Adaptation of organisms to the environment. As a result of a long evolutionary process, all organisms are constantly developing and improving their adaptations to environmental conditions. Fitness is one of the results of evolution, the interaction of its driving forces - heredity, variability, natural selection. The second result of evolution is the diversity of the organic world. The organisms preserved in the process of struggle for existence and natural selection make up the entire organic world that exists today. Mutation processes occurring in a number of generations lead to the emergence of new genetic combinations that are subject to the action of natural selection. It is natural selection that determines the nature of new adaptations, as well as the direction of the evolutionary process. As a result, organisms have a variety of adaptations to life. Any adaptation arises as a result of a long-term selection of random, phenotypically manifested mutations that are beneficial to the species.

Protective coloration. Provides plants and animals with protection from enemies. Organisms with this coloration merge with the background and become less noticeable.

Disguise. An adaptation in which the shape of the body and color of animals merges with surrounding objects. Praying mantises, butterfly caterpillars resemble knots, butterflies look like plant leaves, etc.

Mimicry. Imitation of unprotected species of protected species in shape and color. Some flies look like wasps, snakes look like vipers, and so on.

Warning paint. Many animals have bright colors or certain markings to warn of danger. A predator that attacked once remembers the color of the victim and will be more careful next time.

The relative nature of fixtures. All adaptations are developed in certain environmental conditions. It is under these conditions that the devices are most effective. However, it should be borne in mind that fitness is not absolute. Animals with both protective and warning coloration are eaten, and those who are disguised are attacked. Good flying birds are poor runners and can be caught on the ground; when environmental conditions change, the developed adaptation may turn out to be useless or harmful.

Evidence for evolution. Comparative anatomical the evidence is based on the identification of common and different morphological and anatomical features of the structure of various groups of organisms.

Anatomical evidence for evolution includes:

– the presence of homologous organs, having a general structural plan, developing from similar germ layers in embryogenesis, but adapted to perform different functions (hand - flippers - bird's wing). Differences in the structure and functions of organs arise as a result of divergence;

– the presence of similar organs having a different origin in embryogenesis, a different structure, but performing similar functions (a bird's wing and a butterfly's wing). The similarity of functions results from convergence ;

- the presence of rudiments and atavisms;

- the existence of transitional forms.

Rudiments, - organs that have lost their functional significance (coccyx, ear muscles in humans).

atavisms, - cases of manifestation of signs of distant ancestors (tail and hairy body in humans, remnants of the 2nd and 3rd toes in a horse).

Transitional forms - indicate phylogenetic continuity in the transition from ancestral forms to modern ones, and from class to class.

embryological evidence. Embryology studies the patterns of embryonic development and establishes:

- phylogenetic relationship of organisms;

- regularities of phylogenesis.

The data obtained were reflected in the laws of germinal similarity of K.M. Baer and in the biogenetic law of E. Haeckel and F. Müller.

Beer's law establishes the similarity of the early stages of development of embryos of representatives of different classes within a type. At the later stages of embryonic development, this similarity is lost, and the most specialized characters of the taxon develop, up to the individual characters of the individual.

The Müller-Haeckel biogenetic law states that ontogeny is a brief repetition of phylogeny. In the process of evolution, ontogeny can be rearranged, which leads to the evolution of the organs of an adult organism.

In ontogenesis, only the embryonic stages of the ancestors are repeated and not always completely. If at an early stage the organism is adapted to environmental conditions, then it can reach sexual maturity without going through subsequent stages, as, for example, occurs in axolotls - larvae of the tiger ambistoma.

paleontological evidence- allow you to date the events of ancient history according to the fossil remains of organisms. Paleontological evidence includes the phylogenetic series of horses, proboscis, and humans built by paleontologists.

The unity of the organic world is manifested in chemical composition, the finest structure and basic life processes occurring in organisms.

Question 1. Give examples of the adaptability of organisms to the conditions of existence.

In the course of evolution, organisms acquire various properties that allow them to more successfully adapt to living conditions. For example, the fur of the animals of the north (Arctic foxes, bears) has a white color, making them almost invisible against the background of snow. Insects that feed on flower nectar have a proboscis structure and length that is ideal for this. The seal flippers, modified from the paws of their land ancestors, are perfectly adapted to movement in the water. Giraffes live in the savannah and eat the leaves of trees at high altitudes, in which they are helped by a long neck.

There are many such examples, since each living creature has a large number of features acquired in the process of adapting to specific living conditions.

Question 2. Why do some animals have a bright, unmasking color, while others, on the contrary, are patronizing?

Two types of coloring correspond to two variants of the behavior strategy. In one of them, the animal tends to go unnoticed, trying to avoid a meeting with a predator or sneaking up on a prey. For this, a protective coloration is used, which allows it to blend into the background. On the other hand, animals that are dangerous or poisonous often emphasize this in every possible way. They use a bright unmasking ok-raska warning: "do not eat me." In addition to poisonous organisms, this strategy is used by harmless species mimicking for them. Organisms can have unmasking coloration for a completely different reason - in connection with the desire to attract a breeding partner (the bright color of many male birds, fish, reptiles, butterflies, etc.). In this case, the task of procreation comes into conflict with the instinct of self-preservation, but it turns out to be more significant for the organism.

Question 3. What is the essence of mimicry?

The essence of mimicry (from the Greek mimikos - imitative) lies in the fact that harmless animals in the process of evolution acquire similarities with dangerous (poisonous) species. This allows them to avoid predation. Some non-poisonous snakes serve as an example: there is a species of snake, which is similar in color to the deadly asp and differs from it only in the alternation of stripes. In addition to color, mimic animals have a characteristic behavior: hoverfly flies behave like wasps, imitating aggression.

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

Natural selection affects not only the external signs of the organism, but also behavior. This applies, first of all, to innate (instinctive) forms of behavior. Such forms are very diverse: ways of obtaining food, manifestations of fear and aggression, sexual behavior, parental behavior, etc. stocks and hibernate for the winter, etc. Very complex mating rituals, strict adherence to which is one of the ways for animals to prevent interspecific crossing.

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

The biological mechanism that ensures the emergence of adaptive coloration is natural selection. In the process of evolution in the population, which, due to the diversity of the gene pool, was distinguished by a very wide spectrum of coloration, those individuals that were less noticeable against the background of the environment mainly survived and left offspring. As a result, the proportion of corresponding genotypes was constantly growing. In the future, this phenotype, and hence the genotype, was fixed in the population with the help of stabilizing selection. In the case of warning coloration, similar processes occurred. For example, birds find and eat bright insects more easily. If these insects turn out to be poisonous, then birds quickly learn not to touch them and prefer more modestly colored prey. Thus, individuals with a bright color, which is easy to identify as poisonous, are preserved and leave offspring. Over time, this trait is fixed in the population.

Question 6. Are physiological adaptations factors that determine the level of adaptability of the organism as a whole? material from the site

Physiological adaptations play a huge role in maintaining the working state of the body in changing environmental conditions. They characterize the adaptability of the species as a whole, as they ensure the performance of vital functions. For example, birds and reptiles have special glands that provide a quick release of excess salts. The camel is able to store a large number of fat in your hump. Dolphins and bats have evolved the ability to echolocate. In many snakes, salivary gland enzymes have been converted into poison. In the human brain, zones associated with finger movements, speech, and thinking have developed.

Question 7. What is the essence of the relativity of any adaptation to living conditions? Give examples.

Any adaptation allows you to adapt to environmental conditions, but only to some specific ones. When changing (especially with a sharp change) of these conditions, adaptation may turn out to be useless and even harmful. For example, the white color of animals, designed for snow cover, will give them out in the event of a sudden melting of snow. Thus, all adaptations have relative expediency. In a particularly sharp form, this problem is faced by organisms inhabiting the land, where conditions can change very quickly. In the ocean, environmental conditions are more stable, and we can meet here species that have not undergone significant changes over hundreds of millions of years (sharks, many mollusks).

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"General biology. Grade 11". V.B. Zakharov and others (gdz)

The adaptation of organisms to environmental conditions as a result of natural selection

Question 1. Give examples of the adaptability of organisms to the conditions of existence.
In animals, body shape, color, behavior can be adaptive. So, for example, horse hooves are the most convenient for moving quickly through open spaces, retractable cat claws provide silent movement, aquatic mammals have a fish-like body for the most efficient movement in water, birds with different speeds and flight patterns form one or another wing shape. . Among insects that do not have active defenses, the body shape is widespread, imitating background objects, such as mantis, stick insects, and butterfly caterpillars. Some organisms are able to take on a color that matches the background on which they live (chameleon, flounder).

Question 2. Why do some animal species have a bright unmasking color?
Bright coloration is usually characteristic of poisonous animals and warns predators about the inedibility of the object of their attack; it is characteristic of poisonous, stinging or burning insects (bees, wasps, blister beetles, etc.). A ladybug, very noticeable, is never pecked by birds because of the poisonous secret secreted by insects. Inedible caterpillars, many poisonous frogs, and snakes have a bright warning color. This coloration warns the predator in advance about the futility and danger of the attack. Through trial and error, predators quickly learn to avoid attacking prey with warning coloration.

Question 3. What is the essence of the phenomenon of mimicry?
Mimicry is the resemblance of a defenseless and edible species to one or more unrelated species that are well protected and have a warning color. The phenomenon of mimicry is common in butterflies and other insects. Many insects mimic stinging insects. Beetles, flies, butterflies are known, copying wasps, bees, bumblebees. Mimicry is also found in vertebrates - snakes. In all cases, the similarity is purely external and is aimed at forming a certain visual impression in potential enemies.

Question 4. How is the low number of mimic species maintained?
The imitation of some species by others is justified: a much smaller part of the individuals of both the species that served as a model and the imitator species are exterminated. It is necessary, however, that the number of the mimic species be significantly less than the number of the model species. Otherwise, the enemies will not develop a stable negative reflex to the warning color. The fact that the gene pool of these species is saturated with lethal mutations makes it possible to maintain the number of the imitator species at the required level. In the homozygous state, these mutations cause the death of the organism, as a result of which a high percentage of individuals do not reach the sexually mature state.

Question 5. Does the action of natural selection extend to the behavior of animals? Give examples.
For the survival of organisms in the conditions of the struggle for existence, adaptive behavior is of great importance. The effectiveness of adaptive coloration and body shape increases sharply in combination with behavior. For example, the ability of felines to sit in ambush for a long time and make lightning-fast jumps ensures the success of hunting an ambush predator. The ability of a wolf to come downwind and hunt in a pack - useful qualities for this hunter. Undoubtedly, it is justified for some animals to store food for the unfavorable season of the year. For example, a house vole stores up to 10 kg of cereals, grains, roots and dry grass. Hiding in case of danger to organisms that do not have active methods of protection allows them to save their lives.

Question 6. Why does the number of offspring decrease in animal species that care for offspring? Give examples.
In lowly organized organisms, offspring are most often left to fend for themselves. This explains such a high fecundity of invertebrates and lower vertebrates. A large number of offspring in conditions of high exterminability of juveniles serves as a means of struggle for the existence of the species. With developed care for offspring, the number of surviving and sexually mature offspring increases dramatically, which makes it possible to reduce their initial number.

Question 7. What is the relative nature of adaptive traits in organisms? Give examples specific to plants and animals.
The structure of living organisms is very finely adapted to the conditions of existence. Any species trait or property is adaptive in nature, expedient in a given environment, in given living conditions, only in the usual environment for the species. When environmental conditions change, they become useless or even harmful to the body. Thanks to mimicry, most birds do not touch wasps and bees, but among them there are species that eat both wasps and bees, and their imitators. The hedgehog and the secretary bird eat poisonous snakes without harm. The shell of terrestrial turtles reliably protects them from enemies, but birds of prey lift them into the air and smash them on the ground.
Any adaptations are expedient only in the usual environment for the species. When environmental conditions change, they turn out to be useless or harmful to the body. The constant growth of rodent incisors is a very important feature, but only when eating solid food. If a rat is kept on soft food, the incisors, without wearing out, grow to such a size that feeding becomes impossible. So, all the features of the structure and behavior of cats are appropriate for a predator lying in wait for prey in ambush: soft pads on the fingers, retractable claws, the ability to see in the dark. At the same time, in open spaces, all these devices are useless.
The deep root system of desert plants is not beneficial in wet habitats. The transformation of limbs into flippers in aquatic mammals is useful for living in the water, but on land, cetaceans are immobile, and pinnipeds move very clumsily.
Thus, any structure and any function is an adaptation to specific environmental conditions, i.e. adaptations are relative. None of the adaptive features provides absolute security for their owners.

Fact fitness of organisms to the conditions of their dwelling, the church used for a very long time as supposedly "scientific" proof of the existence of divine power. Only Darwin's theory finally refuted the myth of "original, God-given" fitness. In the light of Darwin's theory, fitness turned out to be a necessary and natural consequence of natural selection.

As an example of the development fitness across natural selection may be the development of protective coloration in many animals. About 100 years ago, the light gray birch moth was very widespread in England. During the day, it sits on birch trunks and the light color of its folded wings camouflages the insect well. But in connection with the development of industry, the soot of numerous factory pipes gradually began to settle on white-trunked birch trees growing in industrial areas. The bark has become darker in color. Under these conditions, the once camouflage coloration of moths has ceased to be useful. In connection with the change in conditions, the direction of selection has also changed. If earlier (on white trunks) birds ate primarily darker butterflies, and lighter ones survived, then now (on dark trunks), on the contrary, the darkest butterflies survived, and the lightest butterflies became victims of birds. This process continued from generation to generation for last 100 years. And now the zoologists of England relied on two different races of the moth: in rural areas, the old light race, and in industrial areas a new, very dark race. So, in a relatively short period of time, natural selection developed one of the adaptations - the protective coloration of these butterflies.

very interesting how examples of adaptations by facial expressions and disguise. In mimicry, individuals of some defenseless species, in their shape, color, and behavior, resemble another species that has active means of protection. An example is defenseless flies, "imitating" such armed insects as bumblebees or wasps. Camouflage is achieved by the similarity of animals with the bodies of inanimate nature. So, for example, the caterpillars of some insects in a motionless state are very similar to a tree knot; the callima butterfly with folded wings is surprisingly similar to a dry leaf of a tree.

Among plants, a wide variety of adaptations for cross-pollination, for the distribution of fruits and seeds are widespread. In animals, various kinds of instincts play a large role as adaptations ( instinct caring for offspring, the instincts associated with the extraction of food, the complex instincts of such social insects as bees, ants, etc.). There are many similar examples in zoology and botany.

One of the main evidence of the natural origin of adaptations their relative nature. Any adaptation is useful only in relation to the conditions in which it historically arose. To take the example discussed above, the light color of the moth is useful in rural areas, the dark color is useful in industrial areas. But even for the given conditions in which this or that device was developed, its usefulness is also relative. Firstly, organisms protected by certain adaptations become victims of their enemies, although in fewer numbers than their less protected counterparts. Secondly, constantly fluctuating environmental conditions often create situations in which the device stops "working". So, for example, for a white hare, a device in the form of a change in the color of the hairline is very useful: in summer this hare is dark, and in winter it is white. But one year the snow cover fell very late, and the hare had long since turned white; under these conditions, its white coloring, instead of being patronizing, will turn out to be unmasking. And at such a time, many hares die. A very important evidence of the relative nature of fitness is the rudiments, that is, organs that have lost their usefulness in the new conditions, but have not yet completely disappeared.