Ways living organisms survive unfavorable conditions (wintering, hibernation, suspended animation, migration, etc.).

Wintering- ways to survive the unfavorable winter period (low temperatures, lack of food) for animals in temperate and cold zones. In invertebrates, there are development cycles where one of the phases is cold-resistant (example: locust eggs, beetle larvae, butterfly pupae). In warm-blooded animals - hibernation (hibernation) - bear, hedgehog, badger - during it biological processes slow down. In plants, wintering is accompanied by a cessation or sharp slowdown of physiological processes. The physiological meaning is to conserve energy in unfavorable conditions. Summer hibernation is associated with seasonal moisture deficiency (estivation) - lungfish.

Anabiosis- a state of the body in which physiological processes temporarily stop or are so slow that there are no visible manifestations of life, observed with a sharp deterioration in living conditions - low temperature, drought. When favorable conditions occur, the normal level of vital activity is restored; cysts are the most stable. In poikilotherms - amphibians (toads, frogs, newts) - long-term exposure high temperatures for awakening. Diapause - special case anabiosis, in insects there is larval (in hawthorn), pupal, imaginal (mosquito) diapause.

Winter dream- inhibition in the cerebral cortex and subcortical areas, accompanied by a decrease in metabolism. Winter sleep allows animals to survive an unfavorable period

of the year. Winter sleep differs from hibernation in the lower intensity of the process of inhibition of all functions and the ability to wake up.

Emigration is a mass relocation of animals from their usual habitats.

Nomadism– short-term and short-term movement of animals from one area to another as an adaptation to surviving unfavorable living conditions. There are seasonal, periodic and random forms of migration. Reason: winter, drought, hibernation, for herbivorous ungulates - availability of food. Moreover, during migrations, animals do not always return to their original places; different routes are observed.

Migration- periodic or non-periodic, horizontal and vertical regular movements of animals to the individual habitat of an individual (group of them) over a season, year or a number of years. Its features: strict seasonality, the presence of a mechanism for controlling its calendar dates, multiple restructuring of the physiological systems of the body due to the upcoming increase in energy consumption, the need for orientation in space, individuals in a certain physiological state are involved in migration, mass character associated with the synchronization of the timing of the development of the migratory state in all individuals. Seasonal migration is known for many animal taxa, most well studied in birds, as well as spawning migrations of fish. Distinguish active, passive, feeding, dispersal and other forms of animal migration.

47. Population structure: spatial and demographic.

Main indicators of population structure – number, distribution of organisms in space and the ratio of individuals of different qualities. Each individual has a certain size, gender, distinctive features morphology, behavioral characteristics, their limits of endurance and adaptability to environmental changes. The distribution of these characteristics in a population also characterizes its structure. The population structure is not stable. The growth and development of organisms, the birth of new ones, death from various causes, changes in environmental conditions, an increase or decrease in the number of enemies - all this leads to changes in various ratios within the population.

Causes of imaginary death (anabiosis) in plant and animal organisms

allowing them to survive unfavorable winter conditions.

O.K. Smirnova, biology teacher highest category Lyceum No. 103, Rostov-on-Don.

Goals: increase the areas of student knowledge; learn to analyze the phenomenon of temporary cessation of vital activity in living organisms that use it as a means to adapt and survive in unfavorable conditions.

Equipment: tables of mollusks, crustaceans, insects, fish, amphibians, reptiles, birds, mammals.

The winter season is unfavorable for many representatives of the animal and plant world, both due to low temperatures and a sharp reduction in the ability to obtain food. During evolutionary development, many species of animals and plants acquired unique adaptive mechanisms to survive in unfavorable seasons. In some species of animals, the instinct to create food reserves arose and became established; others have developed another adaptation - migration. Amazingly long flights of many species of birds, migrations of some species of fish and other representatives of the animal world are known. However, in the process of evolution, another perfect physiological adaptation mechanism has been noticed in many animal species - the ability to fall into a seemingly lifeless state, which manifests itself differently in different animal species and has different names (anabiosis, hypothermia, etc.). Meanwhile, all these conditions are characterized by inhibition of the body’s vital functions to the minimum that allows it to survive unfavorable winter conditions without eating. Those species of animals that are unable to provide themselves with food in winter fall into a similar state of imaginary death and are in danger of dying from cold and hunger. And all this, developed in the process of evolution, is subject to strict natural expediency - the need to preserve the species.

Hibernation is a widespread phenomenon in nature, despite the fact that its manifestations vary among representatives of certain groups of animals, be it animals with an unstable body temperature (poikilothermic), also called cold-blooded, in which the body temperature depends on the surrounding temperature, or animals with a constant body temperature (homeothermic), also called warm-blooded.

Among animals with unstable body temperature, they fall into a state of hibernation. different kinds mollusks, crustaceans, arachnids, insects, fish, amphibians and reptiles, and among animals with a constant body temperature - several species of birds and many species of mammals.

How do snails winter?

Of the soft-bodied type, many species of snails hibernate (for example, all land snails). Common garden snails enter hibernation in October, which lasts until early April. After a long preparatory period, during which they accumulate the necessary nutrients in their bodies, the snails find or dig holes so that several individuals can overwinter together deep underground, where the temperature will be maintained at 7 - 8 ° C. Having sealed the burrows well, the snails descend to the bottom and lie down with the shell opening facing up. They then close this opening, releasing a slimy substance that soon hardens and becomes elastic (film-like). With significant cold weather and lack of nutrients in the body, the snails burrow even deeper into the ground and form another film, thus creating air chambers that act as an excellent insulator. It has been established that during a long winter, snails lose more than 20% of their weight, with the greatest loss occurring in the first 25-30 days. This is explained by the fact that all metabolic processes gradually die out in order to reach the minimum at which the animal falls almost into a state of suspended animation with barely perceptible vital functions. During hibernation, the snail does not feed and breathing almost stops. In the spring, when the first warm days arrive and the soil temperature reaches 8-10°C, when vegetation begins to develop and the first rains fall, snails crawl out of their winter shelters. Then intensive activity begins to restore the depleted food reserves in their body; this is expressed in the absorption of a huge amount of food compared to their body.

Pond water snails also enter a state of hibernation - most of them bury themselves in the silt at the bottom of the reservoir in which they live.

Where do crayfish spend the winter?

Everyone knows the popular threat: “I’ll show you where the crayfish spend the winter!” It is believed that this saying appeared during the times of serfdom, when landowners, punishing guilty serfs, forced them to catch crayfish in the winter. Meanwhile, it is known that this is almost impossible, since crayfish spend the winter buried deep in holes at the bottom of reservoirs.

From a systematic point of view, the class of crustaceans is divided into two subclasses - higher and lower crustaceans.

Among the higher crustaceans, river, marsh and lake crayfish fall into a state of hibernation. Males overwinter in groups in deep holes at the bottom, and females alone in burrows, and in November they glue fertilized eggs to their short legs, from which crustaceans the size of an ant hatch only in June.

Of the lower crustaceans, water fleas (genus Daphnia) are of interest. They lay, depending on conditions, two types of eggs - summer and winter. Winter eggs have a durable shell and are formed when unfavorable living conditions occur. For some species of lower crustaceans, drying and even freezing of eggs is a necessary condition for the continuation of their development.

Diapause in insects.

In terms of the number of species, insects surpass all other classes. Their body temperature depends on the environment, which has strong impact on the speed of life's influences, and low temperatures significantly reduce this speed. At negative temperatures, the entire development of the insect slows down or practically stops. This anabiotic state, known as diapause, is a reversible arrest of developmental processes and is caused by external factors. Diapause occurs when conditions unfavorable for life arise and continues throughout the winter until, with the onset of spring, conditions become more favorable.

The onset of the winter season is delayed different types insects at different stages of their development, in which they overwinter - in the form of eggs, larvae, pupae or adult forms, but usually each individual species enters diapause at a certain stage of its development. So, for example, seven-point ladybug winters as an adult.

It is characteristic that the wintering of insects is preceded by a certain physiological preparation of their body, consisting of the accumulation of free glycerol in their tissues, which prevents freezing. This occurs at the stage of insect development in which they will spend the winter.

Even with the onset of the first signs of cooling in the fall, insects find comfortable shelters (under stones, under the bark of trees, under fallen leaves in burrows in the soil, etc.), where after snowfall the temperature is moderately low and uniform.

The duration of diapause in insects is directly dependent on body fat reserves. Bees do not enter a long diapause, but still become numb at temperatures from 0 to 6°C and can remain in this state for 7-8 days. At lower temperatures they die.

It is also interesting how insects accurately determine the moment when they should exit the anabiotic state. Scientist N.I. Kalabukhov studied suspended animation in some species of butterflies. He found that the duration of diapause varies among individual species. For example, a peacock butterfly remained in a state of suspended animation for 166 days at a temperature of 5.9°C, while silkworm it took 193 days at 8.6°C. According to the scientist, even differences in geographic area affect the duration of diapause.

Do fish hibernate during the winter?

Some species of a wide class of fish also adapt to low water temperatures in winter in a unique way. The normal body temperature of fish is not constant and corresponds to the temperature of the water. When the water temperature suddenly drops sharply, the fish go into a state of shock. However, it is enough for the water to warm up, and they quickly “come to life”. Experiments have shown that frozen fish come to life only in cases where their blood vessels do not freeze.

Some fish that live in Arctic waters adapt to low water temperatures in winter in an original way: they change their blood composition. As the water temperature drops in the fall, salts accumulate in their blood in such a concentration as is typical for sea ​​water, and at the same time the blood freezes with great difficulty (a kind of antifreeze).

From freshwater fish back in November, carp, ruff, perch, catfish and others go into hibernation. When the water temperature drops below 8 - 10°C, these fish move to deeper parts of the reservoirs, bury themselves in large groups in the mud and remain there in a state of hibernation throughout the winter.

Some sea ​​fish They also tolerate extreme cold in a state of hibernation. For example, herring already in the fall approach the coast of the Arctic Ocean in order to fall into a state of hibernation at the bottom of some small bay. The Black Sea anchovy also winters in southern regions sea ​​- off the coast of Georgia, at this time it is not active and does not consume food. And before the onset of winter, the Azov anchovy migrates to the Black Sea, where it gathers in groups in a relatively sedentary state.

Hibernation in fish is characterized by extremely limited activity, complete cessation of nutrition and a sharp decrease in metabolism. At this time, their body is supported by nutrient reserves accumulated due to abundant nutrition in the autumn.

Hibernation of amphibians

In terms of lifestyle and structure, the class of amphibians is transitional between typically aquatic vertebrates and typically terrestrial animals. It is known that various species of frogs, newts, and salamanders also spend the unfavorable winter season in a state of torpor, since these are animals with an unstable body temperature, which depends on the ambient temperature.

Determined that hibernation the life of frogs lasts from 130 to 230 days and its duration depends on the duration of winter.

In water bodies, in order to overwinter, frogs gather in groups of 10-20 individuals, bury themselves in silt, underwater depressions and other voids. During hibernation, frogs breathe only through their skin.

In winter, newts usually roost under warm, rotten stumps and trunks of fallen trees. If they do not find such comfortable “apartments” nearby, they are satisfied with cracks in the soil.

Reptiles also hibernate

From the class of reptiles, almost all species of our fauna fall into a state of hibernation in winter. Low winter temperatures- the main reason for this phenomenon.

Winter quarters are usually underground caves or voids formed around large old stumps with rotten roots, crevices in rocks and other places that are inaccessible to their enemies. Gathers in such shelters big number snakes, forming huge snake balls. It has been established that the temperature of snakes during hibernation is almost no different from the ambient temperature.

Most species of lizards (meadow, striped, green, forest, spindle) also hibernate, burying themselves in the soil, in burrows that are not threatened by flooding. In warm weather sunny days In winter, lizards can “awaken” and crawl out of their winter shelters for a few hours to hunt, after which they retreat back into their burrows, falling into a state of torpor.

Swamp turtles spend the winter burrowing into the silt of the reservoirs in which they live, while land turtles climb to a depth of up to 0.5 m into the soil in some natural shelters or holes of moles, foxes, rodents, covering themselves with peat, moss and wet leaves.

Preparations for wintering begin in October, when turtles accumulate fat. In the spring, with temporary warming, they wake up, sometimes for a whole week.

Do birds hibernate in winter?

Most animals with an unstable body temperature, which depends on the environment, fall into a state of hibernation. But it is surprising that many animals with a constant body temperature, such as birds, can also hibernate during unfavorable seasons. It is known that most birds avoid unfavorable winter conditions by migrating. Aristotle, in his multi-volume History of Animals, drew attention to the fact that “some birds fly away to spend the winter in warm countries, while others take refuge in different shelters, where they hibernate.”

This conclusion was also reached by the prominent Swedish naturalist Carl Linnaeus, who wrote in his work “The System of Nature”: “In autumn, when the weather begins to get colder, swallows, not finding enough insects for food, begin to seek shelter for the winter in reed thickets along the banks of lakes and rivers. "

The torpor into which some species of birds fall differs significantly from the hibernation characteristic of many mammals. First of all, the bird’s body not only does not accumulate energy reserves in the form of fat, but, on the contrary, consumes a significant part of it. While mammals hibernate during the winter, gaining noticeable weight, birds lose a lot of weight before going into torpor. This is why the phenomenon of torpor in birds, according to Soviet biologist R. Potapov, should be called hypothermia rather than hibernation.

Until now, the mechanism of hypothermia in birds has not been fully studied. The fall of birds into a state of torpor under unfavorable living conditions is an adaptive physiological reaction that has been consolidated in the process of evolution.

What mammals hibernate?

As in those animals that were discussed earlier, in mammals, hibernation is a biological adaptation for surviving an unfavorable season of the year. Despite the fact that animals with a constant body temperature usually tolerate cold climate conditions, the lack of suitable food in winter has caused some of them to acquire and gradually consolidate in the process of evolution this peculiar instinct - spending the unfavorable winter season in an inactive state of hibernation.

There are three types of hibernation based on the degree of torpor:

1) mild torpor that easily stops (raccoons, badgers, bears, raccoon dogs);

2) complete torpor, accompanied by periodic awakenings only on warmer winter days (hamsters, chipmunks, bats);

3) real continuous hibernation, which is a stable, prolonged torpor (gophers, hedgehogs, marmots, jerboas).

Winter hibernation in mammals is preceded by a certain physiological preparation of the body. It consists primarily of the accumulation of fat reserves, mainly under the skin. Some winter hibernators experience hibernation. subcutaneous fat reaches 25% of total body weight. For example, ground squirrels gain weight even at the beginning of autumn, increasing their body weight three times compared to the spring-summer weight. Before hibernation, hedgehogs and brown bears, as well as all bats, become significantly fatter.

Other mammals, such as hamsters and chipmunks, do not accumulate large reserves of fat, but store food in their shelter for use during their brief awakening periods in winter.

During hibernation, all species of mammals lie motionless in their burrows, curled up into a ball. This is the best way to retain heat and limit heat exchange with environment. The winter quarters of many mammals are the natural cavities of stems and tree hollows.

Among the insectivorous mammals, the hedgehog, in preparation for hibernation, collects moss, leaves, hay in a secluded place and makes a nest for itself. But it “settles” in its new home only when the temperature for a long time kept below 10°C. Before this, the hedgehog eats heavily to accumulate energy in the form of fat.

Hibernation brown bears is a slight numbness. In nature, in the summer, a bear accumulates a thick layer of subcutaneous fat and, just before the onset of winter, settles down in its den for hibernation. Usually the den is covered with snow, so it is much warmer inside than outside. During hibernation, accumulated fat reserves are used by the bear's body as a source of nutrients, and also protect the animal from freezing.

From a physiological point of view, hibernation in mammals is characterized by a weakening of all vital functions of the body to the minimum that would allow them to survive unfavorable winter conditions without food.

Behavioral - migration of birds, migration of ungulates in search of food, burrowing in sand, soil, snow, etc.

Physiological - a sharp decrease in the activity of vital processes - suspended animation (resting stages in invertebrates, cessation of activity in reptiles during low temperatures, hibernation of mammals).

Morphological - wool and subcutaneous fat in animals in cold climates, economical use of water in desert animals, etc.

Examples of adaptations.

Temperature is one of the main factors that directly affects all organisms.

Ectothermic animals (poikilothermic, cold-blooded).

Everything except birds and mammals. Passive type of adaptation to temperature.

Low metabolic rate. The main source of thermal energy is external. Activity depends on ambient temperature.

Endothermic animals (homeothermic, warm-blooded).

Birds and mammals. Active type of adaptation to temperature. They are provided with heat due to their own heat production and are able to actively regulate heat production and its consumption (the presence of chemical thermoregulation due to heat release, for example, during breathing, and physical thermoregulation due to heat-insulating structures (fat layer, feathers, hair))

"Allen's Rule"

The colder the climate, the shorter the protruding parts of the body (for example, ears).

Example: Arctic fox in polar latitudes, Red fox in temperate latitudes, African fennec fox.

"Bergman's Rule".

Animals of the same species in different climatic conditions have different weights: they are larger in cold conditions and smaller in warm conditions.

Example: Emperor penguin– the largest – lives in Antarctica,

The Galapagos penguin is the smallest penguin and lives at the equator.

"Gloger's Rule"

Geographic races of animals in warm and humid regions are more pigmented (i.e., individuals are darker) than in cold and dry regions.

Example: Polar bear, Brown bear.

Adaptation of plants to survive unfavorable conditions.

Morphological - shedding leaves, overwintering perennial organs (bulbs, rhizomes, tubers) in the soil, storing them in the form of seeds or spores.

Physiological - salt content in the body of halophytes, metabolic features, “physiological” dryness of marsh plants.

Behavioral -“Escape” from unfavorable conditions in time: a short growing season (ephemera and ephemeroids).

Ticket number 10

Life forms and examples.

Life form- external (physiognomic) appearance of an organism, a complex of morphological, anatomical, physiological and behavioral characteristics, which reflects its general adaptability to environmental conditions.

System of life forms of plants.

Phanerophytes – trees.

Chamephytes – bushes.

Hemicryptophytes – bushes.

Geophytes – perennial herbs.

Therophytes – annual herbs.

Hydrophytes – aquatic plants.

Solitary lifestyle.

Individuals of populations are independent and isolated from each other.

Characteristic at certain stages of the life cycle.

Example: ladybug, darkling beetle.

Completely solitary existence of organisms does not occur in nature.

Family lifestyle.

Connections are established between parents and their offspring.

Caring for offspring;

Ownership of the site.

Example: Bear, Tigers.

Flocks.

Temporary associations of animals that exhibit biologically useful organization of actions.

Flocks make it easier to perform any functions in the life of the species, protection from enemies, obtaining food, migration.

Schooling is most widespread among birds and fish; in mammals it is characteristic of many canines.

Herds.

Longer and more permanent associations of animals compared to packs.

The basis of group behavior in herds is the relationship of dominance and submission.

Colonies.

Group settlements of sedentary animals.

They can exist for a long time or appear only during the breeding season.

Example: Colonial settlements of birds, Social insects.

By winter or dry summer, reserve energy substances, such as glycogen, accumulate in the body to help survive a difficult season. Animals get fat to one degree or another. In some species, fat makes up up to 25% of the total body weight. For example, the small ground squirrel in the spring has a mass of about 100-150 g, and in mid-summer - up to 400 g.

Adaptations to unfavorable environmental conditions are also expressed in migrations. Thus, in the fall, as feeding conditions worsen, the bulk of arctic foxes and reindeer migrate from the tundra to the south, into the forest-tundra and even into the taiga, where it is easier to obtain food from under the snow. Following the deer they migrate south and tundra wolves. In the northern regions of the tundra, white hares undertake mass migrations to the south at the beginning of winter, and in the opposite direction in the spring. By summer, mountain ungulates rise to the upper belts of the mountains with their rich grass stand, but in winter, as the depth of the snow cover increases, they descend. And in this case, migrations of some predators, such as wolves, combined with ungulates are observed.

In general, migration is characteristic of a relatively smaller number of species than birds and fish. They are most developed in sea animals, bats and ungulates, while among species they are most numerous groups- rodents, insectivores and small predators - there are practically none.

An alternative to migration in these animals is hibernation. There are facultative seasonal and continuous seasonal hibernation. In the first case, body temperature, number of respiratory movements and general level metabolic processes decrease little. When the situation changes or when there is anxiety, sleep is easily interrupted (bears, raccoons). True continuous seasonal hibernation is characterized by loss of the ability to thermoregulate, a sharp reduction in the number of respiratory movements and contractions of the heart muscle, and a fall in general level metabolism (marmots, gophers).

An important adaptation to surviving unfavorable conditions is collecting food reserves. Among other vertebrates, only a few groups of birds (passerines, owls, woodpeckers) collect food for the winter, but the size of their reserves and the adaptive significance of this activity are negligible compared to mammals.

Burying excess spoils is common in . Thus, weasels and stoats collect 20-30 voles and mice each, black hori collect several dozen frogs under the ice, and minks collect several kilograms of fish. Larger predators (martens, wolverines, cats, bears) hide the remains of their prey in secluded places, under fallen trees, under stones. Leopards often hide part of their prey in tree branches. Characteristic feature The storage of food by predators is due to the fact that no special storerooms are built for its burial; the stock is used only by the one individual that built it. In general, reserves serve only as a small help to survive the lean period, and they cannot prevent the sudden onset of food shortage. Various rodents and pikas store food differently, although in this case there are different degrees of perfection of storage and its significance. Flying squirrels collect several tens of grams of terminal branches and catkins of alder and birch, which they put in hollows. Squirrels are buried in fallen leaves, hollows, and acorns and nuts in the ground. They also hang mushrooms on tree branches. One squirrel in the dark coniferous taiga stores up to 150-300 mushrooms, and in band burs Western Siberia, where feeding conditions are worse than in the taiga, up to 1500-2000 mushrooms, mostly boletus. The reserves made by the squirrel are used by many individuals of this species.

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