Elementary factors of evolution. Forms of natural selection, types of struggle for existence. Interconnection driving forces evolution. The creative role of natural selection in evolution. Research by S.S. Chetverikova Synthetic theory of evolution. The role of evolutionary theory in the formation of the modern natural science picture of the world

6.2.1. Development of evolutionary ideas. The significance of the works of C. Linnaeus, the teachings of J.-B. Lamarck, the evolutionary theory of Charles Darwin. The interconnection of the driving forces of evolution. Elementary factors of evolution

The concepts of the changeability of the organic world have found their supporters since ancient times. Aristotle, Heraclitus, Democritus and a number of other ancient thinkers expressed these ideas. In the XVIII century. K. Linnaeus created an artificial system of nature, in which the species was recognized as the smallest systematic unit. He introduced the nomenclature of double species names (binary), which made it possible to systematize the organisms of different kingdoms known by that time by taxonomic groups.
The creator of the first evolutionary theory was Jean Baptiste Lamarck. It was he who recognized the gradual complication of organisms and the variability of species, thereby indirectly refuting the divine creation of life. At the same time, Lamarck's assumptions about the expediency and usefulness of any emerging adaptations in organisms, the recognition of their desire for progress as the driving force of evolution, were not confirmed by subsequent scientific research... Also, they did not find their confirmation of Lamarck's position on the heritability of characters acquired by an individual during her life and on the influence of organ exercises on their adaptive development.
The main problem that had to be solved was the problem of the formation of new species adapted to the conditions environment... In other words, scientists needed to answer at least two questions: how do new species arise? How do adaptations to environmental conditions arise?
The evolutionary doctrine, which has received its development and is recognized by modern scientists, was created independently of each other by Charles Robert Darwin and Alfred Wallace, who put forward the idea of ​​natural selection based on the struggle for existence. This doctrine was called Darwinism, or the science of historical development wildlife.
The main tenets of Darwinism:
- the evolutionary process is real, determined by the conditions of existence and manifests itself in the formation of new, adapted to these conditions, individuals, species and larger systematic taxa;
- the main evolutionary factors are: hereditary variability and natural selection.
Natural selection plays the role of a guiding factor in evolution (creative role).
The prerequisites for natural selection are: excessive reproductive potential, hereditary variability and changing conditions of existence. Natural selection is a consequence of the struggle for existence, which is subdivided into intraspecific, interspecific and the struggle with environmental conditions. The results of natural selection are:
- preservation of any adaptations that ensure the survival and reproduction of offspring; all adaptations are relative.
Divergence is the process of genetic and phenotypic divergence of groups of individuals by individual traits and the formation of new species - the progressive evolution of the organic world.
The driving forces of evolution, according to Darwin, are: hereditary variability, the struggle for existence, natural selection.

Part A

A1. The driving force behind Lamarck's evolution is
1) the desire of organisms to progress
2) divergence
3) natural selection
4) the struggle for existence
A2. The statement is erroneous
1) species are changeable and exist in nature as independent groups of organisms
2) related species have a historically common ancestor
3) all changes acquired by the body are beneficial and are preserved by natural selection
4) the evolutionary process is based on hereditary variability
A3. Evolutionary changes are entrenched in generations as a result
1) the appearance of recessive mutations
2) inheritance of characteristics acquired during life
3) struggle for existence
4) natural selection of phenotypes
A4. The merit of Charles Darwin lies in
1) recognition of the variability of species
2) establishing the principle of double species names
3) identifying the driving forces of evolution
4) the creation of the first evolutionary teaching
A5. According to Darwin, the reason for the formation of new species is
1) unlimited reproduction
2) the struggle for existence
3) mutational processes and divergence
4) direct influence of environmental conditions
A6. Natural selection is called
1) the struggle for existence between individuals of the population
2) the gradual emergence of differences between individuals of the population
3) survival and reproduction of the strongest individuals
4) survival and reproduction of individuals most adapted to environmental conditions
A7. Fighting for territory between two wolves in the same forest refers to
1) interspecies struggle
2) intraspecific struggle
3) dealing with environmental conditions
4) an inner desire for progress
A8. Recessive mutations undergo natural selection when
1) heterozygosity of an individual for a selected trait
2) homozygosity of an individual for this trait
3) their adaptive value for the individual
4) their harmfulness to the individual
A9. Indicate the genotype of the individual in which the a gene will be subjected to the action of natural selection
1) AaBb 2) AABB 3) Aavb 4) aaBb
A10. C. Darwin created his doctrine in
1) XVII century. 2) XVIII century. 3) XIX century. 4) XX century.

Unified State Exam Part B

IN 1. Select the provisions of the evolutionary teachings of Charles Darwin
1) acquired characteristics are inherited

2) hereditary variability serves as the material for evolution
3) any variability serves as material for evolution
4) the main result of evolution is the struggle for existence
5) speciation is based on divergence
6) both beneficial and harmful traits are exposed to the action of natural selection
AT 2. Correlate the views of J. Lamarck and C. Darwin with the provisions of their teachings

Unified State Exam Part C

C1. What is the progressiveness of Charles Darwin's teachings?

6.2.2. The creative role of natural selection. Synthetic theory of evolution. Research by S.S. Chetverikov. The role of evolutionary theory in the formation of the modern natural science picture of the world

The synthetic theory of evolution arose on the basis of data from comparative anatomy, embryology, paleontology, genetics, biochemistry, and geography.
The synthetic theory of evolution puts forward the following provisions:
- mutations are the elementary evolutionary material;
- elementary evolutionary structure - population;
- elementary evolutionary process - directed change in the gene pool of the population;
- natural selection - the directing creative factor of evolution;
- in nature, there are two conditionally distinguished processes that have the same mechanisms - micro- and macroevolution. Microevolution is a change in populations and species, macroevolution is the emergence and change of large systematic groups.
Mutational process. The studies of mutational processes in populations are devoted to the works of the Russian geneticist S.S. Chetverikov. Ultimately, new alleles emerge from mutations. Since mutations are predominantly recessive, they accumulate in heterozygotes, forming a reserve of hereditary variability. With free crossing of heterozygotes, recessive alleles become homozygous with a probability of 25% and are subject to natural selection. Individuals that do not have selective advantages are rejected. In large populations, the degree of heterozygosity is higher; therefore, large populations adapt better to environmental conditions. In small populations, inbreeding is inevitable, and, consequently, an increase in homozygous populations. This, in turn, threatens disease and extinction.
Gene drift, accidental loss or sudden increase in the frequency of alleles in small populations, leading to a change in the concentration of this allele, an increase in the homozygosity of the population, a decrease in its viability, and the appearance of rare alleles. For example, in religious communities isolated from the rest of the world, there is either a loss or an increase in alleles characteristic of their ancestors. An increase in the concentration of alleles occurs as a result of closely related marriages, the loss of alleles can occur as a result of the departure of community members or their death.
Forms of natural selection. Driving natural selection. Leads to a shift in the norm of the body's reaction towards the variability of the trait in changing environmental conditions. Stabilizing natural selection (discovered by N.I.Shmalgauzen) narrows the rate of reaction under stable environmental conditions. Disruptive selection - occurs when one population, for some reason, is divided into two and they hardly touch each other. For example, as a result of summer mowing, the plant population may be divided in the ripening time. Over time, two types can form from it. Sexual selection ensures the development of reproductive functions, behavior, morphophysiological characteristics.
In this way, synthetic theory evolution combined Darwinism and modern views about the development of the organic world.

Examples of practical tasks for the exam on the topic: ""
Part A

A1. According to S.S. Chetverikov's initial material for speciation are
1) insulation
2) mutations
3) population waves
4) modifications
A2. Small populations are dying out due to the fact that in them
1) fewer recessive mutations than in large populations
2) less likelihood of transferring mutations to a homozygous state
3) more likely to closely related crosses and hereditary diseases
4) higher degree of heterozygosity of individuals
A3. The formation of new genera and families refers to the processes
1) microevolutionary 3) global
2) macroevolutionary 4) intraspecific
A4. In a constantly changing environment, a form of natural selection operates
1) stabilizing 3) driving
2) disruptive 4) sexual selection
A5. An example of a stabilizing form of selection is
1) the appearance of ungulates in the steppe zones
2) the disappearance of white butterflies in the industrial areas of England
3) the survival of bacteria in the geysers of Kamchatka
4) the emergence of tall forms of plants when they are moved from valleys to mountains
A6. Populations will evolve faster
1) haploid drones
2) perch heterozygous for many traits
3) male domestic cockroaches
4) monkeys at the zoo
A7. The gene pool of the population is enriched due to
1) modification variability
2) the interspecies struggle for existence
3) stabilizing form of selection
4) sexual selection
A8. The reason why gene drift can occur
1) high heterozygosity of the population
2) large population size
3) homozygosity of the entire population
4) migration and emigration of carriers of mutations from small populations
A9. Endemics are organisms
1) whose habitats are limited
2) living in a wide variety of habitats
3) the most common on Earth
4) forming the minimum population
A10. The stabilizing form of selection is aimed at
1) preservation of individuals with an average value of traits
2) preservation of individuals with new traits
3) increasing the heterozygosity of the population
4) expansion of the reaction rate
A11. Gene drift is
1) a sharp increase in the number of individuals with new traits
2) a decrease in the number of emerging mutations
3) a decrease in the rate of the mutation process
4) random change in allele frequencies
A12. Artificial selection has led to the emergence
1) arctic fox
2) badgers
3) airedale terriers
4) Przewalski's horses

Unified State Exam Part B

IN 1. Select the conditions that determine the genetic prerequisites of the evolutionary process
1) modification variability
2) mutational variability
3) high heterozygosity of the population
4) environmental conditions
5) inbreeding
6) geographic isolation

Unified State Exam Part C

C1. Find errors in the text provided. Indicate the numbers of the sentences in which they are allowed, explain them
1. Population - a complex of individuals different types occupying a certain territory. 2. Individuals of one population freely interbreed with each other. 3. The set of genes that all individuals of the population possess is called the genotype of the population. 4. Individuals that make up the population are heterogeneous in their genetic makeup. 5. The heterogeneity of the organisms that make up the population creates conditions for natural selection. 6. The population is considered the largest evolutionary unit.

Lecture, abstract. Development of evolutionary ideas. The significance of the works of C. Linnaeus, the teachings of J.-B. Lamarck, the evolutionary theory of Charles Darwin. The interconnection of the driving forces of evolution. - concept and types. Classification, essence and features. 2018-2019.

Book table of contents open close

Biology is the science of life
Cell as a biological system
The structure of pro- and eukaryotic cells. The interrelation of the structure and functions of the parts and organelles of the cell is the basis of its integrity
Metabolism, enzymes, energy metabolism
Biosynthesis of protein and nucleic acids.
A cell is a genetic unit of a living thing.
The organism as a biological system
Ontogenesis and its inherent patterns.
Genetics, its tasks. Heredity and variability are the properties of organisms. Basic genetic concepts
Regularities of heredity, their cytological foundations.
Variability of traits in organisms - modification, mutational, combinative
Breeding, its tasks and practical significance
The variety of organisms, their structure and vital activity
Kingdom of Bacteria.
Kingdom of Mushrooms.
Plant kingdom
Variety of plants
Kingdom of Animals.
Chordates, their classification, structural features and vital activity, role in nature and human life
Pisces superclass
Class Amphibians.
Class Reptiles.
Bird class
Class Mammals
Man and his health
The structure and function of the respiratory system
The structure and function of the excretory system
The structure and vital functions of organs and systems of organs - musculoskeletal, integumentary, blood circulation, lymph circulation.
Skin, its structure and functions
The internal environment of the human body. Blood groups.
Metabolism in the human body
Nervous and endocrine systems
The structure and function of the central nervous system
The structure and function of the autonomic nervous system
Endocrine system
Analyzers. The senses, their role in the body.

Organic evolution - this is historical process the emergence of diversity and adaptation to living conditions at all levels of the organization of living things. The evolutionary process is irreversible and always progressive. The evolutionary process is based on natural selection of random, phenotypically manifested hereditary changes that provide organisms with preferential opportunities for survival and reproduction in certain environmental conditions. Changes that reduce the viability of organisms and species are eliminated.

The creator of the first evolutionary theory was Jean Baptiste Lamarck, who defended the idea of ​​the changeability of species and their purposeful development from simple to complex forms. However, the assignment to organisms of an internal desire for progress (goals), as well as statements about the inheritance of traits acquired during the life of an individual, turned out to be unconfirmed by subsequent studies. The idea of ​​a direct, always adequate, influence of the external environment on the organism and its expedient reaction to this influence turned out to be mistaken. The merit of the development of evolutionary concepts and the creation of a holistic theory of evolution belongs to Charles Darwin and A. Wallace, who substantiated the principle of natural selection and identified the mechanisms and causes of evolution.

Basic terms and concepts tested in examination paper: adaptation, anthropogenesis, biological progress, biological regression, struggle for existence, species, species criteria, homologous organs, Darwinism, driving selection, divergence, evidence of evolution, gene drift, natural selection, idioadaptation, isolation, macroevolution, microevolution, organic evolution, relative expediency, population waves, population, synthetic theory of evolution, factors of evolution, combinative variability, mutational variability, general degeneration.

View- this is a set of individuals actually existing in nature, occupying a certain area, having a common origin, morphological and genetic similarity, freely interbreeding with each other and giving fertile offspring. Due to the fact that it is sometimes very difficult to attribute this or that individual to a particular species, biologists have developed criteria on the basis of which two, outwardly very similar individuals are classified as one or different species.

View criteria:

– morphological- individuals belonging to the same species are similar to each other in their appearance and internal structure;

– physiological- individuals belonging to the same species are similar to each other in many physiological features of life;

– biochemical- individuals belonging to the same species contain similar proteins;

– genetic- individuals belonging to the same species have the same karyotype, interbreed with each other in nature and give fertile offspring. There is no gene exchange between different types of gene exchange;

– ecological- individuals of the same species lead a similar lifestyle in similar environmental conditions;

– geographical- the species is distributed in a certain territory (range).

The most important genetic criterion for determining the belonging of individuals to different species is the genetic criterion. No criterion can be exhaustive. Only on the basis of a set of criterial characteristics can a distinction be made between closely related species.

Population - a stable aggregate of individuals of the same species living together over a number of generations. A population is an elementary evolutionary unit. The minimum population is two individuals of different sexes. Individuals that are part of one population can be born and die, and the population will continue to exist.

Crossbreeding between individuals of the same population occurs much more often than between individuals of different populations. This ensures free genetic exchange between members of the population.

Under the influence of external factors, there is a change in the genetic composition of the population. The genetic composition of the population forms it gene pool ... A long-term and directional change in the gene pool of a population is called elementary evolutionary phenomenon.

The factors causing the evolutionary process in populations are called elementary evolutionary factors... These include mutations, the nature and diversity of which are the cause of the genetic heterogeneity of populations. They provide evolutionary material - the basis for the subsequent action of natural selection. The set of recessive mutations in the genotypes of individuals of the population form reserve of hereditary variability(S.S.Chetverikov), which, when the conditions of existence change, the population size changes, it can phenotypically manifest itself and fall under the influence of natural selection.

Population waves - periodic fluctuations in the number of individuals in the population resulting from a sharp change in the action of any of the environmental factors (for example, lack of food, natural disasters and etc.). After the termination of the action of these factors, the population size increases again. The surviving individuals may prove to be genetically valuable. Changes in the frequency of occurrence of certain genes can lead to a change in the population.

Insulation it can be spatial (geographic) and biological (ecological, physiological, reproductive).

Natural selection - a factor that determines the possibility of survival and reproduction of individuals, and, consequently, the preservation and evolution of the species. Selection acts on individual phenotypes, thereby selecting specific genotypes.

Speciation - the process of the formation of new varieties and species, reproductively isolated from the original population. Share geographic and ecological speciation.

Geographicspeciation begins in populations living in different, remote parts of the range or migrating from the range. Since there is spatial isolation between them, there is no genetic exchange, and a gradual divergence of characters arises, leading to the formation of new species, reproductively isolated from each other. This process is called divergence.

Ecological speciation occurs within the same area. If individuals of a given population, due to genotypic and phenotypic differences, turn out to be adapted to different environmental conditions, then between them there may be reproductive isolation... New species can arise not only as a result of isolation, but also as a result of polyploidy or interspecific hybridization, which often occurs in plants.

Microevolution - an intraspecific process leading to the formation of new populations of a given species, and ultimately new species. A prerequisite is the insulation - geographic and ecological... Microevolution results in reproductive isolation.

Microevolution begins with natural selection of mutations and divergence. As a result of the action of these factors, new populations are formed, genetically and morphologically different from the original ones. If, after the beginning of the divergence processes, a geographical, and then reproductive isolation between new and old populations, this ultimately leads to the emergence of new species.

An example is the finches from the Galapagos Islands described by Charles Darwin. The nature of the food and the remoteness of the islands from the mainland determined the discrepancies in the structure of the beaks, the length of the wings of birds. Gradually, they were divided into different populations that did not interbreed with each other, and later into independent species.

Macroevolution - the process taking place in the historically long periods... It leads to the formation of taxa larger than the species - genera, families, orders, classes, etc. The mechanisms of macroevolution are the same as those of microevolution.

The evolutionary process has such features as: progressiveness, unpredictability, irreversibility, unevenness.

EXAMPLES OF TASKS Part A

A1. The red fox that lives in the forests of Canada and the red fox that lives in Europe belong to

1) one species 3) different genera

2) varieties 4) different types

A2. The main criterion for the emergence of a new species is:

1) the appearance of external differences between individuals

2) geographical isolation of populations

3) reproductive isolation of populations

4) environmental insulation

A3. Evolutionary processes begin at the level

1) species 2) class 3) type 4) populations

A4. The biological prerequisites for microevolution in a population are

1) mutational process and natural selection

2) differences in the karyotypes of individuals

3) physiological differences

4) external differences

A5. The set of recessive mutations accumulated in a population is called its

1) genotype

2) gene pool

3) a reserve of hereditary variability

4) a reserve of modification variability

A6. Populations of one species

1) always live nearby

2) relatively isolated from each other

3) live side by side, but never intersect

4) they always live on different continents

A7. As a result of natural selection of mutations within a population, a process arises

1) reproductive isolation

2) geographical isolation

3) environmental isolation

4) divergence

A8. Divergence in the populations of titmice inhabiting the city park may lead, most likely, to

1) geographical isolation

2) environmental isolation

3) changes in karyotype

4) morphological differences

A9. Bulldog and Doberman Pinscher belong to

1) one breed 3) varieties

2) different types 4) one type

A10. Two populations of the same species evolve:

1) independently of each other and in different directions

2) in one direction, equally changing

3) depending on the direction of evolution of one of the populations

4) in different directions, but at the same speed

A11. Under what conditions will the population evolve?

1) the number of forward and reverse mutations in the population will be the same

2) the number of individuals arriving and leaving the population is the same

3) the population size changes, but the genotypes of individuals are unchanged

4) the number and genotypes of individuals change periodically

A12. As a criterion of the species in relation to the examined outwardly similar individuals, one can conditionally use

1) the same growth of individuals

2) the similarity of life processes

3) living in the same environment

4) the same body weight

A13. Two Galapagos finches (male and female) can be classified as different species based on

1) external differences

2) internal differences

3) isolation of their populations

4) non-interbreeding with each other

A14. What criterion of the species is based on the number of chromosomes in the cells of the body?

1) genetic 3) geographical

2) morphological 4) physiological

Part B

IN 1. Indicate biological factors of speciation

1) geographic isolation

2) mutations and natural selection

3) external differences

4) different habitats

5) divergence

6) common area

AT 2. In what case are the types of organisms named?

1) Siamese cat 4) Vladimir heavy truck

2) german shepherd 5) wild cat

3) common dog 6) wolf marsupial

OT. Establish a correspondence between an example of speciation and its type

AT 4. Determine the sequence of microevolutionary processes in the population.

A) the appearance of mutations

B) isolation of subspecies

B) the beginning of divergence in the population

D) the emergence of new species

E) selection of phenotypes

E) the formation of new populations

Part C

C1. What conditions are necessary for free crossing of individuals of different populations of the same species?

The ideas of the changeability of the organic world have found their supporters since ancient times. Aristotle, Heraclitus, Democritus and a number of other ancient thinkers expressed these ideas. In the XVIII century. K. Linnaeus created an artificial system of nature, in which the species was recognized as the smallest systematic unit. He introduced the nomenclature of double species names (binary), which made it possible to systematize the organisms of different kingdoms known by that time by taxonomic groups.

The creator of the first evolutionary theory was Jean Baptiste Lamarck. It was he who recognized the gradual complication of organisms and the variability of species, thereby indirectly refuting the divine creation of life. However, Lamarck's assertions about the expediency and usefulness of any emerging adaptations in organisms, the recognition of their desire for progress as the driving force of evolution, have not been confirmed by subsequent scientific research. Also, they did not find their confirmation of Lamarck's position on the heritability of characters acquired by an individual during her life and on the influence of organ exercises on their adaptive development.

The main problem that had to be solved was the problem of the formation of new species adapted to environmental conditions. In other words, scientists needed to answer at least two questions: how do new species arise? How do adaptations to environmental conditions arise?

The evolutionary doctrine, which has received its development and is recognized by modern scientists, was created independently of each other by Charles Robert Darwin and Alfred Wallace, who put forward the idea of ​​natural selection based on the struggle for existence. This doctrine was named Darwinism , or the science of the historical development of living nature.

The main tenets of Darwinism:

- the evolutionary process is real, determined by the conditions of existence and manifests itself in the formation of new, adapted to these conditions, individuals, species and larger systematic taxa;

- the main evolutionary factors are: hereditary variation and natural selection .

Natural selection plays the role of a directing factor in evolution (creative role).

The prerequisites for natural selection are: excessive reproductive potential, hereditary variability and changing conditions of existence. Natural selection is a consequence of the struggle for existence, which is subdivided into intraspecific, interspecific and control of environmental conditions. The results of natural selection are:

- preservation of any adaptations that ensure the survival and reproduction of offspring; all adaptations are relative.

Divergence - the process of genetic and phenotypic divergence of groups of individuals for individual traits and the formation of new species - progressive evolution of the organic world.

The driving forces of evolution, according to Darwin, are: hereditary variability, struggle for existence, natural selection.

EXAMPLES OF TASKS Part A

A1. The driving force behind Lamarck's evolution is

1) the desire of organisms to progress

2) divergence

3) natural selection

4) the struggle for existence

A2. The statement is erroneous

1) species are changeable and exist in nature as independent groups of organisms

2) related species have a historically common ancestor

3) all changes acquired by the body are beneficial and are preserved by natural selection

4) the evolutionary process is based on hereditary variability

A3. Evolutionary changes are entrenched in generations as a result

1) the appearance of recessive mutations

2) inheritance of characteristics acquired during life

3) struggle for existence

4) natural selection of phenotypes

A4. The merit of Charles Darwin lies in

1) recognition of the variability of species

2) establishing the principle of double species names

3) identifying the driving forces of evolution

4) the creation of the first evolutionary teaching

A5. According to Darwin, the reason for the formation of new species is

1) unlimited reproduction

2) the struggle for existence

3) mutational processes and divergence

4) direct influence of environmental conditions

A6. Natural selection is called

1) the struggle for existence between individuals of the population

2) the gradual emergence of differences between individuals of the population

3) survival and reproduction of the strongest individuals

4) survival and reproduction of individuals most adapted to environmental conditions

A7. Fighting for territory between two wolves in the same forest refers to

1) interspecies struggle

2) intraspecific struggle

3) dealing with environmental conditions

4) an inner desire for progress

A8. Recessive mutations undergo natural selection when

1) heterozygosity of an individual for a selected trait

2) homozygosity of an individual for this trait

3) their adaptive value for the individual

4) their harmfulness to the individual

A9. Indicate the genotype of the individual in which the a gene will be subjected to the action of natural selection

1) AaBb 2) AABB 3) Aavb 4) aaBb

A10. C. Darwin created his doctrine in

1) XVII century. 2) XVIII century. 3) XIX century. 4) XX century.

Part B

IN 1. Select the provisions of the evolutionary teachings of Charles Darwin

1) acquired characteristics are inherited

2) hereditary variability serves as the material for evolution

3) any variability serves as material for evolution

4) the main result of evolution is the struggle for existence

5) speciation is based on divergence

6) both beneficial and harmful traits are exposed to the action of natural selection

AT 2. Correlate the views of J. Lamarck and C. Darwin with the provisions of their teachings

Part C

C1. What is the progressiveness of Charles Darwin's teachings?

The synthetic theory of evolution arose on the basis of data from comparative anatomy, embryology, paleontology, genetics, biochemistry, and geography.

Synthetic theory of evolution puts forward the following provisions:

- the elementary evolutionary material is mutations;

- elementary evolutionary structure - population;

- elementary evolutionary process - directional change population gene pool;

– natural selection- the directing creative factor of evolution;

- in nature, there are two, conditionally distinguished processes that have the same mechanisms - micro- and macroevolution... Microevolution is a change in populations and species, macroevolution is the emergence and change of large systematic groups.

Mutational process. The studies of mutational processes in populations are devoted to the works of the Russian geneticist S.S. Chetverikov. As a result of mutations, new alleles appear. Since mutations are predominantly recessive, they accumulate in heterozygotes, forming reserve of hereditary variability. With free crossing of heterozygotes, recessive alleles become homozygous with a probability of 25% and are subject to natural selection. Individuals that do not have selective advantages are rejected. In large populations, the degree of heterozygosity is higher; therefore, large populations adapt better to environmental conditions. In small populations, inbreeding is inevitable, and, consequently, an increase in homozygous populations. This, in turn, threatens disease and extinction.

Gene drift, an accidental loss or sudden increase in the frequency of alleles in small populations, leading to a change in the concentration of this allele, an increase in population homozygosity, a decrease in its viability, and the appearance of rare alleles. For example, in religious communities isolated from the rest of the world, there is either a loss or an increase in alleles characteristic of their ancestors. An increase in the concentration of alleles occurs as a result of closely related marriages, the loss of alleles can occur as a result of the departure of community members or their death.

Forms of natural selection. Moving natural selection. Leads to displacement reaction rates organism in the direction of the variability of the trait in changing environmental conditions. Stabilizing natural selection(discovered by N.I.Shmalgauzen) narrows the rate of reaction in stable environmental conditions. Disruptive selection- occurs when one population, for some reason, is divided into two and they hardly touch each other. For example, as a result of summer mowing, the plant population may be divided in the ripening time. Over time, two types can form from it. Sexual selection ensures the development of reproductive functions, behavior, morphophysiological characteristics.

Thus, the synthetic theory of evolution combined Darwinism and modern ideas about the development of the organic world.

EXAMPLES OF TASKS Part A

A1. According to S.S. Chetverikov's initial material for speciation are

1) insulation

2) mutations

3) population waves

4) modifications

A2. Small populations are dying out due to the fact that in them

1) fewer recessive mutations than in large populations

2) less likelihood of transferring mutations to a homozygous state

3) more likely to closely related crosses and hereditary diseases

4) higher degree of heterozygosity of individuals

A3. The formation of new genera and families refers to the processes

1) microevolutionary 3) global

2) macroevolutionary 4) intraspecific

A4. In a constantly changing environment, a form of natural selection operates

1) stabilizing 3) driving

2) disruptive 4) sexual selection

A5. An example of a stabilizing form of selection is

1) the appearance of ungulates in the steppe zones

2) the disappearance of white butterflies in the industrial areas of England

3) the survival of bacteria in the geysers of Kamchatka

4) the emergence of tall forms of plants when they are moved from valleys to mountains

A6. Populations will evolve faster

1) haploid drones

2) perch heterozygous for many traits

3) male domestic cockroaches

A7. The gene pool of the population is enriched due to

1) modification variability

2) the interspecies struggle for existence

3) stabilizing form of selection

4) sexual selection

A8. The reason why gene drift can occur

1) high heterozygosity of the population

2) large population size

3) homozygosity of the entire population

4) migration and emigration of carriers of mutations from small populations

A9. Endemics are organisms

1) whose habitats are limited

2) living in a wide variety of habitats

3) the most common on Earth

4) forming the minimum population

A10. The stabilizing form of selection is aimed at

1) preservation of individuals with an average value of traits

2) preservation of individuals with new traits

3) increasing the heterozygosity of the population

4) expansion of the reaction rate

A11. Gene drift is

1) a sharp increase in the number of individuals with new traits

2) a decrease in the number of emerging mutations

3) a decrease in the rate of the mutation process

4) random change in allele frequencies

A12. Artificial selection has led to the emergence

1) arctic fox

2) badgers

3) airedale terriers

4) Przewalski's horses

Part B

IN 1. Select the conditions that determine the genetic prerequisites of the evolutionary process

1) modification variability

2) mutational variability

3) high heterozygosity of the population

4) environmental conditions

5) inbreeding

6) geographic isolation

Part C

C1. Find errors in the text provided. Indicate the numbers of the sentences in which they are allowed, explain them

1. Population - a set of individuals of different species, occupying a certain territory. 2. Individuals of one population freely interbreed with each other. 3. The set of genes that all individuals of the population possess is called the genotype of the population. 4. Individuals that make up the population are heterogeneous in their genetic makeup. 5. The heterogeneity of the organisms that make up the population creates conditions for natural selection. 6. The population is considered the largest evolutionary unit.

The adaptability of organisms to their environment. As a result of a long evolutionary process, all organisms are constantly developing and improving their adaptations to environmental conditions. Fitness is one of the results of evolution, the interaction of its driving forces - heredity, variability, natural selection. The second result of evolution is the diversity of the organic world. The organisms preserved in the process of the struggle for existence and natural selection make up the entire organic world existing today. Mutational processes occurring in a series of generations lead to the emergence of new genetic combinations, which are subjected to the action of natural selection. It is natural selection that determines the nature of new adaptations, as well as the direction of the evolutionary process. As a result, organisms have a variety of adaptations to life. Any adaptation arises as a result of a long selection of random, phenotypically manifested mutations that are beneficial to the species.

Protective coloration. Provides plants and animals with protection from enemies. Organisms with such a coloration merge with the background and become less noticeable.

Disguise. A device in which the shape of the body and color of animals merges with the surrounding objects. Praying mantises, butterfly caterpillars resemble knots, butterflies resemble plant leaves, etc.

Mimicry. Imitation of unprotected species to protected species in shape and color. Some flies look like wasps, snakes look like vipers, etc.

Warning coloring. Many animals have bright colors or certain identification marks to warn of danger. The predator who attacked once remembers the color of the prey and will be more careful the next time.

The relative nature of the adaptations. All adaptations are developed under certain environmental conditions. It is in these conditions that adaptations are most effective. However, it should be borne in mind that fitness is not absolute. Animals with both protective and warning coloration are eaten, and those who disguise themselves are attacked. Good flying birds are bad runners and can be caught on the ground; when environmental conditions change, the developed adaptation may turn out to be useless or harmful.

Evidence for evolution. Comparative anatomical the evidence is based on the identification of common and different morphological and anatomical features of the structure of various groups of organisms.

Anatomical evidence for evolution includes:

– presence of homologous organs, having a general structure plan, developing from similar germ layers in embryogenesis, but adapted to perform different functions (hand - flipper - bird's wing). Differences in the structure and function of organs result from divergence;

– the presence of similar bodies that have different origins in embryogenesis, different structures, but perform similar functions (bird wing and butterfly wing). The similarity of functions results from convergence;

- the presence of rudiments and atavisms;

- the existence of transitional forms.

Rudiments , - organs that have lost their functional significance (tailbone, ear muscles in humans).

Atavisms , - cases of manifestation of signs of distant ancestors (tail and hairy body in humans, remnants of the 2nd and 3rd toes in a horse).

Transitional forms - indicate phylogenetic continuity in the transition from ancestral forms to modern, and from class to class.

Embryological evidence. Embryology studies patterns embryonic development and sets:

- phylogenetic relationship of organisms;

- regularities of phylogenesis.

The data obtained were reflected in the laws of embryonic similarity by K.M. Baer and in the biogenetic law of E. Heckel and F. Müller.

Beer's law establishes the similarity of the early stages of development of embryos of representatives of different classes within a type. At later stages of embryonic development, this similarity is lost, and the most specialized characters of the taxon develop, up to the individual characters of the individual.

The Müller-Haeckel biogenetic law states that ontogeny is a brief repetition of phylogeny. In the process of evolution, ontogeny can be rearranged, which leads to the evolution of the organs of an adult organism.

In ontogeny, only the embryonic stages of ancestors are repeated and not always completely. If on early stage the organism is adapted to environmental conditions, then it can reach maturity without going through subsequent stages, as, for example, it happens in axolotls - the larvae of the tiger ambistoma.

Paleontological evidence - allow to date events ancient history on the fossil remains of organisms. The paleontological evidence includes the phylogenetic series of horses, proboscis, and humans built by paleontologists.

The unity of the organic world is manifested in the chemical composition, the finest structure and basic life processes in organisms.

EXAMPLES OF TASKS Part A

A1. Provide an example of patronizing coloration

1) the coloring of the ladybug protects it from birds

2) zebra coloring

3) painting of osovka

4) coloring of hazel grouse sitting on the nest

A2. Przewalski's horse is adapted to life in the steppes of Central Asia, but not adapted to life in

1) the prairies of South America

2) jungle of brazil

3) semi-deserts

4) reserve Askania-Nova

A3. Poison resistance of some cockroaches is a consequence

1) driving selection

2) stabilizing selection

3) simultaneous mutation

4) imperfections of poisons

A4. New adaptations to environmental conditions are formed depending on

1) the desire of organisms to progress

2) favorable environmental conditions

4) the norms of the reaction of organisms

A5. An adaptation to pollination by nocturnal insects in small single plants, it serves

1) white color of the corolla

2) dimensions

3) the location of the stamens and pistils

4) smell

A6. The homologue of the human hand is

1) bird wing

2) butterfly wing

3) grasshopper leg

4) crayfish claw

A7. The analogue of the butterfly's wing is

1) jellyfish tentacles 3) human hand

2) bird wing 4) fish fin

A8. The appendix is ​​a vermiform appendix of the cecum, called a rudiment because it

1) confirms the origin of humans from animals

2) has lost its original function

3) is a homologue of the large intestine of primates

4) is analogous to the intestines of arthropods

A9. What are the reasons for the emergence of the diversity of the organic world?

1) adaptability to environmental conditions

2) selection and preservation of hereditary changes

3) the struggle for existence

4) the duration of evolutionary processes

A10. Embryological evidence for evolution includes similarities

1) plan of the structure of organisms

2) anatomical structure

3) embryos of chordates

4) the development of all organisms from the zygote

A11. Phylogenetic series of some refer to evidence of evolution

1) anatomical

2) paleontological

3) historical

4) embryological

A12. An intermediate form between vertebrates and invertebrates is considered a representative

1) cartilaginous fish 3) skullless

2) arthropods 4) molluscs

Part B

IN 1. Anatomical evidence for evolution includes

1) similarity of embryos

2) the similarity of the functions of some organs

3) the presence of a tail in some people

4) common origin of organs

5) fossils of plants and animals

6) the presence of ear muscles in humans and dogs

AT 2. Paleontological data and evidence of evolution include

1) the similarity of trilobites and modern arthropods

2) placentarity of ancient and modern mammals

3) the existence of seed ferns and their fossils

4) comparison of the forms of skeletons of ancient and modern people

5) the presence of multiple nipples in some people

6) three-layer structure of the body of ancient and modern animals

OT. Correlate the factors of evolution with their characteristics. features of the factor

AT 4. Match the examples of fixtures to the types of fixtures.

Part C

C1. Is the given evidence for evolution conclusive?

The main directions of the evolutionary process. The analysis of the problem of progressive evolution was carried out by the Russian scientist A.N. Severtsov.

First of all, A.N. Severtsov proposed to distinguish biological progress and morphophysiological progress.

Biological progress - this is just a certain success of this or that group of living organisms in life: high numbers, great species diversity, wide area of ​​distribution.

Morphophysiological progress - this is the emergence of qualitatively new, more complex forms of life in the presence of already existing, fully formed groups. So, for example, multicellular organisms appeared in a world inhabited by unicellular organisms, and mammals and birds in a world inhabited by reptiles.

According to A.N. Severtsev biological progress can be achieved in three ways:

Aromorphoses . Acquisition of progressive structural features that bring one or another group of organisms to a qualitatively new level It is through aromorphoses that large taxonomic groups arise - genera, families, orders, etc. Examples of aromorphoses include the emergence of photosynthesis, the emergence of a body cavity, multicellularity, circulatory and other organ systems, etc.

Idioadaptation, private adaptations, not of a fundamental nature, but allowing them to succeed in a certain, more or less narrow environment. Examples of idioadaptation: the shape and color of the body, the adaptability of the limbs of insects and mammals to life in a certain habitat, etc.

Degeneration , simplification of the structure, transition to a simpler habitat, loss of already existing adaptations.

Examples of degenerations include: loss of intestines by tapeworms, loss of stem in duckweed.

Along with biological progress, the concept of biological regression is used. Biological regression is called a decrease in the number, species diversity, the area of ​​distribution of a particular group of organisms.

The limiting case of biological regression is the extinction of a particular group of organisms.

The main stages of the evolution of flora and fauna. Plant evolution. The first living organisms arose about 3.5 billion years ago. They apparently ate foods of abiogenic origin and were heterotrophs. The high reproduction rate led to the emergence of competition for food, and therefore to divergence. The advantage was given to organisms capable of autotrophic nutrition - first to chemosynthesis, and then to photosynthesis. About 1 billion years ago, eukaryotes split into several branches, part of which arose multicellular plants (green, brown and red algae), as well as fungi.

Basic conditions and stages of plant evolution. In connection with the formation of a soil substrate on land, plants began to emerge on land. The first were the psilophytes. From them a whole group of terrestrial plants arose - mosses, lycopods, horsetails, ferns, which reproduce by spores. From seed ferns, gymnosperms have evolved. Reproduction by seeds freed the reproductive process in plants from dependence on the aquatic environment. Evolution followed the path of reducing the haploid gametophyte and the prevalence of diploid sporophyte.

In the Carboniferous period Paleozoic era arboreal ferns formed carboniferous forests.

After the general cooling of the climate, gymnosperms became the dominant group of plants. Then the flowering of angiosperms begins, continuing to this day.

The main features of the evolution of the plant kingdom.

- Transition to the predominance of the sporophyte over the gametophyte.

- Development of a female outgrowth on the mother plant.

- Transition from fertilization in water to pollination and fertilization independent of the aquatic environment.

- Dismemberment of the plant body into organs, the development of the vascular system, supporting and protective tissues.

- Improvement of reproductive organs and cross-pollination in flowering plants in connection with the evolution of insects.

- Development of the embryo sac to protect the embryo from adverse environmental influences.

- The emergence of a variety of ways of spreading seeds and fruits.

Evolution of animals. It is assumed that animals originated either from the common stem of eukaryotes, or from unicellular algae This is confirmed by the existence of green euglena and volvox, capable of both autotrophic and heterotrophic nutrition.

The most ancient animals were sponges, coelenterates, worms, echinoderms, trilobites. Then shellfish appear. Later, the flowering of fish begins, first their jawless ancestors, and then fish that had jaws. Ray-finned and cross-finned fishes arose from the first jaw-finned fishes. Cystepenes had supporting elements in their fins, from which the limbs of terrestrial vertebrates later developed. From this group of fish, amphibians arose, and then other classes of vertebrates.

The most ancient amphibians living in the Devonian are ichthyostegs. Amphibians flourished in the Carboniferous.

Reptiles originate from amphibians, which conquered the land due to the appearance of a mechanism for sucking air into the lungs, the rejection of skin respiration, the appearance of horny scales covering the body and egg shells that protect embryos from drying out and other environmental influences. Among the reptiles, a group of dinosaurs presumably stood out, giving rise to birds.

The first mammals appeared in the Triassic period of the Mesozoic era. The main progressive biological features of mammals are the feeding of young with milk, warm-bloodedness, and a developed cerebral cortex.

The main features of the evolution of the animal world. The evolution of animals is characterized by the differentiation of cells and tissues in structure and function, the specialization of organs and organ systems.

Freedom of movement and methods of obtaining food (swallowing pieces) determined the development of complex mechanisms of behavior. The external environment, fluctuations in its factors had less effect on animals than on plants, because in animals, the mechanisms of internal self-regulation of the organism developed and improved.

An important stage in the evolutionary development of animals was the emergence of a solid skeleton. Invertebrates have formed external skeleton, - echinoderms, arthropods, molluscs; vertebrates have internal skeleton... The advantages of the internal skeleton are that, unlike the external skeleton, it does not restrict the increase in body size.

Progressive development nervous system , became the basis for the emergence of a system of conditioned reflexes.

The evolution of animals led to the development of group adaptive behavior, which became the basis for the emergence of humans.

EXAMPLES OF TASKS Part A

A1. Major genetic rearrangements leading to an increase in the level of organization are called

1) idioadaptation 3) aromorphoses

2) degeneration 4) divergence

A2. What type of modern animal ancestors had an internal skeleton?

1) coelenterates 3) molluscs

2) chordates 4) arthropods

A3. Ferns are evolutionarily more progressive than bryophytes because they have

1) stems and leaves 3) organs

2) disputes 4) conducting systems

A4. Aromorphoses of plants include the emergence

1) flower coloring

2) seed

3) inflorescences

4) vegetative propagation

A5. What factors ensured the flourishing of reptiles on land?

1) complete separation of arterial and venous blood

2) egg production, the ability to live in two environments

3) development of eggs on land, five-toed limbs, lungs

4) developed cerebral cortex

A6. The idea of ​​biological evolution of the organic world is consistent with the concept of

1) mutation process

2) inheritance of acquired characteristics

3) divine creation of the world

4) the desire of organisms to progress

A7. The theory of stabilizing selection was developed by

1) V.I. Sukachev

2) A.N. Severtsov

3) I.I. Schmalhausen

4) E.N. Pavlovsky

A8. An example of idioadaptation is the occurrence of:

1) wool in mammals

2) the second signaling system in humans

3) long legs in a cheetah

4) jaws in fish

A9. An example of aromorphosis is the occurrence

bird feathers

a beautiful peacock tail

a strong beak of a woodpecker

long legs of the heron

A10. Give an example of idioadaptation in mammals.

1) the emergence of the placenta

2) development of coat and hair

3) warm-bloodedness

4) mimicry

Part B

IN 1. Aromorphoses of plants include the appearance

1) seed

2) root tubers

3) branched shoots

4) conductive tissue

5) double fertilization

6) compound leaves

AT 2. Establish a Sequence for Evolutionary Ideas

A) the idea of ​​variability of species

B) the idea of ​​divine creation of species

B) recognition of the fact of evolutionary development

D) the emergence of a synthetic theory of evolution

E) elucidation of the mechanisms of the evolutionary process E) embryological evidence of evolution

OT. Correlate the listed signs of plants and animals with the directions of evolution

Part C

C1. What does the Mueller-Haeckel law establish?

C2. Why are small species protected, but not numerous?

Charles Darwin in his work "The Origin of Man and Sexual Selection" substantiated the evolutionary relationship of man with the higher apes. The main directions and results of biological evolution of man, as a separate species in the class of Mammals, were:

- development of bipedal locomotion;

- the release of the upper limb for work;

- an increase in the volume of the forebrain and a significant development of the cerebral cortex;

- complication of higher nervous activity.

Under the influence of biological factors of evolution, the morphological and physiological characteristics of man changed.

Social factors in human evolution formed the basis for the evolution of his behavior, the development of social, labor and communication skills. These factors include:

- the use and then the creation of tools of labor;

- the need for adaptive behavior in the formation of a social lifestyle;

- the need to predict their activities;

- the need to educate and train offspring, passing on the accumulated experience.

The driving forces of the force of anthropogenesis are:

- individual natural selection aimed at certain morphophysiological signs - upright posture, hand structure, brain development.

- Group selection aimed at social organization, biosocial selection, the result of the joint action of the first two forms of selection. He acted at the level of an individual, family, tribe.

Human races, the unity of their origin. Human races are groups of people formed in the process of biological evolution within a species. Homo sapiens... A person's belonging to a particular race is determined by the characteristics of his genotype and phenotype. Representatives different races belong to the same species and, when crossed, produce fertile offspring.

There are three races: Eurasian (Caucasoid), Equatorial (Australo-Negroid), Asian-American (Mongoloid). The reason for the formation of races was the geographical dispersal and subsequent geographical isolation of people. Racial characteristics were of an adaptive nature, which in modern society has lost its meaning.

Often used for political purposes, statements about the superiority of one race over another have no scientific basis.

“Ethnic communities” should be distinguished from races: nationalities, nations, etc. A person's belonging to a particular ethnic community is determined not by his genotype and phenotype, but by the national culture he has mastered.

EXAMPLES OF TASKS Part A

A1. In humans, in comparison with other primates, it is better developed

1) the ability to climb trees

2) protection of offspring

3) cardiovascular system

4) cerebral cortex

A2. Chimpanzees are considered the closest relative of humans because chimpanzees have

1) 48 chromosomes in cells

2) the same genetic code

3) similar primary structure of DNA

4) a similar structure of hemoglobin

A3. Human biological evolution has defined it

1) structure

2) intelligence

3) speech features

4) consciousness

A4. The social factor of human evolution has become

1) native language

2) muscle training

3) eye color

4) running speed

A5. Race is a community of people that was formed under the influence

1) social factors

2) geographic and climatic factors

3) ethnic, linguistic differences

4) fundamental differences between people

A6. All races are one kind of "Homo sapiens". Proof of this is the fact that people of different races

1) move freely around the world

2) learn a foreign language

3) form large families

4) descended from the same race

A7. Representatives of the Mongoloid and Negroid races

1) different sets of chromosomes

2) different brain structure

3) identical sets of chromosomes

4) always different native languages

A8. The transition of primates to upright posture led to such changes in body structure as

1) reducing the load on the spine

2) shaping a flat foot

3) narrowing of the chest

4) shaping the hand with an opposed thumb

A9. A special feature of man, distinguishing him from ape-like ancestors, was the appearance

1) cerebral cortex

2) the first signaling system

3) second signaling system

4) communication signals

A10. Man is capable, but the monkey is not capable of

1) creative work

2) exchange of signs

3) finding a way out of a difficult situation

4) the formation of conditioned reflexes

A11. The son of the French, brought up from early childhood in a Russian family, will speak:

1) in Russian without an accent

2) in Russian with a French accent

3) in French with a Russian accent

4) in French without an accent

Part B

IN 1. Select the traits that are related to anthropogenesis and became its prerequisites.

1) expansion of the chest

2) release of the front limbs

3) brain volume 850 cm 3

4) feeding babies with milk

5) good eyesight and hearing

6) developed motor parts of the brain

7) herd lifestyle

8) arch-shaped spine

AT 2. Establish a correspondence between the signs of great apes and humans

Part C

C1. What signs speak in favor of the relationship between humans and great apes?

Among the factors of the genetic dynamics of a population that violate its equilibrium state, are: mutation process, selection, genetic drift, migration, isolation.

Mutations and natural selection

In each generation, the population's gene pool is replenished with newly emerging mutations... Among them there can be both completely new changes and mutations already existing in the population. This process is called mutational pressure. The magnitude of the mutational pressure depends on the degree of mutability of individual genes, on the ratio of forward and backward mutations, on the efficiency of the repair system, and on the presence of mutagenic factors in the environment. In addition, the magnitude of the mutational pressure is affected by the extent to which the mutation affects the viability and fertility of an individual.

Research shows that natural populations are saturated with mutant genes, which are mostly heterozygous. The mutational process creates the primary genetic variability of the population, with which it is further necessary to act natural selection... In the event of a change in external conditions and a change in the direction of selection, the reserve of mutations allows the population to quickly adapt to the new situation.

The selection efficiency depends on whether the mutant trait is dominant or recessive. Cleansing a population from individuals with a harmful dominant mutation can be achieved in one generation, if its carrier does not leave behind offspring. At the same time, deleterious recessive mutations escape the action of selection if they are in a heterozygous state, and especially in cases where selection acts in favor of heterozygotes. The latter often have a selective advantage over homozygous genotypes due to a broader reaction rate, which increases the adaptive potential of their owners. With the preservation and reproduction of heterozygotes, the likelihood of cleavage of recessive homozygotes simultaneously increases. Selection in favor of heterozygotes is called balancing.

A striking example of this form of selection is the situation with the inheritance of sickle cell anemia. This disease is widespread in parts of Africa. It is caused by a mutation in the gene encoding the synthesis of the b-chain of hemoglobin, in which one amino acid (valine) is replaced by another (glutamine). Homozygotes for this mutation suffer from a severe form of anemia, which almost always leads to death at an early age. The red blood cells of such people are sickle-shaped. Heterozygosity for this mutation does not lead to anemia. Erythrocytes in heterozygotes have normal form, but contain 60% normal and 40% altered hemoglobin. This suggests that both normal and mutant alleles function in heterozygotes. Since homozygotes for the mutant allele are completely eliminated from reproduction, a decrease in the frequency of the harmful gene in the population should be expected. However, in some African tribes, the proportion of heterozygotes for this gene is 30-40%. The reason for this situation is that people with a heterozygous genotype are less prone to contracting tropical fever, which causes high mortality in these areas, compared to the norm. In this regard, selection preserves both genotypes: normal (dominant homozygote) and heterozygous. Reproduction from generation to generation of two different genotypic classes of individuals in a population is referred to as balanced polymorphism. It has an adaptive meaning.

There are other forms of natural selection as well. Stabilizing selection preserves the norm, as the variant of the genotype most corresponding to the prevailing conditions, eliminating the emerging deviations from it. This form of selection usually works when the population is long time is in relatively stable conditions of existence. In contrast, motive selection retains a new trait if the emerging mutation is beneficial and gives its carriers any advantage. Selection disruptive(tearing) acts simultaneously in two directions, preserving the extreme variants of the development of the trait. Charles Darwin gave a typical example of this form of selection. It concerns the preservation of two forms of insects on the islands: winged and wingless, which live on different sides of the island - leeward and calm.

The main result of the activity of natural selection is reduced to an increase in the number of individuals with traits in the direction of which selection is going. At the same time, traits and traits linked to them are also selected that are in correlative relationships with the former. For genes that control traits that are not affected by selection, the population can be in a state of equilibrium for a long time, and the distribution of genotypes over them will be close to the Hardy-Weinberg formula.

Natural selection acts broadly and simultaneously affects many aspects of the body's life. It is aimed at preserving the characteristics that are beneficial to the body, which increase its adaptability and give an advantage over other organisms. In contrast, the effect of artificial selection, which takes place in populations of cultivated plants and domestic animals, is narrower and most often affects traits that are beneficial to humans, and not to their carriers.

Genetic drift

The effect of random causes has a great influence on the genotypic structure of populations. These include: fluctuations in population size, age and sex composition of populations, quality and quantity of food resources, presence or absence of competition, random sampling that gives rise to the next generation, etc. Changes in gene frequencies in a population for random reasons American geneticist S. Wright named genetic drift, and N.P. Dubinin is a genetic automatic process. A particularly noticeable effect on the genetic structure of populations is exerted by sharp fluctuations in population size - population waves, or the waves of life. It was found that in small populations, dynamic processes proceed much more intensively, and the role of randomness in the accumulation of individual genotypes increases. With a decrease in the population size, some mutant genes can be accidentally preserved in it, while others can also be accidentally eliminated. With a subsequent increase in population size, the number of these surviving genes can rapidly increase. Drift rate is inversely proportional to population size. At the time of population decline, the drift is especially intense. With a very sharp decline in the population, there may be a threat of its extinction. This is the so-called bottleneck situation. If the population manages to survive, then as a result of the drift of genes, their frequencies will change, which will affect the structure of the new generation.

Genetic-automatic processes are especially distinct in isolates, when a group of individuals is isolated from a large population and forms a new settlement. There are many such examples in the genetics of human populations. For example, in the state of Pennsylvania (USA) there is a Mennonite sect numbering several thousand people. Marriages are allowed here only between members of the sect. The isolate was started by three married couples who settled in America at the end of the 18th century. This group of people is characterized by an unusually high concentration of the pleiotropic gene, which, in a homozygous state, causes a special form of dwarfism with polydactyly. About 13% of the members of this sect are heterozygous for this rare mutation. It is likely that the “ancestor effect” took place here: by chance one of the founders of the sect was heterozygous for this gene, and closely related marriages contributed to the spread of this anomaly. In other groups of Mennonites scattered throughout the United States, this disease has not been found.

Migrations

Another reason for the change in gene frequencies in a population is migrations... During the movement of groups of individuals and crossing them with members of another population, genes are transferred from one population to another. The effect of migration depends on the size of the migrant group and the difference in gene frequencies between the exchanging populations. If the original frequencies of genes in populations differ greatly, then a significant shift in frequencies can occur. As the migration proceeds, the genetic differences between the populations are leveled. The end result of the pressure of migrations is the establishment of a certain average concentration for each mutation throughout the system of populations between which individuals are exchanged.

An example of the role of migrations is the distribution of genes that determine the blood types of the system in humans. AB0... Europe is characterized by the predominance of the group BUT, for Asia - groups IN... The reason for the differences, according to geneticists, lies in the large migrations of the population that occurred from East to West in the period from 500 to 1500. ad.

Insulation

If individuals of one population do not fully or partially interbreed with individuals of other populations, such a population undergoes the process isolation... If separation is observed over a number of generations, and selection acts in a different direction in different populations, then the process of population differentiation takes place. The isolation process acts both at the intrapopulation and interpopulation levels.

There are two main types of insulation: spatial, or mechanical, insulation and biological insulation. The first type of isolation occurs either under the influence of natural geographic factors (mountain building; the emergence of rivers, lakes and other bodies of water; volcanic eruption, etc.), or as a result of human activities (plowing land, draining swamps, forest plantations, etc.). One of the consequences of spatial isolation is the formation of an intermittent range of the species, which is characteristic, in particular, of the blue magpie, sable, grass frog, sedge, and common loach.

Biological isolation subdivided into morpho-physiological, ecological, ethological and genetic. All these types of isolation are characterized by the emergence of reproductive barriers that limit or exclude free interbreeding.

Morpho-physiological isolation occurs mainly at the level of reproductive processes. In animals, it is often associated with differences in the structure of copulatory organs, which is especially characteristic of insects and some rodents. In plants, such traits as the size of the pollen grain, the length of the pollen tube, and the coincidence of the maturation of pollen and stigmas play a significant role.

When ethological isolation in animals, differences in the behavior of individuals during the reproductive period serve as an obstacle, for example, unsuccessful courtship of a male for a female is observed.

Environmental insulation It can manifest itself in different forms: in the preference for a certain reproductive territory, at different maturation of the sex cells, the rate of reproduction, etc. For example, in marine fish that migrate to reproduce in rivers, a special population is formed in each river. Representatives of these populations can differ in size, color, time of sexual maturity, and other characteristics related to the process of reproduction.

Genetic isolation includes various mechanisms. Most often, it occurs due to violations of the normal course of meiosis and the formation of non-viable gametes. The causes of violations can be polyploidy, chromosomal rearrangements, nuclear-plasma incompatibility. Each of these phenomena can lead to the limitation of panmixia and infertility of hybrids, and, consequently, to the limitation of the process of free combination of genes.

Isolation is rarely created by any one mechanism. Several different forms of isolation usually take place at the same time. They can act both at the stage before fertilization and after it. IN the latter case the insulation system is less economical because a significant amount of energy resources are wasted, for example, in the production of sterile offspring.

The listed factors of genetic dynamics of populations can act individually and jointly. In the latter case, either a cumulative effect can be observed (for example, a mutational process + selection), or the action of one factor can reduce the effectiveness of the action of another (for example, the appearance of migrants can reduce the effect of gene drift).

The study of dynamic processes in populations allowed S.S. Chetverikov (1928) to formulate an idea genetic homeostasis... By genetic homeostasis, he understood the equilibrium state of the population, its ability to maintain its genotypic structure in response to the action of environmental factors. The main mechanism for maintaining an equilibrium state is free crossing of individuals, in the very conditions of which, according to Chetverikov, the apparatus for stabilizing the numerical ratios of alleles is laid.

The genetic processes we have considered, occurring at the level of populations, create the basis for the evolution of larger systematic groups: species, genera, families, i.e. for macroevolution... The mechanisms of micro- and macroevolution are in many respects similar, only the scale of the changes taking place is different.

Development of evolutionary ideas. The significance of the works of C. Linnaeus, the teachings of J.-B. Lamarck, the evolutionary theory of Charles Darwin. The interconnection of the driving forces of evolution. Elementary factors of evolution

The ideas of the changeability of the organic world have found their supporters since ancient times. Aristotle, Heraclitus, Democritus and a number of other ancient thinkers expressed these ideas. In the XVIII century. K. Linnaeus created an artificial system of nature, in which the species was recognized as the smallest systematic unit. He introduced the nomenclature of double species names (binary), which made it possible to systematize the organisms of different kingdoms known by that time by taxonomic groups.

The creator of the first evolutionary theory was Jean Baptiste Lamarck. It was he who recognized the gradual complication of organisms and the variability of species, thereby indirectly refuting the divine creation of life. However, Lamarck's assertions about the expediency and usefulness of any emerging adaptations in organisms, the recognition of their desire for progress as the driving force of evolution, have not been confirmed by subsequent scientific research. Also, they did not find their confirmation of Lamarck's position on the heritability of characters acquired by an individual during her life and on the influence of organ exercises on their adaptive development.

The main problem that had to be solved was the problem of the formation of new species adapted to environmental conditions. In other words, scientists needed to answer at least two questions: how do new species arise? How do adaptations to environmental conditions arise?

The evolutionary doctrine, which has received its development and is recognized by modern scientists, was created independently of each other by Charles Robert Darwin and Alfred Wallace, who put forward the idea of ​​natural selection based on the struggle for existence. This doctrine was named Darwinism , or the science of the historical development of living nature.

The main tenets of Darwinism:

- the evolutionary process is real, determined by the conditions of existence and manifests itself in the formation of new, adapted to these conditions, individuals, species and larger systematic taxa;

- the main evolutionary factors are: hereditary variation and natural selection .

Natural selection plays the role of a directing factor in evolution (creative role).

The prerequisites for natural selection are: excessive reproductive potential, hereditary variability and changing conditions of existence. Natural selection is a consequence of the struggle for existence, which is subdivided into intraspecific, interspecific and control of environmental conditions. The results of natural selection are:

- preservation of any adaptations that ensure the survival and reproduction of offspring; all adaptations are relative.

Divergence - the process of genetic and phenotypic divergence of groups of individuals for individual traits and the formation of new species - progressive evolution of the organic world.

The driving forces of evolution, according to Darwin, are: hereditary variability, struggle for existence, natural selection.

EXAMPLES OF TASKS

Part A

A1. The driving force behind Lamarck's evolution is

1) the desire of organisms to progress

2) divergence

3) natural selection

4) the struggle for existence

A2. The statement is erroneous

1) species are changeable and exist in nature as independent groups of organisms

2) related species have a historically common ancestor

3) all changes acquired by the body are beneficial and are preserved by natural selection

4) the evolutionary process is based on hereditary variability

A3. Evolutionary changes are entrenched in generations as a result

1) the appearance of recessive mutations

2) inheritance of characteristics acquired during life

3) struggle for existence

4) natural selection of phenotypes

A4. The merit of Charles Darwin lies in

1) recognition of the variability of species

2) establishing the principle of double species names

3) identifying the driving forces of evolution

4) the creation of the first evolutionary teaching

A5. According to Darwin, the reason for the formation of new species is

1) unlimited reproduction

2) the struggle for existence

3) mutational processes and divergence

4) direct influence of environmental conditions

A6. Natural selection is called

1) the struggle for existence between individuals of the population

2) the gradual emergence of differences between individuals of the population

3) survival and reproduction of the strongest individuals

4) survival and reproduction of individuals most adapted to environmental conditions

A7. Fighting for territory between two wolves in the same forest refers to

1) interspecies struggle

2) intraspecific struggle

3) dealing with environmental conditions

4) an inner desire for progress

A8. Recessive mutations undergo natural selection when

1) heterozygosity of an individual for a selected trait

2) homozygosity of an individual for this trait

3) their adaptive value for the individual

4) their harmfulness to the individual

A9. Indicate the genotype of the individual in which the a gene will be subjected to the action of natural selection

1) AaBb 2) AABB 3) Aavb 4) aaBb

A10. C. Darwin created his doctrine in

1) XVII century. 2) XVIII century. 3) XIX century. 4) XX century.

Part B

IN 1. Select the provisions of the evolutionary teachings of Charles Darwin

1) acquired characteristics are inherited

2) hereditary variability serves as the material for evolution

3) any variability serves as material for evolution

4) the main result of evolution is the struggle for existence

5) speciation is based on divergence

6) both beneficial and harmful traits are exposed to the action of natural selection

AT 2. Correlate the views of J. Lamarck and C. Darwin with the provisions of their teachings

Part C

C1. What is the progressiveness of Charles Darwin's teachings?

Answers Part A. A1 – 1. A2 – 3. A3 – 4.A4 – 3. A5 – 3. A6- 4.A7– 2. A8 – 2.A9 – 4.A10 – 3.

Part B. B1 – 2, 5, 6. AT 2 A - 1; B - 1; AT 2; G - 2; d one; E - 2.

Part C. C1 C. Darwin revealed the reasons for the origin of the diversity and fitness of organisms, their biological progress over a historically long period of time. His teaching is based on the principles of hereditary variability, the struggle for existence, natural selection and divergence - i.e. factors that no one spoke about before. Darwin gave an explanation for the mechanisms of the evolutionary process that in the second half of the 19th century. was a truly revolutionary breakthrough in science.

In addition, his teaching, together with the synthetic theory of evolution, is the only teaching that helps to logically explain the emergence of fitness in organisms.

The creative role of natural selection. Synthetic theory of evolution. Research by S.S. Chetverikov. The role of evolutionary theory in the formation of the modern natural science picture of the world

The synthetic theory of evolution arose on the basis of data from comparative anatomy, embryology, paleontology, genetics, biochemistry, and geography.

Synthetic theory of evolution puts forward the following provisions:

- the elementary evolutionary material is mutations;

- elementary evolutionary structure - population;

- elementary evolutionary process - directional change population gene pool;

– natural selection- the directing creative factor of evolution;

- in nature, there are two, conditionally distinguished processes that have the same mechanisms - micro- and macroevolution... Microevolution is a change in populations and species, macroevolution is the emergence and change of large systematic groups.

Mutational process. The studies of mutational processes in populations are devoted to the works of the Russian geneticist S.S. Chetverikov. As a result of mutations, new alleles appear. Since mutations are predominantly recessive, they accumulate in heterozygotes, forming reserve of hereditary variability. With free crossing of heterozygotes, recessive alleles become homozygous with a probability of 25% and are subject to natural selection. Individuals that do not have selective advantages are rejected. In large populations, the degree of heterozygosity is higher; therefore, large populations adapt better to environmental conditions. In small populations, inbreeding is inevitable, and, consequently, an increase in homozygous populations. This, in turn, threatens disease and extinction.

Gene drift, an accidental loss or sudden increase in the frequency of alleles in small populations, leading to a change in the concentration of this allele, an increase in population homozygosity, a decrease in its viability, and the appearance of rare alleles. For example, in religious communities isolated from the rest of the world, there is either a loss or an increase in alleles characteristic of their ancestors. An increase in the concentration of alleles occurs as a result of closely related marriages, the loss of alleles can occur as a result of the departure of community members or their death.

Forms of natural selection. Moving natural selection. Leads to displacement reaction rates organism in the direction of the variability of the trait in changing environmental conditions. Stabilizing natural selection(discovered by N.I.Shmalgauzen) narrows the rate of reaction in stable environmental conditions. Disruptive selection- occurs when one population, for some reason, is divided into two and they hardly touch each other. For example, as a result of summer mowing, the plant population may be divided in the ripening time. Over time, two types can form from it. Sexual selection ensures the development of reproductive functions, behavior, morphophysiological characteristics.

Thus, the synthetic theory of evolution combined Darwinism and modern ideas about the development of the organic world.

EXAMPLES OF TASKS

Part BUT

A1. According to S.S. Chetverikov's initial material for speciation are

1) insulation

2) mutations

3) population waves

4) modifications

A2. Small populations are dying out due to the fact that in them

1) fewer recessive mutations than in large populations

2) less likelihood of transferring mutations to a homozygous state

3) more likely to closely related crosses and hereditary diseases

4) higher degree of heterozygosity of individuals

A3. The formation of new genera and families refers to the processes

1) microevolutionary 3) global

2) macroevolutionary 4) intraspecific

A4. In a constantly changing environment, a form of natural selection operates

1) stabilizing 3) driving

2) disruptive 4) sexual selection

A5. An example of a stabilizing form of selection is

1) the appearance of ungulates in the steppe zones

2) the disappearance of white butterflies in the industrial areas of England

3) the survival of bacteria in the geysers of Kamchatka

4) the emergence of tall forms of plants when they are moved from valleys to mountains

A6. Populations will evolve faster

1) haploid drones

2) perch heterozygous for many traits

3) male domestic cockroaches

A7. The gene pool of the population is enriched due to

1) modification variability

2) the interspecies struggle for existence

3) stabilizing form of selection

4) sexual selection

A8. The reason why gene drift can occur

The ideas of the changeability of the organic world have been expressed since ancient times. Aristotle, Heraclitus, Democritus.

In the XVIII century ... K. Linnaeus created an artificial system of nature, in which the species was recognized as the smallest systematic unit. He introduced a nomenclature of double names of the form ( binary), which made it possible to systematize the organisms of different kingdoms known by that time by taxonomic groups.

The creator first evolutionary theory was Jean Baptiste Lamarck. It was he who recognized the gradual complication of organisms and the variability of species, thereby indirectly refuting the divine creation of life. However, Lamarck's assertions about the expediency and usefulness of any emerging adaptations in organisms, the recognition of their desire for progress as the driving force of evolution, have not been confirmed by subsequent scientific research. Also, they did not find their confirmation of Lamarck's position on the heritability of characters acquired by an individual during her life and on the influence of organ exercises on their adaptive development.

The main problem, which needed to be solved, was the problem of the formation of new species adapted to environmental conditions. In other words, scientists needed to answer at least two questions: how do new species arise? How do adaptations to environmental conditions arise?

Evolutionary doctrine, which has received its development and is recognized by modern scientists, was created independently of each other Charles Robert Darwin and Alfred Wallace who put forward the idea of ​​natural selection based on the struggle for existence. This doctrine was named Darwinism , or the science of the historical development of living nature.

The main tenets of Darwinism:

- the evolutionary process is real, determined by the conditions of existence and manifests itself in the formation of new, adapted to these conditions, individuals, species and larger systematic taxa;

- the main evolutionary factors are hereditary variability and natural selection.

Natural selection plays the role of a directing factor in evolution (creative role).

Prerequisites for natural selection are:

excess reproductive potential,

hereditary variability,

changing conditions of existence.

Natural selection is a consequence of the struggle for existence which is subdivided into intraspecific, interspecific and control of environmental conditions.

By natural selection are:

preservation of any adaptations that ensure the survival and reproduction of offspring; all adaptations are relative.

Divergence - the process of genetic and phenotypic divergence of groups of individuals for individual traits and the formation of new species - progressive evolution of the organic world.

Driving forces of evolution according to Darwin are: hereditary variability, struggle for existence, natural selection.

Thematic assignments

A1. The driving force behind Lamarck's evolution is

1) the desire of organisms to progress

2) divergence

3) natural selection

4) the struggle for existence

A2. The statement is erroneous

1) species are changeable and exist in nature as independent groups of organisms

2) related species have a historically common ancestor

3) all changes acquired by the body are beneficial and are preserved by natural selection

4) the evolutionary process is based on hereditary variability

A3. Evolutionary changes are entrenched in generations as a result

1) the appearance of recessive mutations

2) inheritance of characteristics acquired during life

3) struggle for existence

4) natural selection of phenotypes

A4. The merit of Charles Darwin lies in

1) recognition of the variability of species

2) establishing the principle of double species names

3) identifying the driving forces of evolution

4) the creation of the first evolutionary teaching

A5. According to Darwin, the reason for the formation of new species is

1) unlimited reproduction

3) mutational processes and divergence

2) the struggle for existence

4) direct influence of environmental conditions

A6. Natural selection is called

1) the struggle for existence between individuals of the population

2) the gradual emergence of differences between individuals of the population

3) survival and reproduction of the strongest individuals

4) survival and reproduction of individuals most adapted to environmental conditions

A7. Fighting for territory between two wolves in the same forest refers to

1) interspecies struggle

3) dealing with environmental conditions

2) intraspecific struggle

4) an inner desire for progress

A8. Recessive mutations undergo natural selection when

1) heterozygosity of an individual for a selected trait

2) homozygosity of an individual for this trait

3) their adaptive value for the individual

4) their harmfulness to the individual

A9. Indicate the genotype of the individual in which the a gene will be subjected to the action of natural selection

A10. C. Darwin created his doctrine in

IN 1. Select the provisions of the evolutionary teachings of Charles Darwin

1) acquired characteristics are inherited

2) hereditary variability serves as the material for evolution

3) any variability serves as material for evolution

4) the main result of evolution is the struggle for existence

5) speciation is based on divergence

6) both beneficial and harmful traits are exposed to the action of natural selection