What is biological progress and regression? What are their main features? To find answers to these questions, let's analyze these biological terms in more detail.

Features of development in biology

A. N. Severtsov argued that it is possible to achieve transformations and the emergence of new adaptations in a variety of ways. He characterized biological progress and regression, gave definitions to these terms.

Characteristics of biological progress

It assumes the victory of another taxonomic group or a certain species in a fierce struggle for existence. Biological progress has certain signs:

• increase in the number of individuals;
• range expansion;
• increase in the number of child taxonomic forms.

The above features are interrelated. With an increase in the number of individuals, the boundaries of the range of a given species expand, new territories are populated by its representatives, as a result of which new species, subspecies, and populations are formed. In our time, birds, many mammals, insects are precisely in a state of biological progress.

The concept of regress

The main characteristic of biological regression is that this process is the opposite of progress. It also has certain distinctive characteristics that should be mentioned separately:

• a decrease in the number of individuals as a result of the excess of the mortality rate over the birth rate;
• decreased diversity within a species;
• a decrease in the boundaries and integrity of the range, it breaks up into several separate spots;
• due to the insignificant number of individuals, they undergo catastrophic elimination, which can provoke the destruction of the entire group.

Paths of biological progress

The characterization of biological progress and regression would be incomplete without indicating the possible paths of evolutionary change. A. N. Severtsov noted that there are several options for changing the state of a species or genus. If, in his opinion, biological regression has only one variant of existence, then progress is represented in various ways: degeneration, idioadaptation, aromorphosis.

biological evolution

For a long time the problem of evolutionary processes in biology was studied by I. I. Shmalgauzen. It was he who identified the main options for biological progress:

• hypermorphosis;
• allomorphosis;
• aromorphosis;
• hypomorphosis;
• catamorphosis;
• telomorphosis.

Biological regression has no such directions. Aromorphosis is such a path of evolution, which is accompanied by an increase in the level of vital activity, involves the expansion of the habitat of the genus. Arogenesis is characterized by:

• strengthening activities;
• increased differentiation;
• body integration;
• manifestation of active variants of the struggle for existence;
• improvement of the sense organs and the nervous system.

As a result of aromorphosis, changes occur that contribute to the rise of the organization, that is, there is not a biological regression, but development (progress). The species has a chance to move to new conditions of existence. As an example of arogenesis, we can cite a four-chambered heart, the appearance of a live birth, a constant body temperature, two circles of blood circulation, breastfeeding with milk of newborn cubs. Biological regression has no such possibilities. It was through aromorphoses that classes and types appeared, and large taxa developed. A. N. Severtsov said that it is aromorphosis that presupposes the complication of a species, its possibility for subsequent self-improvement. What does biological regression lead to? Examples in history indicate that its result is the complete extinction of a species, genus.

Allogenesis involves the formation of specific adaptations during changes in living conditions. In this case, the progression of the organism does not imply the complication of the whole species, and a general increase in energy is not required. Allogenesis leads to species diversity, a significant increase in numbers. For example, mammals have managed to master various habitat conditions; they can be found both in the Arctic deserts and in the tropics. In addition, their representatives mastered different environments (soil, water, land), which led to a decrease in competition between representatives of different species for habitats and food. But there was no biological regression. The examples given above, on the contrary, testify to a stable level of organization of living organisms. Thanks to idioadaptation, new genera, species, orders, families appear, and taxa of low rank arise.

Telogenesis is recognized as a narrow specialization, adaptation to specific conditions of existence, which does not imply a serious change in the level of organization. For example, chameleons, turtles, sloths are endowed with additional adaptations to living conditions.

Conclusion

According to the theory proposed by A. N. Severtsov, the main factor for increasing the organization of living organisms is private adaptations, which can be accompanied by simplification, that is, degeneration. Thanks to the same arogeneses, various “superstructures” can appear, which give the species the opportunity to survive and develop in particular conditions. Biological regression and progress are those main methods of biological development that allow a particular order, genus to survive, develop, improve, or lead to its complete death and disappearance.

The idea of ​​the directional character of evolution following the path of progress, i.e. along the path of improving organisms from simple to complex, from lower to higher forms of life, is generally accepted. However, one should not think that progress is the only way of evolutionary changes; in fact, it is only one of the possible directions of evolution.

Modern ideas about the directions of evolution are based on the works of Russian biologists A.N. Severtsov and I.I. Schmalhausen and the American paleontologist J.G. Simpson. A.N. Severtsov singled out the concepts of biological progress and regression.

Biological progress means the victory of a species or other systematic group in the struggle for existence. Signs of biological progress are an increase in the number of individuals of a given systematic group, the expansion of its range and the breakdown into subordinate systematic groups. All three signs of biological progress are related to each other. An increase in the number of individuals forces a species (or any other systematic group) to expand the boundaries of its range, populate new habitats, which leads to the formation of new populations, subspecies, and species.

Biological progress is opposed by biological regression. It is characterized by opposite signs: a decrease in the number of individuals, a narrowing of the range, a gradual or rapid decrease in the population and species diversity of the group. Biological regression can lead a species to extinction. The general cause of biological regression is the lag in the rate of evolution of the group from the rate of changes in the external environment. The rapid change in the environment caused by human activities leads to an increase in the number of species that go into a state of biological regression and are doomed to extinction (if an environment acceptable to them is not preserved).

The driving forces of evolution operate continuously, resulting in improved adaptations. However, under the influence of human economic activity, the habitat of living beings changes much faster than adaptations are formed. This leads to a reduction in numbers, narrowing of ranges and the threat of extinction of a number of species. The unprecedented speed of man's attack on nature leads to such rapid changes in the environment that species that were in a state of biological progress a few decades ago, not keeping up with the changes, undergo biological regression. Thus, the plowing of the steppes leads to a sharp decrease in the number of virgin species: ground squirrels, marmots, steppe pikas, cranes, steppe eagles. The minimum chances of survival are large mammals (especially predators), represented by a small number of individuals that live in a small area, breed slowly and do not put up with the human neighborhood. Such, for example, are the tiger, cheetah, leopard, leopard, polar bear. On the contrary, small fertile animals, widespread and easily coexisting with humans, achieve biological progress. Of the mammals, they primarily include a typical urban animal - the pasyuk rat, from birds - a crow, from insects - a red cockroach.

Paleontology has proven that many species that existed in the past have disappeared completely.

Progress and regress in nature are opposite concepts. In the first case, the development and spread of species around the planet occurs. Biological regression is an evolutionary movement characterized by a reduction in habitat, a decrease in the number of individuals due to incapacity. This process is accompanied by a decrease in the number of some group species due to pressure on them by others, as well as the disappearance of the species.

Biological regression is mainly associated with the loss of the ability of organisms to adapt to changing environmental conditions.

For animals that remain immobile throughout their lives, the organ of movement functions exclusively during the larval stage. Their notochord is reduced. Such organisms, in particular, include pogonophora - a representative of a separate type of brachiata. These individuals are not very similar to animals. They live on the sea floor and live motionless. Pogonophora has a heart and a brain, however, her stomach and mouth are reduced. The tentacles are the respiratory organs. Inside they have long hairs supplied with blood vessels. Microorganisms gradually accumulate on them. When there are a lot of them (microorganisms), the pogonophora draws the hairs inward. Under the influence of special enzymes, the smallest organisms are digested and absorbed into the internal outgrowths. The presence of a rudimentary intestine proves the existence of this organ in the ancestors of the Pogonophora. But due to the fact that the process of digestion is carried out outside the body, the organs of the gastrointestinal tract were reduced.

The regression of animals living underground or in caves can be seen in the example of Proteus. This is a representative of the amphibian class, similar to a newt. This animal lives in caves. It has external gills on both sides of its head. Proteus can breathe both in water and on land. In the first case, he uses the gills, and in the second, the lungs. Since the proteus lives in deep-sea caves, it has a serpentine shape. His body is transparent, colorless, has no pigments. Adult representatives are covered with skin, larvae have rudimentary eyes. There are also two pairs of underdeveloped limbs on the body of the proteus.

Mutation is the genetic basis of evolutionary changes leading to a simplification of the organizational level.

There are three directions in the development of the organic world. Aromorphosis characterizes an increase in the level of organization of organisms. Idioadaptation is an adaptation to environmental conditions without fundamental changes in the biological structure. General degeneration is a simplification of the level of organization of living beings.

The directions of evolution described above characterize the phenomenon biological progress.

The increase in organization (aromorphoses) and the divergence of interests (idioadaptation), as the main ways of evolution, exclude organisms from excessive competition, reduce it, and at the same time increase their resistance to eliminating factors. As a rule, these directions of evolution are accompanied by selection for a wide modification adaptability, i.e., for the development of a wide "adaptive fund". Therefore, aromorphoses and allomorphoses (as well as other paths of evolution) entail biological progress.

The main signs of biological progress are:

1. The increase in numbers.
2. Saturation of the species population with diverse mixobiotypes (controlled by selection).
3. Expansion of the area (range) of distribution.
4. Differentiation into local races (ecological and geographical).
5. Further divergence, emergence of new species, genera, families, etc.

Of course, if idioadaptations are of a more special nature, remaining adaptations of a very narrow telomorphic meaning, then the possibilities for expanding the range are limited. However, even in this case, the path of ecological differentiation is not closed, and if the station is extensive (for example, a large tract of forest), then the further expansion of the range to the limits of the station.

Let's look at two examples of biological progress.

2. Pasyuk (Rattus norvegicus) penetrates European Russia in the 18th century. It appeared in Germany (Prussia) around 1750, in England - since 1730, in Paris after 1753, in Switzerland after 1780, in Ireland since 1837. In the middle of the 19th century, there was no pasyuk in Western Siberia . In 1887, Pasyuk occasionally met near Tyumen. In 1897 met in the southern part of the Tobolsk province and was common in Orenburg and throughout the Urals, from Uralsk to Orsk. According to Kashenko, pasyuk appeared in the Orenburg Territory after the construction of the railway. In 1889, there was no pasyuk up to the eastern borders of the Tomsk province. However, in Eastern Siberia, its variety has long existed - the Trans-Baikal pasyuk. Consequently, at the end of the 19th century, around the time of the opening of the Siberian Railway. etc., Western Siberia was free from pasyuk. Movement along the named railway. The village was opened in 1896-97, and on May 29, 1907 (after the Japanese war), the first pasyuk specimen was caught in Omsk. In 1908, Kashchenko received a large number of West Siberian pasyuks, and in 1910 pasyuks "began to play the role of a real disaster." Moving east, the European pasyuks eventually occupied the whole of Western Siberia (except for the extreme north) and met with the Transbaikal variety.

“In the middle of the largest of the continents ... the iron ring formed by the Pasyuk around the globe finally closed, and I, writes Kashchenko (1912), had to be present at this last act of his victorious march.”

Highly active, variable and adaptable in its behavior to different climatic zones, Pasyuk everywhere where there is water, food and people, vigorously expands its range.

An example of a biotically progressive plant species is the Canadian plague (Elodea canadensis), which rapidly invades new habitats.

These are the main features of species that are in a state of biological progress. The expansion of the range, the capture of new habitats is their most important feature, which gives access to intraspecific differentiation and to the formation of new forms due to it.

An excellent illustration of what has been said can be provided by the biologically progressive development of the hare (Folitarek, 1939). Rusak is adapted to open places, with less deep or more dense snow cover. Therefore, it could not spread to the north, into the forest zone with looser, and therefore deeper snow. However, as the forest was cut down, the conditions of the snow cover changed (it became smaller and denser), and the hare began to quickly spread to the north. Interestingly, during the years of numerical growth, the pace of advancement to the north also increased. Having penetrated to the north, the hare formed here a new ecological form - somewhat larger, with winter wool, which turned whiter significantly compared to its winter color in the south. There was a selection (and possibly adaptive modification) for size (the greater the body weight, the higher the heat production with a lower return due to the relatively smaller surface) and selection for whitening, under which the hare is less noticeable to the predator (fox). Thus, the new environmental conditions that caused an increase in numbers opened up the possibility of expanding the range, and the expansion of the range caused the formation of a new form.

biological regression characterized by the opposite:

• a decrease in the number
• narrowing and splitting of the range into separate spots,
• weak or even absent intraspecific differentiation,
• the extinction of forms, species, entire groups of the latter, genera, families, orders, etc.

As a rule, the "adaptive fund" of species undergoing biological regression is narrower than that of forms experiencing biological progress.

As a result of these features, biologically regressive species can become endemic, with a very limited or even point range, examples of which we have already given.

Such biologically regressive species include (partly under human influence) the European beaver, muskrat, European bison, New Zealand tuatara, and many other forms. Among the plants, one can point to the already mentioned Ginkgo biloba, which has survived only in some places in East Asia, while in the Mesozoic (especially in the Jurassic) Ginkgoes were widespread.

The reduction in numbers and narrowing of the range leads the species to a state of biological tragedy, since under these conditions the impact of indiscriminate forms of elimination puts the species at risk of complete extermination. If the reduction in numbers and the narrowing of the range reaches such proportions that the latter is concentrated on a small area, then a single or repeated catastrophic elimination will cut off its existence.

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biological regression- this is an evolutionary movement in which there is a reduction in habitat; decrease in the number of individuals due to inability to adapt to the environment; decrease in the number of species groups due to the pressure of other species, the extinction of the species. The science of paleontology has proven that many species have completely disappeared in the past. If, with biological progress, some species develop and spread widely throughout the globe, then with biological regression, species disappear, unable to adapt to environmental conditions.

Causes of biological regression: the disappearance of the ability of organisms to adapt to changes in environmental conditions.

Biological regression is subject to:

2. Animals leading an immobile lifestyle.

3. Animals living underground or in caves.

2. Examples of degeneration in organisms leading an immobile lifestyle.

In animals leading an immobile lifestyle, the organ of movement acts only during the period of the larval stage, the notochord is reduced. For example, the only representative of a separate type of brachiata - pogonophora - lives at the bottom of the sea, leads a motionless lifestyle. In 1949, the zoologist A.V. Ivanov first found her in the Sea of ​​Okhotsk at a depth of 4 km, she got into the net along with the fish. The elongated worm-like body of the animal is covered with a cylindrical tube. In the front of the body there are tentacles that periodically come out of the tube to the outside for breathing. The body consists of three sections, in the anterior section there are tentacles (in some species there are up to 200-250), a brain, a heart, and excretory organs. The second section is larger, the third is very long. In the inner part of the departments there are respiratory organs, in the outer part there are outgrowths attached to the tube (Fig. 34).

Rice. 34. Pogonophora: 1-tentacles; 2- head; 3-first section of the body; 4-second section of the body; 5-third department of the body; 6-sensitive hairs; 7-back of the body

The pogonophora has a brain and a heart, but the mouth and stomach are reduced, and the tentacles are the respiratory organs. Because of their sedentary lifestyle, they do not look like animals. In the inner part of the tentacles there are long thin hairs that are supplied with blood vessels. In water, the hairs come out of the tube, and microorganisms attach to them. When there are a lot of them, pogonophores pull the hairs inward. Under the influence of enzymes, small organisms are digested and absorbed by internal outgrowths.

The rudimentary intestine in the pogonophora embryo proves the presence of digestive organs in the ancestors. Due to the passage of the process of digestion outside the body, the digestive organs of pogonophores were reduced.

The structure of the ascidian is also simplified in the process of evolution due to the immobile lifestyle. Ascidia belongs to one of the branches of the chordate type - tunicates living in the sea (Fig. 35).

Rice. 35. Ascidia

The sac-like body of the ascidian is covered with a shell, with the sole it is attached to the bottom of the sea and leads a motionless lifestyle. In the upper part of the body there are two holes, through the first hole water passes into the stomach, and from the second - out. Respiratory organs - gill slits. It reproduces by laying eggs. Eggs develop into mobile, tadpole-like larvae with signs of a notochord. In the adult state, the ascidian is attached to the bottom of the sea, the body is simplified. The sea squirt is thought to be a highly degraded chordate.

3. Examples of degeneration of animals living underground or in caves.

In the caves of the former Yugoslavia and Southern Austria, a proteus from the class
amphibians, similar to a newt (Fig. 36).

Rice. 36. Proteus

In addition to the lungs on both sides of the head, it has external gills. In water, proteas breathe with gills; on land, they breathe with lungs. Inhabitants of waters and deep caves, they are serpentine, transparent, colorless, without pigments. In adults, the skin covers the eyes, and the larvae have rudimentary eyes. Thus, the ancestors of ascidians had eyes, and they led a terrestrial lifestyle. In cave organisms, the organs of vision, pigments disappeared, and activity decreased.

In flowering plants that have passed into the aquatic environment, leaf blades have become narrow, filamentous, conductive tissues have ceased to develop. The stomata have disappeared, only the flowers have not changed (water buttercup, duckweed, hornwort).

The genetic basis of evolutionary changes leading to a simplification of the level of organization is mutation. For example, if the remaining underdeveloped organs - rudiments, albinism (lack of pigments) and other mutations - do not disappear in the process of evolution, then they are found in all members of a given population.

Thus, there are three directions in the evolution of the organic world. Aromorphosis- increasing the level of organization of living organisms; idioadaptation- adaptation of living organisms to environmental conditions without a fundamental restructuring of their biological organization; degeneration- simplification of the level of organization of living organisms, leading to biological regression.

The relationship between the directions of biological evolution. The relationship between aromorphosis, idioadaptation and degeneration in the evolution of the organic world is not the same. Aromorphosis occurs less frequently than idioadaptation, but it marks a new stage in the development of the organic world. Aromorphosis leads to the emergence of new highly organized systematic groups that occupy a different habitat and adapt to the conditions of existence. Even evolution follows the path of idioadaptation, and sometimes degeneration, which provide organisms with the habitation of a new habitat for them.

biological regression

biological regression- decrease in the number of species, narrowing of the range, decrease in the level of adaptability to environmental conditions.

1. What is the difference between biological regression and biological progress?

2. How many pathways does degeneration have?

3. Give examples of degeneration in animals.

4. What are examples of degeneration in plants?

How do you explain the reasons for the disappearance of the root and leaves of the dodder?

What and how dodder eat? Does it form organic matter?

1. Explain the reasons for the transformation of broomrape leaves into scales.

2. Analyze examples of degeneration of pogonophores leading an immobile lifestyle.

3. How is food digested in pogonophores if they do not have a digestive organ?

4. What organisms do you know that lead a stationary lifestyle? Describe them.

Where does proteus live? Explain with examples of degeneration. Give examples of degeneration in plants living in an aquatic environment. Write a short essay on aromorphosis, idioadaptation, degeneration.