Mechanisms of plant adaptation to adverse environmental conditions. Adaptations of organisms to living conditions Types of adaptation of organisms

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 membranes between the toes in waterfowl (amphibians, birds, etc.), a thick coat in northern mammals, long legs and a long neck in marsh birds, a flexible body in burrowing predators (for example, in weasels), etc. In warm-blooded animals, when moving north, an increase in the average body size (Bergmann's rule) is noted, which reduces the relative surface and heat transfer. In bottom fish, a flat body is formed (stingrays, flounder, etc.). Plants in northern latitudes and high mountain regions often have creeping and cushion-shaped forms, less damaged by 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 of protection against 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, arctic foxes, pinniped cubs - white 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 potato 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 have a long root system that allows them to extract water 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. The white color of 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, which testify to the extinction of large groups of animals and plants that did not survive the change in living conditions.

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The textbook is addressed to students in grade 11 and is designed to teach the subject 1 or 2 hours a week.

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Rice. 33. Winter coloring of a hare

So, as a result of the action of the driving forces of evolution, organisms develop and improve adaptations to environmental conditions. Fixation in isolated populations of various adaptations can eventually lead to the formation of new species.

Review questions and assignments

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

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

3. What is the essence of mimicry?

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 physiological adaptations factors that determine the level of fitness of the organism as a whole?

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

Think! Execute!

1. Why is there no absolute adaptation to living conditions? Give examples proving the relative nature of any device.

2. Boar cubs have a characteristic striped coloration that disappears with age. Give similar examples of color changes in adults compared to offspring. Can this pattern be considered common to the entire animal kingdom? If not, for which animals and why is it typical?

3. Gather information about warning color animals in your area. Explain why knowledge of this material is important for everyone. Make an information stand about these animals. Give a presentation on this topic in front of elementary school students.

Work with computer

Refer to the electronic application. Study the material and complete the assignments.

Repeat and remember!

Human

Behavioral adaptations are innate unconditioned reflex behavior. Innate abilities exist in all animals, including humans. A newborn baby can suck, swallow and digest food, blink and sneeze, react to light, sound and pain. These are examples unconditioned reflexes. Such forms of behavior arose in the process of evolution as a result of adaptation to certain, relatively constant environmental conditions. Unconditioned reflexes are inherited, so all animals are born with a ready-made complex of such reflexes.

Each unconditioned reflex occurs in response to a strictly defined stimulus (reinforcement): some to food, others to pain, others to the appearance of new information, etc. The reflex arcs of unconditioned reflexes are constant and pass through the spinal cord or brain stem.

One of the most complete classifications of unconditioned reflexes is the classification proposed by Academician P. V. Simonov. The scientist proposed to divide all unconditioned reflexes into three groups, differing in the features of the interaction of individuals with each other and with the environment. Vital reflexes(from lat. vita - life) are aimed at preserving the life of the individual. Failure to comply with them leads to the death of the individual, and the implementation does not require the participation of another individual of the same species. This group includes food and drink reflexes, homeostatic reflexes (maintaining a constant body temperature, optimal breathing rate, heart rate, etc.), defensive ones, which, in turn, are divided into passive-defensive (runaway, hiding) and active defensive (attack on a threatening object) and some others.

TO zoosocial, or role-playing reflexes include those variants of innate behavior that arise when interacting with other individuals of their species. These are sexual, parent-child, territorial, hierarchical reflexes.

The third group is reflexes of self-development. They are not connected with adaptation to a specific situation, but, as it were, turned to the future. Among them are exploratory, imitative and playful behavior.

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Basically, adaptation systems in one way or another relate to the cold, which is quite logical - if you manage to survive in a deep minus, other dangers will not be so terrible. The same, by the way, applies to extremely high temperatures. Who is able to adapt, most likely will not disappear anywhere.

Arctic hare are the largest hares in North America, which for some reason have relatively short ears. This is a great example of what an animal can sacrifice to survive in harsh conditions - while long ears can help hear a predator, short ones reduce the release of precious heat, which is much more important for Arctic hare.

Frogs from Alaska, the species Rana sylvatica, perhaps even outdid the Antarctic fish. They literally freeze into the ice in winter, thus waiting out the cold season, and come back to life in the spring. Such a “cryosleep” is possible for them due to the special structure of the liver, which doubles during hibernation, and the complex biochemistry of blood.

Some praying mantis species, unable to spend all day in the sun, cope with the lack of heat through chemical reactions in their own bodies, concentrating flashes of heat inside for short-term heating.

A cyst is a temporary form of existence of bacteria and many unicellular organisms, in which the body surrounds itself with a dense protective shell in order to protect itself from an aggressive external environment. This barrier is very effective - in some cases, it can help the host survive for a couple of decades.

Nototheniform fish live in Antarctic waters so cold that normal fish would freeze to death there. Sea water freezes only at a temperature of -2 ° C, which cannot be said about completely fresh blood. But Antarctic fish secrete a natural antifreeze protein that prevents ice crystals from forming in the blood - and survive.

Megathermia - the ability to generate heat using body mass, thereby surviving in cold conditions even without antifreeze in the blood. This is used by some sea turtles, remaining mobile when the water around them almost freezes.

Asian mountain geese, when crossing the Himalayas, rise to great heights. The highest flight of these birds was recorded at an altitude of 10 thousand meters! Geese have complete control over their body temperature, even changing their blood chemistry as needed to survive in the icy and thin air.

Mudskippers are not the most common type of fish, although they belong to rather banal gobies. At low tide, they crawl along the silt, getting their own food, climbing trees on occasion. In their way of life, mudskippers are much closer to amphibians, and only fins with gills give out fish in them.

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. Outbred domestic dogs in the Krasnodar Territory, cattle of 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). The ears of the African elephant are indicative, the area of ​​\u200b\u200bwhich is 1/6 of the surface of the entire body of the animal. They have abundant innervation and vascularity. In hot weather, about 1/3 of the entire circulating blood passes through the circulatory system of the ear shells in an elephant. As a result of increased blood flow, excessive heat is given off to the external environment.

The desert hare Lapus alleni is even more impressive with its adaptive abilities to high temperatures. 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, a large amount of excess thermal energy is transferred from the surface of the auricles to the external environment in both the elephant and especially 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 conventional physicochemical properties. 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.

In animals of the 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 African hoofed savannahs, the subcutaneous fat 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 complete absence of 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 the omentums and the 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 found differences in the structure of the kidneys of desert and temperate animals. In hot climate animals, the medulla is more developed due to an increase in the rectal tubular part of the nephron.

For example, in an African lion, the thickness of the renal medulla is 34 mm, while in a 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 of the urinary system were found. So, for a kangaroo rat, the pronounced ability of the bladder to reabsorb water from the secondary urine is normal. 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 impact on the structure of the skin of 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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Living organisms are adapted to the environmental conditions in which their ancestors lived for a long time. Adaptations to environmental conditions are otherwise called adaptations. They arise in the process of population evolution, forming a new subspecies, species, genus, etc. Different genotypes accumulate in the population, manifested in different phenotypes. Those phenotypes that are most suitable for environmental conditions are more likely to survive and leave offspring. Thus, the entire population is “saturated” with adaptations that are useful for a given habitat.

According to their forms (types) of adaptation are different. They can affect the structure of the body, behavior, appearance, cell biochemistry, etc. There are the following forms of adaptations.

Body structure adaptations (morphological adaptations). There are significant (at the level of orders, classes, etc.) and small (at the level of species). Examples of the former are the appearance of wool in mammals, the ability to fly in birds, and the lungs in amphibians. An example of minor adaptations is the different structure of the beak in closely related bird species that feed in different ways.

Physiological adaptations. This is a metabolic restructuring. For each species, adapted to its habitat conditions, its own metabolic characteristics are characteristic. So some species eat a lot (for example, birds), because their metabolism is quite fast (birds need a lot of energy to fly). Some species may not drink for a long time (camels). Marine animals can drink sea water, while freshwater and terrestrial animals cannot.

biochemical adaptations. This is a special structure of proteins, fats, giving organisms the opportunity to live in certain conditions. For example, at low temperatures. Or the ability of organisms to produce poisons, toxins, odorous substances for protection.

Protective coloration. Many animals in the process of evolution acquire a body color that makes them less noticeable against the background of grass, trees, soil, that is, where they live. This allows some to protect themselves from predators, others to sneak up unnoticed and attack. Often, young mammals and chicks have protective coloration. While adults may no longer have a protective coloration.

Warning (threatening) coloration. This coloring is bright and well-remembered. Characteristic of stinging and poisonous insects. For example, birds do not eat wasps. Having tried once, they remember the characteristic color of the wasp for the rest of their lives.

Mimicry- external resemblance to poisonous or stinging species, dangerous animals. Allows you to avoid being eaten by predators who "seem" that they are facing a dangerous species. So hover flies look like bees, some non-venomous snakes on poisonous ones, on the wings of butterflies there can be patterns similar to the eyes of predators.

Disguise- the similarity of the shape of the body of an organism with an object of inanimate nature. Here, not only a protective coloration arises, but the organism itself in its form resembles an object of inanimate nature. For example, a branch, a leaf. Camouflage is mainly characteristic of insects.

Behavioral adaptations. Each species of animals develops a special type of behavior that allows them to best adapt to specific living conditions. This includes food storage, care for offspring, mating behavior, hibernation, hiding before an attack, migration, etc.

Often different adaptations are interconnected. For example, protective coloration can be combined with the animal freezing (with behavioral adaptation) at the moment of danger. Also, many morphological adaptations are due to physiological ones.