forms of adaptation. Mechanisms of plant adaptation to adverse environmental conditions Behavioral adaptation characteristics

Adaptations (devices)

Biology and genetics

The relative nature of adaptation: according to a specific habitat, adaptations lose their significance when it changes; hare hare during a delay in winter or during a thaw in early spring noticeable against the background of arable land and trees; aquatic plants die when water bodies dry up, etc. Examples of adaptation Type of adaptation Characteristics of adaptation Examples Special shape and structure of the body Streamlined body shape gills fins Pinniped fish Protective coloration Sometimes continuous and dissecting; is formed in organisms living openly and makes them invisible ...

Adaptations (devices)

Adaptation (or adaptation) is a complex of morphological, physiological, behavioral and other features of an individual, population or species that ensures success in competition with other individuals, populations or species and resistance to environmental factors.

■ Adaptation is the result of the factors of evolution.

The relative nature of adaptation: corresponding to a specific habitat, adaptations lose their significance when it changes (the white hare during a delay in winter or during a thaw, in early spring it is noticeable against the background of arable land and trees; aquatic plants die when water bodies dry up, etc.).

Adaptation examples

In the process of evolution, as a result of natural selection and the struggle for existence, adaptations (adaptations) of organisms to certain living conditions arise. Evolution itself is essentially a continuous process of formation of adaptations, occurring according to the following scheme: intensity of reproduction -> struggle for existence -> selective death -> natural selection -> fitness.

Adaptations affect different aspects of the life processes of organisms and therefore can be of several types.

Morphological adaptations

They are associated with a change in the structure of the body. For example, the appearance of webbing between the toes in waterfowl (amphibians, birds, etc.), a thick coat in northern mammals, long legs and long neck in marsh birds, a flexible body in burrowing predators (for example, in a weasel), etc. In warm-blooded animals, when moving north, an increase in the average body size is noted (Bergmann's rule), which reduces the relative surface and heat transfer. In bottom fish, a flat body is formed (stingrays, flounder, etc.). Plants in northern latitudes and highlands often creeping and pillow-shaped forms, less damaged strong winds and better warmed by the sun in the soil layer.

Protective coloration

Protective coloration is very important for animal species that do not have effective means protection from predators. Thanks to her, animals become less visible on the ground. For example, female birds hatching eggs are almost indistinguishable from the background of the area. Bird eggs are also colored to match the color of the area. Bottom fish, most insects and many other animal species have a protective coloration. In the north, white or light coloration is more common, helping to camouflage in the snow ( polar bears, polar owls, polar foxes, cubs of pinnipeds - pups, etc.). A number of animals developed a coloration formed by alternating light and dark stripes or spots, making them less noticeable in bushes and dense thickets (tigers, young wild boars, zebras, spotted deer, etc.). Some animals are able to change color very quickly depending on the conditions (chameleons, octopuses, flounder, etc.).

Disguise

The essence of disguise is that the shape of the body and its color make animals look like leaves, knots, branches, bark or thorns of plants. Often found in insects that live on plants.

Warning or threatening coloration

Some types of insects that have poisonous or odorous glands have a bright warning color. Therefore, predators that once encountered them remember this color for a long time and no longer attack such insects (for example, wasps, bumblebees, ladybugs, Colorado beetles and a number of others).

Mimicry

Mimicry is the coloring and body shape of harmless animals that mimics their venomous counterparts. For example, some non-venomous snakes look like poisonous ones. Cicadas and crickets resemble large ants. Some butterflies have large spots on their wings that resemble the eyes of predators.

Physiological adaptations

This type of adaptation is associated with the restructuring of metabolism in organisms. For example, the emergence of warm-bloodedness and thermoregulation in birds and mammals. In simpler cases, this is an adaptation to certain forms of food, the salt composition of the environment, high or low temperatures, humidity or dryness of soil and air, etc.

Biochemical adaptations

Behavioral adaptations

This type of adaptation is associated with a change in behavior in certain conditions. For example, caring for offspring leads to better survival of young animals and increases the resilience of their populations. During the mating season, many animals form separate families, and in winter they unite in flocks, which facilitates their food or protection (wolves, many species of birds).

Adaptations to periodic environmental factors

These are adaptations to environmental factors that have a certain periodicity in their manifestation. This type includes daily alternations of periods of activity and rest, states of partial or complete anabiosis (dropping leaves, winter or summer diapauses of animals, etc.), animal migrations caused by seasonal changes, etc.

Adaptations to extreme living conditions

Plants and animals that live in deserts and polar regions also acquire a number of specific adaptations. In cacti, the leaves have evolved into spines (to reduce evaporation and protect against being eaten by animals), and the stem has evolved into a photosynthetic organ and reservoir. Desert plants are long root system allowing water to be extracted from great depths. Desert lizards can survive without water by eating insects and obtaining water by hydrolyzing their fats. In northern animals, in addition to thick fur, there is also a large supply of subcutaneous fat, which reduces body cooling.

Relative nature of adaptations

All adaptations are expedient only for certain conditions in which they have developed. When these conditions change, adaptations can lose their value or even harm the organisms that have them. white coloring hares, which protects them well in the snow, becomes dangerous during winters with little snow or strong thaws.

The relative nature of adaptations is also well proven by paleontological data indicating extinction. large groups animals and plants that have not survived the change in living conditions.

Such an observation is interesting. In animals of the northern populations, all elongated parts of the body - limbs, tail, ears - are covered with a dense layer of wool and look relatively shorter than in representatives of the same species, but living in a hot climate.

This pattern, known as the Alain rule, applies to both wild and domestic animals.

There is a noticeable difference in the body structure of the northern fox and the fennec fox in the south, the northern wild boar and the wild boar in the Caucasus. Mongrel domestic dogs in Krasnodar Territory, large cattle local selection are distinguished by a lower live weight compared to representatives of these species, say, Arkhangelsk.

Often animals from the southern populations of long-legged and long-eared. Large ears, unacceptable at low temperatures, arose as an adaptation to life in a hot zone.

And the animals of the tropics have just huge ears (elephants, rabbits, ungulates). Indicative ears African elephant, whose area is 1/6 of the surface of the entire body of the animal. They have abundant innervation and vascularity. V hot weather in an elephant, approximately 1/3 of the entire circulating blood passes through the circulatory system of the ear shells. As a result of increased blood flow in external environment excess heat is given off.

Even more impressive is its adaptive ability to high temperatures desert hare Lapus alleni. In this rodent, 25% of the entire body surface falls on bare auricles. It is not clear what the main biological task of such ears is: to detect the approach of danger in time or to participate in thermoregulation. Both the first and the second task are solved by the animal very effectively. The rodent has a keen ear. The developed circulatory system of the auricles with a unique vasomotor ability serves only thermoregulation. By increasing and limiting blood flow through the auricles, the animal changes heat transfer by 200-300%. Its hearing organs perform the function of maintaining thermal homeostasis and saving water.

Due to the saturation of the auricles with thermosensitive nerve endings and rapid vasomotor reactions from the surface of the auricles, a large number of excess thermal energy in the elephant, and especially in the lepus.

The structure of the body of a relative of modern elephants, the mammoth, fits well into the context of the problem under discussion. This northern analogue of the elephant, judging by the preserved remains found in the tundra, was much larger than its southern relative. But the ears of the mammoth had a smaller relative area and, moreover, were covered with thick hair. The mammoth had relatively short limbs and a short trunk.

Long limbs are unfavorable at low temperatures, since too much thermal energy is lost from their surface. But in hot climates, long limbs are a useful adaptation. In desert conditions, camels, goats, horses of local selection, as well as sheep, cats, as a rule, have long legs.

According to H. Hensen, as a result of adaptation to low temperatures in animals, the properties of subcutaneous fat and bone marrow change. In arctic animals, bone fat from the phalanx of the fingers has a low melting point and does not freeze even in severe frosts. However, bone fat from bones that do not come into contact with a cold surface, such as the femur, has the usual physicochemical characteristics. Liquid fat in the bones of the lower extremities provides thermal insulation and joint mobility.

The accumulation of fat is noted not only in northern animals, for which it serves as a thermal insulation and a source of energy during a period when food is not available due to severe bad weather. Fat accumulate and animals living in hot climates. But the quality, quantity and distribution of body fat in northern and southern animals is different. In wild arctic animals, fat is distributed evenly throughout the body in the subcutaneous tissue. In this case, the animal forms a kind of heat-insulating capsule.

Animals temperate zone fat as a heat insulator accumulates only in species with a poorly developed coat. In most cases, stored fat serves as a source of energy during the hungry winter (or summer) period.

In hot climates, subcutaneous fat deposits carry a different physiological burden. The distribution of body fat throughout the body of animals is characterized by great unevenness. Fat is localized in the upper and back parts of the body. For example, in ungulates African savannas the fatty subcutaneous layer is localized along the spine. It protects the animal from the scorching sun. The belly is completely free of fat. It also makes a lot of sense. Ground, grass or water, which is colder than air, ensures efficient heat removal through the abdominal wall in the absence of fat. Small fat deposits and in animals in a hot climate are a source of energy for a period of drought and the associated hungry existence of herbivores.

The internal fat of animals in a hot and arid climate performs another extremely useful function. In conditions of lack or total absence water internal fat serves as a source of water. Special studies show that the oxidation of 1000 g of fat is accompanied by the formation of 1100 g of water.

An example of unpretentiousness in the arid conditions of the desert are camels, fat-tailed and fat-tailed sheep, and zebu-like cattle. The mass of fat accumulated in the humps of a camel and the fat tail of a sheep is 20% of their live weight. Calculations show that a 50-kilogram fat-tailed sheep has a water supply of about 10 liters, and a camel even more - about 100 liters. The last examples illustrate the morphophysiological and biochemical adaptations of animals to extreme temperatures. Morphological adaptations extend to many organs. In northern animals, there is a large volume of the gastrointestinal tract and a large relative length of the intestine, they deposit more internal fat in omentums and perirenal capsule.

Animals of the arid zone have a number of morphological and functional features of the system of urination and excretion. As early as the beginning of the 20th century. morphologists have discovered differences in the structure of the kidneys of desert animals and animals temperate climate. In hot climate animals, the medulla is more developed due to an increase in the rectal tubular part of the nephron.

For example, at African lion the thickness of the renal medulla is 34 mm, while in the domestic pig it is only 6.5 mm. The ability of the kidneys to concentrate urine is positively correlated with the length of the loop of Hendle.

In addition to structural features in animals of the arid zone, functional features urinary system. So, for a kangaroo rat, a pronounced ability is normal Bladder reabsorb water from secondary urine. In the ascending and descending channels of the loop of Hendle, urea is filtered - a process common to the nodule part of the nephron.

The adaptive functioning of the urinary system is based on neurohumoral regulation with a pronounced hormonal component. In kangaroo rats, the concentration of the hormone vasopressin is increased. So, in the urine of a kangaroo rat, the concentration of this hormone is 50 U / ml, in a laboratory rat - only 5-7 U / ml. In the pituitary tissue of a kangaroo rat, the content of vasopressin is 0.9 U/mg, in a laboratory rat it is three times less (0.3 U/mg). Under water deprivation, differences between animals persist, although the secretory activity of the neurohypophysis increases in both one and the other animal.

The loss of live weight during water deprivation in arid animals is lower. If a camel loses 2-3% of its live weight during a working day, receiving only low-quality hay, then a horse and a donkey under the same conditions will lose 6-8% of their live weight due to dehydration.

The temperature of the habitat has a significant effect on the structure skin animals. In cold climates, the skin is thicker, the coat is thicker, and there are downs. All this helps to reduce the thermal conductivity of the body surface. In animals of a hot climate, the opposite is true: thin skin, sparse hair, low heat-insulating properties of the skin as a whole.

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These are the optimal proportions of the body, the location and density of the hair or feather cover, etc. well-known appearance aquatic mammal- a dolphin. 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. The torpedo-shaped shape of the body avoids the formation of eddies of water flows around the dolphin.