Factors of evolution and their significance. Factors (driving forces) of evolution
Question 1. What are the main factors of evolution.
According to the synthetic theory of evolution, an elementary evolutionary phenomenon, from which speciation begins, is a change in the genetic composition (genetic constitution, or gene pool) of a population. Events and processes that contribute to overcoming the genetic inertia of populations and leading to a change in their gene pools are called elementary eulogy factors. The main factors (forces) of evolution are:
1) Factors causing changes in the gene pool of a population. These include hereditary variability, which supplies a population with new genetic material, and population waves, isolation, which form differences between the gene pools of different populations.
2) A factor that allows a population to develop independently relative to other populations or divides the original population into two or more new ones. That factor is isolation.
3) A factor that directs the evolutionary process and ensures that certain adaptations and changes in organisms are fixed in the population. This factor is natural selection.
Question 2. What factor ensures the emergence of new genetic material in a population?
Mutational variability is a factor that ensures the emergence of a fundamentally new genetic material.
Under favorable conditions of existence, small differences between individuals of the same species are not very noticeable and do not play a significant role. However, in adverse conditions even small hereditary changes can be decisive and determine which individuals in a population will die and which will survive. Hereditary variability provides material for the evolutionary process.
Mutations occur with a certain frequency in all organisms inhabiting our planet. The place of mutation (gene and chromosome) is random, therefore mutations can affect any traits and properties of an individual, including those affecting viability, reproduction, and behavior. In a number of generations, the vast majority of mutations are preserved, starting with those that arose in the oldest ancestors. As a result, the set of mutations in two populations of the same species is very similar. On the other hand, different mutations will also be present. Their number is an indicator of how long two populations have been isolated from each other.
Thus, the mutation process is the source of the reserve of hereditary variability of populations. By maintaining a high degree of genetic diversity in populations, it provides the basis for action natural selection.
Question 3. Will there be selection for carriers of recessive mutations?
As a rule, carriers of recessive mutations (heterozygous organisms) do not noticeably differ in properties from homozygous dominant organisms. Moreover, in the heterozygous state, many mutations increase the viability of individuals. Therefore, selection on such individuals usually does not work. After a certain time, the population can accumulate enough big number recessive alleles, i.e. the proportion of heterozygous organisms will increase. This will lead to an increase in the likelihood of their meeting and, as a result, to the birth (in 25% of cases) of recessive homozygotes. It should also be borne in mind that in nature mutations occur in combinations with each other. Some combinations due to the interaction of genes can be positive for an individual, increasing its viability. This is where natural selection comes into play.
Question 4. Give an example illustrating the change in the significance of a mutation when environmental conditions change.
Mutations that are harmful in some conditions can increase the viability of an individual in other environmental conditions. Mutations that are harmful under certain conditions can increase viability. individuals in other environmental conditions. For example, wingless or poorly winged mutants have an advantage on oceanic islands and mountain passes where strong winds blow. For similar reasons, the formation of such species now exterminated by man as the dodo and wingless auk occurred.
An example is a mutation in insects that provides resistance to a particular pesticide. For a long time, this mutation will be neutral, and its occurrence in the population is low. But once the pesticide is used to control insects, the mutation will become useful, as it will ensure the survival of individuals in the changed conditions. Due to the action of selection, the proportion of this mutation in the gene pool of the population will increase sharply - the faster, the more severe the selection is, that is, the greater the percentage of individuals die in each generation from the action of the pesticide. It is clear that such events will manifest themselves much brighter if the pesticide resistance mutation is dominant.
Question 5. Is the mutation process capable of exerting a directing influence on the process of evolution, and why?
The mutation process is a random, non-specific phenomenon. Mutations arise non-directionally, do not have an adaptive value, that is, they cause indefinite hereditary variability (according to Ch. Darwin). With equal probability, mutations can lead to changes in any organ systems. Thus, the mutation process in itself is not capable of exerting a guiding effect on the course of evolution.
Question 6. What is genetic drift?
Gene drift- this is a process of random non-directional change in the frequencies of alleles in a population. It is observed when a population passes through a state of small numbers (the so-called "bottleneck" effect, which occurs as a result of epidemics, natural disasters). As a result of random genetic drift, genetically homogeneous populations living in similar conditions may gradually lose their original similarity. Genetic drift is one of the factors contributing to population change.
Question 7. What factor leads to the termination of the exchange of genetic information between populations? What is its evolutionary significance?
The termination of the exchange of genetic information is facilitated by isolation - the restriction or cessation of interbreeding of individuals belonging to different populations. Isolation can be spatial and ecological.
Geographical isolation consists in the spatial separation of populations due to landscape features within the range of the species - the presence of water barriers for "land" organisms, land areas for hydrobiont species, alternation of elevated areas and plains. It is promoted by a sedentary or immobile (in plants) lifestyle.
Ecological isolation occurs if individuals are separated by ecological obstacles within the same landscape, for example, the probability of meeting the inhabitants of shallow and deep parts of the reservoir during the breeding season is very small. Long-term ecological isolation contributes to the divergence of populations up to the formation of new species. So, it is assumed that human and pig roundworms, morphologically similar, descended from a common ancestor. Their divergence, according to one hypothesis, was facilitated by the ban on human consumption of pork meat, which, for religious reasons, was distributed long time to large numbers of people. Ecological isolation exists due to the nuances of the courtship ritual, coloring, smells, "singing" of females and males from different populations. So, subspecies of goldfinches - gray-headed and black-headed have pronounced marks on the head. Hooded crows from the Crimean and North Ukrainian populations, outwardly indistinguishable, differ in cawing. In physiological isolation, interbreeding is prevented by differences in the structure of the reproductive organs or simply by a difference in body size. In plants, the adaptation of the flower to a particular type of pollinator leads to this form of isolation.
Isolation in the process of speciation interacts with other elementary evolutionary factors. It enhances the genotypic differences created by the mutation process and genetic combinatorics. The intraspecific groupings that arise due to isolation differ in genetic composition and experience unequal selection pressure. The evolutionary significance of isolation lies in the fact that it consolidates and enhances the genetic differences between populations and creates the prerequisites for the further transformation of these populations into separate species.
Evolution is a biological factor. It concerns all changes in the system of living organisms that have occurred during the life of our planet. All manifestations of evolution occur under the influence of certain factors. Which of them have the greatest impact, and how does it manifest itself? Consider the main factors of evolution.
1. One of them is heredity. This is the ability to copy from generation to generation some of the properties of the body that relate to metabolism or other features. individual development generally. This guiding factor of evolution is carried out due to the self-reproduction of units of genes that accumulate in the structure, namely in the chromosomes and cytoplasm. These genes are decisive in ensuring the constancy and species diversity of various life forms. Heredity is considered the main factor that forms the foundation of the evolution of all living nature.
2. Variability, in contrast to the first factor, is a manifestation in living organisms various signs and properties that do not depend on family ties. This property is characteristic of all individuals. It is divided into the following categories: hereditary and non-hereditary, group and individual, directed and non-directed, qualitative and quantitative. Hereditary variability is a consequence of mutations, and non-hereditary - the influence of evolution, heredity and variability can be called decisive in this process.
3. Struggle for existence. It determines the relationship between living organisms or the influence of abiotic features on them. As a result of this process, organisms that are weaker die. Those that have higher viability remain.
4. It is a consequence of the previous factor. This is the process by which the survival of the fittest occurs. The essence of natural selection is the transformation of populations. As a result, new types of living organisms appear. It can be called one of the engines of evolution. Like many other evolutionary factors, it was discovered by Charles Darwin.
5. Fitness. This includes features of the body structure, color, behavior, ways of raising offspring, and much more. There are a lot of these factors, so they have not yet been fully studied.
6. The essence of this factor lies in some fluctuation in the number of certain types of living organisms. As a result, a rare species can become more numerous and vice versa.
7. Insulation. It implies the emergence of obstacles to the spread of living organisms and their interbreeding. There can be various reasons for its occurrence: mechanical, ecological, territorial, morphological, genetic, etc. One of the main reasons is often an increase in differences between previously close organisms.
8. Mutations. These environmental factors can arise under the influence of natural or artificial features. When changes are made to the genetic nature of an organism, mutational changes occur. This factor underlies hereditary changes.
9. There are situations when the population is sharply reduced. This can happen under the influence of various circumstances (flood, fire). The remaining representatives of living organisms become the determining link in the formation of new populations. As a result, some signs of this species may disappear and new ones appear.
Human development has gone its own way. But the factors are similar to those described above.
The main elementary evolutionary factors:
1) Mutation process
2) Combination variability
3) Population waves
4) Genetic drift
5) Insulation
6) Natural selection
mutation process occurs constantly in the form of gene, chromosomal and genomic mutations. A special place is occupied by gene mutations in germ cells. They lead to a series of alleles and thus to a variety of genetic information. The contribution of the mutation process to speciation is twofold:
a) changing the frequency of one allele in relation to another, has direct action on the gene pool of the population;
b) due to mutational alleles, it forms a reserve of hereditary variability.
The mutation process, acting as an elementary evolutionary factor, occurs constantly throughout the existence of life. The gene pools of populations experience continuous pressure from the mutation process, which ensures the accumulation of mutations. The set of alleles resulting from mutations constitutes the initial elementary evolutionary material. In the process of speciation, it is used as the basis for the action of other elementary evolutionary factors.
2. Combination variability is provided by three mechanisms - crossing over, an independent and random combination of non-homologous chromosomes in anaphase I of meiosis, chance meeting gametes during the sexual process. The number of possible genotypes in this case is expressed by an astronomical number, i.e., combinative variability enhances hereditary variability, which is important in speciation.
3. population waves (waves of life) are periodic or aperiodic fluctuations in the number of organisms in natural populations of S.S. Chetverikov (1905).
The reasons for fluctuations are often ecological in nature. So, optimal climatic conditions contribute to an increase in the number of rodents (mouse years).
This leads to an increase in the food supply of predators, their numbers increase, which entails a decrease in the number of rodents.
Sharp non-periodic declines in numbers occur as a result of drought, fire, floods and other natural disasters.
The change in the number of some species is due to human activity (the importation of rabbits to Australia; the destruction of sparrows in China, etc.)
Both on the rise and on the decline, population waves change the gene pools of populations. With an increase in the number of organisms, a merger of previously separated populations is observed and the unification of their gene pools; with a decrease in the number, a disintegration of large populations is observed.
4. genetic drift(genetic - automatic processes) - random, not due to the action of natural selection, non-directional change in allele frequencies in small populations (S. Wright, R. Fisher, Dubinin N.P., Romashov D.D.)
The gene pool in a small population is always poorer than the gene pool of the parent species and the selection of alleles in it is random. Since natural selection is effective when the number of individuals is sufficiently large, the fate of the gene pool of a small population is determined by the action of random factors. This has been experimentally proven in Drosophila (tell experience). Two females and two males of Drosophila flies heterozygous for the allele A (Aa) were planted in several test tubes with food. In such an artificially created population, the ratio of alleles was the same. After several generations, it turned out that the allele frequency changes random manner. In some populations (test tubes), the A allele was lost, in others, the a allele was lost, and some populations contained both alleles.
That. to a decrease in the viability of mutant individuals and, contrary to natural selection, in small populations the mutant allele displaces the completely normal one. This is the result of a random process - genetic drift.
Isolation is the separation of two or more groups of the same species or population by various barriers, i.e., the cessation of panmixia (free crossing).
Forms of isolation:
1.geographic
2.religious (social)
3. biological (environmental, ethological, morphological, genetic)
Geographic isolation – spatial separation of populations by geographical barriers (sea, mountain ranges, forests, desert), large distances, human economic activity (reduction of the sable range).
Religious isolation - characteristic of human populations (castes in India; nationalities in the Middle East)
Environmental isolation - features of the color of the integument or the composition of the food; reproduction in different seasons or at different temperatures, differences in body size and shape, etc.
Ethological (behavioral) isolation – features of the courtship ritual, smell, “nuptial” singing and dancing of males and females from different populations.
Morphological isolation (physical, mechanical) - a difference in the structure or size of the reproductive apparatus, a violation of the reproduction processes.
genetic isolation(reproductive) polyploidy or heteroploidy. They lead to incompatibility of gametes, death of zygotes after fertilization, sterility or low viability of hybrids. Different types of isolation disrupt panicmixia, interact with other evolutionary factors, and thereby perpetuate differences in the frequencies of occurrence of different genotypes.
Natural selection (according to STE) is the preservation of certain genotypes and their selective reproduction.
As an elementary evolutionary factor, natural selection operates in populations. The population is the field of action, individual individuals are the objects of action, and specific characters are the points of application of selection.
Natural selection:
a) driving
b) stabilizing
c) destabilizing
d) disruptive
driving selection was described by Ch. Darwin. It causes a consistent change in the phenotype in a certain direction, which manifests itself in a shift in the average values of traits in the direction of their strengthening or weakening. When living conditions change, a phenotype is fixed in the population that is more appropriate for the new conditions.
Stabilizing selection .
The doctrine of stabilizing selection was developed by I.I. Schmalhausen. This form of natural selection is observed if environmental conditions remain fairly constant for a long time and individuals with an average expression of the trait take advantage, while mutants that differ from them die. As a result of the action of stabilizing selection, mutations with a wide reaction rate are replaced by mutations with the same average value, but with a narrower reaction rate. Stabilizing selection leads to a large phenotypic homogeneity of the population, protects the species from significant changes.
Stabilizing and driving selections are interrelated.
Driving selection preserves the genotypes that are most adapted to the environment, and when environmental conditions are constant, stabilizing selection comes into play, which will maintain typical, predominant genotypes.
Destabilizing selection - described for the first time by the American evolutionist D.G. Simpson called centrifugal selection. The term destabilizing selection was introduced by N.N. Vorontsov. This is the reverse process of stabilizing selection. Individuals with the same value of the average, but with a wider norm of reaction, are preserved.
disruptive (tearing) selection. This form of selection (described by the American evolutionist C. Mather) preserves several different phenotypes with equal fitness. It acts against an individual with an average value of traits, "tearing" the population according to a certain trait into several groups, maintaining the state of genetic polymorphism in populations.
Stage 5 Adaptations, definition of the concept, classification, relative character.
Adaptations - constantly emerging in the process of life, changing self-improving, sometimes disappearing, evolutionarily conditioned adaptations to specific environmental conditions.
Classification of adaptations:
a) active (development nervous system sense organs, organs of movement)
b) passive (mimicry)
The adaptation of organisms to the environment, developed in the course of a long historical development under the influence of natural causes, not absolutely, but relative.
Evidence for the relative nature of fitness :
1. protective devices from some enemies are ineffective from others (for example, poisonous snakes that are dangerous to many animals are eaten by mongooses, hedgehogs, pigs);
2. the manifestation of instincts in animals may turn out to be impractical (moths collect nectar from light flowers, clearly visible at night, but also fly to the fire, although they die at the same time);
3. An organ that is useful in some conditions becomes useless and even relatively harmful in another environment (webs between the fingers of mountain geese, which never sink into the water);
4. More perfect adaptations to a given habitat are also possible. Some species of animals and plants multiplied rapidly and spread widely in areas completely new to them. the globe where they were accidentally or deliberately introduced by humans.
Thus, the relative nature of fitness contradicts the assertion of absolute expediency in living nature.
Methods and ways of speciation.
Speciation is the process of formation of species as a result of the interaction of elementary evolutionary factors.
Depending on the form of isolation, there are 2 ways of species formation:
a) allopatric
b) sympatric
In allopatric speciation (geographically) barriers to interbreeding are primarily due to spatial separation. Genetic isolation develops secondarily. In this case, two new species are formed from one species. This process is slow. New species, as a rule, differ significantly from the parent species in terms of morphophysiological criteria. Most species, especially animals, arose by allopatric means.
With sympatric speciation the new kind formed within the range of the original species, due to genetic isolation. This way of speciation is fast, it gives species close to the original one in terms of morphophysiological parameters. This path is most typical for plants.
There are 3 ways of speciation:
- divergent (true)
- phyletic (true, gradual speciation)
- hybridogenic (sudden speciation)
divergent speciation consists in dividing the original view into 2 or more as a result of isolation.
Phyletic speciation- this is a gradual process of transformation of one species into another, with changing conditions throughout the range.
hybridogenic speciation- the rapid formation of a new species as a result of chromosomal and genomic mutations, hybridization.
Topic: Patterns of macroevolution.
Main questions:
2. The main directions of the evolutionary process.
3. General patterns of evolution of organs.
4. Teaching about phylembryogenesis.
Stages of presentation of the material:
Definitions of the concept of macroevolution.
Definition of the concepts of allogenesis and arogenesis
Characteristics of elementary forms of phylogenesis (phyletic and divergent evolution)
Forms of correlative group evolution (convergent and parallel evolution)
The main directions of the evolutionary process
Biological process, ego characteristic
Biological regression, its essence and significance
Ways to achieve biological progress
Aromorphosis (morphophysiological progress) its essence
The concept of idioadaptation, their meaning
General degeneration
Group evolution rules
Formulation of the biogenetic law
Philembryogenesis, their types, meaning
Heterochronies, heterotopies, their significance in phylogenesis.
macroevolution are evolutionary processes occurring at the supraspecific level. As a result, taxa are formed with a rank higher than the species (genus, family, order, class, etc.)
Macroevolution studies the processes:
1) in large spaces
2) over a long period of time
hereditary variability
Random (non-directional) feature retention
population waves- periodic fluctuations in population size. For example: the number of hares is not constant, every 4 years there are a lot of them, then a decline in numbers follows. Meaning: Genetic drift occurs during a recession.
Gene drift: if the population is very small (due to a catastrophe, illness, pop wave recession), then the traits persist or disappear regardless of their usefulness, by chance.
Struggle for existence
Cause: far more organisms are born than can survive, so there is not enough food and territory for them all.
Definition: the totality of the relationships of an organism with other organisms and with the environment.
Forms:
- intraspecific (between individuals of the same species),
- interspecific (between individuals different types),
- with environmental conditions.
Consequence: natural selection
Natural selection
This is the main, leading, guiding factor of evolution, leads to adaptability, to the emergence of new species.
Insulation
gradual accumulation of differences between populations isolated from each other can lead to the fact that they will not be able to interbreed - there will be biological isolation, two different views will appear.
Types of isolation/speciation:
- Geographical - if there is an insurmountable barrier between populations - a mountain, a river, or very long distance(occurs with a rapid expansion of the range). For example, Siberian larch (in Siberia) and Dahurian larch (in the Far East).
- Ecological - 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.
Insert the missing terms from the proposed list into the text “Variations in the number of individuals”, using numerical designations for this. The number of individuals in populations is not constant. Its periodic oscillations are called (A). Their significance for evolution lies in the fact that with an increase in the population size, the number of mutant individuals increases as much as the number of individuals increased. If the number of individuals in the population is reduced, then its (B) becomes less diverse. In this case, as a result of (C), individuals with certain (D) may disappear from it.
1) population wave
2) struggle for existence
3) variability
4) gene pool
5) natural selection
6) genotype
7) phenotype
8) heredity
Answer
Choose the one most correct option. Combination variability refers to
1) driving forces of evolution
2) directions of evolution
3) the results of evolution
4) stages of evolution
Answer
1. Establish the sequence of formation of adaptations in a plant population in the course of evolution. Write down the corresponding sequence of numbers.
1) fixing a new trait by stabilizing selection
2) the action of the driving form of selection on the individuals of the population
3) change in the genotypes of individuals of the population in new conditions
4) change in the habitat conditions of the population
Answer
2. Establish the sequence of formation of plant fitness in the process of evolution. Write down the corresponding sequence of numbers.
1) reproduction of individuals with beneficial changes
2) the occurrence of various mutations in the population
3) struggle for existence
4) preservation of individuals with hereditary changes that are useful for given environmental conditions
Answer
3. Set the sequence of microevolution processes. Write down the corresponding sequence of numbers.
1) the action of motive selection
2) the appearance of beneficial mutations
3) reproductive isolation of populations
4) struggle for existence
5) subspecies formation
Answer
4. Establish the sequence of action of the driving forces of evolution. Write down the numbers under which they are indicated.
1) struggle for existence
2) reproduction of individuals with beneficial changes
3) the appearance in the population of various hereditary changes
4) preservation of predominantly individuals with hereditary changes that are useful in given environmental conditions
5) the formation of adaptability to the environment
Answer
5. Establish the sequence of formation of the dark-colored moth moth population in polluted industrial areas.
1) the appearance of differently colored butterflies in the offspring
2) an increase in the number of butterflies with a darker color
3) preservation as a result of natural selection of butterflies with a dark color and death with a light color
4) the emergence of a population of dark-colored butterflies
Answer
6n. Set the sequence of processes in speciation. Write down the corresponding sequence of numbers.
1) distribution of useful traits in isolated populations
2) natural selection of individuals with useful traits in isolated populations
3) gap in the range of the species due to changes in relief
4) the emergence of new characters in isolated populations
5) formation of new subspecies
Answer
1. Indicate the sequence of processes of geographic speciation. Write down the corresponding sequence of numbers
1) the distribution of the trait in the population
2) the appearance of mutations in new living conditions
3) spatial isolation of populations
4) selection of individuals with beneficial changes
5) the formation of a new species
Answer
2. Determine the sequence of processes characteristic of geographic speciation
1) formation of a population with a new gene pool
2) the appearance of a geographical barrier between populations
3) natural selection of individuals with traits adaptive to given conditions
4) the emergence of individuals with new traits in an isolated population
Answer
3. Indicate the sequence of processes in geographic speciation
1) accumulation of mutations in new conditions
2) territorial isolation of the population
3) reproductive isolation
4) the formation of a new species
Answer
4. Specify the sequence of stages of geographical speciation
1) divergence of traits in isolated populations
2) reproductive isolation of populations
3) the emergence of physical barriers in the range of the original species
4) the emergence of new species
5) the formation of isolated populations
Answer
5. Set the sequence of stages of geographic speciation. Write down the corresponding sequence of numbers.
1) the appearance of new random mutations in populations
2) territorial isolation of one population of the species
3) change in the gene pool of the population
4) preservation by natural selection of individuals with new traits
5) reproductive isolation of populations and the formation of a new species
Answer
Establish a sequence of stages of ecological speciation. Write down the corresponding sequence of numbers.
1) ecological isolation between populations
2) biological (reproductive) isolation
3) natural selection in new environmental conditions
4) the emergence of ecological races (ecotypes)
5) the emergence of new species
6) development of new ecological niches
Answer
Choose one, the most correct option. With ecological speciation, in contrast to geographical, a new species arises
1) as a result of the collapse of the original range
2) inside the old range
3) as a result of the expansion of the original range
4) due to genetic drift
Answer
Choose one, the most correct option. An evolutionary factor that contributes to the accumulation of various mutations in a population is
1) intraspecific struggle
2) interspecific struggle
3) geographic isolation
4) limiting factor
Answer
Choose one, the most correct option. Hereditary variability in the process of evolution
1) fixes the created feature
2) is the result of natural selection
3) supplies material for natural selection
4) selects adapted organisms
Answer
Choose one, the most correct option. An example of ecological speciation
1) Siberian and Dahurian larch
2) hare hare and hare hare
3) European and Altai squirrel
4) Sevan trout populations
Answer
Choose three correct answers from six and write down the numbers under which they are indicated. Specify the features that characterize natural selection as the driving force of evolution
1) Source of evolutionary material
2) Provides a reserve of hereditary variability
3) The object is the phenotype of the individual
4) Provides selection of genotypes
5) Directional factor
6) Factor of random action
Answer
1. Establish a correspondence between the process occurring in nature and the form of the struggle for existence: 1) intraspecific, 2) interspecific
A) competition between individuals of a population for territory
B) the use of one species by another
C) rivalry between individuals for a female
D) displacement of the black rat by the gray rat
D) predation
Answer
2. Establish a correspondence between the example of the struggle for existence and the form to which this struggle belongs: 1) intraspecific, 2) interspecific. Write the numbers 1 and 2 in the correct order.
A) identification of nesting sites in the forest with crossbills
B) the use of cattle as a habitat by a bull chain
C) rivalry between males for dominance
D) displacement of the black rat by the gray rat
E) fox hunting for mice-voles
Answer
3. Establish a correspondence between examples and types of struggle for existence: 1) intraspecific, 2) interspecific. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) the displacement of the black rat by the gray rat
B) the behavior of male moose during the mating season
C) fox hunting for mice
D) the growth of even-aged beet seedlings on the same bed
D) the behavior of a cuckoo in the nest of another bird
E) rivalry of lions in one pride
Answer
1. Establish a correspondence between the cause of speciation and its method: 1) geographical, 2) ecological. Write the numbers 1 and 2 in the correct order.
A) expansion of the range of the original species
B) the stability of the range of the original species
C) division of the species range by various barriers
D) the diversity of variability of individuals within the range
E) variety of habitats within a stable range
Answer
2. Establish a correspondence between the features of speciation and their methods: 1) geographical, 2) ecological. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) isolation of populations due to a water barrier
B) isolation of populations due to different timing of reproduction
C) isolation of populations due to the emergence of mountains
D) isolation of populations due to large distances
E) isolation of populations within the range
Answer
3. Establish a correspondence between the mechanisms (examples) and methods of speciation: 1) geographical, 2) ecological. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) expansion of the range of the original species
B) preservation of a single original range of the species
C) the appearance of two species of gulls in the North and Baltic seas
D) the formation of new habitats within the original range
E) the presence of populations of Sevan trout that differ in spawning time
Answer
4. Establish a correspondence between the characteristics and methods of speciation: 1) geographical, 2) ecological. Write down the numbers 1 and 2 in the order corresponding to the letters.
A) long-term constancy of the existence of the range of the original species
B) division of the range of the original species by an insurmountable barrier
C) different food specialization within the original range
D) division of the range into several isolated parts
E) development of various habitats within the original range
E) isolation of populations due to different timing of reproduction
Answer
1. Choose from the text three sentences that describe the ecological way of speciation in the evolution of the organic world. Write down the numbers under which they are indicated. (1) Reproductive isolation causes microevolution. (2) Free crossing ensures the exchange of genes between populations. (3) Reproductive isolation of populations can occur within the same range along different reasons. (4) Isolated populations with different mutations adapt to the conditions of different ecological niches within the former range. (5) An example of such speciation is the formation of buttercup species that have adapted to life in a field, meadow, or forest. (6) A species serves as the smallest genetically stable supraorganismal system in living nature.
Answer
2. Read the text. Choose three sentences that indicate the processes of ecological speciation. Write down the numbers under which they are indicated. (1) During speciation, the range of a species is divided into fragments. (2) There are several populations in Lake Sevan that differ in terms of spawning. (3) Speciation may be associated with a change in the ecological niche of a species. (4) If polyploid forms are more viable than diploid ones, they may give rise to a new species. (5) Several species of tits live in Moscow and the Moscow region, differing in the way they get food.
Answer
3. Read the text. Choose three sentences that describe ecological speciation. Write down the numbers under which they are indicated. (1) A species in nature exists in the form of separate populations. (2) Due to the accumulation of mutations, a population can form under changed conditions in the original range. (3) Sometimes microevolution is associated with a gradual expansion of the range. (4) Natural selection reinforces persistent differences between plants of different populations of the same species occupying the same area, but growing in a dry meadow or in a river floodplain. (5) For example, species of buttercups growing in the forest, in the meadow, along the banks of the rivers were formed in this way. (6) Speciation may be caused by spatial isolation caused by mountain building.
Answer
4. Read the text. Choose three sentences that describe ecological speciation. Write down the numbers under which they are indicated. (1) Speciation can occur within the same contiguous range if the organisms inhabit different ecological niches. (2) The reasons for speciation are the mismatch in the timing of reproduction in organisms, the transition to new food without changing the habitat. (3) An example of speciation is the formation of two subspecies of the large rattle growing in the same meadow. (4) Spatial isolation of groups of organisms can occur when the range expands and the population enters new conditions. (5) As a result of adaptations, the South Asian and Eurasian subspecies of the great tit were formed. (6) As a result of isolation, endemic island species animals.
Answer
5. Read the text. Choose three sentences that match the description of ecological speciation. Write down the numbers under which they are indicated. (1) The result of the action of the driving forces of evolution is the spread of the species into new areas. (2) Speciation may be associated with the expansion of the range of the original species. (3) Sometimes it arises as a result of a break in the original range of a species by physical barriers (mountains, rivers, etc.) (4) New species can develop specific living conditions. (5) As a result of food specialization, several species of tits have developed. (6) For example, the great tit feeds on large insects, and the crested tit - seeds of coniferous trees.
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1. Read the text. Choose three sentences that describe the features of geographic speciation. Write down the numbers under which the selected statements are indicated. (1) Associated with spatial isolation due to expansion or dismemberment of the range, as well as human activities. (2) Occurs in the case of a rapid increase in the chromosome set of individuals under the influence of mutagenic factors or in case of errors in the process of cell division. (3) More common in plants than in animals. (4) Occurs by dispersal of individuals to new territories. (5) B different conditions habitats, ecological races are formed, which become the ancestors of new species. (6) Polyploid viable forms can give rise to a new species and completely displace the diploid species from the range.
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2. Choose from the text three sentences that characterize the geographical method of speciation in the evolution of the organic world. Write down the numbers under which they are indicated. (1) The exchange of genes between populations during the reproduction of individuals preserves the integrity of the species. (2) In the event of reproductive isolation, interbreeding becomes impossible and the population takes the path of microevolution. (3) Reproductive isolation of populations occurs when physical barriers occur. (4) Isolated populations expand their range by maintaining adaptations to new living conditions. (5) An example of such speciation is the formation of three subspecies of the great tit, which have mastered the territories of eastern, southern and western Asia. (6) A species serves as the smallest genetically stable supraorganismal system in living nature.
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3. Read the text. Choose three sentences that describe geographic speciation. Write down the numbers under which they are indicated. (1) Speciation is the result of natural selection. (2) One of the reasons for speciation is the discrepancy between the periods of reproduction of organisms and the occurrence of reproductive isolation. (3) An example of speciation is the formation of two subspecies of the large rattle growing in the same meadow. (4) The spatial isolation of groups of organisms may be accompanied by an expansion of the range, in which populations fall into new conditions. (5) As a result of adaptations, the South Asian and Eurasian subspecies of the great tit were formed. (6) As a result of isolation, endemic island animal species have formed.
Answer
4. Read the text. Choose three sentences that describe geographic speciation. Write down the numbers under which they are indicated. (1) A species in nature occupies a certain area and exists in the form of separate populations. (2) Due to the accumulation of mutations, a population with a new gene pool can be formed within the original range. (3) The expansion of the range of a species leads to the emergence of isolated new populations at its borders. (4) At new range boundaries, natural selection reinforces persistent differences between spatially separated populations. (5) Between individuals of the same species, free interbreeding is disturbed as a result of the appearance of mountain barriers. (6) Speciation is gradual.
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Choose three correct answers from six and write down the numbers under which they are indicated. The processes leading to the formation of new species in nature include
1) mitotic cell division
2) spasmodic mutation process
4) geographic isolation
5) asexual reproduction individuals
6) natural selection
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Establish a correspondence between the example and the method of speciation that this example illustrates: 1) geographical, 2) ecological. Write the numbers 1 and 2 in the correct order.
A) the habitation of two populations of common perch in coastal zone and deep in the lake
B) the habitation of different populations of blackbirds in dense forests and near human habitation
C) the disintegration of the range of the May lily of the valley into isolated areas due to glaciation
D) the formation of different types of tits on the basis of food specialization
E) the formation of Dahurian larch as a result of the expansion of the range of Siberian larch to the east
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Choose three options. Under the influence of what evolutionary factors does the process of ecological speciation occur?
1) modification variability
2) fitness
3) natural selection
4) mutational variability
5) struggle for existence
6) convergence
Answer
Choose three options. What factors are the driving forces of evolution?
1) modification variability
2) mutation process
3) natural selection
4) adaptation of organisms to the environment
5) population waves
6) abiotic environmental factors
Answer
1) crossing over
2) mutation process
3) modification variability
4) isolation
5) variety of species
6) natural selection
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Choose three options. The driving forces of evolution are
1) isolation of individuals
2) adaptation of organisms to the environment
3) variety of species
4) mutational variability
5) natural selection
6) biological progress
Answer
Read the text. Choose three sentences that indicate the driving forces of evolution. Write down the numbers under which they are indicated. (1) The synthetic theory of evolution states that species live in populations in which evolutionary processes begin. (2) It is in populations that the most acute struggle for existence is observed. (3) As a result of mutational variability, new traits gradually arise. Including adaptations to environmental conditions - idioadaptation. (4) This process of gradual emergence and maintenance of new characters under the influence of natural selection, leading to the formation of new species, is called divergence. (5) The formation of new large taxa occurs through aromorphoses and degeneration. The latter also leads to the biological progress of organisms. (6) Thus, the population is the initial unit in which the main evolutionary processes take place - changes in the gene pool, the emergence of new traits, the emergence of adaptations.
Answer
Establish a correspondence between the factors of speciation and its method: 1) geographical, 2) ecological, 3) hybridogenic. Write the numbers 1-3 in the correct order.
A) polyploidization of hybrids from inbreeding
B) differences in habitats
C) division of the area into fragments
D) the habitat of different types of lily of the valley in Europe and the Far East
D) food specialization
Answer
Analyze the table "Struggle for existence". For each lettered cell, select the appropriate term from the list provided. Write down the chosen numbers, in the order corresponding to the letters.
1) fight against environmental conditions
2) limited natural resources
3) fight against adverse conditions
4) different ecological criteria of the species
5) seagulls in colonies
6) males in the mating season
7) birch and tinder fungus
8) the need to choose a sexual partner
Answer
Choose one, the most correct option. The division of populations of the same species according to the timing of reproduction can lead to
1) population waves
2) feature convergence
3) strengthening interspecific struggle
4) ecological speciation
Answer
Choose one, the most correct option. Point out the wrong statement. Interspecies struggle leads to
1) increased competition between species
2) prosperity of competing species
3) displacement of the oppressed species from the habitat
4) decrease in the number of the defeated species
Answer
Choose two sentences that indicate processes that are NOT related to the intraspecific struggle for existence. Write down the numbers under which they are indicated.
1) Competition between wolves of the same population for prey
2) Fight for food between gray and black rats
3) Destruction of young animals with an excess population
4) The struggle for dominance in a pack of wolves
5) Leaf reduction in some desert plants
Answer
© D.V. Pozdnyakov, 2009-2019
From the point of view of supporters of "opportunistic evolution", behind the various directions of evolutionary changes there are no regular and organizing tendencies, except for the action of natural selection, which organizes the variability of organisms only in the direction of developing adaptations to changes in the environment. From these positions, the main directions of the evolutionary process (aro-, epecto-, allo- and catagenesis), in fact, are equivalent - in the sense that each of them is only a means for achieving the success of a given group of organisms in the struggle for existence (such a point A. N. Severtsov also adhered to this view).
Indeed, among the driving factors of evolution, only natural selection has an organizing effect on the variability of organisms, and at the same time, selection is really devoid of a certain direction, which was emphasized by Charles Darwin. But Darwin also pointed to the factor that determines the specific directions of evolutionary transformations: "The nature of conditions has a subordinate significance in determining each given change in comparison with the nature of the organism itself" 1 . Although the evolution of organisms is based on probabilistic processes - the occurrence of mutations (the phenotypic manifestation of which is inadequate to the changes in external conditions that caused them) and natural selection, the "nature of the organism", that is, the organizational basis of living systems, limits the manifestations of chance in evolution to certain limits. In other words, system organization channels phylogeny, i.e., directs evolutionary transformations into certain channels, and for any particular group of organisms, the choice of possible evolutionary paths is limited. The concept of hard-coded (nomogenetic) evolution is based on the absolutization of the guiding role in evolutionary process the organizational basis of living systems, while the concept of opportunistic evolution is based on the absolutization of the guiding role of natural selection. Usually the truth should be sought somewhere between extreme points of view.
Specific directions of phylogenetic transformations various groups organisms are determined by the interaction of forces of natural selection and historical organization
"Darwin Ch. Origin of species. - M., 1987. - S. 24.
these groups. Therefore, there are two categories guiding factors of evolution: extraorganismal (forces of selection) and organismal.
For any given species, the features of its organization create preconditions (pre-adaptation) for the development of certain adaptations and prevent the development of others, "allow" some directions of evolutionary transformations and "prohibit" other directions. The totality of these positive and negative characteristics of the evolutionary possibilities of this group is designated as organismic guiding factors of evolution. These factors can be divided (somewhat conditionally) into three categories, in accordance with the level of their manifestation in ontogenesis: 1) genetic, 2) morphogenetic, 3) morphophysiological (morphofunctional).
The action of the first two categories of organismic directing factors is fully manifested already at the level of microevolution. As already noted (Part II, Chapter 1), each genotype and gene pool of each species is characterized by a certain set of possible (“allowed”) mutations, or a spectrum of mutational variability, which is limited not only qualitatively, but also quantitatively, i.e., a certain frequency of occurrence of each type of mutation. At the same time, some mutations turn out to be impossible (forbidden) for a given genotype (and gene pool), for example, blue and green eye colors for fruit flies or blue colors of flowers for rosaceous plants. The reason for this is the absence of appropriate biochemical prerequisites in the genotype.
Since the gene pools of related species retain sets of homologous genes inherited from a common ancestor, homologous mutations naturally appear in them (see p. 71). Homologous mutations can serve as the basis for parallel evolutionary changes in closely related species that have recently diverged from a common ancestor. However, over time, heterogeneous (non-homologous) mutations inevitably accumulate in the gene pools of isolated species; this occurs even under the action of stabilizing selection, when the phenotypic effect of structural gene mutations is blocked by modifier genes. In different species, whose gene pools have been isolated from each other for quite a long time, homologous structures of the phenotype are preserved, but their genetic control can differ significantly (and even almost completely). Therefore, the parallel evolution of phyletic lineages that have long diverged from a common ancestor (to the level different kinds, families, etc.) is based less on homologous mutations than on the action of two other categories of organismal directing factors.
Some mutations that are biochemically possible for a given genotype (i.e., allowed for genetic level), however, ultimately lead to disastrous consequences for the developing organism in the form of morphogenesis disorders (lethal mutations, for example, the morphogenetic consequences of a mutation in congenital hydrocephalus in a house mouse, see p. 331). Each ontogeny can be changed only in a certain way, i.e., within the corresponding spectrum of possible ontogenetic changes. This further narrows the choice of possible directions of evolutionary transformations.
Finally, there are also morphophysiological evolutionary restrictions and prohibitions, the effect of which (as well as the corresponding preadaptations) is fully manifested only on the scale of macroevolution, being one of the specific reasons for its directed nature. They are due to various interrelations within morphophysiological systems and between these systems in the phenotype of adult organisms. At the same time, mutations and rearrangements of ontogeny, which could lead to corresponding changes in the phenotype, are themselves quite possible, and mutant individuals with a certain frequency can appear in populations of a given species. However, the resulting changes in the phenotype (even seemingly having a high adaptive value!) cannot be used to form new adaptations because of their inconsistency with the morphophysiological organization of the given species. Such transformations remain unrealizable until the corresponding morphophysiological prohibitions are lifted.
For example, keratinization can develop in the epidermis of amphibians - there are biochemical prerequisites necessary for this, and there are no morphogenetic prohibitions for this process. Indeed, local keratinization of the epidermis develops in the integument of some amphibian species (for example, horny claws in clawed frogs or male clawed newts, horny “teeth” in tadpoles of many species of anurans). However, for amphibians it turned out to be impossible to form on this basis such keratinization of the integuments that could effectively protect the body from dehydration in the air and in salty water bodies, as in reptiles, birds and mammals. This is due to the need for amphibians to maintain a constantly moist skin surface, which is used as an additional gas exchange organ, primarily to remove carbon dioxide from the body (see below for more details).
Morphophysiological evolutionary restrictions and prohibitions are due to the need for harmonic rearrangements of body systems that are adaptively integrated (i.e., included in a common adaptive complex), functionally, or at least topographically. In phylogenesis, the effect of such restrictions manifests itself in the form of various coordination(i.e., phylogenetic correlations) 1 between different structures and systems of the body. Under topographical coordinations refers to the simplest conjugated evolutionary changes in organs that are closely related spatially. For example, an increase in the size of the eyes is impossible without appropriate restructuring of the skull, changes in the position of muscles, vessels and nerves in the orbit and temporal region. Dynamic coordination represent phylogenetic relationships of organs related to each other in ontogeny by functional correlations. An example of evolutionary limitations based on such coordinations is the impossibility of strengthening any muscle group without a corresponding strengthening of the skeletal structures and some other muscle groups, since this would make the coordinated work of the musculoskeletal system mechanically imperfect. Thus, there is no point in developing powerful femoral muscles while maintaining weaker calf muscles, since the latter cannot effectively transfer the contraction force of the former to the substrate. At the same time, the leg muscles cannot be significantly strengthened in animals adapted to fast running, since this would significantly increase the moment of inertia of the limb. This evolutionary restriction requires the development of a characteristic limb structure in fast-running animals, in which the bulk of the muscles are located in the proximal sections (shoulder, thigh), and the force of their contraction is transmitted to the support through the thin and light distal sections (forearm, lower leg, foot) through the system tendons.
I. I. Schmalhausen singled out the so-called biological coordination, which are understood as conjugated changes in organs and individual structures that are not directly related to each other by any correlations in ontogenesis, but are included in the general adaptive complex (for example, evolutionary relationships between the structure of masticatory muscles, teeth, jaw bones and jaw joints, caused in a certain way nutrition). The coordinated evolutionary changes of these heterogeneous structures are determined by natural selection.
- Homology is the similarity of structures based on the commonality of their origin. The ratio of homologous structures belonging to different levels of the hierarchical organization of biological systems (including genetic and phenotypic homology) is complex and ambiguous.
- The term "coordination" to denote the phylogenetic relationships of organs was introduced by A.N. Severtsov.
- See book: Alexander R. Biomechanics. - M., 1970.
