Subsequently, Severtsov (1922) identified biological, morphological and physiological progress in the progressive development of the organic world.

Thus, the problem of progress was posed as a complex problem, a comprehensive solution of which is possible only by synthesizing data from a number of biological disciplines. He showed that in the development of the organism as a whole, different types of progress can be combined, proceeding in parallel and interconnected. He assigned the leading role in evolution to biological progress, which determines victory in the struggle for existence. In this case, biological progress can be accompanied by morphological and physiological regression. In all the works mentioned above, Severtsov touched upon the problem of progress in passing. His first special summary on this issue appeared in 1925 in the form of a small book, which was republished in a significantly expanded form in 1934. It contained the doctrine of the main directions of evolution.

The teachings of A. N. Severtsov were included in the textbooks of Darwinism. It is enough to recall only its main provisions. In accordance with Darwin's theory of speciation, biological progress, according to Severtsov, occurs sequentially through the formation of first new races, then varieties and, finally, new species. Several types of morphological changes lead to victory in the struggle for existence: aromorphoses, idioadaptations, cenogenesis and general degeneration. With aromorphosis, the overall vital energy of adult offspring increases. This is achieved by differentiation and complication of the functions of organs and a corresponding change in their structure.

The latter is expressed in histological changes, in changes in the size and shape of organs, in the differentiation of organs and in an increase in their number, as well as in the distribution and location of repeating organs and their concentration. Examples of aromorphosis include the evolution of the vertebrate heart, the transformation of limbs from swimming to crawling during the transformation of crossopterygia in terrestrial vertebrates. The examples of aromorphosis given by Severtsov represent changes in the structure of individual organs. How do these changes affect the body as a whole? According to Severtsov, the combination of progressive changes in some parts with the static position of others leads to the rise of the entire organization. In cases where the progress of some parts is combined with the regression of others, the direction of changes in the organization can be judged by a comparison of progressive and regressive signs.

(after: Severtsov, 1939). Aromorphoses (a) are shown as a rise to a higher level (planes II and III); idioadaptations (6) - in the form of deviations within a given plane; specializations - S; the regression is marked by the letters g as a descent to the underlying plane (I).

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Sections: Biology

Goals:

• to form in students knowledge about the main paths and directions of the evolutionary process;
• to develop the ability to correctly compare different directions and paths of evolution, to illustrate the story about them with various examples from the world of plants and animals;
• systematize and generalize knowledge about the process and main results of the historical development of the organic world.

Tasks:

• use examples to show the origin of large systematic groups through aromorphosis;
• consider examples of idioadaptation, degeneration and the relationship between the main paths of evolution;
• introduce the main directions of evolution - biological progress and biological regression;
• characterize the role of humans in biological progress and regression of species.

LESSON STRUCTURE:

I. Learning new material

The idea of ​​the directed nature of evolution, following the path of progress, that is, along the path of improving organisms from simple to complex, from lower forms of life to higher ones, is generally accepted. However, one should not think that progress is the only path of evolutionary change; in fact, it is only one of the possible directions.

Modern ideas about the directions of evolution are based on the works of Ivan Ivanovich Shmalhausen and Alexei Nikolaevich Severtsov. A.N. Severtsov identified the concepts of biological progress, biological stabilization and biological regression.

1. Biological progress

Biological progress is characterized by an increase in the number of individuals of a systematic group, an increase in the number of species, subspecies, and populations included in it, and an expansion of the range. Species in a state of biological progress emerge victorious in the struggle for existence.

Biological progress is characteristic of angiosperms, insects, birds and mammals.

In accordance with the various transformations of the structure of organisms in the process of evolution, there are three ways to achieve biological progress:

• Aromorphoses – arogenesis(morphophysiological progress);
• Idioadaptation – allogenesis;
• General degeneration – catagenesis(morphophysiological regression).

Arogenesis- an evolutionary direction, accompanied by the acquisition of major structural changes - aromorphoses.
Aromorphosis means the complication of organization. Raising it to a higher level. Changes in the structure of animals as a result of the occurrence of aromorphoses are not adaptations to any environmental conditions, but provide an opportunity to expand the use of environmental conditions (new food sources, habitats). An example of aromorphosis in mammals is the division of the heart into left and right halves with the development of two circulation circles. Differentiation of the digestive organs, complication of the dental system, and the appearance of warm-bloodedness reduces the body’s dependence on the environment.

Aromorphoses played an important role in the evolution of all classes of animals: the tracheal respiratory system and the transformation of the oral apparatus in insects, the formation of chitinous cover and the dismemberment of limbs, the development of a complex nervous system, as well as sensory organs - smell, vision, touch. The appearance of speech is a major aromorphosis in human evolution. In the plant world, major aromorphoses are the appearance of organs and tissues, photosynthesis, the appearance of flowers, fruits, and seed reproduction in angiosperms.

The further evolution of angiosperms followed the path idioadaptations, that is, along the path of the emergence of various adaptations to different living conditions.
Idioadaptations have led to the appearance of plants with different flowers, fruits, shoots, leaves, root systems, development periods, adaptations to pollination by wind, water, and insects.
Idioadaptations are a path of evolution in which some adaptations are replaced by others that are biologically equivalent to them.
Idioadaptations, unlike aromorphoses, are of a private nature.
A good example of idioadaptation is protective coloration in animals, various adaptations to cross-pollination by wind and insects, adaptations of fruits and seeds to dispersal, adaptation to a benthic lifestyle (flattening of the body) in many fish.

2. Biological stabilization

Biological stabilization according to A.N. Severtsov means maintaining the fitness of the organism at a certain level. The body changes according to changes in environmental conditions. Its numbers are not increasing, but they are not decreasing either.
In plants, when the average annual temperature decreases, the number of covering hairs of the epidermis increases. This phenomenon allows all individuals to survive, but there is no advantage between other species, since they show the same reaction.

3. Biological regression

Biological regression– direction of evolution, which is characterized by a decrease in the number of species, subspecies and populations, a reduction in the number of individuals and range.
Biological regression means a decrease in the fitness of the organism.
The organism lags behind changes in the external environment, and especially the pace of evolution and spread of ecologically similar forms.
The population of the species is decreasing and the species is heading towards extinction. Biological regression can also affect biologically highly organized forms that flourished in their time, but which turned out to be unadapted to new or changing living conditions (extinct dinosaurs, mammoths).

Cause of biological regression often is human activity. Humans influence species directly, by destroying them, or indirectly, by changing their habitat. Thus, at the beginning of the 17th century, wild aura bulls (the ancestors of modern bulls) were exterminated. In the second half of the 18th century, the marine mammals Steller's cows were completely destroyed. By the beginning of the 19th century, hunters had completely exterminated the large flightless moa birds in New Zealand, whose height reached three meters.
The end result of regression is the extinction of the species.

Laboratory work

Topic: “Aromorphoses in vertebrates”

Target: develop the ability to identify aromorphoses in animals and explain their meaning.

Progress:

1. Consider the diagrams of the structure of hearts and remember the features of the circulatory system of representatives of the class of vertebrates: fish, amphibians, reptiles, birds, mammals.

Fill the table:

2. Remember what the intensity of metabolism and the ability to maintain a constant body temperature, which depends on it, is characteristic of representatives of classes of vertebrate animals.

Fill the table:

3. Consider the diagrams of the structure of the respiratory systems and remember the breathing features of representatives of the class of vertebrates.

Fill the table:

4. Remember the features of fertilization and development of offspring in representatives of the classes of vertebrates.
Fill the table:

5. Analyze the tables. Draw a conclusion: what major aromorphoses contributed to the emergence of amphibians, reptiles, birds, and mammals. Reveal the evolutionary significance of aromorphoses.

II. Conclusions from the lesson:

• The doctrine of the directions of evolution was developed by A.N. Severtsov and I.I. Shmalgauzen;
• Directions of evolution – biological progress and biological regression;
• Biological progress is achieved through aromorphoses, idioadaptations and degeneration;
• The causes of regeneration may be human activity.

Homework:§ 52; finish laboratory work

Literature:

1. Handbook for biology teachers. Authors and compilers: Kalinova G.S. Kuchmenko V.S. Moscow - AST Astrel, 2003.
2. Sivoglazov V.I., Sukhova T.S., Kozlova T.A."General Biology". Lesson plans 11th grade. Teacher's manual. M.Iris-Press, 2004.
3. Virtual School of Cyril and Methodius General biology 11th grade, 2007.

The increase in the degree of adaptation of organisms to the environment during evolution was often accompanied by the improvement and complication of their organization, called progress in living nature. In 1825 A.N. Severtsov (1866-1936) proposed to distinguish between biological progress and morphophysiological progress.

The genetic basis of biological and morphophysiological progress is hereditary variability. Canalized transformation of the gene pool (biological progress) or genotype (morpho-physiological progress) occurs under the influence of natural selection.

Biological progress is the result of the success of a group of organisms (population, species, genus, family, order, etc.) in the struggle for existence. The criteria (indicators) of biological progress are considered: a) an increase in the degree of general adaptability of a group of organisms to environmental conditions;

b) an increase in the number of individuals in the group;

c) expansion of the area (habitat area) occupied by individuals of the group;

d) intensive speciation in this group;

e) the presence in this group of a large number of subordinate groups (populations, species, genera, families, etc.). Currently, insects, bony fish, birds, mammals, and angiosperms are in a state of biological progress.

Biological regression characterizes, accordingly, a decrease in the adaptability of a group of organisms to their environment.

Its criteria are: a) a decrease in the degree of general adaptability of a group of organisms to environmental conditions;

b) reduction in the number of individuals in the group;

c) narrowing of the area occupied by individuals of this group;

d) extinction of species of this systematic group (genus, family, order, etc.);

e) the presence in this group of a small number of subordinate groups (species, populations).

The concepts of “morphophysiological progress” and “morphophysiological regression” are applicable to characterize not only groups, but also individual organisms. Morphophysiological progress (aromorphosis) characterizes the improvement in the course of evolution of the structure and function of the body (morphophysiological organization). Aromorphosis includes the following evolutionary changes:

Major changes in the structure of organisms (for example, the development of a four-chambered heart and cerebral hemispheres in mammals);

The emergence of general adaptations (devices) (for example, warm-bloodedness, terrestrial locomotion);

Dismemberment of organs (for example, the division of muscle layers of worms into separate bundles in arthropods);

Complication and intensification of functions (for example, intensification of the function of supplying tissues with nutrients and oxygen with complete separation of the systemic and pulmonary circulation);

General increase in the intensity of vital activity of organisms;

Increasing the overall level of energy metabolism;

Reducing the body’s dependence on living conditions;

Increasing the degree of influence of the organism on the environment.

"Morphophysiological progress is most characteristic of those groups that lead an active lifestyle, for example, vertebrates and arthropods. Morphophysiological progress allows the body to achieve a higher level of independence from the external environment. Such complication of organization requires the body to increase energy costs and, in connection with this, increase the forces of action of organisms on the surrounding world. Later, a number of scientists proposed other criteria.

ries of morphophysiological progress: improving the integration of living systems (Shmalhausen I.I., 1938), increasing the level of homeostasis of living systems (Huxley J., 1942), increasing the volume of information and methods of processing it. Evolutionary transformations leading to morphophysiological progress, A.N. Severtsov called them arogenesis.

"General biology. 11th grade." V.B. Zakharov and others (GD)

Ways to achieve biological progress (main directions of progressive evolution)

Question 1. What is biological progress?
Biological progress is characterized by: an increase in the general level of organization, an increase in the number of individuals, an increase in the number of subspecies, and an expansion of the range.

Question 3. Which direction of biological evolution raises a group of organisms to a higher level of organization?
Arogenesis- the direction of progressive biological evolution, accompanied by an increase in the general level of organization of organisms - morphophysiological progress due to the acquisition of aromorphoses. Aromorphosis (morphophysiological progress) is an evolutionary transformation of the structure and functions of an organism that increases the general level of its organization, but does not have adaptive significance to environmental conditions.

Question 4. Give examples of aromorphoses.
The most significant aromorphoses were the emergence of photosynthesis, the emergence of multicellular organisms and sexual reproduction. Among the major aromorphoses one can also name the development of homeothermy (maintaining a constant body temperature) in birds and mammals, the occurrence of viviparity and feeding of young with milk in mammals, the transition to reproduction by seeds in seed plants, etc. Aromorphoses have broad adaptive significance and provide ample opportunities for the development of a new habitat. Thus, the appearance of eggs in egg shells in reptiles allowed them to live far from water and colonize even arid places, while their ancestors, amphibians, had to go into the water at least for the breeding season.
Thanks to the acquisition of aromorphoses, new large systematic groups arise - types, classes, orders, etc., thus macroevolution occurs.

Question 5. What is idioadaptation?
Idioadaptation is the partial adaptation of organisms to a certain way of life in specific environmental conditions. Unlike aromorphosis, idioadaptation does not significantly affect the general level of organization of a given biological group. Due to the formation of various idioadaptations, animals of closely related species can live in a wide variety of geographical areas. For example, representatives of the wolf family (Canidae) can be found throughout the territory from the Arctic to the Tropics, which significantly reduces competition between them. Idioadaptation provided this family with a significant expansion of its range and an increase in the number of species, which is a criterion of biological progress. But at the same time, not a single species that is part of this family can be said to be at a higher level of evolution than the others. Examples of idioadaptations include different types of beaks in birds or different adaptations for pollination and seed dispersal in plants. As a result of idioadaptations, small systematic groups arise.

Severtsov, on the basis of the extensive embryological material he had accumulated, came to the conviction that the repetition of the characteristics of ancestors in ontogenesis occurs quite naturally, therefore the embryological method can be widely used for phylogenetic constructions. However, quite often palingenetic signs are absent, and this is not due to the influence of cenogenesis.

Severtsov called phylembryogenesis changes acquired during embryonic development, persisting into adulthood and inherited by descendants.

Anabolia is the formation of a new trait in the later stages of development. Before its occurrence, the organ develops like its ancestor. Recapitulations and the manifestation of biogenetic law take place.

Deviation is associated with the formation of new characteristics in the middle of development. Recapitulation goes only up to a certain point, and then begins to develop along a new path.

Archallaxis alters development at the very beginning. Already in the early stages, the organ begins to develop differently.

The theory of phylembryogenesis shows that embryological studies can be most fully used to solve questions of phylogeny only when anabolism occurs.

Question 4. Aromorphoses in the evolution of invertebrates and vertebrates. Idioadaptation, cenogenesis, morphophysiological progress and regression. The main aromorphoses of the immune system in the evolution of the Chordata type.

Cenogeneh(from the Greek kainós - new and ... genesis), an adaptation of the body that occurs at the stage of the embryo (fruit) or larva and is not preserved in the adult. Examples of c. are the mammalian placenta, which provides the fetus with breathing, nutrition, and excretion; external gills of amphibian larvae; egg tooth in birds, used by chicks to break through the egg shell; organs of attachment in ascidian larvae, swimming tail in trematode larvae - cercariae, etc. The term “C.” introduced in 1866 by E. Haeckel to designate those characteristics that, while disrupting the manifestations of palingenesis, i.e., repetitions of distant stages of phylogenesis in the process of embryonic development of an individual, do not allow us to trace the sequence of stages of the phylogenesis of their ancestors during the ontogenesis of modern forms, i.e., they violate biogenetic law. At the end of the 19th century. Any change in the course of ontogenesis characteristic of the ancestors began to be called color (German scientists E. Mehnert, F. Keibel, and others). Modern understanding of the term “C.” was formed as a result of the work of A. N. Severtsov, who retained for this concept only the meaning of provisional devices, or embryo-adaptations.

IdioadaptAtion(from the Greek ídios - own, peculiar, special and adaptation), one of the main directions of evolution, in which partial changes in the structure and functions of organs occur while generally maintaining the level of organization of ancestral forms. The term was introduced by A. N. Severtsov.

Morphophysiological progress is one of the main directions of biological progress of living beings; the same as aromorphosis. Changes in the structure of the body and the general energy of life, which underlie the evolution of life forms.

Biological regression – decreasing numbers, narrow range. If a species undergoes regression, then it is on the verge of extinction. Reduced adaptability of organisms to the environment.