Since childhood, each of us knows that morphology is the most important section of grammar. However, this concept has another meaning. You will learn about this from our article.

Morphology in biology

Biology is a complex science of life. It includes a range of disciplines. One of them is morphology. In biology, it is the science of the structure of organisms. The author of this concept is the world famous poet and naturalist from Germany, Johann Wolfgang Goethe. His numerous works concern the study of the external features of plants, comparative anatomy, the concept of homologous organs and metamorphoses.

The Russian academician Aleksey Nikolaevich Severtsov continued the study of this concept and its evolutionary significance. He is the founder of animal morphology. Based on the comparative embryological method, the scientist created a hypothesis of the origin of vertebrates and cited a number of its evidence. Together with his student Ivan Ivanovich Schmalhausen, he also proposed the concept of morphological progress and regression as evolutionary factors.

Endonomy

Morphology, as a biological discipline, includes two main areas. The first of them studies the features of the external structure. More precisely, in biology, it can be explained as follows: the distinctive features of various organisms. These include the shape, size, color, number of structures that make up the body. Morphological criterion is one of the factors determining the species affiliation.

For a long time he generally remained the only one. But further research convinced scientists of the partial unreliability of this criterion. For example, in nature there are a sufficient number of animals for which this phenomenon is characteristic. This phenomenon lies in the fact that males and females of the same species differ significantly from each other in appearance. These include peacocks, pheasants, chickens and roosters, guppy fish.

Anatomy

The second section, which includes morphology in biology, studies the internal structure of organisms. It is called the direction of morphology considers the structure at the levels of organization that are above the cellular. These include tissue and organism. The main focus of this science is animals and humans.

At various stages of embryonic development, scientists also study the internal structure of organisms of various systematic groups, comparing them. This made it possible to formulate the concepts of homo- and examples of the former are the forelimbs of birds and whales. In birds, they are turned into wings, and aquatic mammals use them as flippers. However, these structures have the same origin. The existence of such organs indicates the presence of a single ancestor in animals that have them.

Analogies are body parts that have similar functions but different origins. Their examples are the wings of birds and insects. In the former, these are modified forelimbs. But the wings of insects are derivatives of covers. The presence of homologous organs indicates the ability of various organisms to adapt to the same conditions of existence.

General morphology

In science, you can often find the concept of "general morphology". This section studies the salient features of an organism or an entire taxon. For example, all representatives of the phylum Arthropoda have segmented limbs. And based on the number of walking legs, they can already be combined into classes. So, arachnids have four pairs, and insects have three.

So, morphology in biology is a discipline that studies only the structure of organisms. It does not affect the features and conditions of physiological processes. Depending on the subject of study, endonomy, anatomy and general morphology are distinguished.

1. Biological species and its criteria.

All life on the planet is represented by separate species.

A species is a historically established set of individuals that have a hereditary similarity in morphological, physiological and biochemical features; able to freely interbreed with each other and produce fertile offspring; adapted to certain environmental conditions and occupying a certain area.

Each type of organism can be described by a set of characteristic features and properties, which are called features of the species. Features of a species that distinguish one species from another are called type criteria.

The most commonly used general view criteria are: morphological, physiological, genetic, biochemical, geographical and ecological.

Morphological criterion - based on the external and internal similarity of individuals of the same species.

The morphological criterion is the most convenient and is therefore widely used in species taxonomy.

However, the morphological criterion is insufficient to determine the difference sibling species with significant morphological similarity.

Twin species practically do not differ in appearance, however, individuals of such species do not interbreed.

Species-twins are quite common in nature. About 5% of all species of insects, birds, fish, etc. have twin species:

- black rats have two twin species;

- the malarial mosquito has six twin species.

The use of a morphological criterion is also difficult in cases where individuals of the same species differ sharply from each other in appearance, the so-called polymorphic species.

The simplest example of polymorphism is sexual dimorphism, when there are morphological differences between males and females of the same species.

It is difficult to use the morphological criterion in the diagnosis of domestic animal species. Breeds bred by humans can differ significantly from each other, remaining within the same species (breeds of cats, dogs, pigeons).

Thus, the morphological criterion is insufficient to determine the species belonging of individuals.

The physiological criterion characterizes the similarity of life processes in individuals of the same species, primarily the similarity of reproduction.

Between individuals of different species there is a physiological isolation, which is manifested in the fact that individuals of different species almost never interbreed with each other. This is due to differences in the structure of the reproductive apparatus, the timing and places of reproduction, in the rituals of behavior during mating, etc.

If interspecific crossing does occur, then the result is interspecific hybrids that are characterized by reduced viability or are infertile and do not produce offspring:

For example, a hybrid of a horse and a donkey is known - a mule, which is quite viable, but barren.

However, in nature there are such species that can interbreed with each other and produce fertile offspring. (for example, some species of canaries, finches, poplars, willows, etc.).

Consequently, the physiological criterion is insufficient to characterize the species.

A genetic criterion is a set of chromosomes characteristic of each species, a strictly defined number, size and shape.

Individuals of different species cannot interbreed, as they have different sets of chromosomes, differ in number, size and shape:

- for example, two closely related species of black rats differ in the number of chromosomes (one species has 38 chromosomes, and the other 48) and therefore do not interbreed.

However, this criterion is not universal:

- first, in many different species, the number of chromosomes can be the same (for example, many species of the legume family have 22 chromosomes each);

- secondly, within the same species, individuals with a different number of chromosomes can be found, which is the result of mutations (for example, in silver carp there are populations with a set of chromosomes 100, 150, 200, while their normal number is 50).

Thus, on the basis of a genetic criterion, it is also impossible to reliably determine the belonging of individuals to a particular species.

The biochemical criterion makes it possible to distinguish species according to biochemical parameters (the composition and structure of certain proteins, nucleic acids, and other substances).

It is known that the synthesis of certain macromolecular substances is characteristic only of certain species ( for example, many plant species differ in their ability to form and accumulate certain alkaloids).

However, there is significant intraspecific variability in almost all biochemical parameters, up to the sequence of amino acids in protein and nucleic acid molecules.

Therefore, the biochemical criterion is also not universal. In addition, it is not widely used, as it is very laborious.

The geographical criterion is based on the fact that each species occupies a certain territory or water area.

In other words, each species is characterized by a specific geographical area.

Many species occupy different ranges, but most species have overlapping ranges.

There are species that do not have a specific geographical range, i.e. living on vast expanses of land or ocean, the so-called cosmopolitan species :

- some inhabitants of inland waters - rivers and freshwater lakes (many species of fish, reeds);

- Cosmopolitans also include medicinal dandelion, shepherd's purse, etc.;

- cosmopolitans are found among synanthropic animals - species that live near a person or his dwelling (lice, bedbugs, cockroaches, flies, rats, mice, etc.);

- Cosmopolitans also include indoor and cultivated plants, weeds, pets that are under human care.

In addition, there are species that do not have clear distribution boundaries or have a broken geographical range.

Due to these circumstances, the geographical criterion, like others, is not absolute.

The ecological criterion is based on the fact that each species can exist only under certain conditions, fulfilling its functional role in a particular biogeocenosis.

In other words:

Each species occupies a certain ecological niche in a complex system of ecological relationships with other organisms and factors of inanimate nature.

An ecological niche is a set of all environmental factors and conditions within which a species can exist in nature.

It includes the whole complex of abiotic and biotic environmental factors necessary for the organism to live, and is determined by its morphological fitness, physiological reactions and behavior.

The classic definition of an ecological niche was given by the American ecologist J. Hutchinson (1957).

According to the concept formulated by him, an ecological niche is a part of an imaginary multidimensional space (hypervolume), individual dimensions of which correspond to the factors necessary for the normal existence of a species (Fig. 1).

two-dimensional niche three-dimensional niche

Rice. 1. Ecological niche model according to Hutchinson

(F 1, F 2, F 3 - the intensity of various factors).

For example:

- for the existence of a terrestrial plant, a certain combination of temperature and importance is sufficient (two-dimensional niche);

- for a marine animal, temperature, salinity, oxygen concentration (three-dimensional niche) are necessary.

It is important to emphasize that the ecological niche is not just the physical space occupied by a species, but also its place in the community, determined by its ecological functions and its position relative to the abiotic conditions of existence.

According to the figurative expression of Y. Odum, an “ecological niche” is the “profession” of a species, its way of life, and “habitat” is its “address”. ”

For example, a mixed forest is a habitat for hundreds of species of plants and animals, but each of them has its own and only one "profession" - an ecological niche. Elk and squirrel have the same habitat, but their ecological niches are completely different.

Consequently, the ecological niche is not a spatial, but a functional category.

At the same time, it is important to realize that the ecological niche is not something that can be seen. An ecological niche is an abstract abstract concept.

An ecological niche defined only by the physiological characteristics of organisms is called fundamental and the one within which the species actually occurs in nature - implemented.

However, the ecological criterion is also insufficient to characterize the species.

Some different species in different habitats may occupy the same ecological niches:

- antelopes in the savannas of Africa, bison in the prairies of America, kangaroos in the savannas of Australia, marten in the European and sable in the Asian taiga lead the same way of life, have a similar type of nutrition, i.e. in different biogeocenoses they perform the same functions and occupy similar ecological niches.

It often happens the other way around - the same species in different habitats is characterized by different ecological niches. Most often this is due to the availability of food and the presence of competitors:

In addition, the same species in different periods of its development can occupy different ecological niches:

- so, the tadpole eats plant food, and the adult frog is a typical carnivore, so they are characterized by different ecological niches;

- migratory birds in connection with migrations are also characterized by different ecological niches in winter and summer;

- among algae there are species that function either as autotrophs or as heterotrophs. As a result, at certain periods of their lives, they occupy certain ecological niches.

Thus, none of these criteria can be used to determine whether an individual belongs to a particular species. It is possible to characterize a species only by the totality of all or most of the criteria.

A species is one of the main forms of organization of life on Earth (along with a cell, an organism and an ecosystem) and the main unit of biological diversity classification. But at the same time, the term "species" still remains one of the most complex and ambiguous biological concepts.

The problems associated with the concept of biological species are easier to understand when viewed from a historical perspective.

Background

The term "species" has been used to designate the names of biological objects since ancient times. Initially, it was not purely biological: species of ducks (mallard, pintail, teal) did not differ fundamentally from types of kitchen utensils (frying pan, saucepan, etc.).

The biological meaning of the term "species" was given by the Swedish naturalist Carl Linnaeus. He used this concept to designate an important property of biological diversity - its discreteness (discontinuity; from the Latin discretio - to divide). K. Linnaeus considered species as objectively existing groups of living organisms, quite easily distinguishable from each other. He considered them immutable, once and for all created by God.

The identification of species at that time was based on differences between individuals in a limited number of external features. This method is called the typological approach. The assignment of an individual to a particular species was carried out on the basis of a comparison of its features with descriptions of already known species. If its characters could not be correlated with any of the existing species diagnoses, then a new species was described based on this specimen (it was called the type specimen). Sometimes this led to incidental situations: males and females of the same species were described as different species.

With the development of evolutionary ideas in biology, a dilemma arose: either species without evolution, or evolution without species. The authors of evolutionary theories - Jean-Baptiste Lamarck and Charles Darwin denied the reality of species. C. Darwin, the author of "The Origin of Species by Means of Natural Selection ...", considered them "artificial concepts invented for the sake of convenience."

By the end of the 19th century, when the diversity of birds and mammals had been sufficiently thoroughly studied over a large area of ​​the Earth, the shortcomings of the typological approach became obvious: it turned out that animals from different places sometimes, although slightly, but quite reliably differ from each other. In accordance with the established rules, they had to be given the status of independent species. The number of new species grew like an avalanche. Along with this, the doubt grew: should different populations of closely related animals be assigned a species status only on the basis that they are slightly different from each other?

In the 20th century, with the development of genetics and synthetic theory, a species began to be considered as a group of populations with a common unique gene pool, which has its own “protection system” for the integrity of its gene pool. Thus, the typological approach to the identification of species has been replaced by an evolutionary approach: species are determined not by difference, but by isolation. Populations of a species that are morphologically distinct from each other, but are able to interbreed freely with each other, are given the status of subspecies. This system of views formed the basis of the biological concept of the species, which received worldwide recognition thanks to the merit of Ernst Mayr. The change in species concepts "reconciled" the ideas of morphological isolation and evolutionary variability of species and made it possible to approach the task of describing biological diversity with greater objectivity.

View and its reality. C. Darwin, in his book "The Origin of Species" and in other works, proceeded from the fact of the variability of species, the transformation of one species into another. Hence his interpretation of the species as stable and simultaneously changing over time, leading first to the appearance of varieties, which he called "nascent species."

View- a set of geographically and ecologically close populations capable of interbreeding under natural conditions, having common morphophysiological features, biologically isolated from populations of other species.

View criteria- a set of certain features that are characteristic of only one kind of species (T.A. Kozlova, V.S. Kuchmenko. Biology in tables. M., 2000)

View criteria	Indicators of each criterion
Morphological	The similarity of the external and internal structure of individuals of the same species; characteristics of the structural features of representatives of one species
Physiological	The similarity of all life processes, and above all reproduction. Representatives of different species, as a rule, do not interbreed or their offspring are sterile
Biochemical	Species specificity of proteins and nucleic acids
Genetic	Each species is characterized by a specific, unique set of chromosomes, their structure and differentiated coloration.
Ecological-geographical	Habitat and immediate habitat - ecological niche. Each species has its own niche and range of distribution.

It is also significant that the species is a universal discrete (crushable) unit of life organization. A species is a qualitative stage of living nature; it exists as a result of intraspecific relationships that ensure its life, reproduction and evolution.

The main feature of the species is the relative stability of its gene pool, supported by the reproductive isolation of individuals from other similar species. The unity of the species is maintained by free interbreeding between individuals, which results in a constant flow of genes in the intraspecific community. Therefore, each species has stably existed for many generations in one area or another, and its reality is manifested in this. At the same time, the genetic structure of the species is constantly being rebuilt under the influence of evolutionary factors (mutations, recombinations, selection), and therefore the species is heterogeneous. It breaks down into populations, races, subspecies.

The genetic isolation of species is achieved by geographical (related groups are separated by the sea, desert, mountain range) and ecological isolation (mismatch in terms and places of reproduction, animals living in different tiers of the biocenosis). In those cases where interspecific crossing does occur, the hybrids are either weakened or sterile (for example, a hybrid of a donkey and a horse - a mule), which indicates the qualitative isolation of the species and its reality. According to the definition of K. A. Timiryazev, “a species as a strictly defined category, always equal and unchanged, does not exist in nature. But at the same time, we must recognize that the species, at the moment we observe, have a real existence.

population. Within the range of any species, its individuals are unevenly distributed, since in nature there are no identical conditions for existence and reproduction. For example, mole colonies are found only in separate meadows, nettle thickets - along ravines and ditches, frogs of one lake are separated from another neighboring lake, etc. The population of a species breaks up into natural groupings - populations. However, these distinctions do not eliminate the possibility of interbreeding between individuals occupying border areas. The population density of the population is subject to significant fluctuations in different years and different seasons of the year. A population is a form of existence of a species in specific environmental conditions and a unit of its evolution.

A population is a collection of freely interbreeding individuals of the same species that exist for a long time in a certain part of the range within the species and are relatively isolated from other populations. Individuals of one population have the greatest similarity in all characteristics inherent in the species, due to the fact that the possibility of interbreeding within a population is higher than between individuals of neighboring populations and they experience the same selection pressure. Despite this, populations are genetically heterogeneous due to continuously emerging hereditary variability.

Darwinian divergence (divergence of characteristics and properties of descendants in relation to the original forms) can occur only through the divergence of populations. For the first time this position was substantiated in 1926 by S. S. Chetverikov, who showed that behind the apparent external uniformity, any species has a huge hidden reserve of genetic variability in the form of a variety of recessive genes. This genetic reserve is not the same in different populations. That is why the population is the elementary unit of the species and the elementary evolutionary unit.

View types

The selection of species occurs on the basis of two principles (criteria). This is a morphological criterion (revealing differences between species) and a reproductive isolation criterion (estimating the degree of their genetic isolation). The procedure for describing new species is often associated with certain difficulties, associated both with the ambiguous correspondence of the species criteria to each other, and with the gradual and incomplete process of speciation. Depending on what kind of difficulties arose in the selection of species and how they were resolved, the so-called "types of species" are distinguished.

monotypic appearance. Often there are no difficulties in describing new species. Such species usually have a vast, unbroken range over which geographical variability is weakly expressed.

polytypic look. Often, with the help of a morphological criterion, a whole group of closely related forms is singled out, living, as a rule, in a highly dissected area (in the mountains or on islands). Each of these forms has its own, usually rather limited range. If there is geographic contact between the compared forms, then the criterion of reproductive isolation can be applied: if hybrids do not occur, or are relatively rare, these forms are given the status of independent species; otherwise, they describe different subspecies of the same species. A species that includes several subspecies is called polytypic. When the analyzed forms are geographically isolated, the assessment of their status is rather subjective and occurs only on the basis of a morphological criterion: if the differences between them are “significant”, then we have different species, if not, subspecies. It is not always possible to unambiguously determine the status of each form in a group of closely related forms. Sometimes a group of populations closes in a ring, covering a mountain range or the globe. In this case, it may turn out that the "good" (living together and not hybridizing) species are related to each other by a chain of subspecies.

polymorphic look. Sometimes within a single population of a species there are two or more morphs - groups of individuals that are sharply different in color, but able to freely interbreed with each other. As a rule, the genetic basis of polymorphism is simple: the differences between morphs are determined by the action of different alleles of the same gene. The ways in which this phenomenon occurs can be very different.

Mantis adaptive polymorphism

Hybridogenic polymorphism of the Spanish wheatear

The praying mantis has green and brown morphs. The first is poorly visible on the green parts of plants, the second - on tree branches and dry grass. In experiments on transplanting praying mantises to a background that does not match their color, it was possible to show that polymorphism in this case could arise and is maintained due to natural selection: the green and brown coloring of praying mantises is a defense against predators and allows these insects to compete less with each other.

Males of the Spanish wheatear have white-throated and black-throated morphs. The nature of the ratio of these morphs in different parts of the range suggests that the black-throated morph was formed as a result of hybridization with a closely related species, the bald wheatear.

Species-twins- species that live together and do not interbreed with each other, but differ very slightly morphologically. The difficulty of distinguishing such species is associated with the difficulty of isolating or inconvenient use of their diagnostic features - after all, the twin species themselves are well versed in their own "taxonomy". More often, twin species are found among groups of animals that use smell to find a sexual partner (insects, rodents) and less often among those that use visual and acoustic signaling (birds).

Spruce crossbills(Loxia curvirostra) and pine(Loxia pytyopsittacus). These two species of crossbills are one of the few examples of sibling species among birds. Living together in a large area covering Northern Europe and the Scandinavian Peninsula, these species do not interbreed with each other. Morphological differences between them, insignificant and very unreliable, are expressed in the size of the beak: in the pine it is somewhat thicker than in the spruce.

"Half-kinds". Speciation is a long process, and therefore one may encounter forms whose status cannot be objectively assessed. They are not yet independent species, since they hybridize in nature, but these are no longer subspecies, since the morphological differences between them are very significant. Such forms are called "borderline cases", "problem types", or "semi-types". Formally, binary Latin names are assigned to them, as in "normal" species, and they are placed next to each other in taxonomic lists. "Semi-species" are not uncommon, and we ourselves are often unaware that the species around us are typical examples of "borderline cases." In Central Asia, the house sparrow lives together with another closely related species - the black-breasted sparrow, from which it differs well in color. There is no hybridization between them in this region. Their systematic status as distinct species would not be in doubt if there were no second zone of contact in Europe. Italy is inhabited by a special form of sparrows, which arose as a result of the hybridization of brownie and Spanish. At the same time, in Spain, where house and Spanish sparrows also live together, hybrids are rare.

Biology. General biology. Grade 11. Basic level Sivoglazov Vladislav Ivanovich

5. Type: criteria and structure

5. Type: criteria and structure

Remember!

What levels of wildlife organization do you know?

What is a view?

What other systematic categories do you know?

At the heart of the evolutionary theory of Ch. Darwin lies the idea of ​​a species. What is a species and how real is its existence in nature?

The first idea of ​​a species was created by Aristotle, who defined a species as a collection of similar individuals. The very term "species" in Latin means "image". This word accurately defines the main criterion used by researchers until the 19th century. when determining the species affiliation of any organism. The famous scientist K. Linnaeus, who created the doctrine of the species, believed that the species consists of many similar individuals that give fertile offspring.

In modern biology view called a set of individuals with similar morphological and physiological characteristics, capable of interbreeding with the formation of fertile offspring, inhabiting a certain area (habitat), having a common origin and similar behavior.

A biological species is not only the main taxonomic unit in biological taxonomy. This is an integral structure of living nature, which is reproductively isolated from other similar structures and has its own destiny. The integrity of this system is given, firstly, by the processes of interaction between individual individuals. The relationship between organisms of different generations, between parents and children, males and females, features of territorial behavior - all this determines the internal structure of the species. Species traits do not always ensure the survival of an individual, but they are always favorable for the species as a whole. For example, a bee that has lost its sting will die, but at the same time it will protect the rest of the individuals.

The second reason for maintaining the unity and integrity of the species is reproductive isolation, i.e., the impossibility of interbreeding with individuals of another species. This is how protection works species gene pool(the totality of genes of the species) from the influx of alien genetic information. There are various factors preventing interspecific crossbreeding. For example, two closely related pine species grow in California. In one of them, pollen spills out in early February, and in the other in April, so there is seasonal isolation between these species. In higher animals, mating behavior has characteristic species features; therefore, females of one species do not respond to the courtship of males of another closely related species - this is an example of behavioral isolation (Fig. 12).

The presence of reproductive isolation in natural conditions is a decisive factor in defining a species as a genetically closed biological system.

Characteristic features and properties that distinguish some species from others are called species criteria.

View criteria. There are several basic criteria for the type.

Morphological criterion is the similarity of the external and internal structure of organisms. For a long time this criterion was the main, and sometimes the only one. With its help, individuals of non-related species are easily identified. Even a small child can distinguish between a cat and a mouse, any adult can distinguish between a mouse and a rat, but only a specialist can distinguish between a brownie and a small mouse. There are special determinants that are based on the morphological features of the organization. However, within a species, there is always structural variability between different individuals, so it can sometimes be quite difficult to determine the species of a particular individual.

genetic criterion. Sometimes, among very similar individuals, groups are found that do not interbreed with each other. These are the so-called twin species, which are found in almost all large systematic groups and differ from each other in the number of chromosomes. For example, among insects, there are two widespread species of ichneumons, which until recently were considered as a single species (Fig. 13).

Rice. 12. Different types of mating behavior of two closely related species of gulls

Rice. 13. Species-twins. Parasitic insects (A, B) with different karyotypes (C): 2n = 10 and 2n = 14

Each species has a certain set of chromosomes - a karyotype, which differs in the number of chromosomes, their shape, size, and structure. A different number of chromosomes in the karyotype of different species and species differences in genomes provide genetic isolation during interspecific crossing, because they cause the death of gametes, zygotes, embryos or lead to the birth of sterile offspring (hinny is a hybrid of a horse and a donkey). It is the use of the genetic criterion that makes it possible to reliably distinguish twin species.

Physiological criterion reflects the similarity of all vital processes in individuals of the same species: the same methods of nutrition, reproduction, similar reactions to external stimuli, the same biological rhythms (periods of hibernation or migration). For example, in two closely related species of the Drosophila fruit fly, sexual activity is observed at different times of the day: in one species, in the morning, in the other, in the evening.

Biochemical criterion is determined by the similarity or difference in the structure of proteins, the chemical composition of cells and tissues. For example, certain types of lower fungi differ from each other in their ability to synthesize various biologically active substances.

Environmental criterion characterized by certain forms of relationships between organisms of a given species with representatives of other species and factors of inanimate nature, i.e., by the conditions in which this species occurs in nature. In Texas, related species of oak grow on different soils: one species is found only on limestone soil, another on sandy soil, and the third grows on igneous rock outcrops.

Geographic criterion defines the scope, i.e. range, kind. Different species have very different range sizes. Species that occupy vast areas and are found everywhere are called cosmopolitans, but those who live in small areas and are not found in other places, - endemic.

Thus, to determine the species affiliation of an organism, it is necessary to use all the criteria in the aggregate, because individual criteria may coincide in different species.

view structure. In reality, in nature, individuals of any species within the range are unevenly distributed: somewhere they form clusters, and somewhere they may be completely absent. Such partially or completely isolated groupings of individuals of the same species are called populations (from Latin populus - people, population), i.e., in natural conditions, any species consists of a set of populations.

population- this is a collection of individuals of the same species, for a sufficiently long time (a large number of generations) inhabiting a certain territory within the range of the species, freely interbreeding with each other and partially or completely isolated from individuals of other similar populations.

It is the population that is elementary unit of evolution.

Review questions and assignments

1. Define the concept of "view".

2. Tell us what biological mechanisms prevent the exchange of genes between species.

3. What is the reason for the infertility of interspecific hybrids? Explain this phenomenon using your knowledge of the mechanism of meiosis.

4. What criteria do scientists use to characterize a species? What criteria do you consider the most important in determining the species?

5. What is the species range?

6. Describe the type of domestic cat according to the main criteria.

7. Define the term "population".

Think! Execute!

1. Why can one species be distinguished from another only by a combination of various criteria? What criteria do you think are the most important?

2. Do you know examples when the formulation “a species as a genetically closed system” turned out to be incorrect? (Remember the selection material from the 10th grade course.)

3. Do your research. Find out which species in your area are endemic and which are cosmopolitan. Prepare a report on the work done in the form of a stand.

4. In your opinion, can the words "population" and "popular" be considered the same root? Explain your point of view.

5. Provide evidence showing that species objectively exist in nature.

Work with computer

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

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Structure of sleep Night sleep consists of several cycles, each of which lasts about an hour and a half and includes two qualitatively different stages, which are called "non-REM sleep" and "REM sleep". The stages of fast and slow sleep are not only in humans, but also

From the book Human Genetics with the Basics of General Genetics [Tutorial] author Kurchanov Nikolai Anatolievich

Criteria of Truth After evaluating all the possible and available initial data for further reflection, we finally come to the question of "how it works" - how life is created and functions. And, accordingly, they approached the need to put forward theories that

From the book Secrets of Sex [Man and Woman in the Mirror of Evolution] author Butovskaya Marina Lvovna

3.3. Chromosome Structure Each chromatid contains one DNA molecule associated with histone proteins and non-histone proteins. Currently, the nucleosome model of eukaryotic chromatin organization is accepted (Kornberg R., 1974; Olins A., Olins D., 1974). According to this model, histone proteins (they

From the book Biological Chemistry author Lelevich Vladimir Valeryanovich

Chapter 4. Criteria of gender in humans The tradition of dominance of men over women outside the home (primarily in social life and politics) laid down by ancient Greek culture significantly influenced the development of scientific ideas about

From the author's book

Chapter 9 The Knight and the Fair Lady: Criteria for Male and Female Attractiveness Visual Attractiveness: The Multiple Fitness Model Empirical evidence suggests that natural selection can influence social perceptions

- species, m. (scientific). 1. Subordinate Concept, which is part of another, higher concept - the genus (philosophical). The concept of a tree in relation to the generic concept of a plant is a species .........
Explanatory Dictionary of Ushakov

Morphological- morphological, morphological (scientific). App., by value associated with morphology. Morphological observations. composition of the Russian language.
Explanatory Dictionary of Ushakov

To the View Adverb.- 1. By appearance, by appearance, by external signs; outwardly, apparently.
Explanatory Dictionary of Efremova

Morphological Analysis— A forecasting method based on the construction of a matrix of characteristics of the forecasting object and their possible values, followed by enumeration and evaluation of options for combining these values.
Political vocabulary

Analysis Morphological- a method of analyzing all possible ratios of the components of the system under study. A.m. requires a strict classification of objects and parameters of system objects.
Economic dictionary

Type of Audits — -
category of audits; distinguish between: 1) mandatory verification in cases of expressly established
legislation, including
order of the state ........
Economic dictionary

Type of Accounting Statements- - types of financial statements, among which are annual, quarterly and monthly.
Economic dictionary

Kind of activity— General
classification adopted to describe activities in the insurance industry. Most types of insurance are usually classified into two main
........
Economic dictionary

Type of activity of the Accounts Chamber- - counting
the chamber carries out control and revision, expert-analytical, informational and other activities, provides a unified system of control over ........
Economic dictionary

Kind of Control- - composite
part of the current control system, which has its inherent
content, designed to carry out the control function in accordance with ........
Economic dictionary

Kind of forest fire— - classification
unit characterizing forest
fires by objects of distribution (grassroots, riding, underground) and speed (fluent, stable, strong, medium, weak).
Economic dictionary

Type of forest management— - classification
unit characterizing
use of certain products, useful properties and functions of forests (
harvesting wood, resin, ........
Economic dictionary

Type of Mineral Raw Materials, Excisable- - varieties of mineral raw materials subject to excise taxes. Excisable types of mineral raw materials are:
oil, including gas condensate; natural gas.
Economic dictionary

Residence — - 1)
a document issued to foreign citizens or stateless persons for
the right to reside in this state; 2) in pre-revolutionary Russia - a document issued in the stipulated ........
Economic dictionary

Type of main activity- - activity,
whose gross value added exceeds the gross value added
the value of any other activity carried out within the same economic unit.
Economic dictionary

Type of Fixed Assets — -
a group of fixed assets formed according to certain natural-material characteristics. Typical
classification subdivides
fixed assets for
building,........
Economic dictionary

Type of Swimming Maritime shipping is divided into small coastal shipping, large coastal shipping, and overseas navigation. Small cabotage - sailing between the ports of one or two adjacent basins, without crossing ........
Economic dictionary

Duty Type, Special— - type of customs
duties, which can be temporarily applied in order to protect the economic interests of the Russian Federation to imported goods. K O.v.p. duties include: special:........
Economic dictionary

Idle Type- - a form of classification of downtime, such as: 1) downtime due to untimely provision of shops with purchased materials, raw materials, components; 2) downtime due to ........
Economic dictionary

Type of Reverse Mortgage Agreement— The landlord under this agreement takes
loan under
the value of the house, retains its
rights to the house, does not make any payments and at the same time lives in the house.........
Economic dictionary

Insurance type— A. Insurance of homogeneous objects against the dangers characteristic and known to them. B. Similar and frequently repeated insurance contracts.
Economic dictionary

Type of technical condition— level of technical condition
object of insurance, corresponding or not corresponding
requirements for technical documentation.
Economic dictionary

Type of accounting registers- - type, type of accounting
register. Distinguished by appearance
books, cards and free
sheets (sheets), including in the form of machinograms received by ........
Economic dictionary

Type of Damage — -
loss classification form, such as: 1)
losses from
defects due to non-compliance of materials and purchased components and semi-finished products with specifications and ........
Economic dictionary

Type of Securities- - distinguish between the following
types of securities: government
bond, bond,
promissory note, deposit check,
savings certificates, banking
savings........
Economic dictionary

Instruction, Type of Exchange Order Without Responsibility— An order to buy or sell securities at market quotations. The NH instruction means that the client has given the floor broker the right to accept ........
Economic dictionary

Licensed Type of Activity — -
a type of activity for the implementation of which in the territory of the Russian Federation a license is required in accordance with this Federal Law or ........
Economic dictionary

Special Kind of Embeds— Mortgages, the monthly payment of which consists of principal and interest; however, during the initial period, part of the payments is made by a third party, ........
Economic dictionary