Why is Charles Darwin considered the founder of the doctrine of evolution? Charles Darwin is the founder of the theory of evolution. What will the man of the future be like as a result of evolution?
Based on vast factual material and the practice of breeding work to develop new varieties of plants and animal breeds, Charles Darwin formulated the basic principles of his evolutionary theory.
First the principle postulates that variability is an integral property of living things. In nature, it is impossible to find two completely identical, identical organisms. At a superficial glance, it may seem, for example, that all the trees in a pine forest are the same, but one pine produces larger seeds, another is able to better tolerate drought, the third has a higher content of chlorophyll in its needles, etc. etc. Under extremely unfavorable conditions, every tiny difference like this can become the decisive change that determines whether the organism will survive or be destroyed.
Charles Darwin distinguishes two types variability. TO first type – individual or uncertain variability - he refers to that which is inherited. Second type - certain, or group variability. It affects those groups of organisms that are exposed to a certain environmental factor. Subsequently, undefined changes were usually called mutations, and definite changes - modifications.
Second principle Darwin's theory - the principle of the struggle for existence. He proceeds from the fact that, on the one hand, all types of organisms tend to reproduce in geometric progression, and on the other hand, they survive and reach maturity only in arithmetic progression, i.e. a small part of the offspring.
Thus, many plants produce tens and hundreds of thousands of seeds, and fish lay from several hundred to several million eggs. It is under these conditions that the struggle for existence unfolds. Distinguish interspecific And intraspecific struggle, and the most fierce struggle arises between similar organisms, since they are the ones who have the same needs.
Third principle usually called the principle of natural selection, which plays a fundamental role in the theory of evolution not only of Darwin, but also of most theories that appeared later. Darwin put forward a general hypothesis according to which there is in nature special selection mechanism. This mechanism, according to Darwin, is a consequence of “one general law that determines the progress of all organic beings, namely, reproduction, change, survival of the strongest and death of the weakest.”
Darwin emphasizes such characteristics of natural selection as the gradual process of change and the ability to sum up these changes into decisive changes that ultimately lead to the formation of new species. In contrast to supporters of the idea of catastrophism, Darwin draws attention specifically to gradual the nature of changes in biology: “Expressing metaphorically, we can say that natural selection daily and hourly investigates the smallest changes throughout the world, discarding the bad ones, preserving and adding the good ones, working silently and invisibly, wherever and whenever the opportunity presents itself, on the improvement of every organic being in connection with the conditions of its life, organic and inorganic."
The weak point of Charles Darwin's teachings was the idea of heredity. Indeed, if evolution is associated with random the appearance of useful changes and the hereditary transmission of acquired characteristics to offspring, then how they can be preserved and even intensify further? Indeed, as a result of crossing individuals with useful traits with other individuals that do not possess them, they will pass on these traits to their offspring in a weakened form. Over the course of a number of generations, beneficial changes that have arisen by chance should gradually weaken, and then completely disappear.
Darwin himself was forced to admit these arguments were very convincing, although they questioned precisely basic principle of Darwin's theory of evolution - natural selection. Meanwhile, real facts showed that such selection occurs everywhere. Subsequently, some other shortcomings of Darwin's theory were identified regarding the main causes and factors of organic evolution. It became obvious that this theory needed further development. development and justification taking into account subsequent advances in biology, and primarily genetics.
And the history of the formation of evolutionary teaching
Chapter 10. History of the formation of evolutionary teaching
10.1. Pre-Darwinian period of formation of the evolutionary idea
The basis of evolutionary teaching is the recognition of the historical development of living things. Evolution is understood as an irreversible gradual process of historical changes in living things. The first ideas about the historical change of living organisms go back centuries. 2000 BC In China, there were teachings that allowed the transformation of some organisms into others. Ideas, although rather naive, about the development of living things can be found in the works of ancient authors of Ancient Greece. Thus, Anaximander (610-546 BC) believed that man descended from fish. Empedocles (483-423 BC) expressed the idea of the natural development of living nature, of the survival of those who are most efficiently constructed. In the writings of Aristotle (384-322 BC), nature is considered in accordance with gradations of perfection.
The ideas about the changeability of living beings were opposed by those that had prevailed for many centuries and were always supported by the church ideas about the emergence of living things as a result of an act of creation, about the constancy and immutability of everything that exists, which were later united by the idealistic movement -creationism. The ideas of creationism dominated during the Middle Ages, and even the Renaissance, which generally contributed to the development of natural science, was characterized by metaphysical views and teleological explanations of the original purposefulness of everything created by a higher being. The creator of the classical system of the living world, the 18th-century Swedish naturalist Carl Linnaeus (1707-1778), was also a convinced creationist, who argued that “species are extremely constant.”
In the second half of the 18th century, ideas spread in natural science transformism. One of the major transformists was J. Buffon (1707-1788), who in his “Natural History” expressed bold ideas about the formation of the Earth as a result of a cosmic catastrophe, about the origin of “grains of living matter” under the influence of heat, about the appearance of a few species, their modification into numerous species under the influence of environmental factors. Ideas close to the views of J. Buffon were expressed in verse in the poem “The Temple of Nature” by Erasmus Darwin (1731-1803), the grandfather of Charles Darwin. D. Diderot, E. Geoffroy Saint-Hilaire, K.F. contributed to the development of transformism. Roulier et al.
Transformism, like the first evolutionary ideas in general, was developed and spread in Russia thanks to the efforts of M.V. Lomonosov, A.N. Radishcheva, K.F. Wolf, A.A. Kaverzneva. According to M.V. Lomonosov, the world has “great antiquity”, the surface of the Earth, plants and animals were constantly changing.
A.N. Radishchev (1749-1808) built a system based on materialistic ideas "staircase of substances" reflecting the complication of natural objects, ranging from minerals to humans. The steps of the ladder correspond to significant stages in the development of nature - the transformation of inorganic substances into organic ones, the emergence of new qualities in living beings, including sensation, thinking, etc.
A.A. Kaverznev, in his dissertation “On the Rebirth of Animals,” substantiated the assumption that domestic animals descended from wild ancestors, and all animals descended from one trunk. Explaining the fact of animal variability, A.A. Kaverznev attached great importance to the direct influence of environmental factors on organisms- climate, food, temperature.
WITH Jean Baptiste Lamarck (1744-1829)
Progressive evolution as the emergence of more complex and advanced forms of J.B. Lamarck explained "law of gradations" - the desire of living beings to complicate their structure.Once they have arisen, adaptive changes can then, in his opinion, be inherited (the concept of “inheritance of acquired characteristics”). This is how a system of views on the evolutionary process emerged, called Lamarckism.
Reasons for evolution J.B. Lamarck believed that all living organisms strive for progress, development from simple to complex, as well as expedient changes in organisms aimed at adapting to external conditions.Changes these, as stated by Zh.B. Lamarck,are caused by the direct influence of the external environment, the exercise of organs and the inheritance of characteristics acquired during life. According to Zh.B. Lamarck, the influence of external conditions on animals with a central nervous system is carried out indirectly through a primary change in needs and habits, which causes new forms of activity and, as a consequence, intensive exercise of some organs and relative inactivity of others. Exercise of organs stimulates their development and enlargement, and lack of exercise leads to underdevelopment, reduction and often disappearance. The result of this are changes in the shape and structure of the body, which are inherited and thus fixed in the offspring. The dependence of the state of organs on their exercise and the preservation of changes in the offspring are known as the two laws of Zh.B. Lamarck. First Law States that In every animal, more frequent and longer use of organs leads to their enlargement and, conversely, non-use leads to a decrease or disappearance of the organs.Second Law reads: everything that is acquired by organisms under the influence of external conditions, as a result of exercise, or lost due to disuse, is inherited by descendants. Thus, the long neck of giraffes Zh.B. Lamarck explained that they constantly stretch it, trying to reach the leaves located higher and higher in the tree crown (Fig. 130). With such constant exercises some lengthening of the neck can be achieved, but these changes are not transmitted to the offspring. Since the exercise of organs does not affect the structure of germ cells, and only characteristics caused by mutations are inherited, At present, Lamarck's laws have only historical interest.Their progressive significance for their era lies in the recognition of the variability of species and in an attempt to search for a material factor (changing environmental conditions) to explain the historical changes of organisms, which at one time served as the starting point for Darwinism.
Contribution of J.B. Lamarck's contribution to evolutionary teaching as a whole is enormous. He created the first evolutionary concept during the period of dominance of metaphysical and creationist ideas, proclaiming the principle of the variability of species. His concept is fundamentally materialistic, although in recognizing such a property of organisms as a tendency towards improvement, idealism manifested itself, and concessions were made to the idealistic worldview that was dominant at that time. It was also wrong for him to deny
Rice. 130. Evolution of the long neck in giraffes from a Lamarckian point of view
reality of species existence. Contemporaries did not accept the evolutionary teachings of J.B. Lamarck, in which the unconvincingness of his arguments and the speculative nature of his judgments undoubtedly played a role.
Even before the publication of Charles Darwin’s main work, the famous Russian scientist K.M. Baer (1792-1876) held views on the variability of species. His law of “germinal similarity,” a statement about the similarity of individual development of organisms, essentially anticipated the “biogenetic law” formulated later by E. Haeckel and F. Muller.
Professor of Moscow University K.F. Roulier (1814-1858), on the basis of paleontological, comparative anatomical and embryological studies, independently came to the idea of evolution. In his work “On the Animals of the Moscow Province” he wrote that the development of animals is determined by the changing external environment. K.F. Roulier argued that nature changed many times, plants and animals gradually developed and became more complex, and this complication culminated in the appearance of man.
Charles Darwin is the founder of modern evolutionary theory. In 1859, Charles Darwin published the work “The Origin of Species by Natural Selection or the Preservation of Favored Breeds in the Struggle for Life,” in which he presented the results of his many years (more than 20 years) of special research into the evidence of evolution.
To explain the process of evolution in the organic world, Darwin explores four main interrelated factors (properties of living things): variability, heredity, struggle for existence And natural selection. He counted them driving forces of evolution .
When comparing two or more individuals of the same species, it is easy to discover that they always have some differences from each other - in color or size, habits, fertility and other characteristics. Based on such differences in individual individuals of the species, Darwin states that organisms of each species are characterized by variability . Since some of the characters appearing in the offspring were also observed in their parents, Darwin concludes that the individuals received these characters from their parents thanks to heredity . Changes that can be inherited are found in every species, especially if reproduction is sexual. Darwin proposed that some changes (variations) in heredity help individuals survive in certain environmental conditions, while other hereditary properties do not.
Based on a large number of examples, Darwin also notes that each pair of organisms can give rise to a significant number of descendants (animals lay many eggs and eggs, plants produce many seeds and spores), but only a small part of them survive. Most individuals die without reaching not only sexual maturity, but also adulthood. The causes of death are unfavorable environmental conditions: lack of food, enemies, disease or heat, drought, frost, etc. On this basis, Darwin comes to the conclusion that in nature there is a continuous struggle for existence (Fig. 46). It is conducted between individuals of different species ( interspecies struggle for existence), and between individuals of the same species ( intraspecific struggle for existence). Another manifestation of the struggle for existence is the struggle with inanimate nature.
Fig.46. Struggle for existence: 1 - interspecific struggle (cheetah catches up with antelopes);
2 - fight against inanimate nature (the shape of the crown of a tree growing in places blown by strong winds);
3 - intraspecific struggle (same-aged spruce trees in dense growth)
As a result of the struggle for existence, some variations of traits in one individual give it a survival advantage compared to other individuals of the same species that have other variations of inherited traits. Some individuals with unfavorable variations die. Charles Darwin called this process natural selection . Inherited traits that increase the likelihood of survival and reproduction of a given organism, transmitted from parents to offspring, will occur more and more often in subsequent generations (since there is a geometric progression of reproduction). As a result, over a period of time, there are many such individuals with new characteristics and they turn out to be so different from the organisms of the original species that they already represent individuals of a new species. Darwin argued that natural selection is the general way of creating new species.
The kingdom of mushrooms, their characteristic features, obtaining food and medicine from them. By what signs can you distinguish edible mushrooms from poisonous ones using a collection of dummies? What first aid should be provided for mushroom poisoning?
The fungal organism, the mycelium, is formed by thin branching threads - hyphae. Cap mushrooms form a fruiting body consisting of tightly fitting mycelium filaments. Mushrooms reproduce by parts of mycelium or spores. Fruit mushrooms serve as a food product and contain valuable proteins and acids. Porcini mushrooms, saffron milk caps, etc. are especially valued. Although there is evidence that mushroom proteins are absorbed by the human body very little, less than 10%, especially the mushroom stem. Mushrooms are dried, salted, pickled. It is not recommended to preserve mushrooms at home, because... Without air access, botulism can develop on protein products, especially those growing on the ground, leading to severe poisoning.
Most poisonous mushrooms belong to the lamellar mushrooms, although among the tubular mushrooms in some areas there are inedible ones, which you need to know when going for mushrooms. In case of mushroom poisoning, abdominal pain, vomiting, diarrhea, and dizziness occur. It is necessary to do a gastric lavage, take several tablets of activated carbon and call a doctor.
Molds secrete substances that suppress the vital activity of microorganisms with which the fungi compete for food. Such mushrooms are used to obtain medicines - antibiotics: penicillin, erythromycin, tetracycline, etc., which have saved many human lives.
Explain the purpose of measuring a person’s pulse. What is pulse? Where is it determined and what can you find out from the pulse? Count your pulse. Determine if there are deviations from the norm. Explain your answer.
Pulse is measured to judge the state of the cardiovascular system in medicine and sports. The pulse is a vibration of the walls of blood vessels, a wave that propagates along the elastic walls of the arteries when the left ventricle contracts. The pulse can be easily felt in those places where the arteries pass close to the surface of the body, for example on the wrist, on the neck. Using the pulse, you can find out the frequency of heart contractions, the correctness of the rhythm, evaluate their strength, and roughly judge the height of blood pressure. In painful conditions, the pulse becomes sluggish and difficult to palpate.
In an adult, a normal heart rate at rest is 60-80 beats per minute. (In trained athletes, the frequency can decrease to 40 beats per minute.) In children, the frequency is higher. The pulse rate increases significantly during physical activity or under conditions of nervous tension, for example, during an exam, after smoking, drinking coffee, strong tea.
Introduction
1. Charles Darwin - founder of the theory of evolution
2. Causes and forms of the “struggle for existence” in living nature
3. The theory of natural selection, forms of natural selection
4. The role of hereditary variability in the evolution of species
Conclusion
INTRODUCTION
For the first time, the term “evolution” (from the Latin evolutio - deployment) was used in one of the embryological works by the Swiss naturalist Charles Bonnet in 1762. Currently, evolution is understood as an irreversible process of change in any system that occurs over time, due to which something arises. something new, heterogeneous, standing at a higher stage of development.
The process of evolution concerns many phenomena occurring in nature. For example, an astronomer talks about the evolution of planetary systems and stars, a geologist - about the evolution of the Earth, a biologist - about the evolution of living beings. At the same time, the term “evolution” is often applied to phenomena that are not directly related to nature in the narrow sense of the word. For example, they talk about the evolution of social systems, views, some machines or materials, etc.
The concept of evolution takes on special meaning in natural science, where biological evolution is studied primarily. Biological evolution is the irreversible and to a certain extent directed historical development of living nature, accompanied by changes in the genetic composition of populations, the formation of adaptations, the formation and extinction of species, transformations of biogeocenoses and the biosphere as a whole. In other words, biological evolution should be understood as the process of adaptive historical development of living forms at all levels of organization of living things.
The theory of evolution was developed by Charles Darwin (1809-1882) and outlined in his book “The Origin of Species by Means of Natural Selection, or the Preservation of Favored Breeds in the Struggle for Life” (1859).
1. C. DARWIN - FOUNDER OF THE THEORY OF EVOLUTION
Charles Darwin was born on February 12, 1809. in the family of a doctor. While studying at the universities of Edinburgh and Cambridge, Darwin gained a deep knowledge of zoology, botany and geology, and a skill and taste for field research.
The book of the outstanding English geologist Charles Lyell, “Principles of Geology,” played a major role in the formation of his scientific worldview. Lyell argued that the modern appearance of the Earth took shape gradually under the influence of the same natural forces that operate at the present time. Darwin was familiar with the evolutionary ideas of Erasmus Darwin, Lamarck and other early evolutionists, but he did not find them convincing.
The decisive turn in his fate was his trip around the world on the Beagle ship (1832-1837). Observations made during this journey served as the foundation for the theory of evolution. According to Darwin himself, during this journey he was most impressed by: “1) the discovery of giant fossil animals that were covered with a shell similar to the shell of modern armadillos; 2) the fact that as we move across the continent of South America, closely related animal species replace one another; 3) the fact that closely related species of various islands of the Galapagos archipelago differ slightly from each other. It was obvious that these kinds of facts, as well as many others, could only be explained on the basis of the assumption that species were gradually changing, and this problem began to haunt me.
Upon returning from his voyage, Darwin begins to ponder the problem of the origin of species. He considers various ideas, including Lamarck's idea, and rejects them, since none of them explains the facts of the amazing adaptability of animals and plants to their living conditions. What the early evolutionists thought was a given and self-explanatory seems to be the most important question for Darwin. It collects data on the variability of animals and plants in nature and under domestication. Many years later, recalling how his theory arose, Darwin would write: “I soon realized that the cornerstone of man’s success in creating useful races of animals and plants was selection. However, for some time it remained a mystery to me how selection could be applied to organisms living under natural conditions." Just at that time, the ideas of the English scientist T. Malthus about increasing the number of populations in geometric progression were vigorously discussed in England. “In October 1838 I read Malthus’s On Population,” continues Darwin, “and as, from long observations of the mode of life of animals and plants, I was well prepared to appreciate the significance of the universal struggle for existence, I was immediately struck by the thought that under such conditions favorable changes should tend to persist, and unfavorable ones to be destroyed. The result of this should be the formation of new species.”
So, the idea of the origin of species through natural selection arose from Darwin in 1838. He worked on it for 20 years. In 1856, on Lyell's advice, he began preparing his work for publication. In 1858, the young English scientist Alfred Wallace sent Darwin the manuscript of his article “On the Tendency of Varieties to Deviate Unlimitedly from the Original Type.” This article contained an exposition of the idea of the origin of species through natural selection. Darwin was ready to refuse to publish his work, but his friends geologist Charles Lyell and botanist G. Hooker, who had long known about Darwin’s idea and were familiar with the preliminary drafts of his book, convinced the scientist that both works should be published simultaneously.
Darwin's book, On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life, was published in 1859, and its success exceeded all expectations. His idea of evolution met with passionate support from some scientists and harsh criticism from others. This and Darwin’s subsequent works, “Changes in Animals and Plants during Domestication,” “The Descent of Man and Sexual Selection,” and “The Expression of the Emotions in Man and Animals,” were immediately translated into many languages after their publication. It is noteworthy that the Russian translation of Darwin’s book “Changes in Animals and Plants under Domestication” was published earlier than its original text. The outstanding Russian paleontologist V. O. Kovalevsky translated this book from the proofs provided to him by Darwin and published it in separate issues.
Darwin's evolutionary theory is a holistic doctrine of the historical development of the organic world. It covers a wide range of problems, the most important of which are evidence of evolution, identifying the driving forces of evolution, determining the paths and patterns of the evolutionary process, etc.
The essence of evolutionary teaching lies in the following basic principles:
1. All types of living beings inhabiting the Earth were never created by anyone.
2. Having arisen naturally, organic forms were slowly and gradually transformed and improved in accordance with environmental conditions.
3. The transformation of species in nature is based on such properties of organisms as heredity and variability, as well as natural selection that constantly occurs in nature. Natural selection occurs through the complex interaction of organisms with each other and with factors of inanimate nature; Darwin called this relationship the struggle for existence.
4. The result of evolution is the adaptability of organisms to their living conditions and the diversity of species in nature.
2. REASONS AND FORMS OF “STRUGGLE FOR EXISTENCE”
“Struggle for existence” is a concept Charles Darwin used to characterize the entire set of relationships between individuals and various environmental factors. These relationships determine the success or failure of a particular individual in surviving and leaving offspring. All living things have the potential to produce large numbers of their own kind. For example, the offspring that one daphnia (freshwater crustacean) can leave over the summer reaches an astronomical size, more than 10 30 individuals, which exceeds the mass of the Earth. However, unbridled growth in the number of living organisms is never actually observed. What is the reason for this phenomenon? Most individuals die at different stages of development and leave no descendants behind. There are many reasons that limit the growth of animal numbers: these are natural and climatic factors, and the fight against individuals of their own and other species.
Figure 1 - Action of the struggle for existence
It is known that the higher the reproduction rate of individuals of a given type, the more intense the death. Beluga, for example, spawns about a million eggs during spawning, and only a very small part of them reaches mature growth. Plants also produce huge quantities of seeds, but under natural conditions only a tiny fraction of them give rise to new plants. The discrepancy between the possibility of species for unlimited reproduction and limited resources is the main reason for the struggle for existence. The death of descendants occurs for various reasons. It can be either selective or random (in cases of floods, human intervention in nature, forest fire, etc.).
Figure 2 - Forms of the struggle for existence
Intraspecific struggle. The intensity of reproduction and selective death of individuals poorly adapted to changing environmental conditions are of decisive importance for evolutionary transformations. One should not think that an individual with an undesirable trait must certainly die. There is simply a high probability that she will leave behind fewer descendants or none at all, whereas a normal individual will reproduce. Consequently, the fittest always survive and reproduce. This is the main mechanism of natural selection. The selective death of some and the survival of other individuals are inextricably linked phenomena. It is in such a simple and at first glance obvious statement that the genius of Darwin’s idea of natural selection lies, i.e. in the reproduction of more adapted individuals that win the struggle for existence. The struggle of individuals within one species is of a very diverse nature.
Individuals not only compete for sources of food, moisture, sun and territory, but sometimes engage in direct combat.
In dioecious animals, males and females differ primarily in the structure of their reproductive organs. However, differences often extend to external signs and behavior. Remember the rooster’s bright outfit of feathers, a large comb, spurs on his legs, and huge singing. Male pheasants are very beautiful compared to the much more modest chickens. The canines of the upper jaws - tusks - grow especially strongly in male walruses. External differences in the structure of the sexes are called sexual dimorphism and are due to their role in sexual selection. Sexual selection is the competition between males for the opportunity to reproduce. This purpose is served by singing, demonstrative behavior, courtship, and often fights between males.
Sexual dimorphism and sexual selection are quite widespread in the animal world, including primates. This form of selection should be considered a special case of intraspecific natural selection.
The relationships of individuals within a species are not limited to struggle and competition. There is also mutual aid. Mutual assistance of individuals, delimitation of individual territories - all this reduces the severity of intraspecific interactions.
Mutual assistance is most clearly manifested in the family and group organization of animals. When strong and large individuals protect cubs and females, protect their territory and prey, contributing to the success of the entire group or family as a whole, often at the cost of their lives. The reproduction and death of individuals acquire a selective character through competition between genetically diverse individuals within a given population, therefore internal struggle is the most important reason for natural selection. The main engine of evolutionary transformations is the natural selection of the most adapted organisms that arise as a result of the struggle for existence.
Interspecies fight . Interspecific struggle should be understood as the struggle of individuals of different species. Interspecies struggle reaches particular severity in cases where species that live in similar ecological conditions and use the same food sources compete. As a result of interspecific struggle, either the displacement of one of the opposing species occurs, or the displacement of species to different conditions within a single area, or, finally, their territorial separation.
Two species of rock nuthatches can illustrate the consequences of the struggle between closely related species. In places where the ranges of these species overlap, i.e. Birds of both species live on the same theory; the length of their beaks and their ability to obtain food differ significantly. In non-overlapping habitat areas of nuthatches, no differences in beak length and food acquisition method are found. Interspecific struggle thus leads to ecological and geographical separation of species.
3. Combating unfavorable conditions of inorganic nature also enhances intraspecific competition, as individuals of the same species compete for food, light, warmth and other conditions of existence. It is no coincidence that a plant in the desert is said to fight drought. In the tundra, trees are represented by dwarf forms, although they do not experience competition from other plants. The winners in the fight are the most viable individuals (their physiological processes and metabolism proceed more efficiently). If biological characteristics are inherited, this will ultimately lead to the improvement of species adaptations to the environment.
3. THEORY OF NATURAL SELECTION
FORMS OF NATURAL SELECTION
Selection occurs continuously over an endless series of successive generations and preserves mainly those forms that are more consistent with given conditions. Natural selection and the elimination of some individuals of a species are inextricably linked and are a necessary condition for the evolution of species in nature.
The scheme of the action of natural selection in a species system according to Darwin comes down to the following:
1) Variation is characteristic of any group of animals and plants, and organisms differ from each other in many respects;
2) The number of organisms of each species that are born exceeds the number of those that can find food and survive. However, since the number of each species is constant under natural conditions, it should be assumed that most of the offspring die. If all the descendants of any species survived and reproduced, they would very soon supplant all other species on the globe;
3) Since more individuals are born than can survive, there is a struggle for existence, competition for food and habitat. This may be an active life-and-death struggle, or less obvious, but no less effective competition, as, for example, for plants during periods of drought or cold;
4) Among the many changes observed in living beings, some facilitate survival in the struggle for existence, while others lead to the death of their owners. The concept of "survival of the fittest" is the core of the theory of natural selection;
5) Surviving individuals give rise to the next generation, and thus “successful” changes are passed on to subsequent generations. As a result, each subsequent generation turns out to be more adapted to its environment; as the environment changes, further adaptations arise. If natural selection operates over many years, then the latest offspring may turn out to be so different from their ancestors that it would be advisable to separate them into an independent species.
It may also happen that some members of a given group of individuals acquire certain changes and find themselves adapted to the environment in one way, while other members, possessing a different set of changes, turn out to be adapted in a different way; In this way, from one ancestral species, provided that similar groups are isolated, two or more species can arise.
Driving selection. Natural selection always leads to an increase in the average fitness of populations. Changes in external conditions can lead to changes in the fitness of individual genotypes. In response to these changes, natural selection, drawing on the enormous pool of genetic diversity for many different traits, leads to significant shifts in the genetic structure of the population. If the external environment is constantly changing in a certain direction, then natural selection changes the genetic structure of the population in such a way that its fitness in these changing conditions remains maximum. At the same time, the frequencies of individual alleles in the population change. The average values of adaptive traits in populations also change. In a series of generations, their gradual shift in a certain direction can be traced. This form of selection is called driving selection.
A classic example of driving selection is the evolution of color in the birch moth. The color of the wings of this butterfly imitates the color of the lichen-covered bark of trees on which it spends the daylight hours. Obviously, such a protective coloration was formed over many generations of previous evolution. However, with the beginning of the industrial revolution in England, this device began to lose its importance. Atmospheric pollution has led to massive death of lichens and darkening of tree trunks. Light butterflies against a dark background became easily visible to birds. Beginning in the mid-19th century, mutant dark (melanistic) forms of butterflies began to appear in birch moth populations. Their frequency increased rapidly. By the end of the 19th century, some urban populations of the birch moth consisted almost entirely of dark forms, while rural populations continued to be dominated by light forms. This phenomenon has been called industrial melanism . Scientists have found that in polluted areas, birds are more likely to eat light-colored forms, and in clean areas, dark ones. The introduction of air pollution restrictions in the 1950s caused natural selection to reverse course again, and the frequency of dark forms in urban populations began to decline. They are almost as rare these days as they were before the Industrial Revolution.
Driving selection brings the genetic composition of populations into line with changes in the external environment so that the average fitness of populations is maximized. On the island of Trinidad, guppy fish live in different bodies of water. Many of those that live in the lower reaches of rivers and ponds die in the teeth of predatory fish. In the upper reaches, life for guppies is much calmer - there are few predators there. These differences in external conditions led to the fact that the “top” and “bottom” guppies evolved in different directions. The "lower ones", under constant threat of extermination, begin to reproduce at an earlier age and produce many very small fry. The chance of survival for each of them is very small, but there are a lot of them and some of them manage to reproduce. The “mountains” reach sexual maturity later, their fertility is lower, but their offspring are larger. When researchers transferred “low-growth” guppies to uninhabited reservoirs in the upper reaches of rivers, they observed a gradual change in the type of development of the fish. Eleven years after the move, they became significantly larger, began breeding later, and produced fewer but larger offspring.
The rate of change in allele frequencies in a population and the average values of traits under the influence of selection depends not only on the intensity of selection, but also on the genetic structure of the traits for which turnover occurs. Selection against recessive mutations turns out to be much less effective than against dominant ones. In a heterozygote, the recessive allele does not appear in the phenotype and therefore escapes selection. Using the Hardy-Weinberg equation, one can estimate the rate of change in the frequency of a recessive allele in a population depending on the intensity of selection and the initial frequency ratio. The lower the allele frequency, the slower its elimination occurs. In order to reduce the frequency of recessive lethality from 0.1 to 0.05, only 10 generations are needed; 100 generations - to reduce it from 0.01 to 0.005 and 1000 generations - from 0.001 to 0.0005.
The driving form of natural selection plays a decisive role in the adaptation of living organisms to external conditions that change over time. It also ensures the wide distribution of life, its penetration into all possible ecological niches. It is a mistake to think, however, that in stable conditions of existence natural selection ceases. Under such conditions, it continues to act in the form of stabilizing selection.
Stabilizing selection. Stabilizing selection preserves the state of the population that ensures its maximum fitness under constant conditions of existence. In each generation, individuals that deviate from the average optimal value for adaptive traits are removed.
Many examples of the action of stabilizing selection in nature have been described. For example, at first glance it seems that the greatest contribution to the gene pool of the next generation should be made by individuals with maximum fertility. However, observations of natural populations of birds and mammals show that this is not the case. The more chicks or cubs in the nest, the more difficult it is to feed them, the smaller and weaker each of them is. As a result, individuals with average fertility are the most fit.
Selection toward the mean has been found for a variety of traits. In mammals, very low- and very-high-weight newborns are more likely to die at birth or in the first weeks of life than average-weight newborns. A study of the size of the wings of birds that died after the storm showed that most of them had wings that were too small or too large. And in this case, the average individuals turned out to be the most adapted.
What is the reason for the constant appearance of poorly adapted forms in constant conditions of existence? Why is natural selection not able to once and for all clear a population of unwanted deviant forms? The reason is not only and not so much the constant emergence of more and more new mutations. The reason is that heterozygous genotypes are often the fittest. When crossed, they constantly split and their offspring produce homozygous offspring with reduced fitness. This phenomenon is called balanced polymorphism.
Sexual selection. Males of many species display clearly expressed secondary sexual characteristics that at first glance seem non-adaptive: the tail of a peacock, the bright feathers of birds of paradise and parrots, the scarlet crests of roosters, the enchanting colors of tropical fish, the songs of birds and frogs, etc. Many of these features complicate the life of their carriers and make them easily noticeable to predators. It would seem that these characteristics do not provide any advantages to their carriers in the struggle for existence, and yet they are very widespread in nature. What role did natural selection play in their emergence and spread?
It is known that the survival of organisms is an important, but not the only component of natural selection. Another important component is attractiveness to individuals of the opposite sex. Charles Darwin called this phenomenon sexual selection. He first mentioned this form of selection in On the Origin of Species and then analyzed it in detail in The Descent of Man and Sexual Selection. He believed that “this form of selection is determined not by the struggle for existence in the relations of organic beings among themselves or with external conditions, but by the competition between individuals of one sex, usually males, for the possession of individuals of the other sex.”
Sexual selection is natural selection for reproductive success. Traits that reduce the viability of their hosts can emerge and spread if the advantages they provide for reproductive success are significantly greater than their disadvantages for survival. A male who lives short but is liked by females and therefore produces many offspring has much higher overall fitness than one who lives long but produces few offspring. In many animal species, the vast majority of males do not participate in reproduction at all. In each generation, fierce competition arises between males for females. This competition can be direct, and manifest itself in the form of struggle for territory or tournament battles. It can also occur in an indirect form and be determined by the choice of females. In cases where females choose males, male competition manifests itself through displays of flamboyant appearance or complex courtship behavior. Females choose the males they like best. As a rule, these are the brightest males. But why do females like bright males?
The fitness of a female depends on how objectively she is able to assess the potential fitness of the future father of her children. She must choose a male whose sons will be highly adaptable and attractive to females.
Two main hypotheses about the mechanisms of sexual selection have been proposed.
According to the “attractive sons” hypothesis, the logic of female choice is somewhat different. If brightly colored males, for whatever reason, are attractive to females, then it is worth choosing a brightly colored father for his future sons, because his sons will inherit the brightly colored genes and will be attractive to females in the next generation. Thus, a positive feedback arises, which leads to the fact that from generation to generation the brightness of the plumage of males becomes more and more intense. The process continues to grow until it reaches the limit of viability. Let's imagine a situation where females choose males with a longer tail. Long-tailed males produce more offspring than males with short and medium tails. From generation to generation, the length of the tail increases because females choose males not with a certain tail size, but with a larger than average size. Eventually, the tail reaches a length where its detriment to the male's vitality is balanced by its attractiveness in the eyes of females.
In explaining these hypotheses, we tried to understand the logic of the actions of female birds. It may seem that we expect too much from them, that such complex calculations of fitness are hardly possible for them. In fact, females are no more or less logical in their choice of males than in all their other behavior. When an animal feels thirsty, it does not reason that it should drink water in order to restore the water-salt balance in the body - it goes to a watering hole because it feels thirsty. When a worker bee stings a predator attacking a hive, she does not calculate how much with this self-sacrifice she increases the overall fitness of her sisters - she follows instinct. In the same way, females, when choosing bright males, follow their instincts - they like bright tails. All those to whom instinct suggested a different behavior, all of them did not leave offspring. Thus, we were discussing not the logic of females, but the logic of the struggle for existence and natural selection - a blind and automatic process that, acting constantly from generation to generation, has formed all the amazing diversity of shapes, colors and instincts that we observe in the world of living nature .
4. ROLE OF HEREDITARY VARIATION IN THE EVOLUTION OF SPECIES AND ITS FORM
In Darwin's evolutionary theory, the prerequisite for evolution is hereditary variability, and the driving forces of evolution are the struggle for existence and natural selection. When creating an evolutionary theory, Charles Darwin repeatedly turned to the results of breeding practice. He showed that the diversity of varieties and breeds is based on variability. Variability is the process of the emergence of differences in descendants compared to ancestors, which determine the diversity of individuals within a variety or breed. Darwin believes that the causes of variability are the impact of environmental factors on organisms (direct and indirect), as well as the nature of the organisms themselves (since each of them specifically reacts to the influence of the external environment). Variation serves as the basis for the formation of new characteristics in the structure and functions of organisms, and heredity consolidates these characteristics. Darwin, analyzing the forms of variability, identified three among them: definite, indefinite and correlative.
Specific, or group, variability is variability that occurs under the influence of some environmental factor that acts equally on all individuals of a variety or breed and changes in a certain direction. Examples of such variability include an increase in body weight in animal individuals with good feeding, changes in hair coat under the influence of climate, etc. A certain variability is widespread, covers the entire generation and is expressed in each individual in a similar way. It is not hereditary, i.e., in the descendants of the modified group under other conditions, the characteristics acquired by the parents are not inherited.
Uncertain, or individual, variability manifests itself specifically in each individual, i.e. singular, individual in nature. It is associated with differences in individuals of the same variety or breed under similar conditions. This form of variability is uncertain, i.e., a trait under the same conditions can change in different directions. For example, one variety of plants produces specimens with different colors of flowers, different intensities of color of petals, etc. The reason for this phenomenon was unknown to Darwin. Uncertain variability is hereditary in nature, that is, it is stably transmitted to offspring. This is its importance for evolution.
With correlative, or correlative, variability, a change in any one organ causes changes in other organs. For example, dogs with poorly developed coats usually have underdeveloped teeth, pigeons with feathered feet have webbing between their toes, pigeons with a long beak usually have long legs, white cats with blue eyes are usually deaf, etc. Of the factors of correlative variability, Darwin makes an important conclusion: a person, selecting any structural feature, will almost “probably unintentionally change other parts of the body on the basis of mysterious laws of correlation.”
Having determined the forms of variability, Darwin came to the conclusion that only heritable changes are important for the evolutionary process, since only they can accumulate from generation to generation. According to Darwin, the main factors in the evolution of cultural forms are hereditary variability and selection made by humans (Darwin called such selection artificial). Variation is a necessary prerequisite for artificial selection, but it does not determine the formation of new breeds and varieties.
CONCLUSION
Thus, Darwin for the first time in the history of biology constructed the theory of evolution. This was of great methodological importance and made it possible not only to substantiate the idea of organic evolution clearly and convincingly for contemporaries, but also to test the validity of the theory of evolution itself. This was a decisive phase in one of the greatest conceptual revolutions in natural science. The most important thing in this revolution was the replacement of the theological idea of evolution as the idea of primordial purposiveness with the model of natural selection. Despite fierce criticism, Darwin's theory quickly gained recognition due to the fact that the concept of the historical development of living nature explained the observed facts better than the idea of \u200b\u200bthe immutability of species. To substantiate his theory, Darwin, unlike his predecessors, drew on a huge amount of facts available to him from a variety of areas. The highlighting of biotic relationships and their population-evolutionary interpretation was the most important innovation of Darwin's concept of evolution and gives the right to the conclusion that Darwin created his own concept of the struggle for existence, fundamentally different from the ideas of his predecessors. Darwin's doctrine of the evolution of the organic world was the first theory of development created “naturally historical materialism in the depths of natural science, the first application of the principle of development to an independent field of natural sciences.” This is the general scientific significance of Darwinism.
Darwin's merit lies in the fact that he revealed the driving forces of organic evolution. The further development of biology deepened and complemented his ideas, which served as the basis for modern Darwinism. In all biological disciplines, the leading place is now occupied by the historical method of research, which makes it possible to study specific paths of evolution of organisms and deeply penetrate into the essence of biological phenomena. The evolutionary theory of Charles Darwin has found wide application in modern synthetic theory, where the only guiding factor of evolution remains natural selection, the material for which is mutations. A historical analysis of Darwin's theory inevitably gives rise to new methodological problems of science, which can become the subject of special research. The solution to these problems entails an expansion of the field of knowledge, and, consequently, scientific progress in many areas: both in biology, medicine, and in psychology, on which Charles Darwin’s evolutionary theory had no less influence than on the natural sciences.
List of used literature
1. Alekseev V.A. Fundamentals of Darwinism (historical and theoretical introduction). - M., 1964.
2. Velisov E.A. Charles Darwin. Life, work and works of the founder of evolutionary teaching. - M., 1959.
3. Danilova V.S., Kozhevnikov N.N. Basic concepts of natural science. - M.: Aspect Press, 2000. - 256 p.
4. Dvoryansky F.A. Darwinism. - M.: MSU, 1964. - 234 p.
5. Lemeza N.A., Kamlyuk L.V., Lisov N.D. A guide for applicants to universities. - M.: Rolf, Iris-press, 1998. - 496 p.
6. Mamontov S.G. Biology: a guide for applicants to universities. -M.: Higher School, 1992. - 245 p.
7. Ruzavin G.I. Concepts of modern natural science: A course of lectures. - M.: Project, 2002. - 336 p.
8. Sadokhin A.P. Concepts of modern natural science. - M., 2005.
9. Slopov E.F. Concepts of modern natural science. - M.: Vlados, 1999. - 232 p.
10. Smygina S.I. Concepts of modern natural science. - Rostov n/d., 1997.
Abstract on the topic “Evolutionary teaching”
Plan
General characteristics of biology in the pre-Darwinian period.
Works of Carl Linnaeus.
Evolutionary ideas of J.-B. Lamarck.
Evolutionary ideas in Russia.
Historical and scientific prerequisites for the emergence of the teachings of Charles Darwin.
Charles Darwin is the founder of the theory of evolution.
The main provisions of the theory of evolution of Charles Darwin.
Synthetic theory of evolution (neo-Darwinism)
General characteristics of biology in the pre-Darwinian period
Evolution (from lat. evolutio - deployment) is an irreversible process of historical change in living things.
The evolutionary teachings of Charles Darwin were published in 1859. The entire history of biology from the moment of its inception to the publication of Darwin’s teachings is usually called the pre-Darwinian period. Several stages can be distinguished in the history of pre-Darwinian biology.
First stage The development of evolutionary ideas is associated with the activities of ancient philosophers (Heraclitus, Empedocles, Democritus, Lucretius, etc.), who expressed ideas about the variability of the surrounding world, including the historical transformations of organisms.
Aristotle (384-322 BC)– formulated the principles of classifying animals according to their structure, laid the foundations of ancient embryology.
Second phase comes with the establishment of the dominance of the Christian Church in Europe and the spread of a point of view based on biblical texts. The Church pursues the experimental study of nature, and the science of this period is characterized by a metaphysical worldview. The essence of the metaphysical worldview lies in the ideas of constancy, immutability and original purposefulness of all nature. The expression “original expediency” was understood as the complete compliance of an organism or organ with the goal allegedly set by the creator during its creation. All this was the ideological basis of creationism (from lat. creatio - a single act of creation), a direction in the development of biology, according to which all living things were created by God and remain unchanged. The metaphysical worldview was dominant in science until the middle of the 18th century.
Third stage pre-Darwinian biology is associated with a group of scientists who in the history of science were called transformists (from lat. transformo - I transform): R. Hooke, D. Diderot, J. Buffon, E. Geoffroy Saint-Hillaire, I. V. Goethe, C. F. Roulier and others, who were the immediate predecessors of Charles Darwin.
John Ray (1628 – 1705)– gave the first definition of the concept “species”.
Georges Buffon (1707-1788)– the main reasons for the variability of species are the direct influence of environmental conditions on the organism. 
Georges Cuvier (1769-1832)– animal organs are parts of one integral system, and the structure of each organ naturally correlates with the structure of all others (the principle of correlation). Author of the "catastrophe theory".
All these scientists were supporters of the variability of the organic world. They did not create a holistic system of views arguing for the idea of evolution, but at this stage the range of main problems of evolutionary teaching became clearer. What are these problems?
First, the essence and causes of evolution.
Secondly, the reasons for the expediency of the arrangement of organisms.
Thirdly, the reasons for the diversity of forms of organisms.
Fourthly, the reasons for the similarities and differences between different species, and finally, the reasons for the simultaneous existence of higher and lower organisms.
Thus, biology in the pre-Darwinian period was deprived of a coherent concept of evolution, but its development paved the way for the creation of the first evolutionary concepts.
2. Works of Carl Linnaeus.
The largest scientist of the pre-Darwinian period of biology was the Swedish naturalist and naturalist Carl von Linnaeus (1707-1778). Carl Linnaeus was a creationist, but this does not detract from his services to biology.
In 1735, Linnaeus's main work, The System of Nature, was published. In this work, Linnaeus presented a system of the organic world that was progressive for his time.
The merits of Carl Linnaeus include:
He established the universality and reality of species and identified their main feature (free crossing of individuals of the same species);
Introduced the basic units of taxonomy: species, genus, family, order, class;
He created a system of the organic world in which plants were divided into 24 classes: 23 classes of clairvoyance (flowering plants) and 1 class of cryptogamous plants (gymnosperms and spores). Among the phantoms, the first 12 classes were distinguished only by the number of stamens, the 13th included plants that had more than twelve stamens, and when classifying plants into classes 14-23, the structure of the androecium was also taken into account. Animals were divided into 6 classes (worms, insects, reptiles, fish, birds and mammals);
Introduced binary (double) nomenclature instead of cumbersome verbose (polynomial) names, which indicated the belonging of an organism to genus and species;
Described about 10 thousand species of plants and about 4.5 thousand species of animals;
Improved the botanical language, establishing up to 1000 terms;
For the first time he placed humans in the same order with monkeys on the basis of morphological similarity.
Thus, Carl Linnaeus is rightly called the father of systematics. His works contributed to the recovery of biology from the crisis and the accumulation of new knowledge.
Statement:Nature is unchanging, species exist in nature.
Evolutionary ideas of J.-B. Lamarck.
At the beginning of the 19th century, the French scientist Jean Baptiste Lamarck (1744-1829) created the first doctrine of the evolution of living nature, which he outlined in his work "Philosophy of Zoology" (1809).
Lamarck's theory is an orderly edifice of logical constructions that provide answers to most of the questions facing evolutionary teaching, but the answers to them are not taken from scientific facts, but are logically deduced from accepted postulates.
Driving forces of evolution Lamarck considered the innate abilities of organisms for self-improvement and expedient response to environmental conditions, that is, Lamarck decided the question of the driving forces of evolution from an idealistic position; he failed to see in nature itself the forces that cause variability in the organic world.
Directions of evolution Lamarck in his theory called gradations and deviations from gradations. The development of nature according to Lamarck began with the formation of the simplest living bodies from inorganic nature; its progression is from simple to complex. Lamarck called successive stages of increasing complexity in the organization of organisms gradations. Not all organisms manage to reach evolutionary heights, that is, gradations in their pure form rarely appear. Intervention in the evolution of environmental conditions leads to deviations from gradations. Lamarck explains the presence in nature, along with highly organized forms, of lowly organized forms by deviations from gradations. The process of development from lower to higher forms was reflected in Lamarck’s so-called “ladder of beings,” which is a classification of organic nature.
The results of evolution Lamarck called the emergence of adaptations of living organisms to environmental conditions and speciation. A change in environmental conditions causes an appropriate response on the part of the animal’s body, which manifests itself in increased use and development or disuse and weakening of one or another organ. Under the influence of constant exercise or lack of exercise, organs change, and the resulting changes are inherited, that is unit of evolution Lamarck believed separate organism.
Thus, Lamarck's theory is a speculative scheme. He could not correctly name the driving forces of evolution. The theory was not accepted by the majority of scientists of that time, since its contradictions and the instability of its arguments were obvious. But this was the first evolutionary theory in the history of biology.
Lamarck's errors:
The body's internal desire for progress.
Adaptation arises immediately under the influence of the external environment.
Only beneficial changes occur under the influence of external conditions.
He believed that there were no species in nature, but at the end of his life he recognized their existence.
Statement: Nature changes, but species do not exist.
Evolutionary ideas in Russia.
In Russia, since the 18th century, evolutionary ideas about nature have developed. The first Russian evolutionists include: M.V. Lomonosov, A.N. Radishchev, P.S. Pallas, A.A. Kaverznev and others. One of the outstanding predecessors of Charles Darwin was Moscow University professor Karl Frantsevich Roulier (1814- 1858).
Roulier's main views:
An organism cannot be studied in isolation from the environment in which it lives and with which it interacts;
As the environment changes, organisms either adapt to it or die;
The origin of species is associated with the struggle for food and participation in reproduction;
Man is related to animals;
Evidence of evolution is the fossil remains of animals, comparative data on the structure of modern animals, their embryonic development and changes in animals during domestication,
Conducted an anatomical comparison of extinct and living organisms.
Russian evolutionists:
Mikhail Vasilievich Lomonosov (1711-1765) - argued that changes in inanimate nature lead to changes in plants and animals. Living and inanimate nature as a single developing whole.
Alexander Nikolaevich Radishchev
(1749-1802) believed that nature develops from simple to complex substances. 
Afanasy Kaverznev
(late 18th early 19th centuries; exact dates unknown) - argued that species do exist in nature, but they are changeable. He raised the question that species come from one another and are related to each other, confirming with examples from human practice in breeding animal breeds. 
Historical and scientific prerequisites for the emergence of the teachings of Charles Darwin.
At the end of the 18th - beginning of the 19th centuries, the successes of the sciences punched a “gap” in the metaphysical view of nature. TO scientific premises The origins of Darwin's teachings can be attributed to:
Astronomy hypotheses about the origin of the Solar System from a gaseous nebula;
Geologists' discovery of the sequential formation of sedimentary layers of the earth's crust;
Identification by chemistry of the elementary unity of living and inanimate nature;
The discovery by physicists of the law of conservation and transformation of energy;
Advances in biology (development of comparative morphology, creation of cell theory, the emergence of paleontology, embryology and biogeography, etc.).
Charles Darwin (1809-1882) - founder of the doctrine of evolution.
Charles Darwin born in 1809. He was the son of a wealthy doctor and, like many great people, at first he did not particularly stand out as a scientist. In 1831, he accepted an offer to go as a naturalist (without salary) on a voyage on the warship Beagle, which went to sea for five years to conduct topographic surveys off the east coast of South America. The Beagle returned to Falmouth in October 1836, having traveled along the coast of Chile, through the Galapagos Islands, Tahiti, New Zealand, Tasmania and South Africa. Darwin spent most of this time engaged in geological research; however, during a five-week stay in the Galapagos Islands, his attention was drawn to the similarities between the flora and fauna of these islands and the mainland. He was especially interested in the distribution turtles And finches. He collected a lot of data on the variability of organisms, which convinced him that species cannot be considered immutable. 
After returning to England, Darwin began studying the breeding practices of pigeons and other domestic animals, which led him to the concept of artificial selection, but he still could not imagine how selection could operate under natural conditions. In 1778 the priest Thomas Malthus published his work "Treatise on Population" , in which he vividly outlined what population growth could lead to if it were left unchecked. Darwin transferred his reasoning to other organisms and drew attention to the fact that despite their high reproductive potential, population sizes remain relatively constant. Comparing a huge amount of information, he began to understand that in conditions of intense competition between members of the population, any changes favorable for survival in these conditions would increase the ability of the individual to reproduce and leave fertile offspring, and unfavorable changes, obviously, are unfavorable for the organisms that possess them the chances of successful reproduction would decrease.
These considerations formed the basis for the theory of evolution by natural selection, formulated by Darwin in 1839. In essence, Darwin's greatest contribution to science was not that he proved the existence of evolution, but that he explained how it could occur.
Meanwhile, another naturalist, Alfred Russell Wallace, who traveled extensively in South America and the islands of Southeast Asia and also read Malthus, came to the same conclusions about natural selection as Darwin. 
In 1858, Wallace outlined his theory in 20 pages and sent them to Darwin. This stimulated and encouraged Darwin, and in July 1858 Darwin and Wallace gave presentations on their ideas at a meeting of the Linnean Society in London. A little over a year later, in November 1859, Darwin published On the Origin of Species by Means of Natural Selection. All 1,250 copies of the book were sold on the first day, and it is said to be second only to the Bible in its impact on human thinking.
He outlined his views on the theory of evolutionVworks:
1859 - “The Origin of Species by Means of Natural Selection”
1869 - “Change in plant varieties and animal breeds”
1871 - “The Descent of Man and Sexual Selection”
Darwin's theory is one of the three greatest discoveries of the 19th century after the law of conservation of energy, cell theory (Karl Marx)
The main provisions of the theory of evolution of Charles Darwin.
C. R. Darwin's main book, “The Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life,” made a genuine revolution in natural science. It was published on November 24, 1859. In this book, Darwin outlined his views on the problem of the evolution of the organic world.
The main provisions of Charles Darwin's theory can be summarized as follows:
Each species is capable of unlimited reproduction;
Limited vital resources prevent the realization of the potential for reproduction;
The consequence of the discrepancy between the intensity of reproduction and the means of life is the struggle for existence, in which the majority of individuals die, leaving no offspring;
In the struggle for existence, those organisms that are better adapted to environmental conditions survive. Charles Darwin called the selective survival and reproduction of the most adapted organisms natural selection;
Under the influence of selection occurring under different environmental conditions, groups of individuals from generation to generation accumulate different adaptations, and this can lead to the formation of a new species.
Synthetic theory of evolution (neo-Darwinism)
Currently the most generally accepted is synthetic theory of evolution(STE). STE arose in the early 40s. This is the doctrine of the evolution of the organic world, developed on the basis of data from modern genetics, ecology and classical Darwinism. The term comes from the title of the book by English evolutionist Julian Huxley - “Evolution: A Modern Synthesis” (1942). 
Postulates of STS
Mutations serve as the material for evolution. Mutational variability has a directed and non-directional character.
The driving factor of evolution is natural selection, which arises on the basis of the struggle for existence.
The smallest evolutionary unit is a population.
Evolution is divergent in nature, i.e. one taxon can become the ancestor of several daughter taxa, but each species has a single ancestral species, a single ancestral population.
Evolution is gradual and long-term. Speciation is a stage of evolution - the subsequent replacement of a temporary population by a series of other temporary populations.
A species consists of many subordinate morphological, biochemical, ecological, genetically distinct, but not reproductively isolated units - subspecies and populations. However, many species are known with limited ranges and therefore it is not possible to divide the species into independent subspecies, and relict species may consist of a single population.
The species exists as a holistic and closed entity. The integrity of the species is maintained by migrations of individuals from one population to another, in which an exchange of alleles (“gene flow”) is observed,
Since the main criterion of a species is its reproductive isolation, it is not applicable to prokaryotes and lower eukaryotes, i.e. who do not have sexual intercourse.
Macroevolution at a level above the species (genus, family, order, class, etc.) proceeds only through microevolution. According to STE, there are no patterns of macroevolution different from microevolution.
Any real taxon (and not a composite one) is of monophyletic origin.
Evolution is undirected, i.e. does not go towards any final goal. Evolution is not finalistic.
STE revealed the deep mechanisms of the evolutionary process, accumulated many new factors and evidence of the evolution of living organisms, and combined data from many biological sciences. Nevertheless, STE (neo-Darwinism) is in line with the ideas and directions that were laid down by Charles Darwin.
Further development of evolutionism.
In the years since the postulates of STE were formulated, evolutionary biology has continued to develop. Changes have been made to some provisions of the STE in accordance with the modern level of scientific development. Let's take a look at these changes and clarifications.
Natural selection is undoubtedly recognized as the driving factor, but not the only one. Genetic drift plays a formative role in small isolated populations.
Evolution is not always divergent and gradual. Speciation through chromosomal rearrangements, polyploidy, and hybridization is essentially sudden.
Macroevolution can go both through microevolution and bypassing traditional microevolutionary paths.
Evolution can be predicted, despite the enormous number of factors influencing it. Although it is not definitive, by assessing past history, genotypic environment, and possible environmental influences, the general direction of evolution can be predicted.
So, from what has been said it is clear that the years of development of science after the publication of Charles Darwin’s work were not in vain.
At the same time, there is no doubt that the main path of development of evolutionary biology lies in line with those ideas and those directions that were laid down by the genius of Charles Darwin.
