What are the classifications of adaptations. An example of the adaptation of people and animals in the outside world

Ways of origin of adaptations. By origin, pre-adaptive, combinative and post-adaptive adaptations are distinguished. In the case of pre-adaptation, potential adaptation phenomena arise ahead of existing conditions. The mutation process and crossings lead to the accumulation of a latent (mobilization) reserve of hereditary variability in populations. Part of it can be used in the future to create new devices (S.M. Gershenzon).

One example of the transformation of individual mutations that previously existed in a latent form in the gene pool into adaptation was described above in relation to the phenomenon of industrial melanism (see Chapter 10).

In the pre-adaptive way of the emergence of adaptations, the former features of the organism that have arisen under different conditions are often successfully used. At the same time, some complex adaptations can arise, as if “aheading” the conditions under which these features turn out to be adaptations. For example, the presence of sutures in the mammalian skull facilitates childbirth, although their occurrence has not been associated with live birth.

When adaptations occur in a combinative way, the interaction of new mutations with each other and with the genotype as a whole is essential. The effect of mutations depends on the genotypic environment into which they will enter in the future. Crossing individuals produces a varied combination of the mutant allele with other alleles of the same and other genes. This leads to a change in the effect of manifestation of the mutation through the interaction of genes. In this case, there may be either an increase (compliment) or suppression (epistasis) of its expression in the phenotype; in addition, usually a mutant allele under the influence of many genes manifests itself in a graduated manner (polymerism). In all cases, a real opportunity is created for a quick change from one adaptation to another. The combinative way of formation of adaptations is apparently the most common in nature.

The post-adaptive pathway for the emergence of adaptations is associated with the reduction of a previously developed trait and the transfer of the genes that determine its implementation to a recessive state (or the use of a pre-existing organ for other purposes - not those that determined its appearance through the appropriate selection pressure). When genes that affect the development of reducible organs are transferred to a recessive state (which is very likely), they are included in the hidden reserve of hereditary variability. These genes are preserved in the gene pool of populations and from time to time may appear phenotypically (for example, atavisms, see Chapter 6). If selection establishes a positive relationship between such genes and new environmental conditions, they can give rise to the development of new characters and properties.

In the post-adaptive path, new adaptations arise through the use of pre-existing structures in the event of a change in their functions (see Chapter 16). Thus, the visceral skeleton in the ancestors of vertebrates consisted of gill arches, represented by undivided rings and covering the anterior end of the digestive tube. They served as a spacer for the digestive tube, preventing it from falling. However, in the course of further evolution, with an increase in the function of respiration, gill arches become part of the fluid injection system. In further evolution, the gill arches take on the functions of grasping and turn into jaws.

When classifying adaptations from several positions, any adaptation viewed simultaneously in the light of various approaches is characterized quite definitely and clearly (Table 11.1).

Table 11.1. Classification of adaptations (according to N.V. Timofeev-Resovsky et al., 1969)
Principle of classification	Adaptation group
Origin	Arising in pre-adaptive, combinative and post-adaptive ways
By belonging to a different environment	Genotypic (ontogenetic), population-specific, biocenotic
On an evolutionary scale	Specialized and General
By the nature of the changes	Simplifying the structure of the system, complicating the structure, preserving the structure of systems and the level of complexity
According to the duration of preservation in ontogeny	Short-term, recurring and permanent

Obtaining such a clear and definite characterization of adaptation may seem to be of purely theoretical significance. But, as we have repeatedly emphasized, the evolutionary theory in the foreseeable future should become the basis for the conscious existence of mankind in the biosphere, the basis for directed alteration and consideration of the possible consequences of human intervention in planetary processes. And at the same time, the problem of the emergence, formation, transformation of the adaptation of living organisms acquires an immeasurably greater significance than that which it now has in the "biological" branches of the economy (agriculture, microbiology, trade, etc.).

From an evolutionary point of view, it is important not to simply describe many different adaptations, but to classify them according to their origin, belonging to different aspects of the environment, and scale. Ways of origin of adaptations. By origin, pre-adaptive, combinative and post-adaptive adaptations are distinguished. In the case of pre-adaptation, potential adaptive phenomena arise ahead of existing conditions. The mutation process and crossings lead to the accumulation of a hidden (mobilization) reserve of hereditary variability in populations. Part of it in the future can be used to create new devices (S.M. Gershenzon). One example of the transformation of individual mutations that previously existed in a latent form in the gene pool into adaptation was described above in relation to the phenomenon of industrial melanism (see Chapter Yu). With the pre-adaptive way of the emergence of adaptations, the former features of the organism that arose under different conditions are often successfully used. At the same time, some complex adaptations can arise, as if “aheading” the conditions under which these features turn out to be adaptations. For example, the presence of sutures in the mammalian skull facilitates childbirth, although their occurrence has not been associated with live birth. When adaptations occur in a combinative way, the interaction of new mutations with each other and with the genotype as a whole is essential. The effect of mutations depends on the genotypic environment into which they will enter in the future. Crossing individuals produces a varied combination of the mutant allele with other alleles of the same and other genes. This leads to a change in the effect of manifestation of the mutation through the interaction of genes. In this case, there may be either an increase (compliment) or suppression (epistasis) of its expression in the phenotype; in addition, usually the mutant allele under the action of many genes manifests itself in a graduated manner (polymerism). In all cases, a real opportunity is created for a quick change from one adaptation to another. The combinative way of formation of adaptations is apparently the most common in nature. The post-active pathway for the emergence of adaptations is associated with the reduction of a previously developed trait and the transfer of the genes that determine its implementation to a recessive state (or the use of a pre-existing organ for other purposes - not those that determined its appearance through appropriate selection pressure). When genes that affect the development of reduced organs are transferred to a recessive state (which is very likely), they are included in the hidden reserve of hereditary variability. These genes are preserved in the gene pool of populations and from time to time may appear phenotypically (for example, atavisms, see Chapter 6). If selection establishes a positive relationship between such genes and new environmental conditions, they can give rise to the development of new traits and properties. With the post-adaptive path, new adaptations arise through the use of pre-existing structures in the event of a change in their functions (see Chapter 16). Thus, the visceral skeleton in the ancestors of vertebrates consisted of gill arches, represented by undivided rings and covering the anterior end of the digestive tube. They served as a spacer for the digestive tube, preventing it from falling. However, in the course of further evolution, with an increase in the respiratory function, the gill arches become part of the fluid injection system. In further evolution, the gill arches take on the functions of grasping and turn into jaws. When classifying adaptations from several positions, any adaptation viewed simultaneously in the light of various approaches is characterized quite definitely and clearly (Table 11.1). Obtaining such a clear and definite characterization of adaptation may seem to be of purely theoretical significance. Ho, as we have repeatedly emphasized, the evolutionary theory in the foreseeable future should become the basis for the conscious existence of mankind in the biosphere, the basis for directed alteration and consideration of the possible consequences of human intervention in planetary processes. And at the same time, the problem of the emergence, formation, transformation of the adaptation of living organisms acquires an immeasurably greater significance than that which it now has in the "biological" sectors of the economy (agriculture, microbiology, commercial economy, etc.). .). adaptations in different environments. By belonging to the aspects, the environment of adaptation is different. Any result of natural selection is associated with one or another change in the biotic environment, which, in accordance with the levels of organization of the living (see Chapter 4), can be divided into genotypic, ontogenetic, population-specific and biocenotic . Subdivisions of the environment also differ in specific adaptations. Table 11.1. Classification of adaptations (according to N.V. Timofeev-Resovsky et al., 1969) The genotypic environment is characterized by the integrity of the genotype of an individual and the interaction of genes with each other. The integrity of the genotype determines the features of gene dominance and the development of coadaptations. At the molecular level, we encounter a fine adaptive organization of the structure and interaction of molecules that ensure the efficient reproduction and self-construction of biopolymers. The question arises: do all structural features of biopolymers turn out to be adaptive? From the point of view of genetic coding, it is clear that not all, since there is a phenomenon of degeneracy of the genetic code (see further Chapter 20, Section I). However, should we recognize behind the phenomena at the molecular level of the organization of life only the functions of genetic coding? Do we know too little to confidently speak about the absence of other functions in codons, say UCU and UCC, encoding the same serine amino acid? At the cellular level of research, we find numerous organelles with a complex structure and many functions that determine the smooth metabolism of the cell and its functioning as a whole. Adaptations at the level of an individual are associated with ontogenesis - processes of realization of hereditary information ordered in time and space, hereditary implementation of morphogenesis. Here, as, indeed, at other levels, we encounter co-adaptations - mutual adaptations. For example, the scapula and pelvic bone are movably articulated with the head of the humerus and femur. Bones that are movably attached to each other have mutual adaptations to ensure normal operation. Coadaptation is based on various correlations that regulate ontogenetic differentiation. At the ontogenetic level, complex adaptations of a physiological and biochemical nature are diverse. Under conditions of elevated temperature and lack of water, the normalization of plant life is achieved by the accumulation of osmotically active substances in the cells and the closure of stomata. The damaging effect of salts on highly saline soils can be neutralized to some extent by the accumulation of specific proteins, increased synthesis of organic acids, etc. The population-specific environment is manifested in the interaction of individuals within populations and the species as a whole. The population environment corresponds to supraorganismal, population-species adaptations. Population-species adaptations include, for example, the sexual process, heterozygosity, the mobilization reserve of hereditary variability, a certain density of populations, etc. To denote a number of special intraspecific adaptations, there is the term “congruence” (S.A . Severtsov). Congruences are mutual adaptations of individuals resulting from intraspecific relationships. They are expressed in the conformity of the structure and function of the organs of the mother and the offspring, the reproductive apparatus of males and females, the presence of devices for finding individuals of the opposite sex, the signaling system and the division of labor between individuals in herds, colonies, families, etc. e. The methods of interaction of species in biogeocenoses are extremely diverse. Plants influence each other through changes not only in the conditions of illumination and humidity, but also by releasing special active substances that contribute to the displacement of some and the reproduction of other species (allelopathy). It is practically difficult to strictly distinguish between genotypic, ontogenetic, population and biocenotic adaptations. Adaptations related to one of the environments "work" on other environments; all adaptations are subject to the principle of multi-functionality (see Chapter 16). This is understandable, since different evolutionary environments (genotypic, population and biogeocenotic) are closely and inextricably linked: individuals exist only in populations, populations inhabit specific cenoses. The species composition of the biocenosis, determining the nature of interspecific relationships, affects both the genotypic and the population environment. The action of natural selection on populations leads to changes in the biocenotic environment, changing the nature of interspecific relations. Scale of adaptations. According to the scale of adaptation, they are divided into specialized, suitable for narrowly local conditions of life of the species (for example, the structure of the language of anteaters in connection with feeding on ants, adaptations of a chameleon to an arboreal lifestyle, etc.), and general, suitable for a wide range of environmental conditions and character -nye for large taxa. The latter group includes, for example, major changes in the circulatory, respiratory and nervous systems in vertebrates, the mechanisms of photosynthesis and aerobic respiration, seed reproduction and gametophyte reduction in higher plants, ensuring their penetration into new adaptive zones. Initially, general adaptations arise as specialized ones; they will be able to lead certain species to the path of wide adaptive radiation, to the path of arogenesis (see Chap. 15). Promising general adaptations usually affect not one, but many organ systems. There are other approaches to the classification of adaptations. So, according to the nature of changes, adaptations are associated with the complication or simplification of the morphophysiological organization. For example, parasitism usually leads to the simplification and reduction of a number of organs. At the same time, the transition to an active lifestyle is associated with the development and differentiation of a number of important attack and defense organs. Adaptations associated with the development of a social, social way of life in higher invertebrates and vertebrates are more complex acquisitions than adaptations of microorganisms and plants. Like differences in evolutionary scale, adaptations can also differ in ontogenetic scale (the duration of preservation in ontogeny). Some adaptations in ontogenesis are of short-term significance, while others persist for a longer period. Some are limited to the embryonic stages of development (see Chap. 14), others are of a repetitive nature (seasonal changes in color in animals and plants, various modifications, etc.), others are of constant importance in the life of an individual (the structure of vital systems and organs). The study of adaptations that differ in their confinement to different stages of ontogenesis is important for understanding the evolution of ontogenesis 11.4.

Fitness is determined by many indicators: viability (survival), competitiveness, fertility, participation in reproduction, care for offspring, etc. Fitness can only be assessed for comparable groups of organisms, under certain conditions, at certain stages of the life cycle, at certain intervals of time. A variety of traits that increase the fitness of organisms are called adaptation. There are many classifications of adaptations:

1. According to the level of manifestation

– biochemical- the structure of proteins, carbohydrates, lipids and other chemical components of organisms changes;

– physiological and biochemical- the nature of metabolism changes;

– anatomical and morphological- the internal and external structure of organisms changes; anatomical and morphological features are conditionally divided into qualitative (for example, coat color) and quantitative (for example, limb length);

– physiological and reproductive- fertility, the timing of the beginning and end of the reproductive period, the timing of reproduction change;

– ontogenetic- the nature of individual development changes;

– ethological change in the behavior of organisms.

2. By the influence of the genotype of an individual on the formation of adaptations

– genetic(high dependence of the phenotype on the genotype of the individual);

– environmental(high dependence of the phenotype on the environment);

– environmental genetic(the phenotype depends on both the genotype and the environment).

3. According to the interaction of groups of organisms

– individual, or organismal adaptations - each organism is adapted independently of other organisms; for example, the protective coloration of many insects depends only on the color of the background on which they are located, but does not depend on the color of other butterflies;

– intraspecific, or group adaptations - a trait is adaptive only if certain traits are present in other individuals of this species; intraspecific adaptations ensure reproduction, care for offspring, the possibility of joint obtaining food, building a dwelling, experiencing adverse conditions; a special group of intraspecific adaptations are congruences- correspondence of the copulatory organs of males and females, mutual adaptations of the mother and the cub to feeding with milk;

4. By the influence of gender and age characteristics

– genital- characteristic of a certain sex, lead to the emergence of sexual dimorphism; for example, the bright attracting (recognizing) coloring of males and the protective coloring of females in many birds;

– age– characteristic only for certain stages of ontogeny; for example, the external and internal gills of tadpoles, which are lost during metamorphosis.

5. Animals distinguish active and passive adaptations. Active adaptations are associated with behavioral responses. Passive adaptations are associated with the appearance of various protective structures (shells, shells, spikes, spines, scales, horny shields, feathers, wool).

Changing the shape of the body can serve to disguise- imitation of the shape of an inedible object.

6. In a separate group of adaptations are allocated various types of coloring. The effect of the action of coloration is usually associated with some morphological adaptations (body shape) and behavioral responses, for example, with the adoption of a certain posture: either mimetic (imitative) or frightening.

a). patronizing (cryptic) coloring; set of features that provide disguise(color features, body shape and posture features) are called mimeticism. Both prey and predator species (mantises, chameleons) need camouflage.

– solid – corresponds to the background color in the habitat;

- dismembering - the appearance of spots, stripes, false (distracting) eyes.

b). Attractive, or recognition- serves to recognize individuals of a certain species. Usually serves to recognize members of the opposite sex of a given species during the breeding season. Sometimes provides recognition of commensals, for example, predatory fish must distinguish harmless cleaners from possible imitators.

in). repellent- the presence of bright spots, false (frightening) eyes; frightening coloration is usually combined with a protective one, for example, in many night butterflies, the front wings have a protective color, and the hind wings are frightening; in 1957, the zoologist Blest experimentally proved that circles have the maximum deterrent effect.

G). Cautionary -

- mimetic, or false warning - unprotected mimic species imitate protected model species (Batsian mimicry);

In 1862, the English naturalist Henry Walter Bats (Bates) spent eleven years studying animals in the river basin. Amazons, found that butterflies from the heliconid and itomid families, which are inedible for birds, imitate the appearance and manner of flight of edible butterflies - whites and others; the caterpillars of the danaids, feeding on poisonous plants of the gossamer family, are imitated by the caterpillars of the swallowtails and nymphalids. Bats was the first to come to the conclusion that the imitator species, due to the deviation from the appearance of its kindred forms, acquires the best opportunities for survival. Often mimicry is inherent only in females, for example, female sailboats, nymphalids and whites; at the same time, females of the same species of sailboats imitate different types of danaids (female polymorphism). When crossing sailboats, a wide variety of morphs of these butterflies were obtained, which indicates a polygenic control of imitative color, therefore, a high degree of similarity between the imitator and the model is achieved by accumulating small changes.

- actually warning - in protected species (inedible, stinging ...); the effect of warning coloration is enhanced by Mullerian mimicry, i.e. the external similarity of protected species. [In 1878, the German zoologist Fritz Müller, also studying butterflies in Brazil, noticed that two unrelated, inedible species could be very similar to each other. As a result, a whole "cautionary community" is formed.]

Since adaptation is a complex and diverse phenomenon, in biological science there are several dozen classifications of adaptations, which are based on a variety of characteristics.

Adaptations are also divided into organismal and species. Organismal adaptations, in turn, are divided into morphological, physiological, biochemical and ethological.

Morphological adaptations are manifested in the advantages of the structure, protective coloration, warning coloration, mimicry, disguise, and adaptive behavior.

The advantages of the structure are the optimal proportions of the body, the location and density of the hair or feather cover, etc. The appearance of an aquatic mammal - a dolphin - is well known. His movements are light and precise. Independent speed in water reaches 40 kilometers per hour. The density of water is 800 times that of air. How does the dolphin manage to overcome it? In addition to other structural features, the ideal adaptability of the dolphin to the environment and lifestyle is facilitated by the shape of the body. The torpedo-like shape of the body avoids the formation of eddies of water flows around the dolphin.

The streamlined shape of the body contributes to the rapid movement of animals in the air. Flight and contour feathers covering the bird's body completely smooth its shape. Birds are deprived of protruding auricles, in flight they usually retract their legs. As a result, birds are far superior to all other animals in terms of speed of movement. For example, the peregrine falcon dives on its prey at speeds up to 290 kilometers per hour. Birds move quickly even in water. An Antarctic penguin was observed swimming underwater at a speed of about 35 kilometers per hour.

In animals that lead a secretive, lurking lifestyle, adaptations are useful that give them a resemblance to environmental objects. The bizarre body shape of fish living in thickets of algae (rag-picker seahorse, clown fish, sea needle, etc.) helps them successfully hide from enemies. Resemblance to objects of the environment is widespread in insects. Beetles are known, their appearance resembling lichens, cicadas, similar to the thorns of those shrubs among which they live. Stick insects look like a small brown or green twig, while orthopterous insects imitate a leaf. A flat body has fish leading a benthic lifestyle (for example, flounder).

Protective coloring allows you to be invisible among the surrounding background. Thanks to the protective coloration, the organism becomes difficult to distinguish and, therefore, protected from predators. Bird eggs laid on sand or on the ground are gray and brown with spots, similar to the color of the surrounding soil. In cases where eggs are not available to predators, they are usually devoid of coloration. Butterfly caterpillars are often green, the color of the leaves, or dark, the color of the bark or earth. Bottom fish are usually painted to match the color of the sandy bottom (stingrays and flounders). At the same time, flounders also have the ability to change color depending on the color of the surrounding background. The ability to change color by redistributing the pigment in the integument of the body is also known in terrestrial animals (chameleon). Desert animals, as a rule, have a yellow-brown or sandy-yellow color. Monochromatic protective coloration is characteristic of both insects (locusts) and small lizards, as well as large ungulates (antelopes) and predators (lion).

If the background of the environment does not remain constant depending on the season, many animals change color. For example, inhabitants of middle and high latitudes (arctic fox, hare, ermine, ptarmigan) are white in winter, which makes them invisible in the snow.

A variant of protective coloration is a dissecting coloration in the form of alternating light and dark stripes and spots on the body. Zebras and tigers are hard to see already at a distance of 40-50 meters due to the coincidence of the stripes on the body with the alternation of light and shadow in the surrounding area. Dissecting coloring violates ideas about the contours of the body.

Warning (threatening) coloring warns a potential enemy about the presence of protective mechanisms (the presence of toxic substances or special protection organs). Warning coloring distinguishes from the environment with bright spots or stripes of poisonous, stinging animals and insects (snakes, wasps, bumblebees).

The effectiveness of warning coloration caused a very interesting phenomenon - imitation (mimicry). Mimicry is the similarity in color, body shape of harmless animals with poisonous and dangerous animals. Certain types of flies that do not have a sting are similar to stinging bumblebees and wasps, non-poisonous snakes are poisonous. In all cases, the similarity is purely external and is aimed at forming a certain visual impression in potential enemies. Two main types of mimicry are now known: Batesian mimicry and Mullerian mimicry.

In Batesian mimicry, the model is well protected and usually has a bright, warning coloration. With Muller's mimicry, two or more inedible species turn out to be similar: as a result of their similarity, the predator is more likely to wean itself from grabbing such animals. The first type of mimicry can be compared to a small firm imitating the advertisement of some well-known large firm. The second type is comparable to several firms that use general advertising to save money. An example of Bates's mimicry: defenseless flies often hide under the guise of wasps, imitating wasps with a body shape and yellow-black color (a sirfid fly and a big-headed fly). An example of Muller's mimicry: some species of cabbage white butterflies look like inedible South American heliconids.

Mimicry is the result of homologous (same) mutations in different species that help unprotected animals survive. For mimic species, it is important that their numbers be small compared to the model they imitate, otherwise the enemies will not develop a stable negative reflex to warning coloration. The low number of mimic species is supported by a high concentration of lethal genes in the gene pool. In the homozygous state, these genes cause lethal mutations, as a result of which a high percentage of individuals do not survive to adulthood.

In addition to protective coloration, other means of protection are observed in animals and plants. Plants often form needles and spines that protect them from being eaten by herbivores (cacti, wild rose, hawthorn, sea buckthorn, etc.). The same role is played by poisonous substances that burn hairs, for example, in nettles. Calcium oxalate crystals that accumulate in the thorns of some plants protect them from being eaten by caterpillars, snails and even rodents. Formations in the form of a hard chitinous cover in arthropods (beetles, crabs), shells in mollusks, scales in crocodiles, shells in armadillos and turtles protect them well from many enemies. The quills of the hedgehog and porcupine serve the same. All these devices could appear only as a result of natural selection, i.e. preferential survival is better than protected individuals.

Camouflage - adaptations in which the shape of the body and color of animals merge with surrounding objects. For example, in tropical forests, many snakes are indistinguishable among vines, a shaggy seahorse looks like algae, insects on tree bark look like lichens (beetles, barbels, spiders, butterflies). Sometimes adaptation to the color and pattern of the substrate can be carried out by a physiological change in body color (cuttlefish, rays, flounders, tree frogs) or a change in color during the next molt (grasshoppers).

The protective effect of a protective color or body shape is enhanced when combined with the appropriate behavior. Adaptive behavior - the adoption of certain resting postures (caterpillars of some insects in a stationary state are very similar to a tree knot; a callima butterfly with folded wings surprisingly resembles a dry leaf of a tree), or, conversely, demonstrative behavior that scares away predators. In addition to hiding or demonstrative, frightening behavior when an enemy approaches, there are many other options for adaptive behavior that ensures the survival of adults or juveniles. This includes storing food for the unfavorable season of the year. This is especially true for rodents. For example, the housekeeper vole, common in the taiga zone, collects grains of cereals, dry grass, roots - up to 10 kilograms in total. Burrowing rodents (mole rats, etc.) accumulate pieces of oak roots, acorns, potatoes, steppe peas - up to 14 kilograms. A large gerbil living in the deserts of Central Asia cuts grass at the beginning of summer and drags it into holes or leaves it on the surface in the form of piles. This food is used in the second half of summer, autumn and winter. The river beaver collects stumps of trees, branches, etc., which he puts into the water near his dwelling. These warehouses can reach a volume of 20 cubic meters. Feed stocks are also made by predatory animals. Mink and some ferrets store frogs, snakes, small animals, etc. An example of adaptive behavior is the time of greatest activity. In the deserts, many animals come out to hunt at night when the heat subsides.

Physiological adaptations - the acquisition of specific features of metabolism in different environmental conditions. They provide functional benefits to the body. They are conditionally divided into static (constant physiological parameters - temperature, water-salt balance, sugar concentration, etc.) and dynamic (adaptation to fluctuations in the action of the factor - changes in temperature, humidity, illumination, magnetic field, etc.).

The appropriate shape and color of the body, expedient behavior ensure success in the struggle for existence only when these signs are combined with the adaptability of life processes to living conditions, i.e. with physiological adaptation. Without such adaptation, it is impossible to maintain a stable metabolism in the body in constantly fluctuating environmental conditions. Let's give some examples.

Plants living in semi-desert and desert regions have numerous and varied adaptations. This is a root that goes tens of meters deep into the earth, extracting water, and a sharp decrease in water evaporation due to the special structure of the cuticle on the leaves, and the complete loss of leaves. In cacti, this transformation is especially surprising: the transformation of the stem not only into an organ that performs supporting and conducting functions, but also into a structure that stores water and ensures photosynthesis. Large specimens of cacti accumulate up to 2000 liters of water. It is consumed slowly, since the cell sap contains, along with organic acids and sugars, also mucous substances that have water-retaining properties. Prickly pear stems, even after a three-month drought, contained almost 81% water. Evaporation of water is significantly reduced due to the ribbed structure of the stems of cacti, which evenly distributes light and shadow. This is also facilitated by the thickening of the walls of the epidermis, usually covered with a layer of wax, the presence of numerous spines and hairs, and much more.

In terrestrial amphibians, a large amount of water is lost through the skin. However, many of their species penetrate even into deserts and semi-deserts. The survival of amphibians in conditions of lack of moisture in these habitats is provided by a number of adaptations. They change the nature of activity: it is timed to periods of high humidity. In the temperate zone, toads and frogs are active at night and after rainfall. In deserts, frogs hunt only at night, when moisture condenses on the soil and vegetation, and during the day they hide in rodent burrows. In desert amphibian species that breed in temporary reservoirs, the larvae develop very quickly and undergo metamorphosis in a short time.

Various mechanisms of physiological adaptation to adverse conditions have been developed by birds and mammals. Many desert animals accumulate a lot of fat before the onset of the dry season: when it is oxidized, a large amount of water is formed. Birds and mammals are able to regulate water loss from the surface of the respiratory tract. For example, a camel, when deprived of water, drastically reduces evaporation both from the respiratory tract and through the sweat glands.

A person's salt metabolism is poorly regulated, and therefore he cannot do without fresh water for a long time. But reptiles and birds, who spend most of their lives in the sea and drink sea water, have acquired special glands that allow them to quickly get rid of excess salts.

The adaptations that develop in diving animals are very interesting. Many of them can do without oxygen for a relatively long time. For example, seals dive to a depth of 100-200 and even 600 meters and stay under water for 40-60 minutes. What allows pinnipeds to dive for such a long time? This is, first of all, a large amount of a special pigment found in the muscles - myoglobin. Myoglobin is able to bind 10 times more oxygen than hemoglobin. In addition, a number of devices in the water provide a much more economical use of oxygen than when breathing on the surface.

Through natural selection, adaptations arise and improve to facilitate the search for food or a partner for reproduction. The chemical organs of insects are amazingly sensitive. Male gypsy moths are attracted by the smell of the scent gland of a female from a distance of 3 kilometers. In some butterflies, the sensitivity of taste receptors is 1000 times greater than the sensitivity of human tongue receptors. Nocturnal predators such as owls have excellent vision in low light conditions. Some snakes have a well-developed ability to thermolocation. They distinguish objects at a distance if the difference in their temperatures is only 0.2 ° C. Many animals are perfectly oriented in space with the help of echolocation (bats, owls, dolphins).

Biochemical adaptations ensure the optimal course of biochemical reactions in the cell, for example, the ordering of enzymatic catalysis, the specific binding of gases by respiratory pigments, the synthesis of the necessary substances under certain conditions, etc.

Ethological adaptations are all behavioral responses aimed at the survival of individuals and, therefore, the species as a whole. These reactions are:

behavior when searching for food and a sexual partner,

pairing,

rearing offspring,

avoiding danger and protecting life in the event of a threat,

aggression and threatening postures,

innocence and many others.

Some behavioral responses are inherited (instincts), others are acquired during life (conditioned reflexes). In different organisms, the ratio of instinctive and conditioned reflex behavior is not the same. For example, in invertebrates and lower chordates, instinctive behavior prevails, while in higher mammals (primates, carnivores), conditioned reflex behavior prevails. A person has the highest level of behavioral adaptability based on the mechanisms of higher nervous activity.

Of particular importance are devices that protect offspring from enemies.

Species adaptations are found in the analysis of a group of individuals of the same species, in their manifestation they are very diverse. The main ones are different congruences, mutability level, intraspecific polymorphism, abundance level and optimal population density.

Congruences are all morphophysiological and behavioral features that contribute to the existence of a species as an integral system. Reproductive congruences ensure reproduction. Some of them are directly related to reproduction (correspondence of the genital organs, feeding adaptations, etc.), while others are only indirectly (various signal signs: visual - wedding attire, ritual behavior; sound - birdsong, the roar of a male deer during the rut and others; chemical - various attractants, for example, insect pheromones, secretions from artiodactyls, cats, dogs, etc.).

Congruences include all forms of intraspecific cooperation - constitutional, trophic and reproductive. Constitutional cooperation is expressed in the coordinated actions of organisms in adverse conditions, which increase the chances of survival. In winter, the bees gather in a ball, and the heat they give off is spent on co-warming. In this case, the highest temperature will be in the center of the ball and individuals from the periphery (where it is colder) will constantly strive there. Thus, there is a constant movement of insects and together they will safely overwinter. Penguins also huddle together in a close group during incubation, sheep in cold weather, etc.

Trophic cooperation is the association of organisms for the purpose of obtaining food. Joint activity in this direction makes the process more productive. For example, a pack of wolves hunts much more efficiently than a single individual. At the same time, many species have a division of duties - some individuals separate the chosen victim from the main herd and drive it into an ambush, where their relatives hid, etc. In plants, such cooperation is expressed in the joint shading of the soil, which contributes to the retention of moisture in it.

Reproductive cooperation increases the success of reproduction and promotes the survival of offspring. In many birds, individuals gather on leks, and in such conditions it is easier to search for a potential partner. The same thing happens in spawning grounds, pinniped rookeries, etc. The probability of pollination in plants increases when they grow in groups and the distance between individual individuals is small.

Mutability - represents the frequency of occurrence of mutations per unit of time (number of generations) and per gene. Each species has its own frequency, which is determined by the level of stability of the genetic material and resistance to mutagens. Mutations make populations heteromorphic and provide material for selection. Both excessively high and insufficient mutability are dangerous for the species. In the first case, there is a threat to the integrity of the species, and in the second case, selection cannot be carried out.

Intraspecific polymorphism determines the unique combination of alleles in different individuals. The cause of polymorphism is sexual reproduction, which provides combinative variability, and mutations that change the substrate of heredity. Maintaining intraspecific polymorphism ensures the stability of the species and guarantees its existence in various environmental conditions.

The abundance level determines the extreme values of the number of individuals of a species. A decrease in abundance below the threshold level leads to the death of the species. This is due to the impossibility of meeting partners, disruption of intraspecific adaptation, etc. An excessive increase in numbers is also detrimental, since it undermines the food supply, contributes to the accumulation of sick and weakened individuals in the population, and in some this leads to the development of stress.

The optimal population density shows specific features of the coexistence of individuals for each species. Many organisms prefer a solitary lifestyle and meet only for mating. This is how, for example, tigers, leopards, male elephants, etc. behave. Others have a strong collectivity instinct, so they need a large number. For example, the most numerous groups among vertebrates were American passenger pigeons, whose flocks numbered billions (!) of individuals. After their numbers were undermined by humans, passenger pigeons stopped breeding and the species disappeared.

Adaptation is achieved by changing a number of biological characteristics: biochemical, physiological, morphological and behavioral. All these are ways of adapting the body to the requirements of the environment.

Adaptation can be a genetically determined process that occurs in response to the demands of natural selection, or a phenotypic response of an individual that occurs during its life in response to some environmental factors.

In a broad sense, adaptation refers to the harmony of organisms with the environment.

In a narrow sense, adaptation refers to special properties that can ensure the survival and reproduction of organisms in a particular environment.

Adaptation to one environmental factor does not necessarily remain an adaptation to other conditions.

The appearance in the population and biogeocenosis of a new successful phenotype or individuals - carriers of successful mutations - cannot yet be considered as an adaptation. The appearance of a selectively valuable genotype is an elementary adaptive phenomenon. We can talk about adaptation only after the emergence of a specialized trait in a population (species) to the elements of the environment. This is achieved when the elementary adaptive phenomenon is “picked up” by selection and a persistent change in the genotypic composition of the population is achieved. Adaptations do not appear in finished form, but are formed in the process of multi-stage selection of successful options from many changed individuals in a series of generations.

In an evolutionary sense, the concept of "adaptation" should refer not so much to an individual as to a population and species. Changes within an individual in response to certain changes in the environment occur within the limits of the reaction norm inherited by each individual.

4. Classification of adaptations:

By origin, pre-adaptive, combinatorial and post-adaptive adaptations are distinguished.

ü When preadaptation potential adaptive phenomena arise ahead of existing conditions. The mutation process and crossings lead to the accumulation of a latent reserve of hereditary variability in populations. In the pre-adaptive way of the emergence of adaptations, the former features of the organism that have arisen under other conditions are often successfully used. At the same time, some complex adaptations can arise "ahead" of the conditions under which they turn out to be adaptations.

ü When adaptations occur in a combinative way the interaction of new mutations with each other and with the genotype as a whole is essential. The effect of mutations depends on the genotypic environment in which they will enter in the future. Crossing individuals produces a varied combination of the mutant allele with other alleles of the same and other genes. This leads to a change in the effect of manifestation of the mutation through the interaction of genes. In this case, there may be either an increase or suppression of its expression in the phenotype. In all cases, a real opportunity is created for a quick change from one adaptation to another. The combinative way of formation of adaptation is apparently the most common in nature.

ü Postadaptive path the emergence of adaptations is associated with the reduction of a previously developed trait and the use of a pre-existing organ for other purposes - not those that determined its appearance. With the post-adaptive path, new adaptations arise through the use of pre-existing structures in the event of a change in their functions. When genes that affect the development of reduced organs are transferred to a recessive state, they are included in the hidden reserve of hereditary variability. These genes are preserved in the gene pool of the population and from time to time may appear phenotypically. If selection establishes a positive relationship between such genes and new environmental conditions, they can give rise to the development of new characters and properties.

Speaking of adaptation, one cannot fail to mention its various scales. There are specialized adaptations and general ones.

ü Specialized adaptations are suitable in the narrow local conditions of the life of the species.

ü While common are suitable in a wide range of environmental conditions.

Initially, general adaptations arise as specialized ones. Promising general adaptations affect not one, but many organ systems.

5. Conclusion

In addition to the above, with regard to adaptation, the following can be added. The degree of perfection of this or that adaptation that appeared in the process of adaptation is determined by the external environment, and therefore adaptation is always relative. Adapted to one conditions, to one level of organization, it ceases to be such in other conditions, at other levels.

And in conclusion, it should be noted that Adaptation is a tendency to optimize the correspondence between the behavior of an organism and its environment. Selection favors the "optimal solution" to the problems faced by the organism.

Bibliography:

1. "Anthropology" Reader. ed. V.Yu. Bakholdina, M.A. Deryagin. M: 1997

2. "Anthropology" reader. Moscow-Voronezh: 1998 T.E. Rossolimo, L.B. Rybalov, I.A. Moskvina-Tarkhanova.