Particular adaptations to the environment. Adaptation of organisms to the environment, its relative nature

Thanks to selection, organisms that are best adapted to their surrounding conditions survive, but adaptations are always relative. Insignificant changes in the environment are enough for something that was useful under previous conditions to lose its adaptive significance.

Examples of relative adaptations

The Ussuri tiger has a protective coloration that hides it well in the thickets in the summer, but in the winter, after the snow falls, the coloration reveals the predator. With the onset of autumn, the white hare molts, but if the snowfall is delayed, then the white hare becomes clearly visible against the dark background of bare fields.

The characteristics of an organism, even under the conditions in which they have been preserved by selection, never achieve absolute perfection. Thus, the roundworm egg is well protected from the effects of poisons, but quickly dies from lack of moisture and high temperature.

Venom glands are a reliable defense for many animals, but the poison of the karakurt, fatal to camels and large cattle, safe for sheep and pigs. The viper does not pose a danger to the hedgehog.

Milkweed stems are not eaten by herbivorous mammals, but remain defenseless against milkweed hawk moth caterpillars, etc. Selection always has a wide field of activity for further improvement of devices.

If conditions change, then adaptations that were previously appropriate cease to be so. Then new adaptations appear, and forms that were previously “expedient” die out.

ADAPTIVE CHARACTERISTICS

ADAPTIVE CHARACTERS are hereditary characteristics of organisms that correspond to one or another feature of their usual habitat. Favor the life of the organism in this environment.

Ecological encyclopedic dictionary. - Chisinau: Main editorial office of the Moldavian Soviet Encyclopedia. I.I. Dedu. 1989.

See what “ADAPTIVE CHARACTERISTICS” are in other dictionaries:

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The adaptability of organisms to their environment is inextricably linked with their vitality, ability to compete (competitiveness) And leaving normal offspring.

Viability

Animals

Plants

Body coloring of butterflies

The cat and its wild relatives (tiger, leopard) hunt from ambush, concealing their prey. All cats take care of themselves and lick their fur so that there is no smell. After all, the victims should not smell the predator. A cat most often hunts in the dark, because, hiding, at this time it becomes more invisible. Therefore, all cats see well in the dark. A cat is a solitary animal, it “walks on its own”; This is why these animals are difficult to train.

A dog is a completely different matter. Canine relatives (wolves, jackals) mostly hunt in packs, so they are very sociable and easily get used to obeying their leader. The dog can be trained, and it becomes very obedient. Dogs lick themselves very rarely and smell like dogs - after all, these animals do not sit in ambush. To find prey, the dog and its relatives use a keen sense of smell. Dogs have excellent tracking; these animals can follow a scent for a long time.

Having worked through these topics, you should be able to:

1. Formulate in your own words the definitions: evolution, natural selection, struggle for existence, adaptation, rudiment, atavism, idioadaptation, biological progress and regression.
2. Briefly describe how a particular adaptation is preserved by selection. What role do genes play in this, genetic variability, gene frequency, natural selection.
3. Explain why selection does not produce a population of identical, perfectly adapted organisms.
4. Formulate what genetic drift is; give an example of a situation in which it plays an important role, and explain why its role is especially important in small populations.
5. Describe two ways species arise.
6. Compare natural and artificial selection.
7. Briefly list aromorphoses in the evolution of plants and vertebrates, idioadaptations in the evolution of birds and mammals, angiosperms.
8. Name the biological and social factors of anthropogenesis.
9. Compare the effectiveness of consuming plant and animal foods.
10. Briefly describe the features of the most ancient, ancient, fossil man, modern man.
11. Indicate the developmental features and similarities of human races.

Ivanova T.V., Kalinova G.S., Myagkova A.N. "General Biology". Moscow, "Enlightenment", 2000

• Topic 14. "Evolutionary teaching." §38, §41-43 pp. 105-108, pp.115-122
• Topic 15. "Adaptability of organisms. Speciation." §44-48 pp. 123-131
• Topic 16. "Evidence of evolution. Development of the organic world." §39-40 pp. 109-115, §49-55 pp. 135-160
• Topic 17. "The Origin of Man." §49-59 pp. 160-172

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

During evolution, organisms acquire various properties that allow them to more successfully adapt to their living conditions. For example, the fur of northern animals (arctic foxes, bears) is white, making them almost invisible against the background of snow. Insects that feed on flower nectar have the structure and length of their proboscis that is ideal for this. Seal flippers, modified from the paws of their land-dwelling ancestors, are perfectly adapted to movement in water. Giraffes live in the savannah and eat tree leaves at high altitudes, which their long neck helps them do.

There are many such examples, since every living creature has a large number of characteristics acquired in the process of adaptation to specific living conditions.

Question 2. Why do some animals have bright, unmasking colors, while others, on the contrary, have protective colors?

Two types of coloring correspond to two variants of behavioral strategy. In one of them, the animal tries to remain unnoticed, trying to avoid meeting a predator or sneaking up on the prey. For this purpose, protective coloring is used, allowing it to blend into the background. On the other hand, animals that are dangerous or poisonous often make a point of emphasizing this. They use bright, unmasking colors that warn: “don’t eat me.” In addition to poisonous organisms, this strategy is used by harmless species that mimic them. Organisms can have unmasking colors for a completely different reason - in connection with the desire to attract a partner for reproduction (the bright colors 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 turns out to be more significant for the organism.

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

The essence of mimicry (from the Greek mimikos - imitative) is that harmless animals in the process of evolution acquire resemblance to dangerous (poisonous) species. This allows them to avoid attacks from predators. An example is provided by some non-venomous snakes: there is a species of snake that is similar in color to the deadly adder and differs from it only in the alternation of stripes. In addition to coloring, mimicking animals have characteristic behavior: hoverflies behave like wasps, imitating aggression.

Question 4. Does natural selection apply to animal behavior? Give examples.

Natural selection affects not only external signs organism, but also on behavior. This applies, first of all, to innate (instinctive) forms of behavior. Such forms are very diverse: methods of obtaining food, manifestations of fear and aggression, sexual behavior, parental behavior, etc. A spider weaves a web, a bee builds a honeycomb, a cat takes a threatening pose in a moment of danger, chipmunks store supplies and hibernate for the winter and etc. Mating rituals are very complex, 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 (hiding and warning) coloration in animals?

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

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

Adaptation is a set of structural features, physiology and behavior of living organisms to specific conditions in which they can normally exist and leave offspring.

The emergence of adaptation to the environment is the main result of evolution. Therefore, evolution can be viewed as the process of the emergence of adaptations or adaptations.

Organisms that failed to adapt to the environment became extinct.