Recognizing the reality of the species, Darwin proved that in nature there is a process speciation- the emergence of new species on the basis of existing ones under the influence of the driving forces of evolution. According to modern ideas about evolution, the formation of a new species occurs within the population - the elementary unit of evolution. Populations are genetically open systems. And as long as there is a flow of genes between them as a result of the migration of individuals, the species remains a single genetically closed system. However, the emergence of isolation (barrier) between two populations leads to the accumulation of hereditary differences in them, which prevent the individuals of these populations from crossing at subsequent meetings. This proves that populations are becoming genetically closed systems and hence new species. This means that the process of speciation has taken place.

Speciation is an evolutionary process of transformation of genetically open systems - populations - into genetically closed systems - new species.

Speciation is a complex and lengthy process that includes intermediate stages and requires the presence of certain factors.

Speciation factors

In populations of one species, the action of the prerequisites of evolution leads to the emergence of a diversity of genotypes and phenotypes. This is the basis for the struggle for existence and natural selection. The action of natural selection on populations whose living conditions are different makes them slightly different. However, the differences between individuals that have arisen as a result of selection will be smoothed out if the individuals of the populations begin to interbreed with each other. In order for the process of speciation to begin at the level of these populations, there must be isolation between them that prevents the exchange genetic information. There are two forms of isolation: geographical and biological.

Geographic (spatial) isolation- isolation of a certain population from another population of the same species by some barriers that are difficult to overcome. The first reason is large territorial gaps between populations in species with mosaic ranges. The occurrence of these gaps may be associated with glaciers, human activities, or the dispersal of populations outside the original range. The second reason is the geographical barriers separating populations (rivers, mountains, gorges, forest areas, meadows, swamps). Geographical isolation prevents individuals from separated populations from interbreeding freely due to the impossibility of their meeting due to a geographical barrier.

biological isolation due to biological differences between individuals of populations. Depending on the nature of the differences, four types of biological isolation are distinguished: ecological, ethological, morphophysiological and genetic.

Environmental isolation due to a shift in reproductive periods (terms of flowering, nesting, mating, spawning) or different breeding sites, which prevents free crossing of individuals in populations.

If populations herbaceous plants fall into a zone of increased moisture, then their flowering time is shifted compared to other populations. In birds, populations of the same species may differ in terms of nesting and mating, depending on the location of nests in different parts of the tree crown or in the shrub layer.

Ethological isolation due to the peculiarities of the behavior of individuals during the mating season. At first glance, insignificant differences in courtship rituals in the exchange of visual, sound, chemical signals can lead to the termination of this ritual and the restriction of mating.

Morphophysiological isolation due to differences in the size of individuals or in the structure of male copulatory organs (some species of pulmonary mollusks, rodents). It does not interfere with the meeting of the sexes, but prevents the crossing of individuals due to the impossibility of fertilization.

genetic isolation due to large chromosomal and genomic rearrangements that cause differences in the number, shape and composition of chromosomes. It does not interfere with the meeting of the sexes and fertilization. But it excludes the exchange of genetic information between populations due to the death of zygotes after fertilization, varying degrees of sterility of hybrids and their reduced viability.

The effect of any form of isolation on evolutionary material is not directed, but is a necessary condition for enhancing genetic differences between populations. An important characteristic of isolation is its duration, due to which the action of multidirectional natural selection leads to a divergence of signs of populations - divergences. As a result, populations become varieties, or race. Maintaining isolation leads to increased differences between varieties, and they turn into subspecies. If increasing differences between subspecies prevents them from interbreeding, then they have become genetically closed systems. There was a reproductive isolation between them. The subspecies have become new species.

Thus, the factors of speciation are:

1. prerequisites for evolution: mutational and combinative variability, population waves, gene flow and drift, isolation;
2. driving forces of evolution: struggle for existence, natural selection.

The processes occurring within a species at the population level under the influence of these factors and leading to the formation of new species can be considered as the initial stage of evolution - microevolution.

Further, evolution continues at the level of species, genera, families according to the same mechanism and under the influence of the same prerequisites and driving forces of evolution. This stage of evolution is called macroevolution. Microevolution and macroevolution are stages of a single evolutionary process.

Speciation methods

Depending on the form of isolation of populations, two methods of speciation are distinguished: allopatric and sympatric.

allopatric(from Greek. allos- different, patris- motherland) speciation proceeds in the presence of geographic isolation. Populations of the same species are separated by large distances or geographical barriers. The resulting geographic races and subspecies have ranges that do not overlap with the maternal range. An example of allopatric speciation is the presence of two subspecies of the American squirrel and three subspecies of blue jays. They live in different geographical areas North America. On the Eurasian continent, there are three subspecies of the great tit, which were formed as a result of geographic isolation. There are also subspecies of sparrows, wrens, woodpeckers, which have different distribution areas.

Sympatric speciation(from Greek. syn- together, patris- homeland) occurs in the presence of biological isolation. Populations of the same species are within the maternal range, but cannot interbreed due to biological differences between their individuals. Sympatric speciation can manifest itself in plants with the specialization of pollinating insects in the pollination of flowers of a certain shape. For example, bees are an isolating factor between races of snapdragon plants. They never move from flying around the flowers of one race to another. Some plants (large rattle, white mari) form seasonal races that differ in terms of flowering. In a number of fish species (herring, perch, carp, etc.), seasonal races coexist with different spawning periods.

Speciation factors are: preconditions and driving forces of evolution. Allocate geographical and biological forms of isolation. Depending on the form of isolation, allopatric or sympatric speciation can occur in nature. Speciation is the result of microevolution.

BIOLOGY TEST GRADE 11

Part 1

Option 1
A1. Which of the scientists considered the striving for perfection to be the driving force of evolution and claimed
inheritance of acquired traits?
1) Carl Line
2) Jean-Baptiste Lamarck
3) Charles Darwin
4) A.N. Chetverikov
A2. A set of freely interbreeding individuals of the same species that exists for a long time
in a certain part of the range relatively apart from other populations of the same species,
called:
1) View
2) Population
3) Variety
4) Colony
A3. What criterion of species include the features of external and internal structure field
mice?
1) Morphological
2) Genetic
3) Environmental
4) Geographic
A4. Which criterion of the species include the totality of environmental factors, to which
adjusted polar bear?
1) Morphological
2) Genetic
3) Environmental
4) Geographic
A5. TO statistics populations include:
1) Mortality
2) Number
3) Fertility
4) Growth rate
A6. What is the name of a random non-directional change in the frequencies of alleles and genotypes in
populations?
1) Mutational variability
2) Population waves
3) Gene drift
4) Insulation
A7. What are periodic and non-periodic population fluctuations called?
direction of increase or decrease in the number of individuals?
1) Waves of life
2) Gene drift
3) Insulation
4) Natural selection

IN 1. What evolutionary changes can be attributed to aromorphoses?
1) The appearance of a flower
2) The formation of organs and tissues in plants
3) The emergence of thermophilic bacteria
4) Atrophy of roots and leaves in dodder
5) Specialization of some plants for certain pollinators
6) Constant body temperature
AT 2. Evolutionary factors include:
1) Divergence
2) Hereditary variability
3) Convergence
4) Struggle for existence
5) Parallelism
6) Natural selection

Cause of plant death
A) the fruits, along with hay, fall into
stomach of herbivores
B) plants die from severe frosts and
droughts
C) seeds die in deserts and
Antarctica
D) plants crowd each other out
D) fruits are eaten by birds
E) plants die from bacteria and viruses
A form of struggle for existence
1) intraspecific
2) interspecific
3) fight against adverse conditions
A
B
IN
G
D
E

corresponds
Animal sign
A) sexual reproduction
B) education in cetacean flippers
C) the emergence of a 4-chambered heart
D) the emergence of an autotrophic method
nutrition
D) the transformation of leaves into thorns
desert plants
E) loss of leaves, roots and chlorophyll in
dodder
Direction of evolution
1) aromorphosis (arogenesis)
2) idioadaptation (allogenesis)

A
B
IN
G
D
E

BIOLOGY TEST GRADE 11
ON THE TOPIC "BASIC DOCTRINES ABOUT EVOLUTION"
Part 1
For each task A1A15, 4 possible answers are given, of which only one is correct.
Option 2
A1. Who is the author of the first evolutionary doctrine?
1) Carl Line
2) Jean-Baptiste Lamarck
3) Charles Darwin
4) A.N. Chetverikov
A2. The structural unit of a species is...
1) Individual
2) Population
3) Colony
4) Flock
A3. What criterion of the species include the set of chromosomes characteristic of Homo sapiens: their
number, size, shape?
1) Morphological
2) Genetic
3) Environmental
4) Geographic
A4. To what criterion of the species is the growth of Grouse grandiflora in the forests on
rocky places?
1) Geographic
2) Morphological
3) Environmental
4) Ethological
A5. Population dynamics include:
1) Mortality
2) Number
3) Density
4) Structure
A6. Population waves are not caused by:
1) Seasonal temperature fluctuations
2) Natural disasters
3) Aggressiveness of predators
4) Mutational variability
A7. What prevents the exchange of genetic information between populations?
1) Mutational variability
2) Population waves
3) Gene drift
4) Insulation
A8. What is the complex of diverse relationships between organisms and factors called?
inanimate and living nature:
1) Natural selection
2) Struggle for existence
3) Fitness

4) Variability
A9. What form of struggle for existence is the perch eating its fry?
1) Interspecies
2) Intraspecific
3) With adverse environmental conditions
4) Intraspecific mutual assistance
A10. What form of natural selection tends to preserve mutations that lead to less
variability of the mean value of the trait?
1) Driving natural selection
2) Tearing natural selection
3) Stabilizing natural selection
4) Disruptive natural selection
A11. What evolutionary factor contributes to the emergence of barriers to free interbreeding
individuals?
1) Waves of life
2) Natural selection
3) Modifications
4) Insulation
A12. Which group of evidence for evolution organic world are phylogenetic
ranks?
1) Comparative anatomical
2) Embryological
3) Paleontological
4) Biogeographic
A13. Indicate the correct scheme for classifying plants:
1) Species genus family order class type
2) Species genus family order class type
3) Species genus family order class department
4) Species genus order family class type
A14. What organs arise as a result of divergence?
1) Homologous
2) Similar
3) Atavistic
4) Rudimentary
A15. Which of the following adaptations is classified as an idioadaptation?
1) The emergence of a chord
2) The emergence of a creeping stem in strawberries
3) Formation of 2 circles of blood circulation
4) Loss of circulatory organs in bull tapeworm

Part 2.
When completing tasks B1B2, select three correct answers out of six.
When completing tasks B3B4, establish a correspondence between the content of the first and second
column. Enter the numbers of the selected answers in the table.
IN 1. What are the characteristics of biological progress?
1) Reducing the number of species
2) Expansion of the range of the species
3) The emergence of new populations, species
4) Narrowing of the range of the species
5) Simplification of organization and transition to a sedentary lifestyle
6) Increase in the number of species
AT 2. What features illustrate the stabilizing form of natural selection?
1) Operates in changing environmental conditions
2) Operates under constant environmental conditions
3) Maintains the reaction rate of the trait
4) Changes the average value of the attribute either in the direction of decreasing its value, or in
direction of increase
5) Controls functioning organs
6) Leads to a change in the reaction rate
AT 3. Establish a correspondence between the death of plants and the form of the struggle for existence.
Cause of plant death
A) plants of the same species crowd out each other
B) plants die from viruses, fungi, bacteria
C) seeds die from severe frosts and drought
D) plants die from lack of moisture when
germination
D) people, cars trample young plants
E) birds eat the fruits of plants and
mammals
A form of struggle for existence
1) interspecific
2) intraspecific
3) fight against adverse
conditions
A
B
IN
G
D
E
AT 4. Establish a correspondence between the trait of an animal and the direction of evolution to which it
corresponds
Animal sign
A) reduction of the organs of vision in a mole
B) the presence of suckers in the liver fluke
B) warm-bloodedness
D) the emergence of a 4-chambered heart
D) loss of the nervous and digestive systems in
pork tapeworm
E) flattened body of a flounder
Direction of evolution
1) aromorphosis (arogenesis)
2) idioadaptation (allogenesis)
3) general degeneration (catagenesis)
A
B
IN
G
D
E

C1. What type of natural selection is shown in the figure? Under what environmental conditions does he
observed? What mutations does it retain?

Purpose: to identify the level of mastery of students educational material course "General
BIOLOGY TEST IN GRADE 11
INSTRUCTIONS FOR CARRYING OUT
biology" on topics covered

Estimated time to complete the administrative test is 40 minutes.
The topic "Fundamentals of the doctrine of evolution" is studied in the 11th grade in the course " General biology» and is
vast and rather complex topic.
In the course of studying this section, students become familiar with the history of evolutionary ideas, with
the works of C. Linnaeus, the teachings of J. B. Lamarck, the evolutionary theory of Ch. Darwin, the role of
evolutionary theory in the formation of a modern natural-science picture of the world. students
get acquainted with the synthetic theory of evolution. Studying the population as a structural unit
species, unit of evolution; driving forces of evolution, their influence on the gene pool of the population.
To reliably determine the level of assimilation of theoretical material by each student
it is advisable to use test control. The check includes skills not only
reproduce knowledge, but also apply it to formulate worldview conclusions and
generalizations. In addition, testing is a qualitative and objective way
assessment of students' knowledge, it puts all children on an equal footing, excluding subjectivity
teachers.
Testing tasks: to test knowledge of the history of evolutionary ideas, scientific merits of K. Linnaeus and
J. B. Lamarck, C. Darwin; systematize knowledge about the species, population, driving forces
evolution and its results; to test students' understanding of macroevolution and speciation,
the main directions of evolution of the organic world.
Test evaluation criteria.
All tasks are divided by difficulty levels.
Tasks basic level correspond to the minimum content of biological education and
requirements for the level of training of graduates. They are made in accordance with the standard
secondary biological education. For each question, answer options are provided.
of which only one is true. For the correct execution of each such task, 1 is set.
score.
Tasks advanced level aimed at checking the development of students more complex
content. They contain tasks with multiple choice answers from the given, on
establishing correspondence, determining the sequence of biological phenomena,
indication of the truth or falsity of statements. For the correct completion of each such task
given 2 points.
The part C task includes a free answer task. For the correct completion of the task
3 points are given.
Work structure:
1) According to the content, the work includes the following blocks:
 Development of the evolutionary teachings of Ch.Darwin
 Type and its criteria
 Populations

 Struggle for the existence of its form
 Natural selection and its forms
Genetic composition and changes in the gene pool of populations

 Isolation mechanisms. Speciation
 Macroevolution and its evidence
 System of plants and animals - display of evolution

The main directions of evolution of the organic world
2) According to the levels of tasks, the work allows you to identify the assimilation of the material at the base,
elevated and high levels.
3) By forms test items the work consists of tests with the choice of one correct
answer option, open type with a short answer, open type with a full expanded
answer.
Distribution of work tasks by content:
Blocks
Test numbers
assignments
A1
A2, A3, A4
A5
A6, A7
Development of evolutionary doctrine
Ch. Darwin
Type e its criteria
Populations
Genetic composition and variation
population gene pool
The struggle for the existence of her form A8, A9
Natural selection and its forms
isolation mechanisms.
Speciation
macroevolution and its
proof
plant and animal system
evolution display
Main directions of evolution
organic world
TOTAL10
A10
A11
15
A12
A13
A14, A15
Number
assignments
1
Percentage of jobs for
this block
6,7%
3
1
2
2
1
1
1
1
2
15
20%
6,7%
13,3%
13,3%
6,7%
6,7%
6,7%
6,7%
13,3%
100%
Distribution of work tasks in parts.
№
1
2
3
Parts of work
Number of jobs
Part 1 (A)
Part 2 (B)
Part 3 (C)
Total
15
4
1
20
Maximum
primary score
15
8
3
26
Job Type
With a choice
response
With a brief
answer
With deployed
answer
Distribution of work tasks by level of complexity:
Difficulty level
assignments
Test numbers
assignments
Number of jobs
Base
A1A15
15
Percentage of jobs for
given level
DifficultyС1:
1) Stabilizing selection
2) Observed in relatively
constant environmental conditions
environments
3) Saves mutations leading to
less variability of the mean
feature values
driving selection
Observed in unidirectional
C1:
1)
2)
changing environmental conditions
3)
Saves mutations leading to
other extreme manifestations of magnitude
sign (either in the direction of strengthening or in
weakening side)
Evaluation system for completed test work (scale of conversion to assessment):
Maximum points for work 26
A grade of "2" is given if the student scored less than 33% of total number points
Score "3" if scored from 33% to 48% of points
Grade "4" if the student scored from 49% to 81% of the points
Score "5" if the student scored over 82% of the points
Grade "2"
Grade "3"
Rating "4"
Rating "5"
Less than 8 points
8 to 12 points
13 to 21 points
22 to 26 points

The gradual accumulation of differences between populations isolated from each other can lead to the fact that they turn into two different species, i.e. speciation will occur.

Types of isolation/speciation:

Geographic - if there is an insurmountable barrier between the populations - a mountain, a river, or a very large distance (occurs with a rapid expansion of the range). For example, Siberian larch (in Siberia) and Dahurian larch (in the Far East).

Ecological (biological) - if two populations live in the same territory (within the same range), but cannot interbreed. For example, different populations of trout live in Lake Sevan, but they spawn in different rivers that flow into this lake.

Isolation as a biological term refers to the separation of individuals or groups of individuals from each other. Such separation leads to species changes, which is the driving force of evolution, since groups isolated from each other acquire completely different species characteristics. Thus, isolation is one of the factors of evolution - the driving force that causes and perpetuates changes in individual populations. The main factors of evolution are natural selection and mutation processes. Also, such factors include genetic drift, which is especially evident in conditions of isolation. Genetic drift leads to a significant decrease in the genetic diversity of one isolated population, and at the same time, differences between individual populations increase in a number of species traits. This is how isolation becomes the cause of the emergence of a particular species, which differs in its characteristics from others. People can serve as an example - how many different races and peoples, and how many tribes existed and exist now. The difference in the development of each individual people is also very indicative.

By the nature of the insulating barriers are classified:

Geographical isolation - the isolation of a certain population from other populations of the same species by some insurmountable geographical obstacle. Such isolation may result from a change geographical conditions within the range of the species or during the dispersal of groups of individuals outside the range, when the "populations of the founders" can gain a foothold in some isolated areas with favorable environmental conditions for them. Geographical isolation is one of the important factors of speciation, since it prevents interbreeding and thus the exchange of genetic information between isolated populations.

reproductive isolation. Reproductive (biological) isolation leads to disruption of free crossing or the formation of sterile offspring. Ecological, ethological, temporal, anatomical-morphological-physiological and genetic reproductive isolation are classified. With the ethological nature of reproductive isolation for individuals of different populations, the probability of fertilization decreases due to differences in lifestyle and behavior, for example, in different types birds differ in courtship rituals and mating songs. With an ecological character, the living conditions of living organisms differ, for example, fish populations spawn in different places. With temporary isolation, the timing of reproduction differs. With anatomical-morphological-physiological reproductive isolation in living organisms, there are differences in the structure, size of individual organs of the reproductive system, or there are differences in the biochemical aspects of the reproductive function. With the genetic nature of reproductive isolation, incompatible gametes appear or hybrids appear with reduced viability, fertility, or sterility.

The listed forms of reproductive isolation occur independently of each other and can be combined in any combination. However, it is genetic isolation that is considered one of the most important forms of reproductive isolation, since other forms of reproductive isolation during speciation ultimately lead to the emergence of independence of the gene pools of two populations. Reproductive isolation is often facilitated by long-term geographic isolation.

Population waves as a driving factor of evolution.

IN natural conditions Periodic fluctuations in the number of populations of many organisms are constantly occurring. They are called population waves, or life waves. This term was proposed by S. S. Chetverikov.

The number of populations is undergoing significant changes associated with the seasonal nature of the development of many species and their habitat conditions. It can also vary greatly different years. Cases of mass reproduction of populations are known certain types, for example, lemmings, locusts, pathogenic bacteria and fungi (epidemics), etc.

There are frequent cases of a sharp, sometimes catastrophic reduction in the number of populations associated with the invasion of diseases, pests, natural phenomena(forest and steppe fires, floods, volcanic eruptions, prolonged droughts, etc.).

There are known examples of a sharp outbreak in the population of some species, whose representatives found themselves in new conditions for them, where they have no enemies (for example, the Colorado potato beetle and Canadian elodea in Europe, rabbits in Australia, etc.).

These processes are of a random nature, leading to the death of some genotypes and stimulating the development of others, as a result of which significant rearrangements of the gene pool of the population can occur. In small populations, the offspring will give a small number of randomly surviving individuals, therefore, the frequency of closely related crosses in them increases significantly, which increases the likelihood of individual mutations and recessive allelic genes going into a homozygous state. Thus, mutations can actually manifest themselves in populations and serve as the beginning of the formation of new forms or even new species. Rare genotypes can either completely disappear or suddenly multiply in populations, becoming dominant. Dominant genotypes can either be preserved under new conditions, or sharply reduced in number and even completely disappear from populations. The phenomena of reorganization of the structure of the gene pool and changes in the frequencies of occurrence of different allelic genes in it, associated with a sharp and random change in the size of populations, are called gene drift.

Thus, population waves and related phenomena of genetic drift lead to deviations from the genetic equilibrium in populations. These changes can be picked up by selection and can influence further processes of evolutionary transformations.

Migration - as a driving factor of evolution.

Gene introgression - the exchange of genes between populations of different species

Migration is the movement of individuals from one habitat to another, caused by a change in the conditions of existence in the habitat of these individuals. There are regular migrations (seasonal, daily, etc.) and irregular migrations.

The evolutionary significance of migrations lies in the fact that they perform two most important functions in nature: 1) they contribute to the unification of species as complete systems, providing regular or periodic contacts between its individual populations; 2) contribute to the penetration of species into new habitats (in this case, isolation of distant populations from the main species may occur).

Populations of the same species, as a rule, are not isolated from each other. There is a constant exchange of genes between them. The intensity of gene exchange between populations depends on the distance between them.

Due to free interbreeding during migration, genes are exchanged between individuals of a population of the same species (gene flow). In this case, the genes of migrating individuals are included in the gene pool of the population when crossing. As a result, the gene pool of populations is updated.

Natural selection

Darwin's principle of natural selection is fundamental to evolutionary theory. Natural selection is a directed, driving factor in the evolution of the organic world. At present, ideas about natural selection have been supplemented with new facts, expanded and deepened. Natural selection should be understood as selective survival and the possibility of leaving offspring by individual individuals. The biological significance of an individual that has given offspring is determined by the contribution of its genotype to the gene pool of the population. Selection operates in a population; its objects are the phenotypes of individual individuals. The phenotype of an organism is formed on the basis of the realization of genotype information in certain environmental conditions.

Thus, selection from generation to generation according to phenotypes leads to the selection of genotypes, since not traits, but gene complexes are transmitted to descendants. For evolution, not only genotypes are important, but also phenotypes and phenotypic variability.

There are three main forms of selection: stabilizing, moving and tearing (disruptive).

F1-F3 - generations (shaded variants eliminated by selection)

1). Stabilizing selection contributes to the preservation of the characteristics of the species in relatively constant environmental conditions. It maintains average values, rejecting mutational deviations of the previously formed norm. The stabilizing form of selection acts as long as the conditions that led to the formation of a particular trait persist.

2). Motive selection favors a change in the average value of a trait in changed environmental conditions. It conditions permanent transformation adaptations of species in accordance with changes in the conditions of existence. Individuals of the population have some differences in phenotype and genotype.

Purpose of the event: to identify the level of mastering the educational material of the course "General Biology" by students based on the results of the 1st half of the year.

The test is compiled on the topic: "Basic teachings about evolution" to the textbook A.A. Kamensky, E.K. Kriksunov, V.V. Pasechnik.

The estimated time to complete the administrative test is 40 minutes.

Subject"Fundamentals of the doctrine of evolution" is studied in the 11th grade in the course "General Biology" and is an extensive and rather complex topic.

In the course of studying this section, students get acquainted with the history of evolutionary ideas, with the works of C. Linnaeus, the teachings of J. B. Lamarck, the evolutionary theory of Ch. Darwin, the role of evolutionary theory in the formation of a modern natural-science picture of the world is studied. Students are introduced to the synthetic theory of evolution. They study the population as a structural unit of a species, a unit of evolution; driving forces of evolution, their influence on the gene pool of the population.

To reliably determine the level of assimilation of theoretical material by each student, it is advisable to use test control. The test includes the ability not only to reproduce knowledge, but also to apply it to formulate worldview conclusions and generalizations. In addition, testing is a qualitative and objective way of assessing the knowledge of students; it puts all children on an equal footing, excluding the subjectivity of the teacher.

Testing tasks: to check the knowledge of the history of evolutionary ideas, the scientific merits of C. Linnaeus and J. B. Lamarck, C. Darwin; to systematize knowledge about the species, population, driving forces of evolution and its results; check students' understanding of macroevolution and speciation, the main directions of evolution of the organic world.

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Option 1

Part 1

one is correct.

A1. Which of the scientists considered the striving for perfection to be the driving force of evolution and claimed the inheritance of acquired traits?

1. Karl Liney
2. Jean-Baptiste Lamarck
3. Charles Darwin
4. A.N. Chetverikov

A2. A set of freely interbreeding individuals of the same species, which exists for a long time in a certain part of the range relatively apart from other sets of the same species, is called:

1. population
2. Variety
3. The colony

A3. What criterion of species include the features of the external and internal structure of the field mouse?

1. Morphological
2. genetic
3. Ecological
4. Geographic

A4. What criterion of species refers to the totality of environmental factors to which the polar bear is adapted?

1. Morphological
2. genetic
3. Ecological
4. Geographic

A5. Population statistics include:

1. Mortality
2. population
3. fertility
4. growth rate

A6. What is a random non-directional change in the frequencies of alleles and genotypes in populations called?

1. Mutational variability
2. population waves
3. Gene drift
4. Insulation

A7. What are periodic and non-periodic fluctuations in the population size in the direction of increasing or decreasing the number of individuals called?

1. Waves of life
2. Gene drift
3. Insulation
4. Natural selection

A8. An example of an intraspecific struggle for existence is the relationship:

1. Black cockroaches among themselves
2. Black and red cockroaches
3. Black cockroaches with pesticides
4. Black cockroaches and black rats

A9. What form of struggle for existence is the most intense?

A10. What form of natural selection operates under gradually changing environmental conditions?

1. Driving natural selection

A11. Biological isolation is due to:

1. A small number of species
2. Impossibility of mating and fertilization
3. Geographic barriers
4. combinative variability

A12. Which group of evidence for the evolution of the organic world includes the similarity of the embryos of reptiles and birds?

1. Comparative anatomical
2. Embryological
3. Paleontological
4. biogeographic

A13. Specify the correct scheme for classifying animals:

A14. What organs arise as a result of convergence?

1. Homologous
2. Similar
3. atavistic
4. Rudimentary

A15. Which of the following devices Not is an aromorphosis?

1. The origin of the spine in chordates
2. Elephant's trunk
3. Formation of a 3-chambered heart in amphibians

Part 2

three correct answers out of six.

IN 1. What evolutionary changes can be attributed to aromorphoses?

1. The appearance of a flower
2. Formation of organs and tissues in plants
3. The emergence of thermophilic bacteria
4. Atrophy of roots and leaves in dodder
5. Specialization of some plants for certain pollinators
6. Constant body temperature

AT 2. Evolutionary factors include:

1. Divergence
2. hereditary variability
3. Convergence
4. Struggle for existence
5. Parallelism
6. Natural selection

Administrative test in biology for the 1st half of the 11th grade

On the topic "Basic teachings about evolution"

to the textbook A.A. Kamensky, E.K. Kriksunov, V.V. Pasechnik

Option 2

Part 1

For each task A1-A15, 4 answer options are given, of which only one is correct.

1. Karl Liney
2. Jean-Baptiste Lamarck
3. Charles Darwin
4. A.N. Chetverikov

A2. The structural unit of a species is...

1. Individual
2. population
3. The colony
4. flock

A3. To what criterion of species is the set of chromosomes characteristic of Homo sapiens referred: their number, size, shape?

1. Morphological
2. genetic
3. Ecological
4. Geographic

A4. To what criterion of species is the growth of Grouse large-flowered in forests on rocky places?

1. Geographic
2. Morphological
3. Ecological
4. ethological

A5. Population dynamics include:

1. Mortality
2. population
3. Density
4. Structure

A6. Cause of population waves is not:

1. Seasonal temperature fluctuations
2. Natural disasters
3. Aggressiveness of predators
4. Mutational variability

A7. What prevents the exchange of genetic information between populations?

1. Mutational variability
2. population waves
3. Gene drift
4. Insulation

A8. What is the name of the complex of various relationships between organisms and factors of inanimate and living nature:

1. Natural selection
2. Struggle for existence
3. Fitness
4. Variability

A9. What form of struggle for existence is the perch eating its fry?

1. Interspecific
2. Intraspecific
3. With adverse environmental conditions
4. Intraspecific Mutual Assistance

A10. What form of natural selection tends to preserve mutations that lead to less variation in the average value of a trait?

1. Driving natural selection
2. Tearing natural selection
3. Stabilizing natural selection
4. Disruptive natural selection

A11. What evolutionary factor contributes to the emergence of barriers to free interbreeding of individuals?

1. Waves of life
2. Natural selection
3. Modifications
4. Insulation

A12. To which group of evidence for the evolution of the organic world do phylogenetic series belong?

1. Comparative anatomical
2. Embryological
3. Paleontological
4. biogeographic

A13. Indicate the correct scheme for classifying plants:

1. Species genus family order class type
2. species genus family order class type
3. species genus family order class department
4. Species genus order family class type

A14. What organs arise as a result of divergence?

1. Homologous
2. Similar
3. atavistic
4. Rudimentary

A15. Which of the following adaptations is classified as an idioadaptation?

1. The emergence of the chord
2. The emergence of a creeping stem in strawberries
3. Formation of 2 circles of blood circulation
4. Loss of circulatory organs in bull tapeworm

Part 2.

When completing tasks B1-B2, selectthree correct answers out of six.

When completing tasks B3-B4, establish a correspondence between the contents of the first and second columns. Enter the numbers of the selected answers in the table.

IN 1. What are the characteristics of biological progress?

1. Species decline
2. Expansion of the range of the species
3. The emergence of new populations, species
4. Narrowing of the range of the species
5. Simplify organization and transition to a sedentary lifestyle
6. Increasing the number of species

AT 2. What features illustrate the stabilizing form of natural selection?

1. Operates in changing environmental conditions
2. Operates under constant environmental conditions
3. Maintains the reaction rate of the trait
4. Changes the average value of a feature either in the direction of decreasing its value, or in the direction of increasing
5. Controls functioning organs
6. Leads to a change in the rate of reaction

AT 3. Establish a correspondence between the death of plants and the form of the struggle for existence.

AT 4. Establish a correspondence between the sign of an animal and the direction of evolution to which it corresponds

C1. What type of natural selection is shown in the figure? Under what environmental conditions does it occur? What mutations does it retain?

INSTRUCTIONS FOR CARRYING OUT

Administrative testIN BIOLOGY IN 11 CLASS

(I half of 2013-2014 academic year)

Purpose of the event:to identify the level of mastering the educational material of the course "General Biology" by students based on the results of the 1st half of the year.

The test is compiled on the topic: "Basic teachings about evolution" totextbook A.A. Kamensky, E.K. Kriksunov, V.V. Pasechnik.

The estimated time to complete the administrative test is 40 minutes.

Subject "Fundamentals of the doctrine of evolution" is studied in the 11th grade in the course "General Biology" and is an extensive and rather complex topic.

In this section, students will become familiar with andthe history of evolutionary ideas, with the works of K. Linnaeus, the teachings of J. B. Lamarck, the evolutionary theory of Ch. Darwin, the role of evolutionary theory in the formation of the modern natural-science picture of the world is being studied. Students are introduced to the synthetic theory of evolution. They study the population as a structural unit of a species, a unit of evolution; driving forces of evolution, their influence on the gene pool of the population.

To reliably determine the level of assimilation of theoretical material by each student, it is advisable to use test control. The test includes the ability not only to reproduce knowledge, but also to apply it to formulate worldview conclusions and generalizations. In addition, testing is a qualitative and objective way of assessing the knowledge of students; it puts all children on an equal footing, excluding the subjectivity of the teacher.

Testing tasks: to check the knowledge of the history of evolutionary ideas, the scientific merits of C. Linnaeus and J. B. Lamarck, C. Darwin; to systematize knowledge about the species, population, driving forces of evolution and its results; check students' understanding of macroevolution and speciation, the main directions of evolution of the organic world.

Test evaluation criteria.

All tasks are divided by difficulty levels.

The tasks of the basic level correspond to the minimum content of biological education and the requirements for the level of training of graduates. They are compiled in accordance with the standard of secondary biological education. Each question has multiple answers, of which only one is correct. For the correct performance of each such task, 1 point.

Tasks of an increased level are aimed at testing the development of more complex content by students. They contain tasks with a choice of several answers from the given ones, to establish correspondence, to determine the sequence of biological phenomena, to indicate the truth or falsity of statements. For the correct performance of each such task, 2 points each.

The part C task includes a free answer task. For the correct performance of the task is set 3 points.

Work structure:

1) According to the content, the work includes the following blocks:

• Type and its criteria
• Populations

2) According to the levels of tasks, the work allows you to identify the assimilation of the material at the basic, advanced and high levels.

3) According to the forms of test tasks, the work consists of tests with the choice of one correct answer, open type with a short answer, open type with a full detailed answer.

Distribution of work tasks by content:

Blocks	Test item numbers	Number of jobs	Percentage of tasks for this block
Development of the evolutionary teachings of Charles Darwin			6,7%
Type e its criteria	A2, A3, A4
Populations			6,7%
Genetic composition and changes in the gene pool of populations	A6, A7		13,3%
The struggle for the existence of her form	A8, A9		13,3%
Natural selection and its forms	A10		6,7%
isolation mechanisms. Speciation	A11		6,7%
Macroevolution and its evidence	A12		6,7%
The system of plants and animals - a display of evolution	A13		6,7%
The main directions of evolution of the organic world	A14, A15		13,3%
TOTAL-10			100%

Distribution of work tasks in parts.

	Parts of work	Number of jobs	Maximum primary score	Job Type
	Part 1 (A)			Choice of answer
	Part 2 (B)			With a short answer
	Part 3 (C)			With extended answer
	Total

Distribution of work tasks by level of complexity:

Task difficulty level	Test item numbers	Number of jobs	Percentage of tasks for a given level of difficulty
Base	A1-A15		57,7%
elevated	B1-B4		15,5%
High			3,8%

Answers to the tasks of the administrative test:

Option 1	Option 2
A1 - 2 A2 - 2 A3 - 1 A4 - 3 A5 - 2 A6 - 3 A7 - 1 A8 - 1 A9 - 1 A10 - 2 A11 - 2 A12 -2 A13 - 1 A14 - 2 A15 - 2	A1 - 2 A2 - 2 A3 - 2 A4 - 3 A5 - 1 A6 - 4 A7 - 4 A8 - 2 A9 - 2 A10 - 3 A11 - 4 A12 - 3 A13 - 3 A14 - 1 A15 - 2
B1 - 1, 2, 6 B2 - 2, 4, 6 AT 3 - AT 4 -	B1 - 2, 3, 6 B2 - 2, 3, 5 AT 3 - AT 4 -
C1: Stabilizing selection Observed under relatively constant environmental conditions Retains mutations leading to less variability in the mean value of the trait	C1: 1) Driving selection 2) Observed in unidirectional change in environmental conditions 3) Keeps mutations leading to other extreme manifestations of the magnitude of the trait (either in the direction of strengthening or in the direction of weakening)

Based on a large number of examples, Darwin also notes that each pair of organisms can give a significant number of offspring (animals lay many eggs, eggs, many seeds and spores ripen in plants), but only a small part of them survive. Most individuals die before reaching not only sexual maturity, but also adulthood. The causes of death are unfavorable environmental conditions: lack of food, enemies, illness or heat, drought, frost, etc. On this basis, Darwin comes to the conclusion that in nature there is a continuous struggle for existence(Fig. 46). It is carried out both between individuals of different species ( interspecies struggle for existence and between individuals of the same species (intraspecific struggle for existence). Another manifestation of the struggle for existence is

struggle with inanimate nature.

As a result of the struggle for existence, some variations in traits in one individual give it a survival advantage over other individuals of the same species with other variations in inherited traits. Some individuals with unfavorable variations die. Ch. Darwin called this process natural selection. Inherited traits that increase the likelihood of survival and reproduction of a given organism, transmitted from parents to offspring, will occur more and more often in subsequent generations (since there is a geometric progression of reproduction). As a result, over a certain period of time, there are many such individuals with new characters and they turn out to be so different from the organisms of the original species that they already represent individuals of a new species. Darwin argued that natural selection is common path formation of new species.

Darwin puts forward an important new hypothesis about the presence in nature of natural selection, which is carried out by the influences of external conditions among a large number of individuals of a species with various variations of heritable traits.

“Natural selection,” writes Charles Darwin, “acts exclusively by preserving and accumulating changes that are favorable under those organic and inorganic conditions to which every creature is exposed in all periods of its life. From the point of view of our theory, the continued existence of our organisms does not present any difficulty, since natural selection, or the survival of the fittest, does not necessarily imply progressive development, but only picks up the manifestations of changes that are favorable to the being possessing them in the difficult conditions of his life. Natural selection - this must never be forgotten - acts only for the benefit of a given being and through this benefit ...

Natural selection leads to a divergence of characters and a significant extermination of less advanced and intermediate forms of life.

Based on the idea of ​​natural selection, Charles Darwin determined the paths of evolutionary transformations.

He considered the main point in the evolutionary process divergence of symptoms or divergence (lat.divergo - “I deviate”, “I depart”). The divergence of traits leads to a decrease in competition, because organisms, thanks to new properties, were able to use different conditions of existence. Along this path, with the help of divergence, new species are formed from pre-existing species that correspond to new environmental conditions.

Natural selection Darwin considered the main driving force of evolution. The following phenomena are the result of the action of this force: 1) a gradual complication and an increase in the level of organization of living beings; 2) adaptation of organisms to environmental conditions; 3) variety of species.

With the help of natural selection, according to Darwin, in nature, new species are formed from already existing species.

Darwin came to conclusions about the role of natural selection after a thorough study of the history of the emergence of new breeds of animals and varieties of cultivated plants. Under conditions of domestication, the selection is performed by man. From the variety of options determined by variability, a person selects the form that best suits his interests. Darwin called this purposeful creation of new species artificial selection(Fig. 47). The study of the mechanism and results of artificial selection turned out to be for Darwin milestone on a way

substantiation of the theory of natural selection and its action in nature without human participation.

Darwin's doctrine of the evolution of the organic world explains the fitness (adaptation) of organisms to environment and considers the diversity of species as an inevitable result of the action of natural selection in connection with the divergence of inherited traits. Adaptations (Latin adaptatio - “fitting”, “adaptation”) is a set of morphological, physiological, behavioral, population and other adaptive features of a species that provide it with the ability to exist in certain environmental conditions. Adaptations give the structure and life of organisms the features of functional expediency that arose under the influence of natural selection. Darwin emphasized that any adaptive property is relative in nature, since it is useful to the body only in its specific, habitual habitat. However, even in a familiar environment, other, more perfect adaptations of organisms to external conditions are always possible.

Ch. Darwin discovered the driving forces of evolution, to which he attributed heredity, variability, the struggle for existence and natural selection. At the same time, he also noted the great role of the ability of organisms to reproduce according to the type geometric progression. For the first time in science, Darwin emphasized the role of species in evolution and proved that modern views(in nature and domestication) descended from pre-existing species.

Having created the scientific theory of evolution, Darwin comprehensively substantiated historical method in the study of nature. The theory of the origin of species radically changed ideas about the evolution of the organic world and became the largest scientific achievement, a significant event in the 19th century. The fundamental nature of Darwin's theory made representatives of all biological sciences correlate their ideas with its provisions. The modern general understanding of evolution is also based on the teachings of Darwin.

1. What are the main conclusions in the evolutionary theory of Ch. Darwin?

2*. Explain the mechanism of natural selection. 3*. Prove your opinion.

Why did Darwin's teachings turn out to be more convincing than those of J.B. Lamarck?

What is the meaning of Ch. Darwin in the concept of "struggle for existence"?

§ 38 Modern ideas about the evolution of the organic world

Modern evolutionary doctrine is often called synthetic. This is because it includes not only Darwinism (that is, Charles Darwin's ideas about selection and the struggle for existence), but also the discoveries of genetics, taxonomy, morphology, biochemistry, physiology, ecology and other sciences.

Particularly productive for the development of the theory of evolution were the data of genetics and molecular biology. Chromosomal theory and gene theory revealed the causes of mutations and the mechanisms of transmission of heredity, and molecular

biology and molecular genetics have figured out how to store, implement and transmit genetic information using DNA. It was found that elementary unit of evolution, capable of responding to changes in the environment by rearranging its gene pool is a population. According to this discovery, not a species, but its populations are saturated with mutations, which serve as the main material of the evolutionary process under the influence of natural selection.

The modern doctrine of evolution is based on the population concept.

Population (Latin populus - “people”, “population”) is a structural unit of a species. It is represented by a set of individuals of a species that have a common gene pool and occupy a certain territory within the range (distribution area) of this species. Populations are subject to the action of different directions of natural selection, since territorial isolation prevents the frequent exchange of genetic information between isolated populations (Fig. 48). Therefore, gradually between such populations occurs divergence) for a number of genetic traits. They accumulate through mutations. Moreover, individuals of populations acquire noticeable differences from the original, parental species. If the differences that appear ensure the non-crossing of individuals of one population with individuals of other populations of the original species, then the isolated population becomes an independent new species, separated from the original species by divergence.

A population is the smallest subdivision of a species that changes over time. Therefore, the population is called the elementary unit of evolution.

In modern evolutionary teaching, such concepts as elemental

the mental unit of evolution, the elementary phenomena of evolution, the elementary material of evolution and the elementary factors of evolution.

Each population is characterized by the following properties: range, number and density of individuals, genetic heterogeneity (variety) of individuals, age and sex structure, special functioning in nature (intrapopulation, interpopulation contacts and relationships with other species and with the environment). Sexual contacts between individuals within the same population are much easier and more frequent than with individuals from different populations of the same species. Therefore, changes accumulating in one population with the help of recombinations, mutations and natural selection determine its qualitative and reproductive isolation (divergence) from other populations. These changes in populations are called elementary phenomena of evolution. Changes in individual individuals do not lead to evolutionary changes, since a significant accumulation of similar inherited traits is needed, and this is available only to an integral group of individuals, which is a population.

The elemental material of evolution serves as hereditary variability (combinative and mutational) in individuals of a population. It is well known that both types of genotypic variability are observed in all studied prokaryotes and eukaryotes. Both of these types of variability can affect all traits and properties of organisms that can vary (morphological, physiological, chemical, and behavioral), which leads to the emergence of both qualitative and quantitative phenotypic differences in the population. Under certain conditions and for some time, new inherited traits that have arisen can reach sufficiently high concentrations in one or several adjacent populations of the species. Groups of individuals with such new characters can be found on "their" territory within the range of the species.

Elementary Factors of Evolution include such phenomena as natural selection, mutation, population waves, and isolation.

Natural selection eliminates individuals with unsuccessful combinations of genes from the population and preserves individuals with genotypes that do not violate the process of adaptive morphogenesis. Natural selection directs evolution.

mutation process maintains the genetic heterogeneity of natural populations.

population waves supply massive elementary evolutionary material for natural selection. Each population is characterized by a certain fluctuation in the number of individuals in the direction of either increase or decrease. These fluctuations in 1905 domestic genetic scientist S.S. Chetverikov named waves of life.

Isolation provides barriers that prevent free interbreeding of organisms. It can be expressed in territorial-mechanical (spatial, geographical) or

biological (behavioral, physiological, ecological, chemical and genetic) incompatibility (Fig. 49).

By disrupting crossbreeding, isolation divides the original population into two or more that differ from each other, and fixes the differences in their genotypes. The divided parts of the population are already independently subjected to the action of natural selection.

Isolation, the mutation process and population waves, being factors of evolution, influence the evolution of the species, but do not direct it. The direction of evolution is set by natural selection.

1. Replace the highlighted words of the statement with a term.

The smallest subdivision of a species, which changes over time, is involved in the formation of new species.

Divergence of signs of organismsCh. Darwin used to explain

of the diversity of forms in the evolution of organisms.

2*. What is the difference modern teaching about evolution from Darwin's evolutionary theory? 3. Think.

Why is a population called the structural unit of evolution?

How does natural selection direct the course of evolution?

§ 39 Type, its criteria and structure

Species is one of the most basic and complex concepts in biology. This concept allows not only to systematize the huge variety of living organisms on Earth, but also to solve the problem of the ways, causes, and mechanisms of speciation and evolution of living nature.

A species is a really existing genetically indivisible unit of the living world.

The concept of the form underlies the evolutionary theory of Ch. Darwin. Each species has its characteristic life cycle, within which certain processes of growth and development of the bodies of individuals take place, changes in the manifestations of the relationship of organisms with the environment and the alternation of methods of their reproduction.

A species is made up of populations. The commonality of genes inherited from ancestors and characterizing a given species is maintained between populations with the help of individuals. Changes in populations lead to species change.

A species is the main structural unit in the system of organisms, a qualitative stage in the evolution of life.

In the early 60s. 20th century the American evolutionist scientist E. Mayr proposed a "biological concept" of a species, putting forward the following ideas: species are characterized not by difference, but by isolation; species do not consist of individuals, but of populations; main feature species is its reproductive isolation from others. Mayr's views strengthened the concept of a species as a diverse polytypic system consisting of various intraspecific structural subdivisions - populations. The idea of ​​a polytypic species is now accepted by all evolutionary scientists in different countries, and the doctrine of evolution is revealed on the basis of the population concept.

A strict definition of the concept of "species" in biology has not yet been created. Most often, a species is considered as a collection of separate groups of similar individuals - populations. Due to different populations, the species makes fuller use of the diversity of the environment in its range and, therefore, is better adapted to the living conditions. At the same time, the species acts as an integral and independent natural formation, characterized by its history of formation, a special evolutionary “destiny”.

To characterize the species, five main criteria (features) are used: morphological, physiological-biochemical, ecological, geographical and reproductive.

Morphological criterion allows you to distinguish between different types of external and internal features. For example, the currant genus contains several well-differentiated appearance types of currant: black,

red, golden, alpine, Tien Shan, beautiful etc. They have different colors of flowers and fruits, on the shoot differently inflorescences are located, there are some differences in the shape of the leaves (Fig. 50).

Physiological and biochemical criterion fixes the dissimilarity chemical properties different types. So, all types of currants are specific in the composition of proteins, sugars and others. organic compounds in plant cells, which is easily detected even by the taste of their fruits, by the aroma of flowers, fruits, leaves, buds, and bark.

Geographic criterion indicates that each species has its own range. For example, the area black currant are the northern regions of Eurasia, while the range golden currant - central territories of North America, Tyanyan currant - forest belt of the mountains of the Central

Tien Shan in Central Asia.

Environmental criterion makes it possible to distinguish species according to the complex of abiotic and biotic conditions in which they formed, adapting to life. So, black currant arose in conditions of significant soil moisture, its natural thickets are often found along river banks, in lowlands in flood meadows,

while golden currant

formed in arid conditions of steppe foothills and does not grow in damp places. In artificial plantations (in gardens and parks), these two species sometimes

grown side by side, but they bloom at different times: black currant blooms in early spring currant golden- in the first half of summer.

Reproductive criterion causes the reproductive (genetic) isolation of the species from others, even closely related ones. All species have special mechanisms that protect their gene pool from the influx of foreign genes. This is achieved mainly by the peculiarities of the genotype in individuals of each species -

the number and structure of its chromosomes. The genetic criterion is the most significant, since it controls the reproductive isolation of the species.

Isolation of species is also achieved by a number of other auxiliary mechanisms, for example, a mismatch in the timing of reproduction in different species, a difference in ritual behavior during crossing observed in many animals, morphological differences in reproductive organs, etc. If, for example, plants accidentally pollinate a flower with pollen from another species or in animals - random mating, then in the vast majority of cases, male germ cells in a new environment for them will die without having carried out (usually not even reaching the egg) fertilization.

Interbreeding is rare in nature. However, the hybrids that have arisen in this way are either unviable and soon die, or sterile.

Each species is a genetically closed system reproductively isolated from other species.

In reality, the species exists in the form of populations. And although a species is a single genetic system, its gene pool is represented by gene pools of populations. Having accumulated in large numbers over time, new gene variations in the gene pool of a population can lead to its isolation from other populations of this species. In this way, new species arise. That is why the population, as the smallest subdivision of a species that changes over time, is considered the elementary unit of evolution.

1. Name the types of plants and animals you know that live near your home or school.

2*. What mechanisms prevent interbreeding between different species?

3. Why is the reproductive criterion considered the most important characteristic of a species?

§ 40 Speciation processes

Speciation- the most complex process in the development of living matter. The emergence of a new species is always accompanied by a rupture of ties with the parent species and transformation into a new, separate set of populations and organisms. A new species may be formed from one population or a group of adjacent populations.

The emergence of a new species is the central event of evolution.

The problem of speciation was fundamentally solved by Charles Darwin, who showed the role of divergence (divergence of traits), natural selection, and acute intraspecific competition between organisms.

According to modern concepts, speciation is carried out due to populations that have accumulated stable genotypic and phenotypic differences of an adaptive nature. These differences result in the isolation of the population and the formation of a new, independent species. Evolutionary processes occurring in populations on the basis of hereditary variability under the control of natural selection and leading to the formation of new species,

called microevolution.

The formation of species is determined by many reasons. In some cases, this occurs as a result of spatial-territorial (geographical) isolation, which prevents the regular exchange of genetic information. In other cases, this process may be caused by the expansion of the species into new conditions outside its range. In third cases, the formation of a new species may be due to biological (reproductive) isolation that arose suddenly, for example, due to polyploidy or mutation. Microevolution is the main way to increase the diversity of species on Earth and the total "sum of life" in the biosphere.

Microevolution leads to a change in the gene pool of a population within a species and to the formation of new species on Earth.

New species may arise from adjacent populations in different territories or within the range of the original species.

Geographic (alopatric) speciation arises as a result spatial-territorial isolation of one population or group of populations of a species. For example, individual populations in a species' range may be separated by mountains, rivers, deserts, highways, buildings, and other landscape barriers that hinder frequent gene exchange between populations.

Geographical isolation Charles Darwin explained the appearance of a variety of Darwin finches on several islands of the Galapagos archipelago in pacific ocean. It is likely that Darwin's finches are the descendants of several individuals of finches from South America, accidentally carried into the sea during a storm, settled and preserved on the Galapagos Islands. The finches that got there became the founders of populations on different islands. Isolated from each other, these populations after some time separated into new independent species.

The finches, blown away by the wind, having got to a separate island of the Galapagos archipelago, found themselves in an environment different from the one they left. At the same time, they were faced with the conditions of that particular island where they happened to be. Under the pressure of natural selection, the populations of finches evolved on different islands in different directions. In the process, they acquired an unusual appearance, the structure of the beak and peculiar habits, especially in obtaining food.

The same happens when a species spreads over a large area. As a result, the peripheral populations and their groups, which are more distant from the center of settlement, are intensively transformed in connection with the development of new habitats and become the ancestors of new species. An example is the species of dandelion in the territory of Eurasia or pike perch inhabiting water bodies.

Europe (Fig. 51).

pike perch

(Stizostedion lucioperka)

has a huge areola. It is distributed in the basins of the Baltic, Black, Azov and Caspian Seas. Inhabits the rivers

clear lakes and seas. Pike perch enters the salty waters of the seas for fattening, but spawns only in fresh water. Pike perch (S. volgensis] lives in the rivers of the basins of the Caspian, Azov and Black Seas, but is found there mainly in the lower and middle reaches of the rivers, where it spawns. It does not go far into the sea for fattening, it keeps mainly fresh waters. Bersh is smaller in size common zander, and it has no fangs on its lower jaw. Sea pike perch (S. marinusj - large, but different pike-perch Iberian smaller eyes, fewer branched rays in the dorsal fin. Unlike other zanders, the sea zander does not enter rivers at all, avoids desalinated areas and spawns in the sea on rocky coastal areas.

It is characteristic that these types of pike perch can simultaneously be in the same water basins, but do not interbreed, since they have already isolated themselves from each other.

New species may also arise due to the discontinuity (mosaic) of the range. An example of such a process is the emergence of closely related dandelion species from a widely distributed parent species.

The original species of dandelion millions of years ago occupied a vast territory of the entire continent of Eurasia. Changes in soil and climatic conditions in this area, the appearance of mountains, steppes, deserts, saline and damp soils led to the emergence of numerous species of dandelion (more than 200 species) living in cold, temperate and subtropical zones. Widespread species common dandelion (Taraxacum officinale) preserved in meadows, forest clearings, along roadsides and in weedy places near housing. Dandelion kok-saghyz (T. kok-saghyz) was formed in a hot arid climate on hard brackish soil. Unlike common dandelion, dandelion kok-saghyz leaves are narrow, deeply dissected, and the milky vessels of the root contain a significant percentage of rubber. In the highlands, in the cold alpine meadows of the Central Tien Shan, the species dandelion pink (T. roseum), looks very similar in appearance common dandelion, but with inflorescences of pink reed flowers.

Geographic speciation always proceeds rather slowly. This process goes on for hundreds of thousands of generations of individuals in the population. Only for such long periods of time in isolated populations of a species, with the help of their organisms, special features and properties are developed that lead to reproductive isolation.

Sympatric (biological) speciation occurs within the range of the original species as a result of biological isolation. It is carried out on the basis of a territorially unified population, which has clearly different forms of individuals. The emergence of new species during sympatric speciation can occur in various ways.

One of them is the emergence of new species with rapid genotype change. This occurs, for example, in polyploidy, when new forms are immediately genetically isolated from the parent species.

If polyploids that have arisen by chance in nature are capable of producing viable offspring and resisting natural selection, then they can quickly spread and coexist next to the original species. This mode of speciation is often found in plants and protozoa. In multicellular animals, it is rarely observed - only in some invertebrates, for example, in an earthworm.

New species can also arise during hybridization with subsequent doubling of the number of chromosomes. Thus, many cultivated species plants. For example,

cultivated plum (Prunus domestica) created by hybridization blackthorn (Pr. spinosa)

cherry plum (Pr. divaricata)c subsequent duplication of chromosomes.

Another way of sympatric speciation is due to ecological events, for example: seasonal isolation of populations within a species; isolation due to the production of other digestive enzymes in connection with the transition to feeding on another plant species (often observed in aphids); isolation caused by the appearance of special behavior in individuals.