The evolutionary theory of Ch. Darwin

History of evolutionary ideas. The significance of the works of K. Linnaeus, the teachings of J. B. Lamarck

Evolution- the irreversible historical development of living nature.

2. Fill in the table.

History of the development of evolutionary ideas (until the twentieth century).

3. What are the strengths and weaknesses of the system of the organic world of K. Linnaeus?
Developed the first relatively successful artificial system organic world. He took the form as the basis of his system and considered it an elementary unit of living nature. Related species united them into genera, genera into orders, orders into classes. Introduced the principle of binary nomenclature into taxonomy.
The disadvantages of the Linnaean system were that when classifying, he took into account only 1-2 features (in plants - the number of stamens, in animals - the structure of the respiratory and circulatory systems), which do not reflect true kinship, so distant genera were in the same class, and close ones - in different. Linnaeus considered species in nature to be immutable, created by the Creator.

4. Formulate the main provisions of the evolutionary theory of J. B. Lamarck.
Points of Lamarck's evolutionary theory:
The first organisms originated from inorganic nature by spontaneous generation. Their further development led to the complication of living beings.
All organisms have a striving for perfection, originally laid down in them by God. This explains the mechanism of complication of living beings.
The process of spontaneous generation of life continues constantly, which explains the simultaneous presence in nature of both simple and more complex organisms.
The law of exercise and non-exercise of organs: the constant use of an organ leads to its increased development, and non-use leads to weakening and disappearance.
inheritance law acquired traits: changes that have arisen under the influence of constant exercise and non-exercise of the organs are inherited. So, Lamarck believed, formed, for example, the long neck of the giraffe and the blindness of the mole.
He considered the direct influence of the environment to be the main factor of evolution.

5. Why did the contemporaries criticize the theory of J. B. Lamarck?
Lamarck erroneously believed that a change in the environment always causes beneficial changes in organisms. In addition, he could not explain where the “striving for progress” comes from in organisms, and why it is necessary to consider the hereditary property of organisms to respond expediently to external influences.
6. What progressive features do modern evolutionary scientists see in the theory of J. B. Lamarck?
In the book Philosophy of Zoology, Lamarck suggested that over the course of life, each individual changes, adapts to environment. He argued that the diversity of animals and plants is the result historical development organic world - evolution, which I understood as a stepwise development, a complication of the organization of living organisms from lower forms to the highest. He proposed a peculiar system of organizing the world, placing related groups in it in ascending order - from simple to more complex, in the form of a "ladder".

The evolutionary doctrine of Ch. Darwin

1. Give definitions of concepts.
Factors of evolution- according to Darwin, this is natural selection, the struggle for existence, mutational and combinative variability.
artificial selection- the choice by a person of the most economically or decoratively valuable individuals of animals and plants in order to obtain offspring from them with the desired properties.

2. What aspects of the social and scientific environment of the beginning and mid-nineteenth centuries contributed, in your opinion, to the development of evolutionary theory by Charles Darwin?
By the middle of the XX century. a number of important generalizations and discoveries were made that contradicted creationist views and contributed to the strengthening and further development of the idea of evolution, which created the scientific prerequisites for the evolutionary theory of Charles Darwin. This is the development of systematics, Lamarck's theory, Baer's discovery of the law germline similarity and the achievement of other scientists, the development of biogeography, ecology, comparative morphology, anatomy, the discovery of cell theory, as well as the development of breeding and the national economy.

3. Fill in the table.

Stages of the life path of Ch. Darwin

4. Formulate the main provisions of the evolutionary teachings of Ch. Darwin.
1. Organisms are changeable. It is difficult to find such a property by which individuals belonging to this species, would be completely identical.
2. Differences between organisms are, at least in part, inherited.
3. Theoretically, populations of plants and animals tend to multiply exponentially, and theoretically any organism can fill the Earth very quickly. But this does not happen, since life resources are limited, and the strongest survive in the struggle for existence.
4. As a result of the struggle for existence, natural selection occurs - individuals with properties that are useful under given conditions survive. Survivors transmit these properties to their offspring, that is, these properties are fixed in a series of subsequent generations.

5. Fill in the table.

Comparative characteristics of the evolutionary theories of J. B. Lamarck and C. Darwin

6. What is the significance of the evolutionary teachings of Ch. Darwin for the development of biological science?
Darwin's teaching made it possible to harmonize disparate knowledge about the laws that govern the organization of life on our planet. In the past century, Darwin's evolutionary theory was developed and concretized thanks to the creation of the chromosome theory of heredity, the development of molecular genetic research, taxonomy, paleontology, ecology, embryology, and many other areas of biology.

1. Define the concept.
Struggle for existence- this is one of driving factors evolution, along with natural selection and hereditary variability, a set of diverse and complex relationships that exist between organisms and environmental conditions.

2. Fill in the table.

The struggle for existence and its forms

3. Which of the forms of the struggle for existence is, in your opinion, the most intense? Explain the answer.
Intraspecific struggle proceeds most acutely, since individuals have the same ecological niche. Organisms compete for limited resources - food, territorial, males of some animals compete with each other for the fertilization of the female, as well as other resources. To reduce the severity of intraspecific struggle, organisms develop various adaptations - the delimitation of individual areas, complex hierarchical relationships. In many species, organisms at different stages of development occupy different ecological niches, for example, beetle larvae live in the soil, and dragonflies live in water, while adults inhabit the ground-air environment. Intraspecific struggle leads to the death of less adapted individuals, thus contributing to natural selection.

Natural selection and its forms

1. Give definitions of the concept.
Natural selection- this is the selective reproduction of genotypes that best meet the prevailing living conditions of the population. That is, the main evolutionary process, as a result of which the number of individuals with maximum fitness (the most favorable traits) increases in the population, while the number of individuals with unfavorable traits decreases.

2. Fill in the table.

3. What is the consequence of natural selection?
Change in the composition of the gene pool, removal from the population of individuals whose properties do not provide advantages in the struggle for existence. The emergence of adaptations of organisms to environmental conditions.

4. What, in your opinion, is the creative role of natural selection?
The role of natural selection is not only to weed out non-viable individuals. The form that drives it retains not individual features of the organism, but their entire complex, all combinations of genes inherent in the organism. Selection creates adaptations and species, removing from the gene pool populations that are inefficient from the point of view of survival genotypes. The result of its action are new types of organisms, new forms of life.

Biology. General biology. Grade 11. A basic level of Sivoglazov Vladislav Ivanovich

4. The evolutionary theory of Charles Darwin

Remember!

What kinds of variability do you know?

What is artificial selection?

The main work of Charles Darwin, in which the theory of evolution was outlined, is called "The Origin of Species by Means of Natural Selection, or the Preservation of Favored Breeds in the Struggle for Life"; it was published in 1859. On the very first day, the entire circulation was sold out, huge for those times - 1250 copies. The appearance of this work was preceded by almost 30 years of scientific research and reflection.

Participation in the expedition. In 1831, Darwin was asked to take a five-year circumnavigation on the USS Beagle as a naturalist. The young researcher got the opportunity to study the nature of the most remote corners of the globe (Fig. 7).

AT South America Darwin found fossils of giant sloths and armadillos. The modern species of these animals living in the same places were very similar to extinct ones, which led Darwin to think about the possible relationship of these organisms (Fig. 8).

On the Galápagos volcanic islands, Darwin discovered a variety of finches that differed in size and bill structure, but were very similar to the mainland species (Fig. 9). Darwin suggested that once the birds came to the islands from the mainland and changed, adapting to different food sources (hard seeds, fruits, insects).

Rice. 7. Journey of Charles Darwin: A - ship "Beagle"; B - portrait of Ch. Darwin; B - expedition route

Rice. 8. Skeletons of sloths in South America (on the right - a modern view, on the left - a fossil)

In Australia, the scientist was struck by the amazing ancient fauna: marsupials and egg-laying mammals that have long died out in other places on the globe.

Travel has played a decisive role in shaping scientific views Darwin. Having boarded the ship as a supporter of the immutability of wildlife, five years later, when returning home, Darwin was convinced that species could change and give rise to other species.

Ch. Darwin's doctrine of artificial selection. The data collected by Darwin during the expedition and accumulated in scientific research by his contemporaries indicated the existence of the variability of the living world. However, the mechanisms of these changes remained unknown.

Returning to England, Darwin continued his Scientific research. He drew attention to the existence of two opposite phenomena: heredity and variability. At that time, it was still unknown what the nature of these two properties of living organisms was, but Darwin absolutely correctly understood that it was heredity and variability that underlie evolutionary transformations. Darwin distinguished between definite and indefinite variability.

Certain, or group, variability arises under the influence of environmental factors and manifests itself in all individuals in the same way. For example, when the quality of forage is improved, cows produce more milk, and when fertilizers are applied to the fields, crop yields become much higher. However, these changes are not passed on to the next generation, and in order to get a good harvest for the next year, the fields must be fertilized again. At present, this form of variability is usually called non-hereditary or phenotypic (see § 30, class 10).

Rice. 9. Species of finches that live in the Galapagos Islands

Darwin was much more interested in another form of variability - indefinite, or individual. Indefinite variability is the appearance in an individual of a new manifestation of a trait that was not in the ancestral forms. Darwin believed that it is indeterminate variability that ensures the emergence of new species, because it is inherited. In modern biology, it is known that the main reason hereditary variability are mutations (see § 30, class 10).

It was this form of variability that was used by English breeders when creating new breeds of animals. By that time, more than 150 breeds of pigeons had been bred in England, many breeds of dogs, chickens, cattle, etc. Supporters of the immutability of species argued that each breed had its own wild ancestor. Darwin proved that this was not the case. All breeds of chickens are descended from the wild Banking chicken, cattle breeds from wild tours, and all the amazing variety of pigeons from the wild rock pigeon (Fig. 10).

Breeding domestic animals and cultivated plants, English farmers searched among the offspring for those individuals in which the desired trait was expressed most clearly. The selected specimens were crossed with each other, and from the organisms of the next generation, those forms were again selected in which necessary for a person the sign was best expressed. From one initial form, it was possible to obtain many different varieties or breeds at the same time, if selection was carried out according to different characteristics. Consequently, when breeding new varieties and breeds, man used artificial selection.

Rice. 10. Pigeon breeds: A - wild pigeon; B - pout; B - Jacobin: G - Thurman; D - carrier pigeon; E - peacock dove

by artificial selection called the process of creating new breeds of animals and plant varieties through the systematic conservation and reproduction of individuals with certain traits and properties valuable to humans in a series of generations.

Sometimes a single large mutation leads to the emergence of a breed. This is how the Ancona breed of short-legged sheep, dachshund, duck with a crooked beak appeared, and in 2004 a cat with short legs was discovered in the USA, which gave rise to a new breed.

Artificial selection has been carried out by man at all times, but in ancient times it was unconscious. Our distant ancestors left the best animals or kept the best seeds for sowing, based on practical experience, without setting themselves a specific goal. If the breeder sets himself a specific task and selects according to one (two) traits, such selection is called methodical.

Ch. Darwin's doctrine of natural selection. In artificial conditions, the factor that selects this or that organism is a person. Darwin believed that if he could find a similarly acting factor in nature, the problem of the origin of species would be solved.

Impressed by reading the work of T. Malthus about the desire of organisms for unlimited reproduction, Darwin analyzed the patterns of reproduction of various organisms. In 750 years, the offspring of one pair of elephants, the slowest breeding animals, can amount to 19 million individuals. An oyster lays 1 million eggs per season, and the well-known puffball mushroom produces 700 billion spores, and yet Earth not covered by oysters and mushrooms. Despite the fact that individuals tend to reproduce exponentially, the number of adults of each species remains approximately constant. In other words, most of descendants perish in struggle for existence before reaching puberty.

Darwin singled out three forms of the struggle for existence: interspecific, intraspecific, and the struggle against adverse environmental factors (Fig. 11).

Intraspecific struggle occurs between individuals of the same species. This struggle is most acute because organisms belonging to the same species have similar needs. In animals, this struggle is manifested in the competition for food and territory, in many plants - in the shading of other individuals due to faster growth. Males of many species during the breeding season enter into a struggle for the right to start a family. Mating tournaments lead to sexual selection, when the stronger male leaves the offspring, and the weak or sick are excluded from the breeding process, and their genes are not passed on to the offspring.

Rice. 11. Struggle for existence

Fight against adverse environmental factors plays an important role in the survival of organisms. In a dry summer, many plants die, the flood takes the lives of many animals, not all organisms can survive the frosty winter.

In the struggle for existence, some individuals successfully cope with this task, while others cannot leave offspring or die. As a rule, offspring are left mainly by organisms with traits that are useful for given living conditions. The result of the struggle for existence is natural selection.

Darwin called the process of survival and reproduction of the fittest individuals natural selection, the main driving force that directs the evolutionary process. The material for this selection is hereditary variability. In the process of natural selection, there is a gradual accumulation of changes useful for a group of organisms, which leads to the formation of a new species.

The value of Darwin's theory. Darwin was not the first scientist to develop the theory of evolution. His merit lies in the fact that he was the first to scientifically explain the mechanisms of evolution in general and speciation in particular. Darwin considered the main factors of evolution to be hereditary variability, the struggle for existence and natural selection.

Darwin illustrated his point of view on the same example that J. B. Lamarck used in his time to explain his theory of evolution - on the giraffe. Darwin suggested that in some ancestral population of giraffes, individuals differed slightly in the length of the neck and legs. This assumption is quite legitimate, because no two identical individuals exist in any population. During periods of food shortage in the savannah, animals of different sizes were forced to compete for the leaves of trees (intraspecific struggle for existence). Taller animals could reach the leaves growing on the upper branches and inaccessible to short individuals. Therefore, short giraffes died, and with them, such signs as short legs and neck disappeared from the population. The long neck and long legs of the modern giraffe are the result of generational survival and breeding by taller individuals.

Darwin's doctrine serves as a natural scientific basis for a materialistic explanation of the expediency of the structure of living organisms, the origin and diversity of species, and is one of the greatest achievements of natural science in the 19th century.

Simultaneously with C. Darwin, another natural scientist, Alfred Russel Wallace, came to the same conclusions about the mechanisms of evolution. In July 1858, Darwin and Wallace made presentations together on their ideas at a meeting of the Linnean Society in London. Subsequently, Wallace fully recognized the priority of Darwin and introduced the term "Darwinism" to refer to new theory evolution.

The theory of evolution proposed by Darwin was later expanded and revised in the light of new data from genetics, molecular biology, paleontology, and ecology, and was called synthetic theory of evolution.

Review questions and assignments

1. What observations of Charles Darwin shook his faith in the immutability of species?

2. What are the causes of group variability?

3. What is artificial selection?

4. What are the reasons for the struggle for existence in wildlife? Give examples of three forms of struggle for existence that you have observed in nature.

5. Which relationship results in natural selection?

6. What is the role of natural selection in evolution?

7. Consider Figure 11. What forms of struggle for existence does it illustrate? Justify your answer.

Think! Execute!

1. In the very first Russian translation of Charles Darwin's work, instead of the now familiar word "selection", the term "selection" was used (which is also an analogous word for the English selection used by Charles Darwin). Why was it subsequently replaced? Express your opinion.

2. Select the criteria yourself and compare the theories of J. B. Lamarck and C. Darwin.

Work with computer

Refer to the electronic application. Study the material and complete the assignments.

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Most biologists of that time had no doubts that evolution is real: nature is changeable, some species replace others, and life on Earth develops. Therefore, it was not the evidence of evolution that became relevant, but the need to find out exactly how evolutionary transformations occur; find the answer to the question of what causes living organisms to change over time. In other words, it was necessary to find out the mechanisms, causes and factors of evolution.

This was done in the outstanding work of the English naturalist, traveler and explorer Charles Robert Darwin (1809-1882) "The origin of species by natural selection, or the preservation of favorable breeds in the struggle for life" (Fig. 161), in which he outlined his vision of the mechanisms of evolutionary transformation. Briefly, the ideas of the book boil down to the following.

Organisms reproduce exponentially, while a very small part of them survive to adulthood. (note: in nature there are always more young individuals than adults). Consequently, most individuals die in the struggle for existence (Fig. 162), which manifests itself mainly in the competition of individuals of the same species among themselves for the best habitats, food, resources, and in animals, moreover, competition males for a female.
Nature is characterized by universal variability. Each organism has individual features that distinguish it from others. According to Darwin, in nature there is a non-hereditary group (he called it "definite", and now it is called modification) and individual ("indefinite", in modern interpretation genetic) variability, which is inherited. It is the last form of variability according to Darwin's theory that plays key role in evolution, provides material for it.
Since individuals of the same species are different from each other, they have different chances of surviving and reproducing. More often survive and, accordingly, leave offspring organisms that are more adapted to the living conditions, having some signs or properties that are especially useful in the struggle for life. This survival of the fittest in the struggle for existence is natural selection, which, according to Darwin, is the main factor - driving force of the evolutionary process. As the main evidence of the reality of natural selection, Darwin cited artificial selection, with the help of which a person brought out many of the animal breeds and plant varieties he needed with properties previously unknown in nature. So nature, with the help of natural selection, creates the species it needs.
Since the habitat of organisms is constantly changing, each time in the struggle for existence, individuals with new traits that are fixed hereditarily have an advantage. These changes, accumulating and spreading under the influence of natural selection in a number of generations, inevitably lead to significant changes in the structure of the body and the functioning of groups of individuals, resulting in the formation of a new species.

Thus, the main the idea of the doctrine of natural selection- main driving force organic evolution - consists in the survival of the fittest in the struggle for existence(Fig. 163). At the same time, the organisms that leave the largest offspring are the most adapted.

Unlike Lamarck's theory Darwin's theory of evolution enthusiastically perceived not only by the scientific, but also by the entire enlightened European public of that time. The first edition of The Origin of Species, which was released on November 24, 1859, sold out in a few days. The success was due to the understandable and clear logic of the theory of natural selection, the argumentation of the arguments. In addition, the idea of the survival of the strongest and fittest in the competitive struggle corresponded to the spirit of the time - the capitalist relations of the middle of the 19th century - and was understandable to society. material from the site

Darwin's doctrine of the evolutionary significance of natural selection as the main factor in evolution is commonly called Darwinism. Most modern biologists identify this doctrine with theory of evolution and consider it the only correct interpretation of the mechanisms of the evolutionary process. In contrast to the evolutionary teachings of Lamarck, Darwin not only proved the fact of evolution (the variability of species, the origin of one species from another, the change of species over time), but was also the first to propose natural scientific mechanisms of the evolutionary process acceptable to the science of his time. Thanks to Darwin's theory, progressive changes occurred in biology that can be compared with the scientific revolution. The evolutionary doctrine began to penetrate into all biological disciplines. There are brand new scientific directions(comparative anatomy and physiology, evolutionary morphology, evolutionary embryology and others). Significant progress has been made in taxonomy and phylogeny. The system of animals and plants ceased to be artificial; it increasingly began to be based not on the external similarity of organisms, but on their phylogenetic relationship.

English naturalist and scientist Ch. Darwin, who put forward the idea of natural selection as the main driving force of evolution, formulated the natural causes of evolutionary development. Ch. Darwin is recognized as the founder contemporary theories of evolution, because he not only convincingly proved its reality, but also substantiated its natural causes.

On this page, material on the topics:

Report on the teachings of Charles Darwin on natural selection
The mechanisms of the evolutionary process according to Darwin briefly
What is the struggle for existence
Darwin's doctrine of natural selection summary
Biology abstract Darwin's doctrine of natural selection

Questions about this item:

What is the merit of Darwin?
How is the theory of evolution different from the theory of evolution?
Why did Darwin's theory so quickly win a huge number of adherents?
Today, few will deny huge contribution Darwin in biology. The name of this scientist is familiar to every adult. Many of you can say in a nutshell what Darwin's contribution to biology is. However, only a few will be able to tell in detail about the theory he created. After reading the article, you will be able to do it.
Achievements of the ancient Greeks
Before describing Darwin's contributions to biology, let us briefly describe the achievements of other scientists towards the discovery of the theory of evolution.
Anaximander, an ancient Greek thinker, back in the 6th century BC. e. He said that man is descended from animals. His ancestors were allegedly covered in scales and lived in water. A little later, in the 4th c. BC e., Aristotle noted that useful signs that appear randomly in animals, nature preserves in order to make them more viable in the future. And brothers who do not have these signs die. It is known that Aristotle created the "ladder of beings". He arranged the organisms in order from the simplest to the most complex. This staircase began with stones and ended with a man.
Transformation and creationism
The Englishman M. Hale in 1677 first used the term "evolution" (from Latin "deployment"). He designated by it the unity of the historical and individual development of organisms. In biology in the 18th century, the doctrine of how different types of plants and animals changed. It was opposed to creationism, according to which God created the world and all species remain unchanged. The supporters of transformism include the French scientist Georges Buffourt, as well as the English researcher Erasmus Darwin. The first theory of evolution was proposed by Jean-Baptiste Lamarck in his 1809 work "Philosophy of Zoology". However, it was Charles Darwin who revealed its true factors. The contribution to the biology of this scientist is invaluable.
Credit to Charles Darwin
He owns the evolutionary theory, justified scientifically. He expounded it in a work called The Origin of Species by Means of Natural Selection. This book was published by Darwin in 1859. Contributions to biology can be briefly described as follows. Darwin believed that - hereditary variability, as well as the struggle for existence. Under conditions of struggle, the inevitable result of this variability is natural selection, which is the preferential survival of the fittest individuals of a particular species. Through their participation in reproduction, beneficial hereditary changes are accumulated and summarized, as Charles Darwin noted.
His contribution to biology was recognized by scientists who continued research in this direction. The development of science further confirmed that Darwin's theory was correct. Therefore, today the terms "evolutionary doctrine" and "Darwinism" are often used as synonyms.
So, we have briefly characterized the contribution of Darwin to biology. We propose to consider in more detail the theory he created.
Observations that prompted Darwin's theory of evolution
At first, Charles Darwin began to think about the reasons why there are certain similarities and differences between species. The contribution to biology, briefly described by us, he made not at once. First, it was necessary to study the achievements of the predecessors, as well as make several trips. It was they who prompted the scientist to important thoughts.
He made the main find in South America, in geological deposits. These are the skeletons of giant edentulous, very similar to modern sloths and armadillos. In addition, Darwin was greatly impressed by the study of animal species living on the Scientist discovered on these volcanic islands, which are of recent origin, close species of finches that are similar to the mainland, but have adapted to various food sources - flower nectar, insects, hard seeds. Charles Darwin concluded that these birds came to the island from the mainland. And the changes that have occurred to them are explained by adaptation to new conditions of existence.
Charles Darwin raised the question that environmental conditions play a certain role in speciation. The scientist observed a similar pattern off the coast of Africa. Living on animals, despite a certain similarity with the species inhabiting the mainland, nevertheless differ from them in very significant features.
Darwin could not explain the creation of species and the features of the development of the tuco-tuco rodent, which he described. These rodents live underground in burrows. They have sighted cubs, which subsequently go blind. All these and many other facts significantly shook the scientist's belief in the creation of species. Darwin, returning to England, set himself a massive task. He decided to solve the problem of the origin of species.
Major writings
Darwin's contribution to the development of biology is presented in several of his works. In 1859, in his work, he summarized the empirical material of breeding practice and biology, contemporary to him. In addition, he used the results of his observations made during his travels. His circumnavigation of the world shed light on various species.
Charles Darwin supplemented the main work "The Origin of Species ..." with factual materials in his next book, published in 1868. It is known as "Changing Pets and cultivated plants". In another work written in 1871, the scientist put forward the hypothesis that man is descended from an ape-like ancestor. Today, many agree with the assumption made by Charles Darwin. Contribution to biology allowed him to become a great authority in scientific world. Many even forget that the origin of man from a monkey is just a hypothesis, which, although very likely, is still not fully proven.
The property of heredity and its role in evolution
Note that the Darwinian theory is based on the property of heredity, that is, the ability of organisms to repeat the types of metabolism and, in general, individual development in a number of generations. Together with variability, heredity ensures the diversity and constancy of life forms. It is the basis of the evolution of the entire organic world.
Struggle for existence
"Struggle for existence" is a concept that is one of the main concepts in the theory of evolution. Charles used it to refer to the relationships between organisms. In addition, Darwin used it to describe the relationship between abiotic conditions and organisms. Abiotic conditions lead to the survival of the fittest individuals and to the death of the less fit.
Two forms of variability
With regard to variability, Darwin identified two main forms of it. The first of these is a certain variability. This is the ability of all individuals of a particular species, under certain environmental conditions, to respond in the same way to given conditions (soil, climate). The second form - Its character does not correspond to the observed changes in external conditions. Indefinite variability in modern terminology is called a mutation.
Mutation
Mutation, unlike the first form, is hereditary. According to Darwin, the slight changes observed in the first increase in subsequent generations. The scientist emphasized that the decisive role in evolution belongs to the indeterminate variability. It is usually associated with deleterious or neutral mutations, but there are also those that are called promising.
Mechanism of evolution
According to Darwin, the inevitable result of hereditary variability and the struggle for existence is the survival and reproduction of new organisms that are most adapted to living in the appropriate environment. And in the course of evolution, the death of the unfit occurs, that is, natural selection. Its mechanism operates in nature similarly to breeders, that is, indefinite and insignificant individual differences are added, from which the necessary adaptations in organisms are then formed, as well as differences between species.
Charles Darwin spoke and wrote about all this, as well as many other things. Contributions to biology, briefly described, are not limited to what we have talked about. However, its main achievements were characterized in general terms. Now you can tell in detail about what contribution Darwin made to biology.

Charles Darwin (1809 - 1882) formulated the theory of evolution as a result of natural selection.
Background of evolutionary theory
1859 "The Origin of Species by Means of Natural Selection, or the Preservation of Chosen Breeds in the Struggle for Life."
The logical structure of Darwinism
Heredity. Variability. The intensity of reproduction (geometric progression). Limited space and resources for life.
Obvious properties of organisms
Struggle for existence
Natural selection

The theory of the origin of species created by Darwin is based on the following fundamentally important provisions:
The main provisions of the theory of Darwin and Wallace
Essence The theory of evolution is as follows: a huge variety of species on Earth, adapted to certain conditions of existence, were formed due to constantly arising in nature multidirectional hereditary changes and natural selection. The ability of organisms to intensive reproduction and the simultaneous survival of a few individuals, the most adapted to specific environmental conditions, is a consequence of the struggle for existence. Thus, between species there is a struggle for existence, as a result of which the organisms most adapted to specific environmental conditions survive. Meaning Darwin's theory consists in establishing the main driving forces for the evolution of the organic world and introducing the natural-historical method into biology.
The creation by man of new varieties of plants or animal breeds is based on three factors - variability, heredity and selection.
Heredity is the property of living organisms to preserve and transmit to offspring the features of their structure and development with the help of genes. Due to heredity from generation to generation, the characteristics of a species, variety, breed, strain are preserved. Communication between generations is carried out during reproduction through haploid or diploid cells. The leading role in heredity belongs to chromosomes capable of self-duplication and formation with the help of genes of the entire complex of traits characteristic of the species. The entire set of genes characteristic of an individual of a species makes up the genotype.
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