Imitative similarity of animals of different species. Mimicry (imitative resemblance)

Mimicry of the soul Mimicry of the soul Mail "LG" Careerism has always existed, and not only with a minus sign. Didn't the young Dostoevsky think of a literary career as he began his immortal novels? Or Kutuzov, who surrendered Moscow, made a risky maneuver, did not

Protective coloration is a protective color and shape of animals that make their owners invisible in their habitats. In fact, this is a kind of passive defense against natural predators. Protective coloration is combined with a certain behavior of its owner. Usually the animal hides against a background that matches its color, in addition, it takes a certain pose. For example, many butterflies settle on the surface of a tree in such a way that the spots on their wings coincide with the spots on the bark, and the bittern, which nests in the reeds, in case of danger stretches its body along the stems of plants.

The role of passive protection in animal life

Protective coloration is especially important for protecting organisms at an early stage of ontogenesis (larvae, eggs, chicks), as well as for adults leading a sedentary mode of existence or at rest (for example, sleep) for a long period. Besides big role she plays in a rapidly changing environment. So, in many animals, the possibility of changing color when moving to another background is due. For example, in the agama, flounder, chameleon. AT temperate latitudes many animals and birds are susceptible seasonal change colors.

It is customary to distinguish between three types of patronizing demonstration and mimicry. All of them arise as a result of the interaction of living beings in biogeocenosis against the background of certain environmental conditions. Protective coloration is a biocenotic adaptation developed as a result of the coupled evolution of predators and prey. In addition to patronizing, there are also warning, attractive and dismembering colors.

Protective coloring

As mentioned above, the protective coloration of animals always bears a resemblance to the environment in which they live. For example, desert lizards or snakes have a yellow-gray color to match the vegetation and soil, and the inhabitants of the snowy regions have white feathers and fur. This disguise of animals allows them to remain invisible to enemies. It can be to some extent the same for the inhabitants of completely different natural zones. For example, praying mantises or grasshoppers, lizards or frogs living in the grassy cover of the middle zone are characterized by green colors. It also predominates in insects, reptiles, amphibians, and even in some species of tropical forest birds. Often, protective coloration may include a pattern. For example, ribbon butterflies have an ornament of many stripes, spots and lines on their wings. When they sit on a tree, they completely merge with the pattern of its bark. Another important element protective coloration is the effect of countershading - this is when the illuminated side of the animal has a darker color than that which is in the shade. This principle is observed in fish that live in the upper layers of the water.

seasonal coloring

For example, consider the inhabitants of the tundra. So, partridges or arctic foxes in summer have a brown color to match the color of vegetation, stones and lichens, and in winter it becomes white. Also inhabitants middle lane, such as foxes, weasels, hares, ermines, change their coat color twice a year. Seasonal coloration exists in insects as well. For example, a leaf-winged plant with folded wings is remarkably similar to a tree leaf. In summer it is green, and in autumn it becomes brown-yellow.

Frightening coloration

Animals with bright colors are clearly visible, they often keep open, in case of danger they do not hide. They do not need to be careful, as they are often poisonous or inedible. Their warning coloring signals to everyone around - do not touch. Most often, it includes various combinations of such colors: red, black, yellow, white. Examples include a number of insects: wasps, bees, hornets, ladybugs, etc.; and animals: dart frogs, salamanders. For example, poison dart frog slime is so poisonous that it is used to treat arrowheads. One such arrow can kill a large leopard.

Let's look at what is meant by this term. Mimicry in animals is the resemblance of defenseless species to species that are well protected. A similar phenomenon in nature was first discovered in South American butterflies, so in flocks of hyliconids (inedible for birds) whites were seen, which were very similar in color, size, shape and manner of flight to the first. This phenomenon is widespread among insects (glass butterflies disguise themselves as hornets, syphid flies as wasps and bees), fish and snakes. Well, we have considered what mimicry is, now we will deal with the concept of form, dismembering and changing coloring.

Protective form

There are many animals in which the shape of the body is similar to various objects of the environment. Such properties save them from enemies, especially if the shape is combined with a protective color. There are many types of caterpillars that can stretch out at an angle to a tree branch and freeze, in which case they become like a twig or knot. The resemblance to plants is widespread in tropical species diabolical, cicada adelungia, cycloper, acridoxena, etc. With the help of the body, a sea clown or a rag-picker horse can be disguised.

Dissecting coloration

The coloring of many representatives of the animal world is a combination of stripes and spots that do not correspond to the shape of the owner, but merge with the surrounding background in tone and ornament. Such a coloring, as it were, dismembers the animal, hence its name. An example would be a giraffe or a zebra. Their spotted and striped figures are almost invisible among the vegetation. African savannah, especially at twilight, when hunting comes out A large masking effect due to dismembering coloring can be observed in some amphibians. For example, the body of the South African toad Bufo superciliaris is visually divided into two parts, as a result it completely loses its shape. Many also have dissecting colors, which makes them invisible against the background of fallen leaves and variegated vegetation. In addition, this type of disguise is actively used by residents underwater world and insects.

changing color

This property makes animals hardly noticeable when the situation changes. There are many fish that can change their color when the background changes. For example, flounder, thalassoma, sea needles, skates, dogs, etc. Lizards can also change their color, this is most pronounced in the tree chameleon. In addition, the octopus mollusk changes its color in case of danger, it can also skillfully disguise itself as soils of any color, while repeating the most cunning seabed ornament. Various crustaceans, amphibians, insects and spiders masterfully manage their colors.

Mimicry, in the narrowest sense of the word, is an imitation by a species, defenseless against some predators, of the appearance of another species, which these predators avoid due to inedibility or the presence of special means of protection. In a broader sense, mimicry is the imitative similarity of some animals, mainly insects, with other types of living organisms or inedible objects of the external environment, providing protection from enemies. At the same time, it is difficult to draw a clear line between mimicry and protective coloration or form. Mimicry is one of the least studied areas of entomology.

So, for example, the butterfly Limenitis archippus imitates the butterfly Danaus plexippus, which is not pecked by birds because it tastes unpleasant. However, mimicry, as applied to insects, can also be called several other types of protective adaptations. For example, a stick insect looks like an "inanimate" thin twig. The pattern on the wings of many butterflies makes them almost indistinguishable against the background of tree bark, mosses or lichens. On the one hand, strictly speaking, this is a protective coloration, but there is also a clear protective imitation of other objects, i.e. it is, in a broad sense, mimicry.

There are three main types of mimicry - apathetic, sematic and epigamous.

Apathetic mimicry is the similarity of a species with an object of the natural environment - animal, plant or mineral origin. Due to the diversity of such objects, this type of mimicry falls into many smaller categories.

Thousands of species of insects imitate their appearance to animal excrement. Many beetles resort to this form of mimicry, which complement their resemblance to animal feces by pretending to be dead when they sense danger. Other beetles at rest resemble plant seeds.

The most amazing imitators include representatives of the squad of stick insects, or ghosts. At rest, these insects are almost indistinguishable from thin twigs. At the first appearance of danger, they freeze, but when the fright passes, they begin to move slowly, and if they are disturbed again after a short period of time, they fall from the plant to the ground. The famous representatives of the leaf family, living in the Pacific and South Asian regions, are so similar to the leaves of some plants that you can only notice them when they move. In this regard, only leaf butterflies, which on a branch are indistinguishable from a dry leaf of a plant, can compete with them. Some types of diurnal butterflies have chosen a different method of disguise: their wings are transparent, so these insects are almost invisible in flight.

Perhaps one of the most effective types of mimicry is the complete loss by an animal of external resemblance to an animated object and, in general, to anything specific (a kind of “anti-mimicry”). Bed bugs are known in which the shape of the legs, chest or head is so atypical for living creatures that the insect as a whole looks completely “non-bug-like”. In some cockroaches, grasshoppers, bedbugs, spiders and many other species, the “dissected” body coloration, consisting of irregular outlines of stripes and spots, breaks its contours, as it were, allowing the animal to more fully merge with the background. Legs, antennae and other parts of the body sometimes look so “atypical” that this alone scares off potential predators.

Sematic (warning) mimicry- this is an imitation in shape and color of a species avoided by predators due to the presence of special protective equipment or an unpleasant taste. It occurs in larvae, nymphs, adults, and possibly even pupae.

Harmless diurnal insects often achieve an outward resemblance to stinging or inedible species through the movements of their bicolored legs. Bees and wasps serve as favorite role models. Their appearance and behavior are copied by many species of flies. Some of the imitators not only use wasp coloration, but, when caught, pretend that they are going to sting and buzz almost the same as the "originals". Like bees and wasps also - in flight or at rest - many species of moths from several families.

Found in many regions of Southeast Asia and Australia, danaid butterflies and many types of sailboats have an unpleasant taste for birds and other predators. Their appearance, as far as possible, is copied by completely edible species of sailboats and butterflies of other families. Moreover, sometimes sailboats and Danaids, protected from enemies, copy each other's appearance no less skillfully than their defenseless imitators do. A similar situation is observed in the tropics of America and Africa. One of the classic examples of mimicry is the African butterfly Hypolimmas misippus, which, depending on the geographical area, imitates different species of danaids and, thus, is itself represented by outwardly different forms.

The caterpillars of one of the South American hawk moth species in a calm state look extremely unremarkable, however, if they are disturbed, they rear up and arch the body, inflating its front end. The result is a complete illusion of a snake head. For greater reliability, the caterpillars slowly sway from side to side.

In North America, the most striking example of mimicry is the imitation of the butterfly Limenitis archippus (its English name is viceroy, viceroy) to another butterfly - Danaus plexippus (this large beautiful butterfly is called the monarch). They are very similar in coloration, although the imitator is somewhat smaller than the original and carries an “extra” black arc on the hind wings. This mimicry is limited to adults (adults), and the caterpillars of the two species are completely different. In the "original" - the caterpillars carry a bright black-yellow-green pattern, which they boldly show to birds and other predators. The larvae of the imitator species, on the contrary, are inconspicuous, speckled, outwardly resembling bird droppings. Thus, the imago stage here serves as an example of mimicry in the narrow sense of the word, and the caterpillar shows a protective coloration.

Spiders are the worst enemies of insects. Some ants and other insects at certain stages of their development resemble spiders in appearance and habits. However, the spider synemosina ant-like is so similar to an ant that, only by looking closely, it is possible to recognize mimicry.

An important indicator that affects the effectiveness of mimicry is the ratio of the numbers of copied and copying species. The inedible form copied by another species must obviously be so abundant that natural enemies very quickly (after the first one or two attempts to feast on individuals of the corresponding appearance) learn to avoid it. If there are more imitators than originals, such training will naturally be delayed, and both the original and the copy will have to suffer from this. As a rule, the number of copied individuals is many times higher than that of copying individuals, although here there may be rare exceptions, for example, when development conditions for the former are unfavorable, and for the latter are close to ideal.

Epigamic mimicry, or coloration, can be observed in species with sexual dimorphism. An inedible animal is imitated either by males or females. At the same time, females sometimes imitate several differently colored species that occur either in a given area in different seasons or in different parts of the range of the imitator species. Darwin considered this type of mimicry the result of sexual selection, in which a defenseless form becomes more and more like a protected one in the process of destroying less perfect imitators by natural enemies. Those who manage to more accurately copy someone else's appearance survive thanks to this similarity and give offspring.

Current page: 11 (total book has 19 pages) [accessible reading excerpt: 13 pages]

Font:

100% +

34. Main directions of evolution

Remember!

Life forms of plants and animals Predators

There are three main directions of evolution, each of which leads to the prosperity of a group of organisms: 1) aromorphosis (morphophysiological progress); 2) idioadaptation; 3) general degeneration.

Aromorphosis(from Greek. airo- I raise morph- sample, form) means the complication of the structural and functional organization, raising it to more high level. Changes in the structure of animals as a result of aromorphosis are not adaptations to any special conditions environment, they are of a general nature and allow wider use of environmental conditions (new sources of food, new habitats).

Aromorphoses ensure the transition from passive to active nutrition (the appearance of jaws in vertebrates), increase the mobility of animals (the appearance of the skeleton as a place of attachment of muscles and the replacement of layers of smooth muscles in worms with bundles of striated arthropods), respiratory function (the appearance of gills and lungs), tissue oxygen supply (appearance of a heart in fish and separation of arterial and venous blood flow in birds and mammals). All these changes, not being particular adaptations to specific environmental conditions, increase the intensity of animal life, reduce their dependence on the conditions of existence.

All aromorphoses are preserved in the course of further evolution and lead to the emergence of new large systematic groups - classes, types, some orders (in mammals).

Idioadaptation(from Greek. idiot- peculiarity, adaptation- adaptation) - adaptation to special environmental conditions, useful in the struggle for existence, but not changing the level of organization of animals or plants. Since each species of organisms lives in certain habitats, it develops adaptations precisely to these conditions. Different types of idioadaptations include the protective coloration of animals, the spines of plants, the flat shape of the body of stingrays and flounders. Depending on the living conditions and lifestyle, the five-fingered limb of mammals undergoes numerous transformations. In Figure 66, consider how diverse the shapes of the limbs are among representatives of the orders of rodents and lagomorphs. Similarly, the differences appearance and details of the structure of animals belonging to the orders of artiodactyls and corns (Fig. 67), are caused by the unequal conditions of their existence.

After the occurrence of aromorphoses, and especially when a group of animals enters the new environment habitation, the adaptation of individual populations to the conditions of existence begins precisely through idioadaptation. Thus, the class of birds in the process of settling over land gave an enormous variety of forms. Considering the structure of hummingbirds, sparrows, canaries, eagles, gulls, parrots, pelicans, penguins, etc., we can conclude that all the differences between them come down to particular adaptations, although the main structural features of all birds are the same (Fig. 68 , 69).

The extreme degree of adaptation to limited conditions of existence is called specializations. Eating only one type of food, living in a homogeneous and constant environment, leads to the fact that organisms cannot live outside these conditions. These are hummingbirds that feed only on the nectar of flowers of tropical plants, anteaters that specialize in feeding exclusively on ants, chameleons that are adapted to living on thin branches of trees.

Rice. 66. Types of rodents (3–8) and lagomorphs (1.2)

Rice. 67. Species of artiodactyls (1–6) and calluses (7)

Rice. 68. The characteristic shape of the beak of a pine crossbill that feeds on pine seeds differs sharply from the beaks of birds whose food is insects or seeds of other plants.

Rice. 69. The shape of the beak various kinds finches depends on the nature of the food

Rice. 70. Trichinella from muscle tissue

The transition to a sedentary lifestyle and passive feeding (for example, ascidia - see Fig. 34) is accompanied by a simplification of organization and elimination from competition with other species, which also leads to the conservation of the species.

1. What are the main directions of the evolution of organisms.

2. Give examples of aromorphoses in plants.

3. Consider figures 66 and 67. Give examples of idioadaptations in mammals.

5. Do you agree with the statement that general degeneration can contribute to biological prosperity and success? Justify your answer.

6. What biological mechanism ensures the movement of groups of organisms in a particular evolutionary direction?

7. Can it be argued that evolution can be both progressive and regressive? Justify the answer.

Work with computer

Search online

Remember!

Homologous Organs Leaf modifications

Shoot modifications burrowing animals

jumping animals crawling animals

Divergence. The emergence of new forms is always associated with adaptation to local geographical and environmental conditions existence. Thus, the class of mammals consists of numerous orders, whose representatives differ in the type of food, the characteristics of their habitats, i.e., the conditions of existence (insectivores, bats, carnivores, artiodactyls, cetaceans, etc.). Each of these orders includes suborders and families, which, in turn, are characterized not only by specific morphological features, but also ecological features(forms running, jumping, climbing, burrowing, floating). Within any family, species and genera differ in their way of life, food objects, etc.

As Darwin pointed out, the whole evolutionary process is based on divergence(from lat. divergo- deviate, depart). This is the process of divergence of signs of organisms arising from a common ancestor in the course of their adaptation to different living conditions. Not only species can diverge, but also genera, families, and orders.

The leaves of plants, depending on the conditions, can turn into antennae (for peas), into needles (for barberry), into thorns (for cactus), but all these are modified leaves. Lily of the valley rhizome, potato tubers, onion bulbs, which are so different in appearance, are modified shoots. Divergent evolution is based on a common gene pool. Relationships between groups of organisms formed in the process of divergence can be established by studying homologous organs- organs that have a common origin and a similar structural plan (see § 12).

Convergence. Under the same conditions of existence, animals belonging to different, often distant, systematic groups can acquire a similar structure. Such a similarity of structure arises with the similarity of functions and is limited only to organs directly related to the same environmental factors. This phenomenon is called convergence(from lat. converto- I'm coming, I'm coming).

At the same time, the historically established organization as a whole never undergoes convergence. Outwardly, chameleons and climbing agamas that live on tree branches are very similar, although they belong to different suborders (Fig. 71). A convergent similarity is found in the limbs of various animals that lead a burrowing lifestyle (Fig. 72). The same way of life of marsupial and placental mammals led them independently of each other to the similarity of many structural features. The European mole and the marsupial mole, the marsupial flyer and the flying squirrel are similar, the marsupial wolf resembles a "real" wolf. A prime example the appearance of similar structures in unrelated groups of organisms is the structure of the eye of an octopus and a person (Fig. 73).

Organisms capable of flight have wings and other adaptations (Fig. 74). But the wings of a bird and bat- modified forelimbs, and butterfly wings are outgrowths of the body wall.

When developing land, unrelated groups of animals, arthropods and vertebrates, develop an adaptation to retain water in the body - dense covers with a waterproof outer layer. Most aquatic animals are characterized by the excretion of nitrogen metabolism products in the form of ammonia with a large amount of water. In terrestrial animals, nitrogen is excreted in the form of uric acid, which makes it possible to reduce water consumption as much as possible. Thus, in the process of evolution, the physiological improvement of unrelated organisms is carried out in similar ways on the basis of structures of different origin. Bodies that have different origin, but perform similar functions, called similar bodies.

Rice. 71. Chameleon (left) and climbing dragon (right)

Rice. Fig. 72. Convergent similarity of limbs in an insect (bear, left) and a mammal (mole, right), leading a burrowing lifestyle

Rice. 73. The structure of the eye of an octopus (A) and a person (B): 7 - optic nerve; 2 - retina; 3 - vitreous body; 4 - lens; 5 - iris; 6 - anterior chamber of the eye; 7 - cornea

Rice. 74. Devices for gliding flight in mammals, reptiles and amphibians. In the photo: lizard (top) and flying squirrels (bottom)

The irreversibility of evolution. To general rules evolution of groups of living organisms applies the rule of irreversibility of evolutionary transformations. So, if at some stage reptiles arose from primitive amphibians, then with further evolution, reptiles cannot give rise to amphibians again, and amphibians, in turn, will not turn into fish over time. Terrestrial vertebrates that returned to the water (among reptiles - ichthyosaurs, among mammals - cetaceans and pinnipeds) did not become fish. The previous history of development for any group of organisms does not pass without a trace, and adaptation to the environment in which the ancestors once lived is already carried out on a different genetic basis.

Review questions and assignments

1. What determines the divergence of features in related groups of organisms and the appearance of external similarity in unrelated ones?

2. Expand and compare the content of the concepts of "divergence" and "convergence".

3. Give examples of similar and homologous organs. How can you prove that these structures belong to one or another group of organs?

4. Prove that divergent or convergent development of groups of living organisms is adaptive. Give examples.

5. What is the essence of the irreversibility of evolution?

Work with computer

Please refer to the electronic application. Study the material of the lesson and complete the suggested tasks.

Search online sites, the materials of which can serve as an additional source of information, revealing the content of the key concepts of the paragraph.

Get ready for the next lesson. Using additional sources of information (books, articles, Internet resources, etc.), make a report on the key words and phrases of the next paragraph.

Chapter 13

Plants and animals are remarkably adapted to the environment in which they live. The concept of "species fitness" includes not only external signs, but also the conformity of the structure internal organs the functions they perform (for example, the long and complex digestive tract of plant-eating ruminants). The correspondence of the physiological functions of the organism to the conditions of their habitat, their complexity and diversity are also included in the concept of fitness.

Indicators of good fitness of a group of organisms are its high abundance, wide range and a large number of subordinate systematic groups. A systematic group (species, genus, family, etc.) is in a state of prosperity, or biological progress, if it includes a significant number of lower ranking systematic groups. For example, within an order there are always numerous families, which in turn include a large number of genera, which are also rich in their species. In this way, biological progress represents the result of success in the struggle for existence.

The lack of the necessary level of fitness leads to an oppressed state of the taxonomic group - biological regression– a decrease in the number, a reduction in the range, a decrease in the number of systematic groups of a lower rank. Biological regression is fraught with the danger of extinction. For example, as a result of increased shooting, the number of sables has sharply decreased and the distribution area has narrowed. On the brink of extinction are Ussurian tiger, bowhead whale, dune cat and other animals.

Remember!

Protective coloration Warning coloration

Adaptive behavior Demonstrative behavior

Mimicry Tiger Zebra Turtle stingray Flounder

Animals are adaptive body shape. The appearance of an aquatic mammal - a dolphin - is well known. Its movements are light and precise, and the speed of movement in the water reaches 40 km/h. The density of water is 800 times that of air. How does the dolphin manage to overcome it? This is facilitated by the torpedo-shaped shape of its body, due to which turbulences of water flows flowing around the dolphin do not slow down the movement.

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 do not have protruding auricles, in flight they usually retract their legs. As a result, they are far superior to all other animals in terms of speed of movement. For example, a peregrine falcon dives on its prey at speeds up to 290 km/h. Birds move quickly even in water. A chinstrap penguin has been observed swimming underwater at about 35 km/h.

In animals that lead a hidden lifestyle, adaptations are useful that give them a resemblance to environmental objects. This method of protection is called disguise. The bizarre shape of the body of fish living in thickets of algae (Fig. 75, 76) helps them successfully hide from enemies. Resemblance to objects of the environment is widespread in insects. Beetles are known that outwardly resemble lichens, cicadas, similar to the thorns of those shrubs among which they live. Stick insects and moth caterpillars look like brown or green twigs (Fig. 78), and some insects imitate the leaves of trees and shrubs among which they live (Fig. 77, 79). Flattened in the dorsal-abdominal direction, the body has fish leading a benthic lifestyle.

It also serves as a defense against enemies. protective coloration. Thanks to her, the birds that incubate their eggs on the ground merge with the surrounding background. Their eggs, which have a pigmented shell, and the chicks hatching from them are hardly noticeable (Fig. 80, 81). The protective nature of egg pigmentation is confirmed by the fact that in birds whose eggs are inaccessible to enemies, the protective color of the shell does not develop.

Rice. 75. The body shape of a seahorse (left) makes it invisible against the background of algae.

Rice. 76. Soft coloration and elongated body sea ​​needles allow them to hide in kelp beds

Protective coloration is widespread among a wide variety of animals. 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 can also change color depending on the color of the surrounding background (Fig. 82). The ability to change color by redistributing pigment in the integument of the body is also known in terrestrial animals, for example, in a chameleon (Fig. 83). Desert animals are usually yellow-brown or sandy-yellow in color. Monochromatic protective coloration is characteristic of both insects (locusts) and small lizards, as well as large ungulates (antelopes, deer) and predators (lion).

Rice. 77. Indian plant bug

Rice. 78. Moth caterpillar in a resting pose

Rice. 79. Callima butterfly on a bush

If the background of the environment changes depending on the season of the year, many animals change color. For example, in inhabitants of middle and high latitudes (arctic fox, hare, ermine, ptarmigan) after autumn molt the fur or plumage turns white, making them invisible in the snow.

However, often in animals, body color does not mask them, but, on the contrary, draws attention to them. This coloration is characteristic, for example, of poisonous or stinging insects: bees, wasps, blister beetles. ladybug, very noticeable, the birds do not peck because of the poisonous secret it secretes. Bright warning coloring have inedible caterpillars, many Poisonous snakes. This coloration warns the predator in advance about the futility and even the danger of the attack. Through trial and error, predators quickly learn to "avoid" a potential prey with a warning coloration.

Rice. 80. Tundra partridge at the nest

Rice. 81. Small plover on egg laying

The protective effect of protective coloration increases when it is combined with the corresponding behavior. For example, the bittern nests in the reeds. In moments of danger, she stretches her neck, raises her head up and freezes. In this position, it is difficult to detect even at close range. Many other animals that do not have means of active protection, in case of danger, take a resting position (insects, fish, amphibians, birds) (see Fig. 78). The warning coloration in animals, on the contrary, is combined with demonstrative behavior that scares off a predator (Fig. 84).

Rice. 82. Some demersal fish, such as flounder, have the ability to adjust their coloration to the color and character of the seabed.

Rice. 83. Chameleons change color according to their surroundings.

In addition to color, 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, horny shields in crocodiles, shells in armadillos and turtles (Fig. 88) save them from many enemies. The quills of the hedgehog and porcupine serve the same. All these adaptations could appear only as a result of natural selection, i.e., the preferential survival of better protected individuals.

Rice. 84. Intimidating posture of the Australian bearded lizard often scares away enemies from her

Rice. 85. Danaid butterfly (left) owes its inedibility to the fact that its caterpillars feed on leaves poisonous plant. Its tissues contain substances that cause severe poisoning in birds. Birds quickly learn not to touch danaids, and at the same time their imitators - edible nymphalids (on the right)

Rice. 86. Egg of a small cuckoo in the nest of a small warbler (left). On the right is a young little cuckoo

Rice. 87. Many birds are forced to feed cuckoo chicks. Above - a warbler feeds a deaf cuckoo chick. Below, a Siberian shrike is feeding an Indian cuckoo chick. Adoptive parents perform their duties, despite the fact that the chicks are larger than them

Rice. 88. The thick shell of an elephant tortoise reliably protects it even from large predators.

For the survival of organisms in the struggle for existence, it is of great importance adaptive behaviour. In addition to hiding or demonstrative, intimidating behavior when an enemy approaches, there are many other options. adaptive behavior that ensures the survival of adults or juveniles. So, many animals store food for the unfavorable season of the year. In deserts, for many species, the time of greatest activity is at night, when the heat subsides.

Review questions and assignments

1. Give examples of the adaptability of organisms to the conditions of existence based on your own observations.

2. Why do some animals have a bright, unmasking color, while others, on the contrary, have a protective one?

3. What is the essence of mimicry? Compare mimicry and disguise. What are their fundamental differences? How are they similar?

4. Does the action of natural selection extend to the behavior of animals? Give examples.

5. What are the biological mechanisms for the emergence of adaptive (concealing and warning) coloration in animals?

6. Are there living organisms that do not have adaptive structural features? Justify the answer.

7. Plan the paragraph.

Work with computer

Please refer to the electronic application. Study the material of the lesson and complete the suggested tasks.

Search online sites, the materials of which can serve as an additional source of information, revealing the content of the key concepts of the paragraph.

Get ready for the next lesson. Using additional sources of information (books, articles, Internet resources, etc.), make a report on the key words and phrases of the next paragraph.

In translation means - masking, imitation.

There are cases when animals acquire an extraordinary resemblance not only in color, but also in shape with individual objects among which they live, which is called imitation. There are especially many such examples between insects.

Caterpillars of moths (Geometridae) live on the branches of plants with which they are similar in color, and have the habit, attached with their hind legs, to stretch and hold their body motionless in the air. In this respect, they are so reminiscent of small dry twigs of plants that the most keen and experienced eye can hardly see them. Other caterpillars resemble bird excrement, fallen birch catkins, etc.

Tropical stick insect (Phyllocrania paradoxa)

Tropical stick insects from the Phasmidae family represent amazing adaptations: they imitate the color and shape of the body - some are dry sticks several inches long, others are leaves. Butterflies from the genus Kallima from Southeast Asia, brightly colored on the upper side of the wings, when they sit on a branch and fold their wings, take the form of a withered leaf: the butterfly rests on the branch with short outgrowths of the hind wings, and they resemble a petiole; the pattern and color of the back side of the folded wings are so reminiscent of the color and venation of a dried leaf that at the closest distance the butterfly is extremely difficult to distinguish from the leaves.

There are three main types of mimicry - apathetic, sematic and epigamous.

Apathetic mimicry is the similarity of a species with an object of the natural environment - animal, plant or mineral origin. Due to the diversity of such objects, this type of mimicry falls into many smaller categories.

Sematic (warning) mimicry is an imitation in shape and color of a species avoided by predators due to the presence of special means of protection or an unpleasant taste. It occurs in larvae, nymphs, adults, and possibly even pupae.

Epigamic mimicry, or coloration, can be seen in sexually dimorphic species. An inedible animal is imitated either by males or females. At the same time, females sometimes imitate several differently colored species that occur either in a given area in different seasons or in different parts of the range of the imitator species. Darwin considered this type of mimicry the result of sexual selection, in which a defenseless form becomes more and more like a protected one in the process of destroying less perfect imitators by natural enemies. Those who manage to more accurately copy someone else's appearance survive thanks to this similarity and give offspring.

Corymica spatiosa(female)

Cleora injectaria

Cleora replusaria

Coremecis nigrovittata

Antitrygodes vicina

Antitrygodes divisaria