give rise to new species. The reasons for the death of most species are still unknown, most likely this is due to abrupt changes in climate, geological processes and their displacement by more adapted organisms. At present, one of the reasons for the death of a significant number of species is a man who exterminates the largest animals and the most beautiful plants, and if in the 17th century this process had just begun with the extermination of the last round, then in the 21st century more than 10 species disappear every hour.

Preservation of species diversity as the basis for the sustainability of the biosphere

Despite the fact that, according to various estimates, there are 5-10 million species of organisms that have not yet been described, we will never know about the existence of most of them, since about 50 species disappear from the face of the Earth every hour. The disappearance of living organisms at the present time is not at all necessarily associated with their physical extermination, more often this is due to the destruction of their natural habitats as a result of human activity. The death of a single species is unlikely to lead to fatal consequences for the biosphere, but it has long been established that the extinction of one plant species entails the death of 10–12 animal species, and this already poses a threat both to the existence of individual biogeocenoses and to the global ecosystem in the whole.

The sad facts accumulated over the previous decades forced the International Union for the Conservation of Nature and Natural Resources (IUCN) to begin collecting information on rare and endangered plant and animal species in 1949. In 1966, the IUCN published the first Red Book of Facts.

Red Book is an official document containing regularly updated data on the status and distribution of rare and endangered species of plants, animals and fungi.

This document adopted a five-stage scale of the status of a protected species, and the first stage of protection includes species that cannot be saved without special measures, and the fifth includes restored species, the state of which, thanks to the measures taken, does not cause concern, but they are not yet subject to industrial use. The development of such a scale makes it possible to direct priority efforts in the field of protection precisely to the most rare species, such as the Amur tigers.

In addition to the international version of the Red Book, there are also national and regional versions. In the USSR, the Red Book was established in 1974, and in Russian Federation the procedure for its maintenance is regulated by the Federal Laws "On Environmental Protection", "On the Animal World" and the Decree of the Government of the Russian Federation "On the Red Book of the Russian Federation". Today, 610 plant species, 247 animal species, 42 lichen species and 24 mushroom species are listed in the Red Book of the Russian Federation. The populations of some of them, at one time endangered (European beaver, bison), have already been quite successfully restored.

The following species of animals have been taken under protection in Russia: Russian desman, tarbagan (Mongolian marmot), polar bear, Caucasian European mink, sea otter, manul, Amur tiger, leopard, snow leopard, sea lion, walrus, seals, dolphins, whales, Przewalski's horse, kulan, pink pelican, common flamingo, black stork, small swan, steppe eagle, golden eagle, black crane, Siberian crane, bustard, eagle owl, white gull, Mediterranean turtle, Japanese snake, gurza, reed toad, Caspian lamprey, all types of sturgeon fish, lake salmon, stag beetle, unusual bumblebee, common apollo, mantis shrimp, common pearl mussel, etc.

The plants of the Red Data Book of the Russian Federation include 7 types of snowdrops, some types of wormwood, real ginseng, 7 types of bells, toothed oak, bluebill, 11 species of iridescent whales, Russian hazel grouse, Schrenck's tulip, nut-bearing lotus, Venus real slipper, fine-leaved peony, feather grass, Julia's primrose, lumbago (dream-grass) meadow, belladonna belladonna, pitsunda pine, yew berry, Chinese shrimp, lacustrine mushroom, soft sphagnum, curly phyllophora, hara filiform, etc.

Rare mushrooms are represented by summer truffle, or Russian black truffle, varnished tinder fungus, etc.

The protection of rare species in most cases is associated with the prohibition of their destruction, their preservation in an artificially created habitat (zoos), the protection of their habitats and the creation of low-temperature genetic banks.

Most effective measure protection of rare species is the preservation of their habitats, which is achieved by organizing a network of specially protected protected areas that, in accordance with the Federal Law "On Specially Protected Natural Areas" (1995), have international, federal, regional or local significance. These include state nature reserves, national parks, natural parks, state nature reserves, natural monuments, dendrological parks, botanical gardens, etc.

State nature reserve - this is a specially protected natural complex (land, water bodies, mineral resources, flora and fauna) completely withdrawn from economic use, which has environmental, scientific, ecological and educational significance as an example of the natural environment, typical or rare landscapes, places of conservation of the genetic fund of plant and the animal world.

Reserves, which are part of the international system of biosphere reserves that carry out global environmental monitoring, have the status state natural biosphere reserves... The reserve is an nature conservation, research and environmental education institution aimed at preserving and studying the natural course of natural processes and phenomena, the genetic fund of flora and fauna, individual species and communities of plants and animals, typical and unique ecological systems.

Currently, there are about 100 state natural reserves in Russia, 19 of which have the status of biosphere reserves, including Baikalsky, Barguzinsky, Caucasian, "Kedrovaya Pad", Kronotsky, Prioksko-Terrasny, etc.

Unlike nature reserves, territories (water areas) national parks include natural complexes and objects of special ecological, historical and aesthetic value, and are intended for use in nature conservation, educational, scientific and cultural purposes and for regulated tourism. This status has 39 specially protected natural areas, including the Zabaikalsky and Sochi national parks, as well as the national parks "Curonian Spit", "Russian North", "Shushensky Bor", etc.

Natural parks are nature conservation recreational institutions under the jurisdiction of the constituent entities of the Russian Federation, the territories (water areas) of which include natural complexes and objects of significant ecological and aesthetic value, and are intended for use in nature conservation, educational and recreational purposes.

State nature reserves are territories (water areas) that are of particular importance for the preservation or restoration of natural complexes or their components and the maintenance of the ecological balance.

Development of evolutionary ideas. The importance of the evolutionary theory of Charles Darwin. The relationship of the driving forces of evolution. Forms of natural selection, types of struggle for existence. Synthetic theory of evolution. Elementary factors of evolution. Research by S. S. Chetverikov. The role of evolutionary theory in the formation of the modern natural science picture of the world

Development of evolutionary ideas

All theories of the origin and development of the organic world can be reduced to three main directions: creationism, transformationism and evolutionism. Creationism is the concept of species constancy, which considers the diversity of the organic world as a result of its creation by God. This trend was formed as a result of the establishment of the dominance of the Christian Church in Europe, based on biblical texts. Prominent representatives of creationism were C. Linnaeus and J. Cuvier.

"Prince of botanists" K. Linnaeus, who discovered and described hundreds of new plant species, and created their first harmonious system, nevertheless, proved that the total number of species of organisms has been constant since the creation of the Earth, that is, they not only do not appear again, but and do not disappear. Only towards the end of his life did he come to the conclusion that the work of the hands of God is childbirth, while species can develop as a result of adaptation to local conditions.

The contribution of the outstanding French zoologist J. Cuvier (1769-1832) to biology was based on numerous data from paleontology, comparative anatomy and physiology correlation theory - the relationship of parts of the body. Thanks to this, it became possible to reconstruct the external appearance of the animal in separate parts. However, in the process of paleontological research, J. Cuvier could not help but pay attention to both the apparent abundance of fossil forms, and the sharp changes in animal groups during geological history. These data served as a starting point for the formulation catastrophe theory, according to which all or almost all organisms on Earth have repeatedly died as a result of periodic natural disasters, and then the planet was re-populated by species that survived the catastrophe. The followers of J. Cuvier counted up to 27 such catastrophes in the history of the Earth. However, considerations about evolution seemed to J. Cuvier to be divorced from reality.

The contradictions in the initial positions of creationism, which became more and more obvious as the accumulation of scientific facts, served as a starting point for the formation of another system of views - transformism, recognizing the real existence of species and their historical development. Representatives of this trend - J. Buffon, I. Goethe, E. Darwin and E. Geoffroy Saint-Hilaire, being unable to reveal the true causes of evolution, reduced them to adaptation to environmental conditions and inheritance of acquired characters. The roots of transformism can be found in the works of ancient Greek and medieval philosophers who recognized the historical changes in the organic world. Thus, Aristotle expressed the idea of \u200b\u200bthe unity of nature and the gradual transition from bodies of inanimate nature to plants, and from them to animals - the "ladder of nature." He considered the main reason for the changes in living organisms to be their inner striving for perfection.

The French naturalist J. Buffon (1707-1788), whose main work of life was the 36-volume "Natural History", contrary to the ideas of creationists, expanded the framework of the history of the Earth to 80-90 thousand years. At the same time, he noted the unity of the flora and fauna, as well as the possibility of changing related organisms under the influence of environmental factors as a result of domestication and hybridization.

The English physician, philosopher and poet E. Darwin (1731-1802), Charles Darwin's grandfather, believed that the history of the organic world goes back millions of years, and the diversity of the animal world is the result of mixing several "natural" groups, the influence of the external environment, exercise and non-exercise organs, and other factors.

The unity of the plan of the structure of groups of animals was considered one of the main proofs of the development of the living world by E. Geoffroy Saint-Hilaire (1772–1844). However, unlike his predecessors, he was inclined to believe that the change in species is due to the influence of environmental factors not on adults, but on the embryos.

Despite the fact that in the discussion that flared up in 1831 between J. Cuvier and E. Geoffroy Saint-Hilaire in the form of a series of reports at the Academy of Sciences, the clear preponderance remained on the side of the former, it was transformism that became the forerunner of evolutionism. Evolutionism (theory of evolution, evolutionary doctrine) is a belief system that recognizes the development of nature according to certain laws. It is the theoretical pinnacle of biology, which allows us to explain the diversity and complexity of living systems we observe. However, due to the fact that the evolutionary doctrine describes phenomena that are difficult to observe, it encounters significant difficulties. Sometimes the theory of evolution is called "Darwinism" and is identified with the teachings of Charles Darwin, which is fundamentally incorrect, since, although the theory of Charles Darwin made an invaluable contribution to the development of not only evolutionary doctrine, but biology in general (as well as many other sciences ), the foundations of evolutionary theory were laid by other scientists, it continues to develop to this day, and "Darwinism" in many aspects has only historical significance.

The creator of the first evolutionary theory - Lamarckism - was the French naturalist JB Lamarck (1744–1829). He considered the driving force of evolution to be the internal striving of organisms for perfection ( law of gradation), however, adaptation to environmental conditions forces them to deviate from this main line. At the same time, the organs that are intensively used by the animal in the process of life, develop, and unnecessary for him, on the contrary, weaken and may even disappear ( the law of exercise and non-exercise of organs). The signs acquired in the process of life are fixed and passed on to descendants. So, the presence of membranes between the toes of waterfowl, he explained by the attempts of their ancestors to move in the aquatic environment, and the long neck of giraffes, according to Lamarck, is a consequence of the fact that their ancestors tried to get leaves from the tops of trees.

The disadvantages of Lamarckism were the theoretical nature of many constructions, as well as the admission of the Creator's intervention in evolution. In the process of development of biology, it became clear that individual changes acquired by organisms in the process of life, for the most part, fit within the limits of phenotypic variability, and their transmission is practically impossible. For example, the German zoologist and theorist of evolutionary doctrine A. Weismann (1834–1914) cut off the tails of mice for many generations and always got only tailed rodents in the offspring. J. B. Lamarck's theory was not accepted by his contemporaries, but at the turn of the century it formed the basis of the so-called neo-Lamarckism.

The importance of the evolutionary theory of Charles Darwin

The prerequisites for the creation of the most famous evolutionary theory of Charles Darwin, or Darwinism, were the publication in 1778 of the work of the English economist T. Malthus "A Treatise on Population", the work of the geologist Charles Lyell, the formulation of the cell theory, the success of selection in England and Ch. Darwin (1809-1882), made during the years of study at Cambridge, on the expedition as a naturalist on the ship "Beagle" and after its completion.

Thus, T. Malthus argued that the population of the Earth is increasing in geometric progression, which significantly exceeds the planet's capabilities to provide it with food and leads to the death of some of the offspring. The parallels drawn by Charles Darwin and his co-author A. Wallace (1823–1913) indicated that in nature, individuals reproduce at a very high rate, but the population size remains relatively constant. Studies by the English geologist C. Lyell made it possible to establish that the surface of the Earth was far from always the same as it is now, and its changes were caused by the effects of water, wind, volcanic eruptions and the activity of living organisms. Charles Darwin himself, even in his student years, was struck by the extreme degree of variability of beetles, and during the trip - by the similarity of the flora and fauna of continental South America and the nearby Galapagos Islands, and at the same time a significant diversity of species, for example, finches and turtles. In addition, on the expedition, he could observe the skeletons of giant extinct mammals, similar to modern armadillos and sloths, which significantly shaken his faith in the creation of species.

The main provisions of the theory of evolution were expressed by Charles Darwin in 1859 at a meeting of the Royal Society of London, and later developed in the books "The Origin of Species by Natural Selection, or the Preservation of Favored Breeds in the Struggle for Life" (1859), "Change of Domestic Animals and Cultivated Plants "(1868)," The Origin of Man and Sexual Selection "(1871)," Expression of Emotions in Man and Animals "(1872), etc.

Essence developed by Charles Darwin evolutionary concepts can be reduced to a number of consequential provisions that have appropriate proof of:

1. Individuals that make up any population produce many more offspring than is necessary to maintain the population size.
2. Due to the fact that vital resources for any kind of living organisms are limited, between them inevitably arises struggle for existence... C. Darwin distinguished between intraspecific and interspecific struggle, as well as the struggle with environmental factors. At the same time, he pointed out that we are talking not only about the struggle of a particular individual for existence, but also for the abandonment of offspring.
3. The consequence of the struggle for existence is natural selection - the predominant survival and reproduction of organisms that happen to be the most adapted to the given conditions of existence. Natural selection is in many ways analogous to artificial selection, which man has been using since ancient times to develop new varieties of plants and breeds of domestic animals. By selecting individuals that have some desirable trait, a person retains these traits by artificial breeding through selective breeding or pollination. A special form of natural selection is sexual selection for traits that usually do not have a direct adaptive meaning (long feathers, huge horns, etc.), but contribute to the achievement of reproductive success, since they make an individual more attractive to the opposite sex or more formidable to rivals of the same sex.
4. The material for evolution is the differences in organisms that arise as a result of their variability. C. Darwin distinguished between indefinite and definite variability. Certain (group) variability manifests itself in all individuals of the species in the same way under the influence of a certain factor and disappears in the offspring when the effect of this factor stops. Indefinite (individual) variability is the changes that occur in each individual individual, regardless of fluctuations in the values \u200b\u200bof environmental factors, and are transmitted to descendants. Such variability has no adaptive (adaptive) character. Subsequently, it turned out that a certain variability is non-hereditary, and an indefinite one is hereditary.
5. Natural selection ultimately leads to a divergence in the characteristics of individual isolated species - divergence, and, ultimately - to the formation of new species.

Charles Darwin's theory of evolution not only postulated the process of the emergence and development of species, but also revealed the very mechanism of evolution, which is based on the principle of natural selection. Darwinism also denied that evolution was programmed and postulated its continuous nature.

At the same time, Charles Darwin's evolutionary theory could not answer a number of questions, for example, about the nature of genetic material and its properties, the essence of hereditary and non-hereditary variability, and their evolutionary role. This led to the crisis of Darwinism and the emergence of new theories: neo-Lamarckism, saltationism, the concept of nomogenesis, etc. Neo-Lamarckism is based on the theory of J. B. Lamarck about the inheritance of acquired characters. Saltationism is a system of views on the process of evolution as abrupt changes leading to the rapid emergence of new species, genera and larger systematic groups. Concept nomogenesis postulates the programmed direction of evolution and the development of various features based on internal laws. Only the synthesis of Darwinism and genetics in the 1920s and 1930s was able to overcome the contradictions that inevitably arose when explaining a number of facts.

The interconnection of the driving forces of evolution

Evolution cannot be associated with the action of any one factor, since mutations in themselves are random and undirected changes, and cannot provide adaptation of individuals to environmental factors, while natural selection already sorts these changes. Likewise, selection itself cannot be the only factor in evolution, since selection requires the appropriate material supplied by mutations.

It can be noted, however, that mutation and gene flow create variability, while natural selection and gene drift sort this variability. This means that the factors that create variability start the process of microevolution, while those sorting variability continue it, leading to the establishment of new frequencies of variants. Thus, evolutionary change within a population can be viewed as a result of the action of opposing forces that create and sort genotypic variability.

An example of the interaction between mutation and selection is hemophilia in humans. Hemophilia is a condition caused by decreased blood clotting. Previously, it led to death in the pre-reproductive period, since any damage to soft tissues could potentially lead to large blood loss. This disease is caused by a recessive mutation in the sex-linked H (Xh) gene. Women rarely get hemophilia, more often they are heterozygous carriers, but their sons can inherit this disease. Theoretically, within several generations, such men die before puberty and gradually this allele should disappear from the population, however, the incidence of this disease does not decrease due to repeated mutations in this locus, as happened in Queen Victoria, who transmitted the disease to three generations of the royal houses of Europe. The constant frequency of this disease indicates a balance between the mutational process and selection pressure.

Forms of natural selection, types of struggle for existence

Natural selection they call selective experience and the abandonment of offspring by the most adapted individuals and the death of the least adapted.

The essence of natural selection in the theory of evolution is the differentiated (non-random) preservation of certain genotypes in the population and their selective participation in the transfer of genes to the next generation. Moreover, it affects not a single trait (or gene), but the entire phenotype, which is formed as a result of the interaction of the genotype with environmental factors. Natural selection in different environmental conditions will be different. Currently, several forms of natural selection are distinguished: stabilizing, driving, and disruptive.

Stabilizing selection is aimed at consolidating a narrow reaction rate, which turned out to be most favorable under the given conditions of existence. It is typical for those cases when phenotypic traits are optimal for unchanging environmental conditions. A striking example of the effect of stabilizing selection is the maintenance of a relatively constant body temperature in warm-blooded animals. This form of selection was investigated in detail by the outstanding Russian zoologist I.I.Shmalgauzen.

Driving selection arises in response to changes in environmental conditions, as a result of which mutations that deviate from the average value of the trait persist, while the previously dominant form is subject to destruction, since it does not sufficiently meet the new conditions of existence. For example, in England, as a result of air pollution from industrial emissions, birch moth butterflies with dark colored wings, which were less noticeable to birds against the background of smoked birch trunks, widespread hitherto unseen in many places. Driving selection is not conducive to the complete elimination of the form against which it acts, because due to measures taken by the government and environmental organizations, the situation with air pollution has improved dramatically, and there is a return of the color of the butterfly wings to the original version.

Tearing, or disruptive selection favors the preservation of extreme variants of the trait and removes intermediate ones, as, for example, as a result of the use of pesticides, groups of insects resistant to it appear. By its mechanism, disruptive selection is the opposite of stabilizing selection. Due to this form of selection, several sharply differentiated phenotypes arise in the population. This phenomenon is called polymorphism... The emergence of reproductive isolation between sharply expressed forms can lead to speciation.

Sometimes also separately considered destabilizing selection, which retains mutations leading to a wide variety of any trait, for example, the color and structure of the shells of some mollusks living in the heterogeneous micro-conditions of the rocky strip of the sea surf. This form of selection was discovered by D.K.Belyaev in the study of the domestication of animals.

In nature, none of the forms of natural selection exists in a pure form, but on the contrary, there are various combinations of them, and as environmental conditions change, one or the other of them comes to the fore. So, upon completion of changes in the environment, the driving selection is replaced by the stabilizing one, which optimizes the group of individuals in the new conditions of existence.

Natural selection occurs at different levels, and therefore also distinguish between individual, group and sexual selection. Individual selection eliminates less adapted individuals from participation in reproduction, while group selection is aimed at preserving a trait that is useful not for an individual individual, but for the group as a whole. Under pressure group whole populations, species and larger groups of organisms can die out completely without leaving offspring. Unlike individual selection, group selection reduces the variety of forms in nature.

Sexual selection carried out inside one floor. It promotes the development of traits that ensure success in leaving the largest offspring. Thanks to this form of natural selection, sexual dimorphism has developed, which is expressed in the size and color of the peacock's tail, deer antlers, etc.

Natural selection is the result struggle for existence based on hereditary variability. The struggle for existence is understood as the entire set of relationships between individuals of their own and other species, as well as with abiotic environmental factors. This relationship determines the success or failure of a particular individual in survival and procreation. The reason for the struggle for existence is the appearance of an excess number of individuals in relation to the available resources. In addition to competition, these relationships should include mutual assistance, which increases the chances of individuals for survival.

Interaction with environmental factors can also lead to the death of the vast majority of individuals, for example, in insects, only a small part of which survive the winter.

Synthetic theory of evolution

The successes of genetics at the beginning of the twentieth century, for example, the discovery of mutations, suggested that hereditary changes in the phenotype of organisms occur suddenly, and do not form for a long time, as the evolutionary theory of Charles Darwin postulated. However, further research in the field of population genetics led to the formulation in the 20-50s of the twentieth century, a new system of evolutionary views - synthetic theory of evolution... A significant contribution to its creation was made by scientists from different countries: Soviet scientists S.S.Chetverikov, I.I.Shmalgauzen and A.N.Severtsov, English biochemist and geneticist D. Haldane, American geneticists S. Wright and F. Dobrzhansky, evolutionist D. Huxley, paleontologist D. Simpson and zoologist E. Mayr.

The main provisions of the synthetic theory of evolution:

1. The elementary material of evolution is hereditary variability (mutational and combinative) in individuals of the population.
2. The elementary unit of evolution is a population in which all evolutionary changes take place.
3. An elementary evolutionary phenomenon is a change in the genetic structure of a population.
4. Elementary factors of evolution - gene drift, waves of life, gene flow - are of an undirected, random nature.
5. The only directional factor in evolution is natural selection, which is creative. Natural selection can be stabilizing, propelling, and disruptive.
6. Evolution is divergent, that is, one taxon can give rise to several new taxa, while each species has only one ancestor (species, population).
7. Evolution is gradual and continuous. Speciation as a stage in the evolutionary process is a sequential replacement of one population by a succession of other temporary populations.
8. There are two types of evolutionary process: microevolution and macroevolution. Macroevolution does not have its own special mechanisms and is carried out only thanks to microevolutionary mechanisms.
9. Any systematic group can either thrive (biological progress) or die out (biological regression). Biological progress is achieved through changes in the structure of organisms: aromorphoses, idioadaptations, or general degeneration.
10. The main laws of evolution are its irreversible nature, the progressive complication of life forms and the development of the adaptation of species to the environment. At the same time, evolution has no ultimate goal, that is, the process is undirected.

Despite the fact that the evolutionary theory over the past decades has been enriched with data from related sciences - genetics, breeding, etc., it still does not take into account a number of aspects, for example, directed changes in hereditary material, therefore, in the future, it is possible to create a new concept of evolution that will replace the synthetic theory. ...

Elementary factors of evolution

According to the synthetic theory of evolution, an elementary evolutionary phenomenon consists in a change in the genetic composition of a population, and the events and processes that lead to a change in gene pools are called elementary factors of evolution... These include mutation, population waves, gene drift, isolation, and natural selection. In view of the exceptional importance of natural selection in evolution, it will be considered separately.

Mutation process which is as continuous as evolution itself, maintains the genetic heterogeneity of the population due to the emergence of more and more new variants of genes. Mutations arising under the influence of external and internal factors are classified as genetic, chromosomal and genomic.

Gene mutations occur with a frequency of 10 –4 –10 –7 per gamete, however, since the total number of genes in humans and most higher organisms can reach several tens of thousands, it is impossible to imagine that two organisms would be absolutely identical. Most of the mutations that arise are recessive, especially since the dominant mutations are immediately subjected to natural selection. Recessive mutations create the very reserve of hereditary variability, however, before they appear in the phenotype, they must be fixed in many individuals in a heterozygous state due to free crossing in the population.

Chromosomal mutations associated with the loss or transfer of a part of a chromosome (a whole chromosome) to another, are also quite common in different organisms, for example, the difference between some rat species lies in a single pair of chromosomes, which makes it difficult to cross them.

Genomic mutationsassociated with polyploidization, also lead to reproductive isolation of the newly arisen population due to disturbances in mitosis of the first division of the zygote. Nevertheless, in plants they are quite widespread and such plants can grow in the Arctic and in alpine meadows due to their greater resistance to environmental factors.

Combinative variability, which ensures the emergence of new variants of combining genes in the genotype, and, accordingly, increases the likelihood of the appearance of new phenotypes, also contributes to evolutionary processes, since only in humans the number of variants of chromosome combinations is 2 23, that is, the appearance of an organism similar to existing, it is almost impossible.

Population waves. The opposite result (depletion of the gene composition) is often caused by fluctuations in the number of organisms in natural populations, which in some species (insects, fish, etc.) can change tens and hundreds of times - population waves, or "Waves of life"... An increase or decrease in the number of individuals in populations can be as follows periodicand non-periodic... The former are seasonal or perennial, such as migrations in migratory birds, or breeding in daphnia, in which in spring and summer there are only females, and by autumn there are males necessary for sexual reproduction. Non-periodic fluctuations in numbers are often caused by a sharp increase in the amount of food in a favorable year, violation of habitat conditions, reproduction of pests or predators.

Since the restoration of the population size occurs due to a small number of individuals that do not have the entire set of alleles, the new and original populations will have a different genetic structure. The change in the frequency of genes in a population under the influence of random factors is called gene drift, or genetic-automatic processes... It also takes place during the development of new territories, because an extremely limited number of individuals of a given species fall on them, which can give rise to a new population. Therefore, the genotypes of these individuals ( founder effect). As a result of gene drift, new homozygous forms (for mutant alleles) are often cleaved out, which may be adaptively valuable and will be subsequently picked up by natural selection.

So, among the Indian population of the American continent and the Laplanders, there is a very high proportion of people with I (0) blood groups, while III and IV groups are extremely rare. Probably, in the first case, the founders of the population were persons who did not have the I B allele, or it was lost in the selection process.

Until a certain moment, alleles are exchanged between neighboring populations as a result of crossing between individuals of different populations - gene flow, which reduces the discrepancy between individual populations, but it stops with the onset of isolation. Essentially, gene flow is a delayed mutational process.

Insulation. Any changes in the genetic structure of the population must be fixed, which is due to isolation - the emergence of any barriers (geographic, ecological, behavioral, reproductive, etc.) that complicate and make it impossible to interbreed individuals of different populations. While isolation itself does not create new forms, it nevertheless preserves genetic differences between populations undergoing natural selection. There are two forms of isolation: geographic and biological.

Geographic isolation arises as a result of the division of the range by physical barriers (water obstacles for terrestrial organisms, land areas for aquatic species, alternating elevated areas and plains); this is facilitated by a sedentary or attached (in plants) lifestyle. Sometimes geographic isolation can be caused by the expansion of the range of a species with the subsequent extinction of its populations in the intermediate territories.

Biological isolation is a consequence of certain divergences of organisms within the same species, which somehow prevent free interbreeding. There are several types of biological isolation: ecological, seasonal, ethological, morphological and genetic. Environmental insulation achieved through the separation of ecological niches (for example, the preference for certain habitats or the nature of food, as in the spruce crossbill and pine crossbill). Seasonal (temporary) isolation is observed in the case of reproduction of individuals of the same species at different times (different herring herds). Ethological isolation depends on the characteristics of behavior (features of the courtship ritual, coloration, "singing" of females and males from different populations). When morphological isolation an obstacle to crossing is a discrepancy in the structure of reproductive organs or even body size (Pekingese and Great Dane). Genetic isolation has the greatest impact and manifests itself in the incompatibility of germ cells (death of the zygote after fertilization), sterility or reduced viability of hybrids. The reasons for this are the peculiarities of the number and shape of chromosomes, as a result of which it becomes impossible to complete cell division (mitosis and meiosis).

By disrupting free crossbreeding between populations, isolation thereby fixes in them those differences that have arisen at the genotypic level due to mutations and fluctuations in numbers. At the same time, each of the populations is exposed to natural selection separately from the other, and this ultimately leads to divergence.

The creative role of natural selection in evolution

Natural selection performs the function of a kind of "sieve" sorting genotypes according to the degree of fitness. However, Charles Darwin emphasized that selection is not only and not so much aimed at preserving the exceptionally best, but at removing the worst, that is, it allows you to preserve multivariance. The function of natural selection is not limited to this, since it ensures the reproduction of adapted genotypes, and, thus, determines the direction of evolution, consistently adding random and numerous deviations. Natural selection does not have a specific goal: on the basis of the same material (hereditary variability) in different conditions, different results can be obtained.

In this regard, the factor of evolution under consideration cannot be compared with the work of a sculptor carving a marble block, rather he acts as a distant ancestor of man, making a tool of labor from a stone fragment, without imagining the final result, which depends not only on the nature of the stone and its shape, but and on the strength, direction of impact, etc. However, in case of failure, selection, like a humanoid being, rejects the "wrong" shape.

Selection fee is the occurrence genetic load, that is, the accumulation of mutations in the population, which over time may become predominant due to the sudden death of most individuals or the migration of a small number of them.

Under the pressure of natural selection, not only the diversity of species is formed, but also their level of organization increases, including their complication or specialization. However, unlike artificial selection carried out by man only for economically valuable traits, often to the detriment of adaptive properties, natural selection cannot contribute to this, since no adaptation in nature can compensate for the harm from a decrease in the viability of a population.

Research S. S. Chetverikov

One of the important steps towards the reconciliation of Darwinism and genetics was made by the Moscow zoologist S. S. Chetverikov (1880-1959). Based on the results of studying the genetic composition of natural populations of the fruit fly Drosophila, he proved that they carry many recessive mutations in a heterozygous form that do not violate the phenotypic uniformity. Most of these mutations are unfavorable for the body and create the so-called genetic load, reducing the fitness of the population as a whole to the environment. Some mutations that do not have an adaptive value at a given moment in the development of a species can acquire a certain value later, and thus are reserve of hereditary variability. The spread of such mutations among individuals of the population as a result of successive free crosses can ultimately lead to their transition to a homozygous state and manifestation in a phenotype. If the given state of the feature is hair dryer - is adaptive, then after a few generations it will completely displace the dominant phene, which is less appropriate for these conditions, from the population, together with its carriers. Thus, due to such evolutionary changes, only the recessive mutant allele is retained, and its dominant allele disappears.

Let's try to prove this with a specific example. When studying any particular population, it can be found that not only its phenotypic, but also genotypic structures can remain unchanged for a long time, which is due to free crossing, or panmixia diploid organisms.

This phenomenon is described by law Hardy - Weinberg, according to which in an ideal population of infinitely large sizes in the absence of mutations, migrations, population waves, gene drift, natural selection and under the condition of free crossing, the frequencies of alleles and genotypes of diploid organisms will not change over a number of generations.

For example, in a population, a certain trait is encoded by two alleles of the same gene - the dominant ( AND) and recessive ( and). The frequency of the dominant allele is denoted as r, and recessive - q... The sum of the frequencies of these alleles is 1: p + q \u003d 1. Therefore, if we know the frequency of the dominant allele, then we can determine the frequency of the recessive allele: q = 1 – p... In fact, the allele frequencies are equal to the probabilities of the corresponding gametes formation. Then, after the formation of zygotes, the frequencies of genotypes already in the first generation will be:

(pA + qa) 2 = p 2 AA + 2pqAa + q 2 aa = 1,

where p 2 AA - frequency of dominant homozygotes;

2pqAa - frequency of heterozygotes;

q 2 aa - the frequency of recessive homozygotes.

It is not difficult to calculate that in subsequent generations the frequencies of genotypes will remain the same, maintaining the genetic diversity of the population. But in nature, ideal populations are absent, and therefore mutant alleles in them can not only be preserved, but also spread, and even replace previously more common alleles.

S.S.Chetverikov clearly realized that natural selection not only eliminates individual less successful traits, and, accordingly, the alleles encoding them, but also acts on the entire complex of genes that affect the manifestation of a particular gene in the phenotype, or genotypic environment... As a genotypic environment, the entire genotype is currently considered as a set of genes that can enhance or weaken the manifestation of specific alleles.

No less important in the development of evolutionary doctrine and research of S. S. Chetverikov in the field of population dynamics, in particular, "life waves", or population waves. While still a student, in 1905, he published an article on the possibility of outbreaks of mass reproduction of insects and an equally rapid decline in their numbers.

The role of evolutionary theory in the formation of the modern natural science picture of the world

The importance of evolutionary theory in the development of biology and other natural sciences is difficult to overestimate, since it was the first to explain the conditions, causes, mechanisms and results of the historical development of life on our planet, i.e., it gave a materialistic explanation of the development of the organic world. In addition, the theory of natural selection was the first truly scientific theory of biological evolution, since when creating it, Charles Darwin relied not on speculative constructions, but proceeded from his own observations and relied on the real properties of living organisms. At the same time, she enriched the biological tools with the historical method.

The formulation of the evolutionary theory not only caused a heated scientific debate, but also gave impetus to the development of such sciences as general biology, genetics, breeding, anthropology and a number of others. In this regard, one cannot but agree with the assertion that the theory of evolution crowned the next stage in the development of biology and became the starting point for its progress in the twentieth century.

Evidence for the evolution of wildlife. Evolutionary results: adaptability of organisms to their environment, diversity of species

Evidence for the evolution of wildlife

In various fields of biology, even before Charles Darwin and after the publication of his theory of evolution, a number of evidences were obtained to support it. These testimonies are called evidence of evolution... The most often cited are paleontological, biogeographic, comparative embryological, comparative anatomical and comparative biochemical evidence of evolution, although taxonomy and plant and animal breeding data cannot be disregarded.

Paleontological evidence based on the study of fossil remains of organisms. These include not only well-preserved organisms frozen into ice or enclosed in amber, but also "mummies" found in acidic peat bogs, as well as remains of organisms and fossils preserved in sedimentary rocks. The presence in ancient rocks of simpler organisms than in later layers, and the fact that species found at one level disappear at another, is considered one of the most significant evidence of evolution and is explained by the emergence and extinction of species in the corresponding epochs due to changes in environmental conditions.

Despite the fact that so far few fossil remains have been found and many fragments are absent from the fossil record due to the low probability of preserving organic remains, forms of organisms have been found that have signs of both evolutionarily older and younger groups of organisms. Such forms of organisms are called transitional forms... Vivid representatives of transitional forms, illustrating the transition from fish to terrestrial vertebrates, are cross-finned fishes and stegocephals, and Archeopteryx occupies a certain place between reptiles and birds.

The series of fossil forms, consistently connected with each other in the process of evolution, not only by general, but also by particular features of the structure, are called phylogenetic series... They can be represented by fossil remains from different continents, and claim to be more or less complete, but their study is impossible without comparing with living forms in order to demonstrate the progress of the evolutionary process. A classic example of a phylogenetic series is the evolution of horse ancestors, studied by the founder of evolutionary paleontology V.O.Kovalevsky.

Biogeographic evidence. Biogeography how science studies the patterns of distribution and distribution on the surface of our planet of species, genera and other groups of living organisms, as well as their communities.

The absence in any part of the earth's surface of species of organisms that are adapted to such a habitat and take root well with artificial importation, like rabbits in Australia, as well as the presence of close forms of organisms in parts of the land spaced at considerable distances from each other indicate, first of all, that the appearance of the Earth was not always the same, and geological transformations, in particular, the drift of continents, the formation of mountains, the rise and fall of the level of the World Ocean, affect the evolution of organisms. For example, in the tropical regions of South America, South Africa and Australia, there are four similar species of lungfish, while the ranges of camels and llamas belonging to the same order are located in North Africa, most of Asia and in South America. Paleontological studies have shown that camels and llamas descend from a common ancestor that once lived in North America, and then spread to Asia through the pre-existing isthmus at the site of the Bering Strait, as well as across the Isthmus of Panama to South America. Subsequently, all representatives of this family in the intermediate areas died out, and in the marginal areas, new species were formed in the process of evolution. The earlier separation of Australia from the rest of the land mass allowed the formation of a very special flora and fauna there, in which such forms of mammals as monotremes - the platypus and the echidna - have survived.

From the point of view of biogeography, the diversity of Darwin's finches on the Galapagos Islands, 1200 km from the coast of South America and having a volcanic origin, can also be explained. Apparently, representatives of the only species of finches in Ecuador once flew on them or were introduced, and then, as they multiplied, some of the individuals settled on the rest of the islands. On the central large islands, the struggle for existence (food, nesting places, etc.) was most acute, therefore, species slightly differing from each other in appearance were formed, consuming various foods (seeds, fruits, nectar, insects, etc.) .).

Influenced the spread of various groups of organisms and changes in climatic conditions on Earth, which contributed to the prosperity of some groups and the extinction of others. Individual species or groups of organisms that have survived from previously widespread flora and fauna are called relics... These include ginkgo, sequoia, tulip tree, cross-finned coelacanth fish, etc. In a broader sense, plant and animal species that live in limited areas of the territory or water area are called endemic, or endemic... For example, all representatives of the indigenous flora and fauna of Australia are endemic, and in the flora and fauna of Lake Baikal there are up to 75% of them.

Comparative anatomical evidence. The study of the anatomy of related groups of animals and plants provides convincing evidence of the similarity in the structure of their organs. Despite the fact that environmental factors certainly leave their mark on the structure of organs, in angiosperms, with all their amazing variety, flowers have sepals, petals, stamens and pistils, and in terrestrial vertebrates the limb is built according to a five-toed plan. Organs that have a similar structure, occupy the same position in the body and develop from the same primordia in related organisms, but perform different functions, are called homologous... Thus, the auditory ossicles (malleus, incus, and stapes) are homologous to the gill arches of fish, the venomous glands of snakes are similar to the salivary glands of other vertebrates, mammalian mammary glands are sweat glands, the flippers of seals and cetaceans are related to the wings of birds, the limbs of horses and moles.

The organs that do not function for a long time, most likely, in the process of evolution turn into rudimentary (rudiments) - structures underdeveloped in comparison with the ancestral forms, which have lost their main significance. These include the tibia in birds, eyes in moles and mole rats, hair, tailbone and appendix (appendix) in humans, etc.

In some individuals, however, there may be signs that are absent in this species, but that were present in distant ancestors - atavismsfor example, three-toedness in modern horses, the development of additional pairs of mammary glands, tail and hairline throughout the human body.

If homologous organs are evidence in favor of the kinship of organisms and divergence in the process of evolution, then similar bodies - structures similar in organisms of different groups, performing the same functions, on the contrary, refer to examples convergence (convergence is generally called the independent development of similar traits in different groups of organisms existing in the same conditions) and confirm the fact that the environment leaves a significant imprint on the organism. Analogs are the wings of insects and birds, the eyes of vertebrates and cephalopods (squids, octopuses), the articulated limbs of arthropods and terrestrial vertebrates.

Comparative embryological evidence. Studying embryonic development in representatives of different groups of vertebrates, K. Baer discovered their striking structural unity, especially in the early stages of development ( embryonic similarity law). Later E. Haeckel formulated biogenetic law, according to which ontogeny is a brief repetition of phylogenesis, that is, the stages that an organism goes through in the process of its individual development repeat the historical development of the group to which it belongs.

Thus, the embryo of a vertebrate in the first stages of development acquires structural features characteristic of fish, and then amphibians and, ultimately, the group to which it belongs. This transformation is explained by the fact that each of the above classes has common ancestors with modern reptiles, birds and mammals.

However, the biogenetic law has a number of limitations, and therefore the Russian scientist A. N. Severtsov significantly limited the scope of its application by repeating exclusively the features of the embryonic stages of development of ancestral forms in ontogenesis.

Comparative biochemical evidence. Development of more precise methods biochemical analysis provided evolutionary scientists with a new group of data in favor of the historical development of the organic world, since the presence of the same substances in all organisms indicates a possible biochemical homology, similar to that at the level of organs and tissues. Comparative biochemical studies of the primary structure of such widespread proteins as cytochrome from and hemoglobin, as well as nucleic acids, especially rRNA, showed that many of them have practically the same structure and perform the same functions in representatives of different species, while the closer the relationship, the greater the similarity is found in the structure of the studied substances.

Thus, the theory of evolution is confirmed by a significant amount of data from various sources, which once again testifies to its reliability, but it will still be changed and refined, since many aspects of the life of organisms remain outside the field of vision of researchers.

Evolutionary results: adaptability of organisms to their environment, diversity of species

In addition to the general features characteristic of representatives of a particular kingdom, the types of living organisms are characterized by an amazing variety of features of the external and internal structure, life activity and even behavior, which appeared and were selected in the process of evolution and ensure adaptation to habitat conditions. However, it should not be assumed that since birds and insects have wings, this is due to the direct action of the air environment, because there are plenty of wingless insects and birds. The aforementioned adaptations were selected by natural selection from the entire spectrum of available mutations.

Epiphytic plants that live not on soil, but on trees, have adapted to the absorption of atmospheric moisture using roots without root hairs, but with a special hygroscopic tissue - velamen... Some bromeliads can absorb water vapor in the humid atmosphere of the tropics using hairs on their leaves.

Insectivorous plants (sundew, Venus flytrap) living on soils where nitrogen is not available for one reason or another have developed a mechanism for attracting and absorbing small animals, most often insects, which are the source of the desired element for them.

To protect themselves from being eaten by herbivores, many plants leading an attached way of life have formed passive means of defense, such as thorns (hawthorn), thorns (rose), stinging hairs (nettle), accumulation of crystals of calcium oxalate (sorrel), biologically active substances in tissues (coffee, hawthorn), etc. In some of them, even seeds in unripe fruits are surrounded by stony cells that prevent pests from reaching them, and only by autumn does the process of lignification take place, which allows the seeds to get into the soil and germinate (pear).

The environment also has a formative effect on animals. Thus, many fish and aquatic mammals have a streamlined body, which makes it easier for them to move in its thickness. However, one should not assume that water directly affects the shape of the body; just in the process of evolution, it was precisely those animals that had this trait that were most adapted to it.

The body of whales and dolphins is not covered with hair, while the related group of pinnipeds has a somewhat reduced coat, since, unlike the former, they spend part of their time on land, where, without wool, their skin would immediately become icy ...

The body of most fish is covered with scales, which are lighter colored on the underside than on the upper, as a result of which these animals are hardly noticeable from above to natural enemies against the background of the bottom, and from below against the sky. Coloring that ensures the invisibility of animals for their enemies or victims is called patronizing... It is widespread in nature. A striking example of such a coloration is the coloration of the underside of the wings of a callima butterfly, which, sitting on a twig and folding its wings together, turns out to be like a dry leaf. Other insects, such as stick insects, disguise themselves as plant twigs.

Spotted or striped coloration is also adaptive, since birds such as quails or eiders cannot be seen against the background of the soil, even at close range. Spotted eggs of birds nesting on the ground are also invisible.

The color of animals is not always as constant as that of a zebra, for example, flounder and a chameleon are able to change it depending on the nature of the place where they are. Cuckoos, laying their eggs in the nests of various birds, can vary the color of their shells so that the “owners” of the nest do not notice the differences between them and their own eggs.

Coloring of animals can not always make them invisible - many of them are simply striking, which should warn of danger. Most of these insects and reptiles are poisonous to one degree or another, such as, for example, a ladybug or a wasp, so the predator, having experienced unpleasant sensations several times after eating such an object, avoids it. Nonetheless, warning coloring is not universal, since some birds have adapted to feed on them (wasp eater).

The increased chances of survival in individuals with warning coloration contributed to its appearance in representatives of other species without proper reason. This phenomenon is called mimicry... So, non-poisonous caterpillars of some species of butterflies imitate poisonous ones, and ladybirds - one of the types of cockroaches. However, birds can quickly learn to distinguish poisonous organisms from non-poisonous ones and consume the latter, avoiding individuals that served as a role model.

In some cases, the opposite phenomenon can also be observed - predatory animals imitate harmless ones in color, which allows them to approach the prey at a close distance, and then attack (saber-toothed blend).

Protection for many species is also provided by adaptive behavior, which is associated with storing food for the winter, caring for offspring, freezing in place, or vice versa, adopting a threatening pose. For example, river beavers harvest several cubic meters of branches, parts of trunks and other plant food for the winter, flooding it in the water near the "huts".

Caring for offspring is inherent mainly in mammals and birds, however, it is also found in representatives of other classes of chordates. For example, the aggressive behavior of stickleback males is known, driving away all enemies from the nest in which the eggs are located. Male clawed frogs wrap eggs on their legs and carry them until the tadpoles hatch from them.

Even some insects are able to provide their offspring with a more favorable habitat. For example, bees feed their larvae, while young bees at first "work" only in the hive. Ants move their pupae up and down in the anthill, depending on the temperature and humidity, and in case of the threat of flooding, they generally carry them away. Beetle beetles prepare special balls for their larvae from animal waste.

Many insects, when threatened with an attack, freeze in place and take the form of dry sticks, twigs and leaves. And vipers, on the contrary, rise and inflate their hood, while a rattlesnake makes a special sound with a rattle located at the end of its tail.

Behavioral adaptations are complemented by physiological ones associated with the characteristics of the environment. So, a person is able to be under water without scuba gear for only a few minutes, after which he can lose consciousness and die due to lack of oxygen, and whales do not emerge for a sufficiently long time. Their lung capacity is not too large, but there are other physiological adaptations, for example, in the muscles there is a high concentration of respiratory pigment - myoglobin, which, as it were, stores oxygen and gives it away during diving. In addition, whales have a special formation - a "miraculous network" that allows the use of oxygen even from venous blood.

Animals in hot habitats such as deserts are constantly at risk of overheating and losing excess moisture. Therefore, the fennec fox has extremely large auricles that allow it to radiate heat. In order to avoid moisture loss through the skin, amphibians of desert regions are forced to switch to a nocturnal lifestyle when the humidity rises and dew appears.

Birds that have mastered the air habitat, in addition to anatomical and morphological adaptations to flight, have important physiological features. For example, due to the fact that movement in the air requires an extremely large expenditure of energy, this group of vertebrates is characterized by a high metabolic rate, and the excreted metabolic products are excreted immediately, which contributes to a decrease in the specific density of the body.

Adaptations to the environment, despite all their perfection, are relative. So, some species of milkweed produce alkaloids that are poisonous for most animals, however, the caterpillars of one of the species of butterflies - the Danaids - not only feed on milkweed tissues, but also accumulate these alkaloids, becoming inedible for birds.

Moreover, adaptations are only advisable in a particular habitat and not useful in another environment. For example, the rare and large predator, the Ussuri tiger, like all cats, has soft pads on its paws and retractable sharp claws, sharp teeth, excellent vision even in the dark, sharp hearing and strong muscles, which allows it to detect a prey, sneak up on it and ambush. However, its striped coloration disguises it only in spring, summer and autumn, while in the snow it becomes clearly visible and the tiger can only count on a lightning attack.

Fig inflorescences, which give valuable infructescence, have such a specific structure that they are pollinated only by wasps with blastophages, and therefore, introduced into culture, they did not bear fruit for a long time. Only the breeding of parthenocarpic varieties of figs (forming fruits without fertilization) could save the situation.

Despite the fact that examples of speciation are described for very short periods of time, as in the case of the rattle in the Caucasian meadows, which, due to regular mowing, first divided into two populations - early flowering and fruiting and late flowering, in fact, microevolution is most likely requires much longer periods of time - many centuries, because humanity, whose different groups have been torn away from each other for millennia, nevertheless, has not been divided into different species. However, since evolution has practically unlimited time, for hundreds of millions and billions of years, several billion species have already lived on Earth, most of which have become extinct, and those that have come down to us are qualitative stages of this persistent process.

According to modern data, there are over 2 million species of living organisms on Earth, most of which (approximately 1.5 million species) belong to the animal kingdom, about 400 thousand to the plant kingdom, over 100 thousand to the mushroom kingdom, and the rest - to bacteria. This striking diversity is the result of the divergence (divergence) of species in various morphological, physiological-biochemical, ecological, genetic and reproductive traits. For example, one of the largest genera of plants belonging to the Orchid family - dendrobium - includes more than 1,400 species, and the genus of kaloid beetles - more than 1,600 species.

The classification of organisms is a task of systematics, which for 2 thousand years has been trying to build not just a harmonious hierarchy, but a "natural" system reflecting the degree of kinship of organisms. However, all attempts to do this have not yet been crowned with success, since in a number of cases in the course of evolution, not only divergence of characters was observed, but also convergence (convergence), as a result of which, in very distant groups, organs acquired features of similarity, such as, for example, the eyes of cephalopods. and mammalian eyes.

Macroevolution. Directions and ways of evolution (A. N. Severtsov, I. I. Shmalgauzen). Biological progress and regression, aromorphosis, idioadaptation, degeneration. Causes of biological progress and regression. Hypotheses of the origin of life on Earth. The main aromorphoses in the evolution of plants and animals. Complication of living organisms in the process of evolution

Macroevolution

The formation of a species marks a new round of the evolutionary process, since individuals of this species, being more adapted to environmental conditions than individuals of the mother species, gradually settle into new territories, and already in its populations mutagenesis, population waves, isolation and natural selection play their creative role ... Over time, these populations give rise to new species, which, due to genetic isolation, have much more signs of similarity with each other than with the species of the genus from which the species ancestor spun off, and thus a new genus appears, then a new family, order (order) , class, etc. The set of evolutionary processes that lead to the emergence of supraspecific taxa (genera, families, orders, classes, etc.) is called macroevolution. Macroevolutionary processes, as it were, generalize microevolutionary changes that have taken place over a long time, while revealing the main trends, directions and patterns of the evolution of the organic world that cannot be observed at a lower level. Until now, no specific mechanisms of macroevolution have been identified, therefore it is believed that it is carried out only through microevolutionary processes, but this position is constantly subjected to well-founded criticism.

The emergence of a complex hierarchical system of the organic world is largely the result of the unequal rate of evolution of various groups of organisms. So, the already mentioned ginkgo biloba, as it were, "preserved" for thousands of years, while quite close to it pines have changed significantly during this time.

Directions and ways of evolution (A. N. Severtsov, I. I. Shmalgauzen). Biological progress and regression, aromorphosis, idioadaptation, degeneration

Analyzing the history of the organic world, one can notice that at certain intervals separate groups of organisms dominated, which then tended to decline or disappeared altogether. Thus, three trunk lines can be distinguished. directions of evolution: biological progress, biological regression and biological stabilization. The Russian evolutionists A. N. Severtsov and I. I. Shmal'gauzen made a significant contribution to the development of the theory of the directions and ways of evolution.

Biological progress associated with the biological prosperity of the group as a whole and characterizes its evolutionary success. It reflects the natural development of living nature from simple to complex, from a lower degree of organization to a higher one. According to A. N. Severtsov, the criteria for biological progress are the increase in the number of individuals of a given group, the expansion of its range, as well as the appearance and development of groups of lower rank within it (transformation of a species into a genus, a genus into a family, etc.). Currently, biological progress is observed in angiosperms, insects, teleost fish and mammals.

According to A. N. Severtsov, biological progress can be achieved as a result of certain morphophysiological transformations of organisms, while he identified three main ways of achieving: arogenesis, allogenesis and catagenesis.

Arogenesis, or morphophysiological progress, is associated with a significant expansion of the range of this group of organisms due to the acquisition of large structural changes - aromorphoses.

Aromorphosis is called the evolutionary transformation of the structure and functions of an organism, which increases its level of organization and opens up new possibilities for adapting to various conditions of existence.

Examples of aromorphoses are the emergence of a eukaryotic cell, multicellularity, the appearance of a heart in fish and its division by a complete septum in birds and mammals, the formation of a flower in angiosperms, etc.

Allogenesis, in contrast to arogenesis, is not accompanied by an expansion of the range, however, within the old, a significant variety of forms appears, which have particular adaptations to the habitat - idioadaptation.

Idioadaptation - this is a small morphophysiological adaptation to special environmental conditions, useful in the struggle for existence, but does not change the level of organization. These changes illustrate the protective coloration in animals, a variety of mouthparts in insects, plant thorns, etc. An equally successful example is Darwin's finches, specializing in various types of food, in which transformations first affected the beak, and then other parts of the body - plumage, tail etc.

Paradoxical as it may seem, simplification of organization can also lead to biological progress. This path is called catagenesis.

Degeneration is a simplification of organisms in the process of evolution, which is accompanied by the loss of certain functions or organs.

The phase of biological progress is replaced by a phase biological stabilization, the essence of which is to preserve the characteristics of a given species as the most favorable in a given microenvironment. According to II Shmalgauzen, it does not at all mean the termination of evolution, on the contrary, it means the maximum consistency of the organism with changes in the environment. The “living fossils” of coelacanth, gingko and others are in the phase of biological stabilization.

The antipode of biological progress is biological regression - the evolutionary decline of this group due to the inability to adapt to environmental changes. It manifests itself in a decrease in the number of populations, a narrowing of areas, and a decrease in the number of groups of lower rank within a higher taxon. A group of organisms that is in a state of biological regression is threatened with extinction. Many examples of this phenomenon can be seen in the history of the organic world, and at present, regression is characteristic of some ferns, amphibians and reptiles. With the advent of man, biological regression is often caused by his economic activity.

The directions and ways of evolution of the organic world are not mutually exclusive, that is, the appearance of aromorphosis does not mean that idioadaptation or degeneration can no longer occur. On the contrary, according to the developed by A.N.Severtsov and I.I.Shmalgauzen phase change rule, various directions of the evolutionary process and ways of achieving biological progress naturally replace each other. In the course of evolution, these paths are combined: rather rare aromorphoses transfer a group of organisms to a qualitatively new level of organization, and in the future, historical development follows the path of idioadaptation or degeneration, ensuring adaptation to specific environmental conditions.

Causes of biological progress and regression

In the process of evolution, the bar of natural selection is overcome and, accordingly, only those groups of organisms progress, in which hereditary variability creates a sufficient number of combinations that can ensure the survival of the group as a whole.

The same groups, which for some reason do not have such a reserve, in most cases are doomed to extinction. This is often due to low selection pressures at earlier stages of the evolutionary process, leading to narrow group specialization or even degenerative phenomena. The consequence of this is the impossibility of adapting to new environmental conditions during its abrupt changes. A striking example of this is the sudden death of dinosaurs due to the fall of a giant celestial body to the Earth 65 million years ago, which resulted in an earthquake, the raising of millions of tons of dust into the air, a sharp cooling, the death of most of the plants and herbivorous animals. At the same time, the ancestors of modern mammals, having no narrow preferences for food sources and being warm-blooded, were able to survive these conditions and occupy a dominant position on the planet.

Hypotheses of the origin of life on Earth

Of the entire spectrum of hypotheses for the formation of the Earth, the largest number of facts testifies in favor of the Big Bang theory. In view of the fact that this scientific assumption is based mainly on theoretical calculations, the Large Hadron Collider, built at the European Center for Nuclear Research near Geneva (Switzerland), is designed to experimentally confirm it. According to the Big Bang theory, the Earth was formed over 4.5 billion years ago together with the Sun and other planets of the Solar System as a result of condensation of a gas and dust cloud. The decrease in the planet's temperature and the migration of chemical elements on it contributed to its stratification into the core, mantle and crust, and the subsequent geological processes (movement of tectonic plates, volcanic activity, etc.) caused the formation of the atmosphere and hydrosphere.

Life has also existed on Earth for a very long time, as evidenced by the fossil remains of various organisms in rocks, but physical theories cannot answer the question of the time and causes of its occurrence. There are two opposite points of view on the origin of life on Earth: the theory of abiogenesis and biogenesis. Abiogenesis theories assert the possibility of the origin of the living from the non-living. These include creationism, the hypothesis of spontaneous generation and the theory of biochemical evolution by A.I. Oparin.

Fundamental position creationismwas the creation of the world by a certain supernatural being (Creator), which is reflected in the myths of the peoples of the world and religious cults, but the age of the planet and life on it is much higher than the dates indicated in these sources, and there are plenty of inconsistencies in them.

The founder spontaneous generation theory life is considered the ancient Greek scientist Aristotle, who argued that multiple emergence of new creatures is possible, for example, earthworms from puddles, and worms and flies from rotten meat. However, these views were refuted in the 17th – 19th centuries by the courageous experiments of F. Redi and L. Pasteur.

The Italian physician Francesco Redi in 1688 placed pieces of meat in pots and sealed them tightly, but no worms were kept in them, while they appeared in open pots. In order to refute the then prevailing belief that the life principle is contained in the air, he repeated his experiments, but did not seal the pots, but closed them with several layers of muslin, and life did not appear again. Despite the convincing data obtained by F. Redi, the studies of A. van Leeuwenhoek provided new food for discussions about the "beginning of life", which continued throughout the next century.

Another Italian researcher, Lazzaro Spallanzani, modified F. Redi's experiments in 1765 by boiling meat and vegetable decoctions for several hours and sealing them. After several days, he also did not find any signs of life there and concluded that living things can arise only from living things.

The last blow to the theory of spontaneous spontaneous generation was struck by the great French microbiologist Louis Pasteur in 1860, who placed a boiled broth in a flask with an S-shaped neck and did not receive any embryos. It would seem that this testified in favor of the theories of biogenesis, but the question remained about how the very first organism arose.

The Soviet biochemist A.I. Oparin tried to answer it, who came to the conclusion that the composition of the Earth's atmosphere in the early stages of its existence was not at all the same as in our time. Most likely, it consisted of ammonia, methane, carbon dioxide and water vapor, but did not contain free oxygen. Under the action of high-power electrical discharges and at high temperatures, the simplest organic compounds could be synthesized in it, which was confirmed by the experiments of S. Miller and G. Urey in 1953, who obtained from the above-mentioned compounds several amino acids, simple carbohydrates, adenine, urea, and protozoa fatty, formic and acetic acids.

Nevertheless, the synthesis of organic substances does not yet mean the emergence of life, therefore A.I. Oparin put forward biochemical evolution hypothesis, according to which a variety of organic substances arose and combined into larger molecules in the shallow waters of the seas and oceans, where conditions for chemical synthesis and polymerization are most favorable. The first carriers of life are currently considered to be RNA molecules.

Some of these substances gradually formed stable complexes in water - coacervates, or coacervate dropsresembling drops of fat in broth. These coacervates received a variety of substances from the surrounding solution, which underwent chemical transformations in the droplets. Like organic substances, coacervates were not living beings in themselves, but were the next step in their emergence.

Those of the coacervates that had a good ratio of substances in their composition, especially proteins and nucleic acids, due to the catalytic properties of enzyme proteins, over time acquired the ability to reproduce their own kind and carry out metabolic reactions, while the structure of proteins was encoded by nucleic acids.

However, in addition to reproduction, living systems are characterized by dependence on the supply of energy from the outside. This problem was initially solved due to the oxygen-free decomposition of organic substances from the environment (there was no oxygen in the atmosphere at that time), i.e.

heterotrophic nutrition. Some of the absorbed organic substances were able to accumulate energy from sunlight, such as chlorophyll, which made it possible for a number of organisms to switch to autotrophic nutrition. The release of oxygen into the atmosphere during photosynthesis led to the appearance of more efficient oxygen respiration, the emergence of the ozone layer and, ultimately, the release of organisms to land.

Thus, the result of chemical evolution was the emergence protobionts - primary living organisms, from which, as a result of biological evolution, all currently existing species originated.

The theory of biochemical evolution in our time is the most confirmed, but the idea of \u200b\u200bthe specific mechanisms of the origin of life has changed. For example, it turned out that the formation of organic substances begins in space, and organic substances play an important role even in the very formation of planets, ensuring the adhesion of small parts. Also, the formation of organic matter occurs in the bowels of the planet: with one eruption, the volcano ejects up to 15 tons of organic matter. There are other hypotheses regarding the mechanisms of concentration of organic substances: freezing of a solution, absorption (binding) on \u200b\u200bthe surface of certain mineral compounds, the action of natural catalysts, etc. The emergence of life on Earth is currently impossible, since any organic matter spontaneously formed at any point planets would immediately be oxidized by free atmospheric oxygen or used by heterotrophic organisms. Charles Darwin understood this as early as 1871.

Biogenesis theories deny the spontaneous origin of life. The main ones are the steady state hypothesis and the panspermia hypothesis. The first of them is based on the fact that life exists forever, nevertheless, there are very ancient rocks on our planet, in which there are no traces of the activity of the organic world.

Panspermia hypothesis claims that the embryos of life were brought to Earth from space by some aliens or by divine providence. This hypothesis is supported by two facts: the need for all living things, which is rather rare on the planet, but often found in meteorites, molybdenum, as well as the discovery of organisms similar to bacteria on meteorites from Mars. However, how life originated on other planets remains unclear.

The main aromorphoses in the evolution of plants and animals

Plant and animal organisms, representing various branches of the evolution of the organic world, in the process of historical development independently acquired certain structural features, which will be characterized below.

In plants, the most important of them are the transition from haploid to diploid, independence from water in the process of fertilization, the transition from external to internal fertilization and the emergence of double fertilization, the dismemberment of the body into organs, the development of the conducting system, the complication and improvement of tissues, as well as the specialization of pollination using insects and the spread of seeds and fruits.

The transition from haploidy to diploidy made plants more resistant to environmental factors due to a reduced risk of recessive mutations. Apparently, this transformation affected the ancestors of vascular plants, which do not include bryophytes, which are characterized by the predominance of gametophyte in the life cycle.

The main aromorphoses in animal evolution are associated with the emergence of multicellularity and the increasing dismemberment of all organ systems, the emergence of a strong skeleton, the development of the central nervous system, as well as social behavior in various groups of highly organized animals, which gave impetus to human progress.

Complication of living organisms in the process of evolution

The history of the organic world on Earth is studied by the surviving remains, imprints and other traces of the vital activity of living organisms. She is the subject of science paleontology... Based on the fact that the remains of different organisms are located in different layers of rocks, a geochronological scale was created, according to which the history of the Earth was divided into certain periods of time: eons, eras, periods and centuries.

Aeonis called a large period of time in geological history, uniting several eras. Currently, only two aeons are distinguished: cryptose (latent life) and phanerozoic (explicit life). Era - This is a period of time in geological history, which is a subdivision of the aeon, uniting, in turn, periods. In the Cryptozoic, two eras are distinguished (Archaean and Proterozoic), while in the Phanerozoic, three (Paleozoic, Mesozoic and Cenozoic).

An important role in the creation of the geochronological scale was played by leading fossils - the remains of organisms that were abundant at certain intervals and well preserved.

Development of life in cryptozoic. Archaea and Proterozoic make up most of the history of life (period 4.6 billion years - 0.6 billion years ago), but there is not enough information about life during that period. The first remnants of organic matter of biogenic origin are about 3.8 billion years old, and prokaryotic organisms already existed 3.5 billion years ago. The first prokaryotes were part of specific ecosystems - cyanobacterial mats, due to the activity of which specific sedimentary rocks of stromatolites ("stone carpets") were formed.

The discovery of their modern analogues - stromatolites in Shark Bay in Australia and specific films on the soil surface in Sivash Bay in Ukraine - helped to understand the life of long-standing prokaryotic ecosystems. Photosynthetic cyanobacteria are located on the surface of cyanobacterial mats, and under their layer there are extremely diverse bacteria of other groups and archaea. Mineral substances that settle on the surface of the mat and are formed due to its vital activity are deposited in layers (approximately 0.3 mm per year). Such primitive ecosystems can exist only in places unsuitable for other organisms, and indeed, both of the above-mentioned habitats are characterized by extremely high salinity.

Numerous data indicate that at first the Earth had a renewable atmosphere, which included: carbon dioxide, water vapor, sulfur oxide, as well as carbon monoxide, hydrogen, hydrogen sulfide, ammonia, methane, etc. The first organisms of the Earth were anaerobes However, due to the photosynthesis of cyanobacteria, free oxygen was released into the medium, which at first quickly bounded with the reducing agents in the medium, and only after binding all the reducing agents, the medium began to acquire oxidizing properties. Such a transition is evidenced by the deposition of oxidized forms of iron - hematite and magnetite.

About 2 billion years ago, as a result of geophysical processes, almost all iron unbound in sedimentary rocks moved to the core of the planet, and oxygen began to accumulate in the atmosphere due to the absence of this element - an "oxygen revolution" took place. It was a turning point in the history of the Earth, which entailed not only a change in the composition of the atmosphere and the formation of an ozone screen in the atmosphere - the main prerequisite for the settlement of land, but also the composition of rocks that form on the surface of the Earth.

Another important event took place in the Proterozoic - the emergence of eukaryotes. In recent years, it has been possible to collect convincing evidence for the theory of the endosymbiogenetic origin of the eukaryotic cell - through the symbiosis of several prokaryotic cells. Probably, the "main" ancestor of eukaryotes was archaea, which switched to the absorption of food particles by phagocytosis. The hereditary apparatus moved deeper into the cell, nevertheless retaining its connection with the membrane due to the transition of the outer membrane of the arisen nuclear envelope into the membranes of the endoplasmic reticulum.

Geochronological history of the Earth Aeon Era Period Beginning, million years ago Duration, million years Life development Phanerozoic Cenozoic Anthropogen 1.5 1.5 Four ice ages, followed by floods, led to the formation of cold-resistant flora and fauna (mammoths, musk oxen, reindeer, lemmings). The exchange of animals and plants between continents due to the emergence of land bridges. Dominance of placental mammals. Extinction of many large mammals. Formation of man as a biological species and its dispersal. Domestication of animals and domestication of plants. The disappearance of many species of living organisms due to human economic activity Neogen 25 23.5 Distribution of cereals. Formation of all modern orders of mammals. The emergence of great apes Paleogene 65 40 Dominance of flowering plants, mammals and birds. The emergence of ungulates, carnivores, pinnipeds, primates, etc. Mesozoic Mel 135 70 The emergence of angiosperms, mammals and birds become numerous Jura 195 60 The era of reptiles and cephalopods. The emergence of marsupials and placental mammals. Dominance of gymnosperms Trias 225 30 The first mammals and birds. Reptiles are plentiful. Distribution of herbaceous spores in the Paleozoic Perm 280 55 The emergence of modern insects. Reptile development. Extinction of a number of invertebrate groups. Distribution of conifers Carbon 345 65 The first reptiles. The emergence of winged insects. Ferns and horsetails prevail. Devon 395 50 Fish are abundant. The first amphibians. The emergence of the main groups of spore, first gymnosperms and fungi Silurian 430 35 Algae are abundant. The first land plants and animals (spiders). Common jaw-toed fishes and crustaceans Ordovician 500 70 Corals and trilobites are abundant. Blossoming of green, brown and red algae. The emergence of the first chordate Cambrian 570 70 Numerous fish fossils. Sea urchins and trilobites are common. The emergence of multicellular algae by Cryptose Proterozoa 2600 2000 The emergence of eukaryotes. Mainly unicellular green algae are widespread. The emergence of multicellularity. Outbreak of diversity of multicellular animals (the emergence of all types of invertebrates) Archaea 3500 1500 The first traces of life on Earth - bacteria and cyanobacteria. The emergence of photosynthesis

The bacteria absorbed by the cell could not be digested, but remained alive and continued to function. It is believed that mitochondria originate from purple bacteria that have lost the ability to photosynthesize and have gone on to oxidize organic matter. Symbiosis with other photosynthetic cells led to the formation of plastids in plant cells. Probably, the flagella of eukaryotic cells arose as a result of symbiosis with bacteria, which, like modern spirochetes, were capable of wriggling movements. At first, the hereditary apparatus of eukaryotic cells was arranged approximately in the same way as in prokaryotes, and only later, due to the need to control a large and complex cell, chromosomes were formed. The genomes of intracellular symbionts (mitochondria, plastids, and flagella) generally retained their prokaryotic organization, but most of their functions have passed to the nuclear genome.

Eukaryotic cells have arisen repeatedly and independently of each other. For example, red algae arose as a result of symbiogenesis with cyanobacteria, and green algae - with prochlorophyte bacteria.

The rest of the single-membrane organelles and the nucleus of the eukaryotic cell, according to the endomembrane theory, arose from the invaginations of the membrane of the prokaryotic cell.

The exact time of the appearance of eukaryotes is unknown, since already in deposits about 3 billion years old, there are imprints of cells with similar sizes. Precisely eukaryotes were recorded in rocks about 1.5-2 billion years old, but only after the oxygen revolution (about 1 billion years ago) conditions favorable for them developed.

At the end of the Proterozoic era (at least 1.5 billion years ago), multicellular eukaryotic organisms already existed. Multicellularity, like a eukaryotic cell, has repeatedly appeared in different groups of organisms.

There are different views on the origin of multicellular animals. According to some data, their ancestors were multinucleated, ciliate-like cells, which then disintegrated into separate mononuclear cells.

Other hypotheses link the origin of multicellular animals with the differentiation of colonial unicellular cells. The discrepancies between them concern the appearance of cell layers in the original multicellular animal. According to E. Haeckel's hypothesis of gastrea, this occurs by invagination of one of the walls of a single-layer multicellular organism, as in coelenterates. In contrast, I.I.Mechnikov formulated the hypothesis of phagocytella, considering the ancestors of multicellular single-layered spherical colonies like volvox, which absorbed food particles by phagocytosis. The cell that captured the particle lost its flagellum and moved deep into the body, where it carried out digestion, and at the end of the process returned to the surface. Over time, there was a division of cells into two layers with certain functions - the outer one provided movement, and the inner one - phagocytosis. I. I. Mechnikov called such an organism phagocytella.

For a long time, multicellular eukaryotes lost in the competition to prokaryotic organisms, however, at the end of the Proterozoic (800-600 million years ago) due to a sharp change in conditions on Earth - a decrease in sea level, an increase in oxygen concentration, a decrease in the concentration of carbonates in seawater, regular cycles cold snaps - multicellular eukaryotes gained advantages over prokaryotes. If until that time there were only individual multicellular plants and, possibly, fungi, then from that moment in the history of the Earth, animals are also known. Of the faunas that arose at the end of the Proterozoic, the Ediacaran and Vendian are the best studied. It is customary to include animals of the Vendian period in a special group of organisms or to include such types as coelenterates, flatworms, arthropods, etc. However, none of these groups have skeletons, which may indicate the absence of predators.

Development of life in the Paleozoic era.The Paleozoic era, which lasted more than 300 million years, is divided into six periods: Cambrian, Ordovician, Silurian, Devonian, Carboniferous (Carboniferous) and Permian.

IN cambrian period land consisted of several continents, located mainly in the southern hemisphere. The most numerous photosynthetic organisms during this period were cyanobacteria and red algae. Foraminifera and radiolarians lived in the water column. A huge number of skeletal animal organisms appear in the Cambrian, as evidenced by numerous fossils. These organisms belonged to about 100 types of multicellular animals, both modern (sponges, coelenterates, worms, arthropods, molluscs), and extinct, for example: the huge predator anomalocaris and colonial graptolites that floated in the water column or were attached to the bottom. The dry land remained almost uninhabited throughout the Cambrian, but the process of soil formation had already begun by bacteria, fungi and, possibly, lichens, and at the end of the period, small-bristled worms and millipedes came out onto the land.

IN ordovician period the sea level rose, which led to the flooding of the continental lowlands. The main producers during this period were green, brown and red algae. Unlike the Cambrian, in which the reefs built sponges, in the Ordovician they are replaced by coral polyps. Gastropods and cephalopods flourished, as well as trilobites (now extinct relatives of arachnids). In this period, chordates were also recorded for the first time, in particular the jawless. At the end of the Ordovician, a huge extinction took place, which destroyed about 35% of families and more than 50% of genera of marine animals.

Silurian characterized by increased mountain building, which led to the drainage of continental platforms. The leading role in the Silurian invertebrate fauna was played by cephalopods, echinoderms, and giant crustaceans, while among vertebrates there is a wide variety of jawless and fish appear. At the end of the period, the first vascular plants, rhinophytes and lycopods, came out onto the land, and began to colonize the shallow waters and the intertidal zone of the coasts. The first representatives of the arachnid class also came out on land.

IN devonian period as a result of the uplift of the land, large shallow waters were formed, which dried up and even froze through, since the climate became even more continental than in the Silurian. Corals and echinoderms predominate in the seas, while cephalopods are represented by spirally twisted ammonites. Among the vertebrates of the Devonian, fish reached their heyday, and cartilaginous and bony ones, as well as lungs and cross-finned ones, came to replace the shell ones. At the end of the period, the first amphibians appear, which first lived in water.

In the Middle Devonian, the first forests of ferns, lycopods and horsetails appeared on land, which were inhabited by worms and numerous arthropods (centipedes, spiders, scorpions, wingless insects). At the end of the Devonian, the first gymnosperms appeared. The assimilation of land by plants led to a decrease in weathering and an increase in soil formation. The consolidation of soils led to the emergence of river beds.

IN carboniferous period land was represented by two continents separated by an ocean, and the climate became noticeably warmer and more humid. By the end of the period, there was a slight rise in land, and the climate was replaced by a more continental one. The seas were dominated by foraminifera, corals, echinoderms, cartilaginous and bony fish, and freshwater bodies were inhabited by bivalve molluscs, crustaceans and various amphibians. In the middle of the Carboniferous, small insectivorous reptiles arose, and winged ones (cockroaches, dragonflies) appeared among insects.

The tropics were characterized by swampy forests dominated by giant horsetails, ploons and ferns, the dead remains of which subsequently formed deposits of coal. In the middle of the period in the temperate zone, thanks to their independence from water in the process of fertilization and the presence of semen, the spread of gymnosperms began.

Permian period characterized by the merger of all continents into a single supercontinent Pangea, the retreat of the seas and the strengthening of the continentality of the climate to such an extent that deserts formed in the interior regions of Pangea. By the end of the period, tree ferns, horsetails and moss almost disappeared on land, and drought-resistant gymnosperms took the dominant position. Despite the fact that large amphibians still continued to exist, different groups of reptiles arose, including large herbivorous and carnivorous ones. At the end of the Permian, the largest extinction in the history of life occurred, as many groups of corals, trilobites, most cephalopods, fish (primarily cartilaginous and cross-finned), and amphibians disappeared. The marine fauna lost 40–50% of families and about 70% of genera.

Development of life in the Mesozoic. The Mesozoic era lasted for about 165 million years and was characterized by land uplift, intense mountain building and a decrease in climate humidity. It is divided into three periods: Triassic, Jurassic and Cretaceous.

At the beginning triassic the climate was arid, but later, due to the rise in sea level, it became more humid. Gymnosperms, ferns, and horsetails predominated among the plants, but the arboreal forms of spore-bearing species were almost completely extinct. Some corals, ammonites, new groups of foraminifera, bivalve molluscs and echinoderms have reached a high development, while the diversity of cartilaginous fish has decreased, and groups of bony fish have changed. Reptiles dominating land began to master the aquatic environment, like ichthyosaurs and plesiosaurs. Among the reptiles of the Triassic, crocodiles, tuataras and turtles have survived to this day. At the end of the Triassic, dinosaurs, mammals and birds appeared.

IN jurassic the supercontinent Pangea split into several smaller ones. Most of the Jurassic was very humid, and towards the end the climate became more arid. The dominant group of plants were gymnosperms, of which sequoias survived from that time. In the seas, molluscs (ammonites and belemnites, bivalves and gastropods), sponges, sea urchins, cartilaginous and bony fish flourished. Large amphibians almost completely died out in the Jurassic period, however, modern groups of amphibians (tailed and tailless) and scaly (lizards and snakes) appeared, and the diversity of mammals increased. By the end of the period, the possible ancestors of the first birds appeared - Archeopteryx. However, all ecosystems were dominated by reptiles - ichthyosaurs and plesiosaurs, dinosaurs and flying dinosaurs - pterosaurs.

Cretaceous period got its name in connection with the formation of chalk in sedimentary rocks of that time. All over the Earth, except for the polar regions, there was a persistent warm and humid climate. In this period, angiosperms arose and became widespread, displacing gymnosperms, which led to a sharp increase in the diversity of insects. In the seas, in addition to mollusks, teleost fish, plesiosaurs, a huge number of foraminifera reappeared, the shells of which formed chalk deposits, and dinosaurs predominated on land. Birds better adapted to the air began to gradually displace the flying dinosaurs.

At the end of the period, there was a global extinction, as a result of which ammonites, belemnites, dinosaurs, pterosaurs and sea lizards, ancient groups of birds, as well as some gymnosperms, disappeared. About 16% of families and 50% of animal genera have disappeared from the face of the Earth as a whole. The crisis at the end of the Cretaceous is associated with the fall of a large meteorite into the Gulf of Mexico, but it, most likely, was not the only cause of global changes. During the subsequent cold snap, only small reptiles and warm-blooded mammals survived.

Development of life in the Cenozoic. The Cenozoic era began about 66 million years ago and continues to this day. It is characterized by the dominance of insects, birds, mammals and angiosperms. The Cenozoic is divided into three periods - paleogene, Neogene and Anthropogen - the last of which is the shortest in the history of the Earth.

In the Early and Middle Paleogene, the climate remained warm and humid; by the end of the period it became cooler and drier. Angiosperms became the dominant group of plants, however, if at the beginning of the period evergreen forests prevailed, then at the end many deciduous forests appeared, and steppes formed in arid zones.

Among fishes, bony fishes occupied a dominant position, and the number of cartilaginous species, despite their significant role in salt water bodies, is insignificant. On land, of the reptiles, only scaly, crocodiles and turtles survived, while mammals occupied most of their ecological niches. In the middle of the period, the main orders of mammals appeared, including insectivores, carnivores, pinnipeds, cetaceans, ungulates, and primates. The isolation of the continents made the fauna and flora geographically more diverse: South America and Australia became centers of development of marsupials, and other continents - placental mammals.

Neogene period. The earth's surface in the Neogene acquired a modern look. The climate became cooler and drier. In the Neogene, all the orders of modern mammals were already formed, and in the African shrouds the Hominid family and the Mankind arose. By the end of the period, coniferous forests spread in the circumpolar regions of the continents, tundra appeared, and grasses occupied the steppes of the temperate zone.

Quaternary period (anthropogen) is characterized by periodic changes of glaciations and warming. During glaciers, high latitudes were covered with glaciers, the ocean level dropped sharply, the tropical and subtropical belts narrowed. In the territories adjacent to the glaciers, a cold and dry climate was established, which contributed to the formation of cold-resistant groups of animals - mammoths, giant deer, cave lions, etc. The decrease in the level of the World Ocean accompanying the glaciation process led to the formation of land bridges between Asia and North America, Europe and the British Isles etc. Animal migrations, on the one hand, led to the mutual enrichment of flora and fauna, and on the other, to the displacement of relics by aliens, for example, marsupials and ungulates in South America. These processes, however, did not affect Australia, which remained isolated.

In general, periodic changes in climate have led to the formation of an extremely abundant species diversity characteristic of the current stage of the evolution of the biosphere, and also influenced human evolution. During the anthropogenes, several species of the genus Man settled from Africa to Eurasia. About 200 thousand years ago, the species Homo sapiens appeared in Africa, which after a long period of existence in Africa about 70 thousand years ago went to Eurasia and about 35-40 thousand years ago - to America. After a period of coexistence with closely related species, he displaced them and settled throughout the globe. About 10 thousand years ago, human economic activity in moderately warm regions of the globe began to influence both the appearance of the planet (plowing of lands, burning of forests, overgrazing, desertification, etc.), and on the fauna and flora due to the reduction of habitats their habitat and extermination, and the anthropogenic factor came into play.

Human Origins. Man as a species, his place in the system of the organic world. Hypotheses of human origin. Driving forces and stages of human evolution. Human races, their genetic relationship. The biosocial nature of man. Social and natural environment, human adaptation to it

Human Origins

Even 100 years ago, the overwhelming majority of people on the planet did not even think that man could descend from such "little respectable" animals as monkeys. In a discussion with one of the defenders of the Darwinian theory of evolution, Professor Thomas Huxley, his ardent opponent, Bishop of Oxford, Samuel Wilberforce, who relied on religious dogma, even turned to him with the question of whether he considered himself connected with ape ancestors through his grandfather or grandmother.

Nevertheless, ancient philosophers expressed thoughts about the evolutionary origin, and the great Swedish taxonomist K. Linnaeus in the 18th century gave a species name to man Homo sapiens L. (Homo sapiens) and took him along with the monkeys to the same order - Primates. JB Lamarck supported K. Linnaeus and believed that man even had common ancestors with modern monkeys, but at some point in his history he descended from a tree, which was one of the reasons for the formation of man as a species.

Charles Darwin also did not ignore this issue and in the 70s of the XIX century published the works "The Origin of Man and Sexual Selection" and "On the Expression of Emotions in Animals and Man", in which he gave no less convincing evidence of the common origin of man and apes. than the German researcher E. Haeckel ("Natural History of Creation", 1868; "Anthropogenesis, or History of the Origin of Man", 1874), who even compiled the genealogy of the animal kingdom. However, these studies concerned only the biological side of the formation of man as a species, while the social aspects were revealed by the classic of historical materialism - the German philosopher F. Engels.

Currently, the origin and development of man as a biological species, as well as the diversity of populations of modern man and the patterns of their interaction are studied by science anthropology.

Man as a species, his place in the system of the organic world

Homo sapiens ( Homo sapiens) as a biological species belongs to the animal kingdom, the sub-kingdom of multicellular. The presence of notochord, gill slits in the pharynx, neural tube, and bilateral symmetry in the process of embryonic development makes it possible to classify it as chordate, while the development of the spine, the presence of two pairs of limbs and the location of the heart on the ventral side of the body indicates its relationship with other representatives of the vertebrate subtype.

Feeding babies with milk secreted by mammary glands, warm-bloodedness, a four-chambered heart, the presence of hair on the surface of the body, seven vertebrae in the cervical spine, the vestibule of the mouth, alveolar teeth and the change of milk teeth to permanent are signs of the mammalian class, and intrauterine development of the embryo and its connection with the mother's body through the placenta - a subclass of placentals.

More frequent signs, such as grasping limbs with opposed thumb and fingernails, development of the clavicle, forward-looking eyes, an increase in the size of the skull and brain, and the presence of all groups of teeth (incisors, canines and molars) leave no doubt that that his place is in the order of primates.

The significant development of the brain and mimic muscles, as well as the structural features of the teeth, make it possible to classify a person as a suborder of higher primates, or monkeys.

The absence of a tail, the presence of bends of the spine, the development of the cerebral hemispheres of the forebrain, covered with a bark with numerous grooves and convolutions, the presence of the upper lip and thinning of the hairline give reason to place it among the representatives of the family of higher narrow-nosed, or great apes.

However, even the most highly organized human monkeys are distinguished by a sharp increase in the volume of the brain, upright walking, a wide pelvis, a protruding chin, articulate speech and the presence of 46 chromosomes in the karyotype and determine its belonging to the genus Man.

The use of the upper limbs for work, the manufacture of tools, abstract thinking, collective action and development based on more social than biological laws are the specific characteristics of Homo sapiens.

All modern people belong to one species - Homo sapiens ( Homo sapiens), and subspecies H. sapiens sapiens... This species is a collection of populations that give fertile offspring when crossed. Despite a fairly significant variety of morphophysiological characters, they are not evidence of a higher or lower degree of organization of certain groups of people - they are all at the same level of development.

In our time, a sufficient number of scientific facts have already been collected in the interests of the formation of man as a species in the process of evolution - anthropogenesis... The specific course of anthropogenesis has not yet been fully elucidated, but thanks to new paleontological findings and modern research methods, one can hope that a clear picture will appear soon enough.

Hypotheses of human origin

If we do not take into account the hypotheses of the divine creation of man and his penetration from other planets, which are not related to the field of biology, then all more or less consistent hypotheses of the origin of man lead him to common ancestors with modern primates.

So, hypothesis of the origin of man from the ancient tropical primate tarsier, or tarzial hypothesis, formulated by the English biologist F. Wood Jones in 1929, relies on the similarity of the proportions of the human and tarsier bodies, the features of the hairline, the shortening of the facial part of the skull of the latter, etc. However, the differences in the structure and vital activity of these organisms are so great that it has not universal acceptance.

With anthropoid apes, humans have too many similarities. So, in addition to the anatomical and morphological features already mentioned above, attention should be paid to their postembryonic development. For example, small chimpanzees have a much sparser hairline, a much larger brain-to-body ratio, and a slightly wider range of movement on the hind legs than in adults. Even puberty in great apes occurs much later than in representatives of other orders of mammals with similar body sizes.

In the course of cytogenetic studies, it was revealed that one of the human chromosomes was formed as a result of the fusion of chromosomes of two different pairs present in the karyotype of great apes, and this explains the difference in the number of their chromosomes (in humans, 2n \u003d 46, and in large great apes, 2n \u003d 48 ), and is also another evidence of the relationship of these organisms.

The similarity between humans and great apes is also very great in molecular-biochemical data, since humans and chimpanzees have the same AB0 and rhesus blood group proteins, many enzymes, and the amino acid sequences of hemoglobin chains have only 1.6% differences, while with other monkeys this discrepancy somewhat more. And at the genetic level, the differences in the nucleotide sequences in DNA between these two organisms are less than 1%. If we take into account the average rate of evolution of such proteins in related groups of organisms, it can be determined that the ancestors of humans separated from other groups of primates about 6-8 million years ago.

The behavior of monkeys in many ways resembles that of humans, since they live in groups in which social roles are clearly distributed. Joint protection, mutual assistance and hunting are not the only goals of creating a group, since within it the monkeys feel affection for each other, express it in every possible way, and emotionally react to various stimuli. In addition, in groups there is an exchange of experience between individuals.

Thus, the similarity of humans with other primates, especially the higher narrow-nosed apes, is found at different levels of biological organization, and the differences between humans as a species are largely determined by the characteristics of this group of mammals.

The hypotheses of polycentrism and monocentrism belong to the group of hypotheses that do not question the origin of man from common ancestors with modern great apes.

Initial position polycentric hypothesis is the emergence and parallel evolution of the modern species of man in several regions of the world at once from different forms of ancient or even ancient man, but this contradicts the main provisions of the synthetic theory of evolution.

Hypotheses of a single origin of modern man, on the contrary, postulate the emergence of man in one place, but differ on where it happened. So, hypothesis of extratropical human origin is based on the fact that only the harsh climatic conditions of the high latitudes of Eurasia could contribute to the "humanization" of monkeys. The discovery in the territory of Yakutia of sites from the time of the ancient Paleolithic - the Deering culture, testified in its favor, but later it was established that the age of these finds is not 1.8–3.2 million years, but 260–370 thousand years. Thus, this hypothesis is also insufficiently confirmed.

The largest amount of evidence currently collected is in favor of hypothesis of human African descent, but it is not devoid of shortcomings, which are designed to take into account a complex broad monocentrism hypothesis, combining the arguments of the hypotheses of polycentrism and monocentrism.

Driving forces and stages in human evolution

Unlike other representatives of the animal world, in the process of his evolution, man was exposed to not only biological factors of evolution, but also social ones, which contributed to the emergence of a species of qualitatively new creatures with biosocial properties. Social factors led to a breakthrough into a fundamentally new adaptive environment, which provided enormous advantages for the survival of human populations and sharply accelerated the rate of its evolution.

Biological factors of evolution, which play a role in anthropogenesis to this day, are hereditary variability, as well as the flow of genes that supply the primary material for natural selection. However, isolation, population waves and gene drift have almost completely lost their significance as a result of scientific and technological progress. This gives reason to some scientists to believe that in the future, even minimal differences between representatives of different races will disappear due to their mixing.

Since changing environmental conditions forced human ancestors to descend from trees into open space, and switch to walking on two limbs, the released upper limbs were used by them to carry food and children, as well as make and use tools. However, such a tool can be made only if there is a clear idea of \u200b\u200bthe final result - the image of the object, therefore, abstract thinking also developed. It is well known that complex movements and the process of thinking are necessary for the development of certain areas of the cerebral cortex, which has happened in the process of evolution. However, it is impossible to inherit such knowledge and skills, they can only be transferred from one individual to another during the life of the latter, which resulted in the creation of a special form of communication - articulate speech.

Thus, the social factors of evolution should include human labor activity, abstract thinking and articulate speech. The manifestations of the altruism of the primitive man, who took care of children, women and people of old age, should not be discarded either.

The labor activity of a person not only influenced the appearance of himself, but also allowed at first to partially alleviate the conditions of existence through the use of fire, making clothes, building housing, and in the future, actively changing them by deforestation, plowing up land, etc. Since then, uncontrolled economic activity has put humanity in the face of a global catastrophe as a result of soil erosion, drying up of freshwater reservoirs, destruction of the ozone screen, which, in turn, can increase the pressure of biological factors of evolution.

Driopithecus, who lived about 24 million years ago, most likely was the common ancestor of humans and great apes. Despite the fact that he climbed trees and ran on all four limbs, he could walk on two legs, and carry food in his hands. The complete separation of the higher apes and the line leading to humans took place about 5-8 million years ago.

Australopithecus... From Dryopithecus, apparently, there was a genus ardipithecus, which formed over 4 million years ago in the savannas of Africa as a result of a cold snap and the retreat of forests, which forced these monkeys to move on their hind legs. This small animal, most likely, gave rise to a fairly numerous genus australopithecus ("Southern monkey").

Australopithecus appeared about 4 million years ago and lived in the African savannas and dry forests, where the benefits of bipedal movement were fully affected. From the Australopithecus went two branches - large herbivores with powerful jaws paranthropes and smaller and less specialized people... Over the course of a certain time, these two genera developed in parallel, which, in particular, manifested itself in an increase in the volume of the brain, and in the complexity of the tools used. The peculiarities of our family are the manufacture of stone tools (parantropes used only bone) and a relatively large brain.

The first representatives of the genus Man appeared about 2.4 million years ago. They belonged to the kind of man of skill (Homo habilis) and were short creatures (about 1.5 m) with a brain volume of about 670 cm 3. They used coarse gravel tools. Apparently, the representatives of this species had well-developed facial expressions and rudimentary speech. A skilled man left the historical scene about 1.5 million years ago, giving rise to the following species - a straightened person.

Man straightened (H. erectus) as a biological species formed in Africa about 1.6 million years ago and existed for 1.5 million years, quickly spreading over vast territories in Asia and Europe. A representative of this species from the island of Java was at one time described as pithecanthropus ("Monkey man") discovered in China was named sinanthropus, while their European counterpart is heidelberg man.

All these forms are also called archanthropics (by the most ancient people). A straightened man was distinguished by a low forehead, large brow ridges and a sloping chin backward, the volume of his brain was 900–1200 cm 3. The body and limbs of a straightened person resembled those of a modern person. Without a doubt, representatives of this family used fire and made double-edged chops. As recent finds have shown, this species even mastered navigation, because its descendants were found on remote islands.

Paleoanthropus. About 200 thousand years ago from the Heidelberg man came neanderthal man (H. neandertalensis)which belongs to paleoanthropus (to ancient people) who lived in Europe and Western Asia within 200-28 thousand years ago, including during the glacial epochs. They were strong, physically strong enough and hardy people with a large brain volume (even larger than that of a modern person). They had articulate speech, made sophisticated tools and clothing, buried their dead, and, perhaps, even had some rudiments of art. Neanderthals were not the ancestors of Homo sapiens, this group developed in parallel. Their extinction is associated with the disappearance of the mammoth fauna after the last glaciation, and possibly also the result of competitive displacement by our species.

The most ancient find of a representative homo sapiens is 195 thousand years old and comes from Africa. Most likely, the ancestors of modern man are not Neanderthals, but some form of archantropus, for example, Heidelberg man.

Neoanthrope. About 60 thousand years ago, as a result of unknown events, our species almost died out, so all the following people are descendants of a small group, which consisted of only a few dozen individuals. Having overcome this crisis, our species began to settle in Africa and Eurasia. It differs from other species in a more slender physique, a higher reproduction rate, aggressiveness and, of course, the most complex and most flexible behavior. People of the modern type who inhabited Europe 40 thousand years ago are called cro-Magnons and refer to neoanthropists (to modern people). They did not differ biologically from modern people: height 170–180 cm, brain volume about 1600 cm 3. The Cro-Magnons developed art and religion, they domesticated many species of wild animals and domesticated many species of plants. Modern people originated from Cro-Magnons.

Human races, their genetic relationship

During the resettlement of mankind across the planet, certain discrepancies arose between different groups of people regarding skin color, facial features, hair character, as well as the frequency of occurrence of certain biochemical features. The set of such hereditary traits characterizes a group of individuals of the same species, the differences between which are less significant than the subspecies - race.

The study and classification of races is complicated by the lack of clear boundaries between them. All modern mankind belongs to one species, within which three large races are distinguished: Australo-Negroid (black), Caucasoid (white) and Mongoloid (yellow). Each of them is divided into small races. Differences between races come down to features of skin color, hair, nose shape, lips, etc.

Australian negroid, or equatorial race characterized by dark skin color, wavy or curly hair, wide and slightly protruding nose, transverse nostrils, thick lips and a number of cranial signs. Caucasoid, or eurasian race characterized by light or dark skin, straight or wavy soft hair, good development of hair on the face of men (beard and mustache), a narrow protruding nose, thin lips and a number of cranial signs. Mongoloid (Asian American) race characterized by dark or fair skin, often coarse hair, medium width of the nose and lips, flattening of the face, strong protrusion of the cheekbones, relatively large size of the face, noticeable development of the "third century".

These three races also differ in settlement. Before the era of European colonization, the Australo-Negroid race was widespread in the Old World south of the Tropic of Cancer; Caucasoid race - in Europe, North Africa, Western Asia and Northern India; Mongoloid race - in Southeast, North, Central and East Asia, Indonesia, North and South America.

However, the differences between races concern only minor traits that have an adaptive meaning. So, the skin of Negroids gets burned at a tenfold higher dose of ultraviolet radiation than the skin of Caucasians, but Caucasians suffer less from rickets in high latitudes, where there may be a lack of ultraviolet radiation necessary for the formation of vitamin D.

Previously, some people sought to prove the perfection of one of the races in order to gain a moral advantage over others. At the present time, it is clear that racial characteristics reflect only the different historical paths of groups of people, but are in no way connected with the advantage or biological backwardness of one or another group. Human races are less well-defined than the subspecies and races of other animals, and can in no way be compared, for example, with breeds of domestic animals (which are the result of purposeful selection). Biomedical research shows that the effects of interracial marriage depend on the individual characteristics of the man and woman, and not on their race. Therefore, any prohibitions on interracial marriage or certain superstitions are unscientific and inhuman.

More specific than races, groups of people are nationalities - historically formed linguistic, territorial, economic and cultural communities of people. The population of a particular country forms its people. With the interaction of many nationalities, a nation may arise as part of a people. Now on Earth there are no "pure" races, and every sufficiently large nation is represented by people who belong to different races.

The biosocial nature of man

Undoubtedly, humans as a species must be under the pressure of evolutionary factors such as mutagenesis, population waves and isolation. However, as human society matures, some of them weaken, while others, on the contrary, intensify, since on the planet, captured by the processes of globalization, there are almost no isolated human populations in which closely related interbreeding takes place, and the number of the populations themselves is not subject to sharp fluctuations. Accordingly, the driving factor of evolution - natural selection - thanks to the success of medicine, no longer plays the role in human populations that is characteristic of it in populations of other organisms.

Unfortunately, the weakening of selection pressure leads to an increase in the frequency of hereditary diseases in populations. For example, in industrialized countries up to 5% of the population suffer from color blindness (color blindness), while in less developed countries this figure is up to 2%. The negative consequences of this phenomenon can be overcome thanks to preventive measures and progress in such areas of science as gene therapy.

However, this does not mean that human evolution is over, since natural selection continues to act, eliminating, for example, gametes and individuals with unfavorable gene combinations even at the pro-embryonic and embryonic periods of ontogenesis, as well as for resistance to pathogens of various diseases. In addition, the material for natural selection supplies not only the mutational process, but also the accumulation of knowledge, the ability to learn, the perception of culture and other traits that can be transmitted from person to person. Unlike genetic information, the experience accumulated in the process of individual development is passed on from parents to offspring, and in the opposite direction. And competition already arises between communities that are culturally different. This form of evolution, peculiar exclusively to humans, is called cultural, or social evolution.

Nevertheless, cultural evolution does not exclude biological, since it became possible only as a result of the formation of the human brain, and human biology itself is currently determined by cultural evolution, since in the absence of society and a variety of movements in the brain, certain zones are not formed.

Thus, a person has a biosocial nature, which leaves an imprint on the manifestation of biological, including genetic, laws that govern his individual and evolutionary development.

Social and natural environment, human adaptation to it

Under social environment understand, first of all, the social material and spiritual conditions of his existence and activity surrounding a person. In addition to the economic system, social relations, social consciousness and culture, it also includes the immediate environment of a person - family, working and student collectives, as well as other groups. The environment, on the one hand, has a decisive influence on the formation and development of the personality, and on the other hand, it itself changes under the influence of man, which entails new changes in people, etc.

The adaptation of individuals or their groups to the social environment for the realization of their own needs, interests, life goals and includes adaptation to the conditions and nature of study, work, interpersonal relationships, ecological and cultural environment, conditions of leisure and everyday life, as well as their active change for meet their needs. An important role in this is played by the change of oneself, one's motives, values, needs, behavior, etc.

Informational loads and emotional experiences in modern society are often the main cause of stress, which can be overcome with the help of clear self-organization, physical training and auto-training. In some, especially severe cases, it is required to consult a psychotherapist. An attempt to find oblivion of these problems in overeating, smoking, drinking alcohol and other bad habits does not lead to the desired result, but only aggravates the state of the body.

The natural environment has no less influence on man, despite the fact that man has been trying for about 10 thousand years to form a comfortable artificial environment for himself. So, climbing to a considerable height due to a decrease in the concentration of oxygen in the air leads to an increase in the number of red blood cells in the blood, increased respiration and heartbeat, and prolonged exposure to the sun contributes to increased skin pigmentation - tanning. However, the listed changes fit into the reaction norm and are not inherited. However, peoples who have lived in such conditions for a long time may have some adaptations. For example, among northern peoples, the nasal sinuses have a much larger volume for warming the air, and the size of the protruding parts of the body decreases to reduce heat loss. Africans are distinguished by darker skin color and curly hair, since the melanin pigment protects the organs of the body from the penetration of harmful ultraviolet rays, and the hair cap has thermal insulation properties. The light eyes of Europeans are an adaptation for a sharper perception of visual information at dusk and fog, and the Mongoloid eye shape is the result of natural selection for the action of winds and dust storms.

These changes take centuries and millennia, but life in a civilized society entails some changes. So, a decrease in physical activity leads to a lightening of the skeleton and a decrease in its strength, a decrease in muscle mass. Low mobility, an excess of high-calorie food, stress entail an increase in the number of overweight people, and high-grade protein nutrition and the continuation of daylight hours with the help of artificial lighting contribute to acceleration - acceleration of growth and puberty, an increase in body size.

Insert in the text "Lamarckism" the missing terms from the proposed list, using the numerical designations. Write down the numbers of the selected answers in the text, and then enter the resulting sequence of numbers (according to the text) into the table below. LAMARKISM

Lamarckism is an evolutionary concept based on a theory put forward at the beginning of the 19th century _________ (A) in the treatise "Philosophy of Zoology".

In a broad sense, Lamarckian refers to various evolutionary theories that arose in the 19th - first third of the 20th centuries, in which the internal desire for __________ (C) is considered as the main ____________ (B) force of evolution. As a rule, great importance in such theories is attached to the influence of __________ (D) organs on the evolutionary fate of organisms, since it is assumed that the consequences of exercise and non-exercise can be transmitted through _________________ (D).

LIST OF TERMS:

1) stabilizing

2) driving

3) inheritance

4) exercise

5) progress

AND	B	IN	D	D

Explanation.

Lamarckism is an evolutionary concept based on the theory put forward at the beginning of the 19th century by Lamarck in his treatise The Philosophy of Zoology.

In a broad sense, various evolutionary theories that arose in the 19th - first third of the 20th centuries, in which the internal striving for progress is considered as the main driving force of evolution, are referred to as Lamarckian. As a rule, great importance in such theories is attached to the influence of organ exercise on the evolutionary fate of organisms, since it is assumed that the consequences of exercise and non-exercise can be inherited.

Answer: 62543.

Answer: 62543

Source: RESHU OGE

Insert in the text "Darwinism" the missing terms from the proposed list, using the numerical designations. Write down the numbers of the selected answers in the text, and then enter the resulting sequence of numbers (according to the text) into the table below.

DARWINISM

Darwinism - named after the English naturalist _________ (A) - is the direction of evolutionary thought, the adherents of which agree with the main ideas of Darwin on the issue of evolution, according to which the main ___________ (B) of evolution is _______________ (C) selection. In a broad sense, it is often (and not entirely correctly) used to denote evolutionary doctrine or evolutionary biology in general. Darwinism is opposed to the ideas of ____________ (D) who believed that the main driving force of evolution is the inherent tendency of organisms to _____________ (D).

LIST OF TERMS:

1) property

3) perfection

4) artificial

5) natural

Write down the numbers in the answer, arranging them in the order corresponding to the letters:

AND	B	IN	D	D

Explanation.

Darwinism - named after the English naturalist Darwin - is a line of evolutionary thought whose adherents agree with Darwin's basic ideas on evolution, according to which natural selection is the main factor in evolution. In a broad sense, it is often (and not entirely correctly) used to denote evolutionary doctrine or evolutionary biology in general. Darwinism is contrasted with the ideas of Lamarck, who believed that the main driving force of evolution is the inherent desire for perfection in organisms.

Answer: 82563.

Answer: 82563

Source: RESHU OGE

1) the theory of transformism

2) Lamarck's evolutionary theory

3) Darwin's evolutionary teaching

4) the theory of creationism

5) synthetic theory of evolution

Explanation.

The theory of creationism - the theory of transformism - the evolutionary theory of Lamarck - the evolutionary doctrine of Darwin - the synthetic theory of evolution. Transformism is the doctrine of the continuous change of the species of the animal and plant kingdom and the origin of the forms of the organic world from one or more of the simplest forms.

Answer: 41235.

Establish a correspondence between the features of the evolutionary factor and the factors for which these features are characteristic.

Write down the numbers in the answer, arranging them in the order corresponding to the letters:

A	B	IN	D	D	E

Explanation.

Population waves: one of the sources of evolutionary material; represents fluctuations in population size, is random. Natural selection: the action of the factor is directed; provides selection of genotypes; changes the frequency of alleles in the gene pool of the population.

Answer: 112212.

Note.

Population waves or waves of life (S.S.Chetverikov) are called periodic or aperiodic fluctuations in the number of organisms in natural populations. This phenomenon applies to all species of animals and plants, as well as microorganisms. The reasons for the fluctuations are often ecological in nature. Thus, the size of the “prey” (hare) populations grows as the pressure on them from the “predator” populations (lynx, fox, wolf) decreases. An increase in food resources noted in this case contributes to an increase in the number of predators, which, in turn, intensifies the extermination of prey. Population gene pools change both on the rise and fall of the population wave.

a guest 08.06.2014 20:32

Allele frequencies in the gene pool of a population are altered by both population waves (undirectedly, can lead to gene drift) and natural selection (directed, leading to the formation of adaptations, etc.).

a guest 09.06.2014 00:19

It was incorrect to give item "E", since both population waves and natural selection alter the frequency of alleles in the population, i.e. her gene pool. Population waves change the gene pool in an undirected manner, due to gene drift during population decline, for example. As a result, any alleles can be fixed, regardless of their adaptive value. Incl. and harmful. And natural selection contributes to the accumulation of genes and gene complexes that ensure success in the struggle for existence, which leads to the emergence of adaptations, etc.

Alena Selezneva 13.06.2018 06:11

Population waves, like natural selection, change the frequency of alleles in the gene pool of the population (point E), why do you think natural selection is the correct answer, please explain

Natalia Evgenievna Bashtannik

Because it is more complete.

Insert in the text "Evolutionary doctrine" the missing terms from the proposed list, using numbers for this. Write down the numbers of the selected answers in the text, and then enter the resulting sequence of numbers (according to the text) into the table below.

EVOLUTIONARY TEACHING

The founder of modern evolutionary doctrine was ________ (A). Before him, ideas about the changeability of the world had already been expressed. However, it was Darwin who taught about ________ (B) and the survival of the organisms most adapted to ________ (C). Charles Darwin and at the same time Alfred Wallace explained the reasons for the emergence of the ________ (D) organic world.

LIST OF TERMS:

1) variety

2) Charles Darwin

3) natural selection

4) fitness

5) creation of the world

6) environmental conditions

7) spontaneous generation

Write down the numbers in the answer, arranging them in the order corresponding to the letters:

AND	B	IN	D

Explanation.

Charles Darwin was the founder of modern evolutionary teaching. Before him, ideas about the changeability of the world had already been expressed. However, it is Darwin who owns the doctrine of natural selection and survival of organisms most adapted to environmental conditions. Charles Darwin and at the same time Alfred Wallace explained the reasons for the emergence of the diversity of the organic world.

Answer: 2361.

Answer: 2361

Source: RESHU OGE

1. The first evolutionary concept belongs to Zh.B. Lamarck. 2. Lamarck was the first to put forward the idea of \u200b\u200bthe variability of living nature and its natural development. 3. He was the first to recognize natural selection and the direct influence of the environment on the organism as the driving forces of evolution. 4. In the middle of the 19th century, the English scientist Charles Darwin created an evolutionary doctrine, in which he called indefinite variability, the struggle for the existence and inheritance of acquired traits as the driving forces of evolution. 5. Charles Darwin in his doctrine argued that the formation of new species is based on the gradual accumulation of differences between individuals - the convergence of characters. 6. The results of evolution C. Darwin considered the diversity of species and the relative fitness of organisms.

Explanation.

Errors are contained in sentences 3, 4, 5.

1) 3 - the theory of natural selection was created by Charles Darwin;

2) 4 - the idea of \u200b\u200binheritance of acquired characteristics belongs to JB Lamarck;

3) 5 - Divergence is the cornerstone of evolutionary processes.

The accumulation of differences between individuals is not called convergence.

J. B. Lamarck in his teaching did not speak about the changeability of living nature. He talked about the variability of some species, moreover, speculatively established variability. For which he was criticized by biologists of that time. The narrowness of his views and the paucity of the empirical base were even ridiculed among scientists.

It is necessary to make adjustments to the proposal so as not to embarrass the deciding ones. In fact - 4 incorrect sentences out of six

Natalia Evgenievna Bashtannik

It is possible, if you correct 4 sentences without admitting biological errors, then it will be evaluated by 3 points

Select statements related to the synthetic theory of evolution.

1) Microevolution is a process that occurs in populations.

2) There is a struggle for existence between organisms.

3) The driving forces of evolution are indefinite variability, natural selection, the struggle for existence.

4) The main evolutionary directions are: aromorphosis, idioadaptation, degeneration.

5) Certain variability is not hereditary.

6) The species consists of populations.

Explanation.

The main provisions of the synthetic theory of evolution in general terms can be expressed as follows:

The material for evolution is hereditary changes - mutations (usually genetic) and their combinations.

According to STE, the driving forces of evolution include the mutational process, population waves, gene drift, isolation and natural selection. All of them, with the exception of natural selection, act randomly, not directed.

The smallest unit of evolution is the population.

In most cases, evolution is of a divergent character, i.e. one taxon can become the ancestor of several daughter taxa.

Evolution is gradual and long-term. Speciation as a stage in the evolutionary process is a sequential change of one temporary population by a succession of subsequent temporary populations.

The species consists of many subordinate, morphologically, physiologically, ecologically, biochemically and genetically distinct, but reproductively not isolated units - subspecies and populations.

The species exists as an integral and closed formation. The integrity of the species is maintained by migrations of individuals from one population to another, in which there is an exchange of alleles ("gene flow"),

Macroevolution at a higher level than a species (genus, family, order, class, etc.) proceeds by way of microevolution. According to the synthetic theory of evolution, there are no laws of macroevolution that differ from microevolution. In other words, the evolution of groups of species of living organisms is characterized by the same prerequisites and driving forces as for microevolution.

Any real (and not collective) taxon has a monophyletic origin. Evolution is undirected, that is, it does not go in the direction of any final goal.

Correct statements: microevolution is a process that occurs in populations; the main evolutionary directions (according to AN Severtsov) are: aromorphosis, idioadaptation, degeneration; a species consists of populations. Incorrect statements:

2) There is a struggle for existence between organisms - it is wrong, because the struggle for existence can be both interspecific and intraspecific and with unfavorable conditions.

3) The driving forces of evolution are indefinite variability, natural selection, the struggle for existence - these are the driving forces of evolution according to Darwin.

5) Certain variability is not hereditary - Certain, or group, modification variability is variability that occurs under the influence of some environmental factor that acts equally on all individuals - the statement is not true, since it is not a factor of evolution.

Answer: 146.

Answer: 146

1) the emergence of organisms on land

2) the occurrence of photosynthesis

3) formation of the ozone screen

4) formation of coacervates in water

5) the emergence of cellular life forms

Explanation.

Evolutionary processes on Earth in chronological order: the formation of coacervates in water → the emergence of cellular life forms → the emergence of photosynthesis → the formation of the ozone screen → the emergence of organisms on land.

Answer: 45231.

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Natalia Evgenievna Bashtannik

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Natalia Evgenievna Bashtannik

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{!LANG-86e4922bf999181d14bb5e6f9fb5346d!}

{!LANG-9d8cb1d0a553d23d27221422c620b5b9!}

{!LANG-c0062015e0245b312640fd4c8a730598!} {!LANG-067fa598c60cd3d0279e1fff2b6e5b0e!} .

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– natural selection{!LANG-f265221c9c0ba5898de8c586d9f97609!}

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{!LANG-2cc89056385607e91ca1c8361d64bc7a!} {!LANG-8678381a0644a78507403aad78013928!}

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{!LANG-ec4b083548ee57c0faace7d643771d88!}

– {!LANG-feda7db231db24396965fc3d90d4c9e7!}{!LANG-4f6487fd51567e5630048a497608e1c4!}

– {!LANG-357f56112ee9d66935b060e091a39665!}{!LANG-07e5f9d3f82a3d861d3f1f6e3cff1dd9!} convergence;

{!LANG-8ae795e92641d266bc8443951950d351!}

{!LANG-0baf8e653d4f7db5cfcad4a5b47796a1!}

{!LANG-26b63a76a55d1c9b936b72751faa2c4a!} {!LANG-00dcec83d7db4caf10bb9da9870c74ab!}

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{!LANG-a564b2815c58f1636fcccf69381dc68c!}

{!LANG-7fc425bfa48c8793965ea3634673c5ac!} {!LANG-113ffedf7164eef92691dc3f0dcef540!}

{!LANG-b0797ff0ff41eef605c9af8efc743df4!}

{!LANG-830b6418541232e80c36d3702eb0ea42!}

{!LANG-8fc8d7ae76f1540401867285154e4879!}

{!LANG-ed65927758387b5d99d3a3808d509fe8!}

{!LANG-80e9b5548430de7edbf1e34c44dd1dde!}

{!LANG-56f376e5746ae85eeeaadaa2b7770313!}

Paleontological evidence {!LANG-106883ed43dcc0b8041a9f6f086c1164!}

{!LANG-272246b80abc19c17ccbc937e4793fa1!}

{!LANG-26ba1fbd76fe80e3181f9a0bcc34202e!}

{!LANG-867641fb058b6134acf84710fb080d1d!}

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{!LANG-7d114152a0298b6891579ee65ed52814!}

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{!LANG-590a81431ccff67d93df22f5ae7d5fd2!}

{!LANG-7b8eac091314a234f6c551ddc394f9bf!}

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