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 wading 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 (Bergman'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 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.

To survive in adverse climatic conditions, plants, animals and birds have some features. These features are called "physiological adaptations," examples of which can be seen in virtually every mammalian species, including humans.

Why do we need physiological adaptation?

Living conditions in some parts of the world are not entirely comfortable, however, there are various representatives of wildlife. There are several reasons why these animals did not leave the hostile environment.

First of all, climatic conditions could change when a certain species already existed in a given area. Some animals are not adapted to migration. It is also possible that territorial features do not allow migration (islands, mountain plateaus, etc.). For a certain species, the changed living conditions still remain more suitable than in any other place. And physiological adaptation is the best option problem solving.

What is meant by adaptation?

Physiological adaptation is the harmony of organisms with a specific habitat. For example, a comfortable stay in the desert of its inhabitants is due to their adaptation to high temperatures and lack of access to water. Adaptation is the appearance of certain signs in organisms that allow them to get along with any elements of the environment. They arise in the process of certain mutations in the body. Physiological adaptations, examples of which are well known in the world, are, for example, the ability to echolocation in some animals (bats, dolphins, owls). This ability helps them navigate in a space with limited lighting (in the dark, in water).

Physiological adaptation is a set of body reactions to certain pathogenic factors in the environment. It provides organisms with a greater likelihood of survival and is one of the methods of natural selection of strong and resistant organisms in a population.

Types of physiological adaptation

Adaptation of the organism is distinguished genotypic and phenotypic. The genotypic is based on the conditions of natural selection and mutations that led to changes in the organisms of a whole species or population. It was in the process of this type of adaptation that the modern views animals, birds and humans. The genotypic form of adaptation is hereditary.

The phenotypic form of adaptation is due to individual changes in a particular organism for a comfortable stay in certain climatic conditions. It can also develop due to constant exposure to an aggressive environment. As a result, the body acquires resistance to its conditions.

Complex and cross adaptations

Complex adaptations are manifested in certain climatic conditions. For example, the body's adaptation to low temperatures at long stay in the northern regions. This form of adaptation develops in each person when moving to another climatic zone. Depending on the characteristics of a particular organism and its health, this form of adaptation proceeds in different ways.

Cross-adaptation is a form of body habituation in which the development of resistance to one factor increases the resistance to all factors of this group. The physiological adaptation of a person to stress increases his resistance to some other factors, such as cold.

On the basis of positive cross-adaptations, a set of measures was developed to strengthen the heart muscle and prevent heart attacks. IN vivo those people who more often faced stressful situations in their lives are less susceptible to the consequences of myocardial infarction than those who led a calm lifestyle.

Types of adaptive reactions

There are two types of adaptive reactions of the body. The first type is called "passive adaptations". These reactions take place at the cellular level. They characterize the formation of the degree of resistance of the organism to the effects of a negative environmental factor. For example, a change in atmospheric pressure. Passive adaptation allows you to maintain the normal functionality of the body with small fluctuations in atmospheric pressure.

The most well-known physiological adaptations in animals of the passive type are the protective reactions of the living organism to the effects of cold. Hibernation, in which life processes slow down, is inherent in some species of plants and animals.

The second type of adaptive reactions is called active and implies protective measures of the body when exposed to pathogenic factors. In this case, the internal environment of the body remains constant. This type of adaptation is inherent in highly developed mammals and humans.

Examples of physiological adaptations

The physiological adaptation of a person is manifested in all non-standard situations for his environment and lifestyle. Acclimatization is the most famous example adaptations. For different organisms this process takes place at different speeds. Some take a few days to get used to the new conditions, for many it will take months. Also, the rate of habituation depends on the degree of difference with the habitual environment.

In aggressive habitats, many mammals and birds have a characteristic set of body reactions that make up their physiological adaptation. Examples (in animals) can be observed in almost every climate zone. For example, desert dwellers accumulate reserves of subcutaneous fat, which oxidizes and forms water. This process is observed before the onset of the drought period.

Physiological adaptation in plants also takes place. But she is passive. An example of such an adaptation is the shedding of leaves by trees when the cold season sets in. The places of the kidneys are covered with scales, which protect them from the harmful effects of low temperatures and snow with wind. Metabolic processes in plants slow down.

In combination with morphological adaptation, the physiological reactions of the body provide it with high level survival in adverse conditions and with drastic changes in the habitat.

Reactions to unfavorable environmental factors only under certain conditions are detrimental to living organisms, and in most cases they have an adaptive value. Therefore, these responses were called by Selye "general adaptation syndrome". In later works, he used the terms "stress" and "general adaptation syndrome" as synonyms.

Adaptation- this is a genetically determined process of formation of protective systems that provide an increase in stability and the flow of ontogenesis in unfavorable conditions for it.

Adaptation is one of the most important mechanisms that increases the stability of a biological system, including a plant organism, in the changed conditions of existence. The better the organism is adapted to some factor, the more resistant it is to its fluctuations.

The genotypically determined ability of an organism to change metabolism within certain limits, depending on the action of the external environment, is called reaction rate. It is controlled by the genotype and is characteristic of all living organisms. Most of the modifications that occur within the limits of the reaction norm are of adaptive significance. They correspond to changes in habitat and provide better survival of plants under fluctuating environmental conditions. In this regard, such modifications are of evolutionary importance. The term "reaction rate" was introduced by V.L. Johansen (1909).

The greater the ability of a species or variety to modify according to environment, the wider its reaction rate and the higher the ability to adapt. This property distinguishes resistant varieties of agricultural crops. As a rule, slight and short-term changes in environmental factors do not lead to significant violations of the physiological functions of plants. This is due to their ability to maintain relative dynamic balance. internal environment and stability of basic physiological functions in a changing environment. At the same time, sharp and prolonged impacts lead to disruption of many functions of the plant, and often to its death.

Adaptation includes all processes and adaptations (anatomical, morphological, physiological, behavioral, etc.) that increase stability and contribute to the survival of the species.

1.Anatomical and morphological adaptations. In some representatives of xerophytes, the length of the root system reaches several tens of meters, which allows the plant to use groundwater and not experience a lack of moisture in conditions of soil and atmospheric drought. In other xerophytes, the presence of a thick cuticle, pubescence of leaves, and the transformation of leaves into spines reduce water loss, which is very important in conditions of lack of moisture.

Burning hairs and spines protect plants from being eaten by animals.

Trees in the tundra or at high mountain heights look like squat creeping shrubs, in winter they are covered with snow, which protects them from severe frosts.

In mountainous regions with large diurnal temperature fluctuations, plants often have the form of flattened pillows with densely spaced numerous stems. This allows you to keep moisture inside the pillows and a relatively uniform temperature throughout the day.

In marsh and aquatic plants, a special air-bearing parenchyma (aerenchyma) is formed, which is an air reservoir and facilitates the breathing of plant parts immersed in water.

2. Physiological and biochemical adaptations. In succulents, an adaptation for growing in desert and semi-desert conditions is the assimilation of CO 2 during photosynthesis along the CAM pathway. These plants have stomata closed during the day. Thus, the plant keeps the internal water reserves from evaporation. In deserts, water is the main factor limiting plant growth. The stomata open at night, and at this time, CO 2 enters the photosynthetic tissues. The subsequent involvement of CO2 in the photosynthetic cycle occurs in the daytime already with closed stomata.

Physiological and biochemical adaptations include the ability of stomata to open and close, depending on external conditions. Synthesis of abscisic acid, proline, protective proteins, phytoalexins, phytoncides in cells, increased activity of enzymes that counteract the oxidative breakdown of organic substances, accumulation of sugars in cells and a number of other changes in metabolism contribute to an increase in plant resistance to adverse conditions external environment.

The same biochemical reaction can be carried out by several molecular forms of the same enzyme (isoenzymes), with each isoform exhibiting catalytic activity in a relatively narrow range of some environmental parameter, such as temperature. The presence of a number of isoenzymes allows the plant to carry out the reaction in a much wider range of temperatures, compared with each individual isoenzyme. This enables the plant to successfully perform vital functions in changing temperature conditions.

3. Behavioral adaptations, or avoidance of an adverse factor. An example is ephemera and ephemeroids (poppy, starflower, crocuses, tulips, snowdrops). They go through the entire cycle of their development in the spring for 1.5-2 months, even before the onset of heat and drought. Thus, they kind of leave, or avoid falling under the influence of the stressor. In a similar way, early-ripening varieties of agricultural crops form a crop before the onset of adverse seasonal events: August fogs, rains, frosts. Therefore, the selection of many agricultural crops is aimed at creating early ripe varieties. Perennial plants overwinter as rhizomes and bulbs in the soil under snow, which protects them from freezing.

Adaptation of plants to unfavorable factors is carried out simultaneously at many levels of regulation - from a single cell to a phytocenosis. The higher the level of organization (cell, organism, population), the greater the number of mechanisms simultaneously involved in the adaptation of plants to stress.

Regulation of metabolic and adaptive processes inside the cell is carried out with the help of systems: metabolic (enzymatic); genetic; membrane. These systems are closely related. Thus, the properties of membranes depend on gene activity, and the differential activity of the genes themselves is under the control of membranes. The synthesis of enzymes and their activity are controlled by genetic level at the same time, enzymes regulate the nucleic acid metabolism in the cell.

On organism level to the cellular mechanisms of adaptation, new ones are added, reflecting the interaction of organs. Under unfavorable conditions, plants create and retain such a number of fruit elements that are provided in sufficient quantities with the necessary substances to form full-fledged seeds. For example, in the inflorescences of cultivated cereals and in the crowns of fruit trees, under adverse conditions, more than half of the laid ovaries can fall off. Such changes are based on competitive relations between organs for physiologically active and nutrients.

Under stress conditions, the processes of aging and falling of the lower leaves are sharply accelerated. At the same time, the substances necessary for plants move from them to young organs, responding to the survival strategy of the organism. Thanks to the recycling of nutrients from the lower leaves, the younger ones, the upper leaves, remain viable.

There are mechanisms of regeneration of lost organs. For example, the surface of the wound is covered with a secondary integumentary tissue (wound periderm), the wound on the trunk or branch is healed with influxes (calluses). With the loss of the apical shoot, dormant buds awaken in plants and lateral shoots develop intensively. Spring restoration of leaves instead of fallen ones in autumn is also an example of natural organ regeneration. Regeneration as a biological adaptation that provides vegetative reproduction plants by segments of the root, rhizome, thallus, stem and leaf cuttings, isolated cells, individual protoplasts, is of great practical importance for plant growing, fruit growing, forestry, ornamental gardening, etc.

The hormonal system is also involved in the processes of protection and adaptation at the plant level. For example, under the influence of unfavorable conditions in a plant, the content of growth inhibitors sharply increases: ethylene and abscissic acid. They reduce metabolism, inhibit growth processes, accelerate aging, fall of organs, and the transition of the plant to a dormant state. Inhibition of functional activity under stress under the influence of growth inhibitors is a characteristic reaction for plants. At the same time, the content of growth stimulants in the tissues decreases: cytokinin, auxin and gibberellins.

On population level selection is added, which leads to the appearance of more adapted organisms. The possibility of selection is determined by the existence of intrapopulation variability in plant resistance to various environmental factors. An example of intrapopulation variability in resistance can be the unfriendly appearance of seedlings on saline soil and an increase in the variation in germination time with an increase in the action of a stressor.

A species in the modern view consists of a large number of biotypes - smaller ecological units, genetically identical, but showing different resistance to environmental factors. Under different conditions, not all biotypes are equally vital, and as a result of competition, only those of them remain that best meet the given conditions. That is, the resistance of a population (variety) to a particular factor is determined by the resistance of the organisms that make up the population. Resistant varieties have in their composition a set of biotypes that provide good productivity even in adverse conditions.

At the same time, in the process of long-term cultivation, the composition and ratio of biotypes in the population changes in varieties, which affects the productivity and quality of the variety, often not for the better.

So, adaptation includes all processes and adaptations that increase the resistance of plants to adverse environmental conditions (anatomical, morphological, physiological, biochemical, behavioral, population, etc.)

But to choose the most effective way of adaptation, the main thing is the time during which the body must adapt to new conditions.

With the sudden action of an extreme factor, the response cannot be delayed, it must follow immediately in order to exclude irreversible damage to the plant. With long-term impacts of a small force, adaptive rearrangements occur gradually, while the choice of possible strategies increases.

In this regard, there are three main adaptation strategies: evolutionary, ontogenetic And urgent. The task of the strategy is the efficient use of available resources to achieve the main goal - the survival of the organism under stress. The adaptation strategy is aimed at maintaining the structural integrity of vital macromolecules and the functional activity of cellular structures, maintaining vital activity regulation systems, and providing plants with energy.

Evolutionary or phylogenetic adaptations(phylogeny - the development of a biological species in time) - these are adaptations that arise during the evolutionary process on the basis of genetic mutations, selection and are inherited. They are the most reliable for plant survival.

Each species of plants in the process of evolution has developed certain needs for the conditions of existence and adaptability to the ecological niche it occupies, a stable adaptation of the organism to the environment. Moisture and shade tolerance, heat resistance, cold resistance and others ecological features specific plant species were formed as a result of long-term action of the relevant conditions. Thus, heat-loving and short-day plants are characteristic of southern latitudes, less heat-demanding and long-day plants are characteristic of northern latitudes. Numerous evolutionary adaptations of xerophyte plants to drought are well known: economical use of water, deep root system, shedding of leaves and transition to a dormant state, and other adaptations.

In this regard, varieties of agricultural plants show resistance precisely to those environmental factors against which breeding and selection of productive forms is carried out. If the selection takes place in a number of successive generations against the background of the constant influence of some unfavorable factor, then the resistance of the variety to it can be significantly increased. It is natural that the varieties of breeding research institutes Agriculture South-East (Saratov), ​​are more resistant to drought than varieties created in the breeding centers of the Moscow region. In the same way, in ecological zones with unfavorable soil and climatic conditions, resistant local plant varieties were formed, and endemic plant species are resistant to the stressor that is expressed in their habitat.

Characterization of the resistance of spring wheat varieties from the collection of the All-Russian Institute of Plant Industry (Semenov et al., 2005)

Variety Origin Sustainability
Enita Moscow region Medium drought resistant
Saratovskaya 29 Saratov region drought resistant
Comet Sverdlovsk region. drought resistant
Karazino Brazil acid resistant
Prelude Brazil acid resistant
Kolonias Brazil acid resistant
Thrintani Brazil acid resistant
PPG-56 Kazakhstan salt tolerant
Osh Kyrgyzstan salt tolerant
Surkhak 5688 Tajikistan salt tolerant
Messel Norway Salt tolerant

In a natural environment, environmental conditions usually change very quickly, and the time during which the stress factor reaches a damaging level is not enough for the formation of evolutionary adaptations. In these cases, plants use not permanent, but stressor-induced defense mechanisms, the formation of which is genetically predetermined (determined).

Ontogenetic (phenotypic) adaptations are not associated with genetic mutations and are not inherited. The formation of such adaptations requires a relatively long time, so they are called long-term adaptations. One of these mechanisms is the ability of a number of plants to form a water-saving CAM-type photosynthesis pathway under conditions of water deficit caused by drought, salinity, low temperatures, and other stressors.

This adaptation is associated with the induction of expression of the phosphoenolpyruvate carboxylase gene, which is inactive under normal conditions, and the genes of other enzymes of the CAM pathway of CO2 uptake, with the biosynthesis of osmolytes (proline), with the activation of antioxidant systems, and with changes in the daily rhythms of stomatal movements. All this leads to very economical water consumption.

In field crops, for example, in corn, aerenchyma is absent under normal growing conditions. But under conditions of flooding and a lack of oxygen in the tissues in the roots, some of the cells of the primary cortex of the root and stem die (apoptosis, or programmed cell death). In their place, cavities are formed, through which oxygen is transported from the aerial part of the plant to the root system. The signal for cell death is the synthesis of ethylene.

Urgent adaptation occurs with rapid and intense changes in living conditions. It is based on the formation and functioning of shock protective systems. Shock defense systems include, for example, the heat shock protein system, which is formed in response to a rapid increase in temperature. These mechanisms provide short-term conditions for survival under the action of a damaging factor and thus create the prerequisites for the formation of more reliable long-term specialized adaptation mechanisms. An example of specialized adaptation mechanisms is the new formation of antifreeze proteins at low temperatures or the synthesis of sugars during the overwintering of winter crops. At the same time, if the damaging effect of the factor exceeds the protective and reparative capabilities of the body, then death inevitably occurs. In this case, the organism dies at the stage of urgent or at the stage of specialized adaptation, depending on the intensity and duration of the extreme factor.

Distinguish specific And non-specific (general) plant responses to stressors.

Nonspecific reactions independent of nature operating factor. They are the same under the action of high and low temperatures, lack or excess of moisture, high concentrations of salts in the soil or harmful gases in the air. In all cases, the permeability of membranes in plant cells increases, respiration is disturbed, the hydrolytic decomposition of substances increases, the synthesis of ethylene and abscisic acid increases, and cell division and elongation are inhibited.

The table shows a complex of nonspecific changes occurring in plants under the influence of various environmental factors.

Changes in physiological parameters in plants under the influence of stressful conditions (according to G.V., Udovenko, 1995)

Options The nature of the change in parameters under conditions
droughts salinity high temperature low temperature
The concentration of ions in tissues growing growing growing growing
Water activity in the cell Falling down Falling down Falling down Falling down
Osmotic potential of the cell growing growing growing growing
Water holding capacity growing growing growing —
Water scarcity growing growing growing —
Protoplasm permeability growing growing growing —
Transpiration rate Falling down Falling down growing Falling down
Transpiration efficiency Falling down Falling down Falling down Falling down
Energy efficiency of breathing Falling down Falling down Falling down —
Breathing intensity growing growing growing —
Photophosphorylation Decreases Decreases — Decreases
Stabilization of nuclear DNA growing growing growing growing
Functional activity of DNA Decreases Decreases Decreases Decreases
Proline concentration growing growing growing —
Content of water-soluble proteins growing growing growing growing
Synthetic reactions Suppressed Suppressed Suppressed Suppressed
Ion uptake by roots Suppressed Suppressed Suppressed Suppressed
Transport of substances Depressed Depressed Depressed Depressed
Pigment concentration Falling down Falling down Falling down Falling down
cell division slows down slows down — —
Cell stretch Suppressed Suppressed — —
Number of fruit elements Reduced Reduced Reduced Reduced
Organ aging Accelerated Accelerated Accelerated —
biological harvest Downgraded Downgraded Downgraded Downgraded

Based on the data in the table, it can be seen that the resistance of plants to several factors is accompanied by unidirectional physiological changes. This gives reason to believe that an increase in plant resistance to one factor may be accompanied by an increase in resistance to another. This has been confirmed by experiments.

Experiments at the Institute of Plant Physiology of the Russian Academy of Sciences (Vl. V. Kuznetsov et al.) have shown that short-term heat treatment of cotton plants is accompanied by an increase in their resistance to subsequent salinization. And the adaptation of plants to salinity leads to an increase in their resistance to high temperatures. Heat shock increases the ability of plants to adapt to the subsequent drought and, conversely, in the process of drought, the body's resistance to high temperature increases. Short-term exposure to high temperatures increases resistance to heavy metals and UV-B radiation. The preceding drought favors the survival of plants in conditions of salinity or cold.

The process of increasing the body's resistance to a given environmental factor as a result of adaptation to a factor of a different nature is called cross-adaptation.

To study the general (nonspecific) mechanisms of resistance, of great interest is the response of plants to factors that cause water deficiency in plants: salinity, drought, low and high temperatures, and some others. At the level of the whole organism, all plants react to water deficiency in the same way. Characterized by inhibition of shoot growth, increased growth of the root system, the synthesis of abscisic acid, and a decrease in stomatal conductance. After some time, the lower leaves rapidly age, and their death is observed. All these reactions are aimed at reducing water consumption by reducing the evaporating surface, as well as by increasing the absorption activity of the root.

Specific reactions are reactions to the action of any one stress factor. So, phytoalexins (substances with antibiotic properties) are synthesized in plants in response to contact with pathogens (pathogens).

The specificity or non-specificity of responses implies, on the one hand, the attitude of a plant to various stressors and, on the other hand, the characteristic reactions of plants of different species and varieties to the same stressor.

The manifestation of specific and nonspecific responses of plants depends on the strength of stress and the rate of its development. Specific responses occur more often if the stress develops slowly, and the body has time to rebuild and adapt to it. Nonspecific reactions usually occur with a shorter and stronger effect of the stressor. The functioning of nonspecific (general) resistance mechanisms allows the plant to avoid large energy expenditures for the formation of specialized (specific) adaptation mechanisms in response to any deviation from the norm in their living conditions.

Plant resistance to stress depends on the phase of ontogeny. The most stable plants and plant organs in a dormant state: in the form of seeds, bulbs; woody perennials - in a state of deep dormancy after leaf fall. Plants are most sensitive at a young age, since growth processes are damaged in the first place under stress conditions. The second critical period is the period of gamete formation and fertilization. The effect of stress during this period leads to a decrease in the reproductive function of plants and a decrease in yield.

If stress conditions are repeated and have a low intensity, then they contribute to the hardening of plants. This is the basis for methods for increasing resistance to low temperatures, heat, salinity, and an increased content of harmful gases in the air.

Reliability plant organism is determined by its ability to prevent or eliminate failures in different levels biological organization: molecular, subcellular, cellular, tissue, organ, organism and population.

To prevent disruptions in the life of plants under the influence of adverse factors, the principles redundancy, heterogeneity of functionally equivalent components, systems for the repair of lost structures.

The redundancy of structures and functionality is one of the main ways to ensure the reliability of systems. Redundancy and redundancy has multiple manifestations. At the subcellular level, the reservation and duplication of genetic material contribute to the increase in the reliability of the plant organism. This is provided, for example, by the double helix of DNA, by increasing the ploidy. The reliability of the functioning of the plant organism under changing conditions is also maintained due to the presence of a variety of messenger RNA molecules and the formation of heterogeneous polypeptides. These include isoenzymes that catalyze the same reaction, but differ in their physical and chemical properties and the stability of the molecular structure under changing environmental conditions.

At the cellular level, an example of redundancy is an excess of cellular organelles. Thus, it has been established that a part of the available chloroplasts is sufficient to provide the plant with photosynthesis products. The remaining chloroplasts, as it were, remain in reserve. The same applies to the total chlorophyll content. The redundancy also manifests itself in a large accumulation of precursors for the biosynthesis of many compounds.

At the organismic level, the principle of redundancy is expressed in the formation and laying at different times of more shoots, flowers, spikelets than is required for the change of generations, in a huge amount of pollen, ovules, seeds.

At the population level, the principle of redundancy is manifested in a large number of individuals that differ in resistance to a particular stress factor.

Repair systems also work at different levels - molecular, cellular, organismal, population and biocenotic. Reparative processes go with the expenditure of energy and plastic substances, therefore, reparation is possible only if a sufficient metabolic rate is maintained. If metabolism stops, then reparation also stops. In extreme conditions of the external environment, the preservation of respiration is especially important, since it is respiration that provides energy for reparation processes.

The regenerative ability of cells of adapted organisms is determined by the resistance of their proteins to denaturation, namely, the stability of the bonds that determine the secondary, tertiary, and quaternary structure of the protein. For example, the resistance of mature seeds to high temperatures is usually associated with the fact that, after dehydration, their proteins become resistant to denaturation.

The main source of energy material as a substrate for respiration is photosynthesis, therefore, the energy supply of the cell and related reparation processes depend on the stability and ability of the photosynthetic apparatus to recover from damage. To maintain photosynthesis under extreme conditions in plants, the synthesis of thylakoid membrane components is activated, lipid oxidation is inhibited, and the plastid ultrastructure is restored.

At the organismic level, an example of regeneration is the development of replacement shoots, the awakening of dormant buds when growth points are damaged.

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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. Anchoring in isolated populations various adaptations may 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 world? 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 conditions environment. Unconditioned reflexes are inherited, so all animals are born with a ready-made complex of such reflexes.

Each unconditioned reflex occurs 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 unconditioned reflexes is a 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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The identification of limiting factors is of great practical importance. First of all, for growing crops: applying the necessary fertilizers, liming the soil, reclamation, etc. allow to increase productivity, improve soil fertility, improve the existence of cultivated plants.

  1. What does the prefix "evry" and "steno" mean in the species name? Give examples of eurybionts and stenobionts.

Wide tolerance limit of the species in relation to abiotic environmental factors, denoted by adding prefixes to the name of the factor "evry. The inability to tolerate significant fluctuations in factors or a low endurance limit is characterized by the prefix "steno", for example, stenothermic animals. Small temperature changes have little effect on eurythermal organisms and can be fatal for stenothermic ones. The species adapted to low temperatures is cryophilic(from the Greek krios - cold), and to high temperatures - thermophilic. Similar patterns apply to other factors as well. Plants can be hydrophilic, i.e. demanding on water and xerophilous(dry-hardy).

In relation to content salts in the habitat, eurygales and stenogals are distinguished (from Greek gals - salt), to illumination - euryphotes and stenophots, in relation to to the acidity of the environment- Euryionic and stenionic species.

Since eurybiontism makes it possible to populate a variety of habitats, and stenobiontism sharply narrows the range of places suitable for the species, these 2 groups are often called evry - and stenobionts. Many terrestrial animals living in the environment continental climate able to withstand significant fluctuations in temperature, humidity, solar radiation.

Stenobionts include- orchids, trout, Far Eastern hazel grouse, deep-sea fish).

Animals that are stenobiont simultaneously with respect to several factors are called stenobionts in the broad sense of the word ( fish that live in mountain rivers and streams that cannot tolerate too high temperatures and low oxygen content, inhabitants of the humid tropics, unadapted to low temperatures and low air humidity).

The eurybionts are Colorado potato beetle, mouse, rats, wolves, cockroaches, reeds, wheatgrass.

  1. Adaptation of living organisms to environmental factors. Types of adaptation.

adaptation ( from lat. adaptation - adaptation ) - this is an evolutionary adaptation of the organisms of the environment, expressed in a change in their external and internal features.

Individuals that for some reason have lost the ability to adapt, in the conditions of changes in the regimes of environmental factors, are doomed to elimination, i.e. to extinction.

Types of adaptation: morphological, physiological and behavioral adaptations.

Morphology is the doctrine of the external forms of organisms and their parts.

1.Morphological adaptation- this is an adaptation that manifests itself in adaptation to fast swimming in aquatic animals, to survival in conditions of high temperatures and moisture deficiency - in cacti and other succulents.

2.Physiological adaptations are the features of the enzymatic set in digestive tract animals, determined by the composition of food. For example, the inhabitants of dry deserts are able to provide the need for moisture due to the biochemical oxidation of fats.

3.Behavioral (ethological) adaptations appear in a variety of forms. For example, there are forms of adaptive behavior of animals aimed at ensuring optimal heat exchange with the environment. Adaptive behavior can be manifested in the creation of shelters, movement in the direction of more favorable, preferred temperature conditions, the choice of places with optimal humidity or light. Many invertebrates are characterized by a selective attitude towards light, which manifests itself in approaching or moving away from the source (taxis). Diurnal and seasonal migrations of mammals and birds are known, including migrations and flights, as well as intercontinental movements of fish.

Adaptive behavior can manifest itself in predators in the process of hunting (tracking and chasing prey) and in their prey (hiding, confusing the trail). The behavior of animals during the mating season and during the rearing of offspring is exceptionally specific.

There are two types of adaptation to external factors. Passive way of adaptation- this is an adaptation according to the type of tolerance (tolerance, endurance) consists in the emergence of a certain degree of resistance to this factor, the ability to maintain functions when the strength of its influence changes .. This type of adaptation is formed as a characteristic species property and is realized at the cellular and tissue level. The second type of fixture active. In this case, the body, using specific adaptive mechanisms, compensates for the changes caused by the influencing factor, so that the internal environment remains relatively constant. Active adaptations are adaptations of a resistant type (resistance) that maintain the homeostasis of the internal environment of the body. An example of a tolerant type of adaptation is poikiloosmotic animals, an example of a resistant type is homoyosmotic .

  1. Define a population. Name the main group characteristics of the population. Give examples of populations. Growing, stable and dying populations.

population- a group of individuals of the same species that interact with each other and jointly inhabit a common territory. The main characteristics of the population are as follows:

1. Number - the total number of individuals in a certain area.

2. Population density - the average number of individuals per unit area or volume.

3. Fertility - the number of new individuals that appeared per unit of time as a result of reproduction.

4. Mortality - the number of dead individuals in the population per unit of time.

5. Population growth - the difference between fertility and mortality.

6. Growth rate - average growth per unit of time.

Populations are characterized by a certain organization, the distribution of individuals over the territory, the ratio of groups by sex, age, behavioral features. It is formed, on the one hand, on the basis of common biological properties species, and on the other hand, under the influence of abiotic environmental factors and populations of other species.

The structure of the population is unstable. 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 a change in various ratios within the population.

Increasing or growing population- this is a population in which young individuals predominate, such a population is growing in number or is being introduced into the ecosystem (for example, countries of the "third" world); More often, there is an excess of births over deaths and the population grows to such an extent that an outbreak of mass reproduction may occur. This is especially true for small animals.

With a balanced intensity of fertility and mortality, a stable population. In such a population, mortality is compensated by growth and its number, as well as its range, are kept at the same level. . Stable population - this is a population in which the number of individuals of different ages varies evenly and has the character of a normal distribution (as an example, we can name the population of Western European countries).

Decreasing (dying) population is a population in which the death rate exceeds the birth rate . A declining or dying population is a population dominated by older individuals. An example is Russia in the 1990s.

However, it cannot shrink indefinitely either.. At a certain level of abundance, the intensity of mortality begins to fall, and fecundity increases. . Ultimately, a declining population, having reached a certain minimum number, turns into its opposite - a growing population. The birth rate in such a population gradually increases and at a certain moment levels off with mortality, i.e., the population becomes stable for a short period of time. Decreasing populations are dominated by old individuals that are no longer able to reproduce intensively. Such age structure indicates unfavorable conditions.

  1. Ecological niche of the organism, concepts and definitions. Habitat. Mutual arrangement of ecological niches. The ecological niche of man.

Any kind of animal, plant, microbe is able to normally live, feed, reproduce only in the place where it has been "registered" by evolution over many millennia, starting from its ancestors. To refer to this phenomenon, biologists have borrowed term from architecture - the word "niche" and they began to say that each type of living organism occupies its own, unique ecological niche in nature.

Ecological niche of an organism- this is the totality of all its requirements for environmental conditions (the composition and regimes of environmental factors) and the place where these requirements are met, or the totality of the set of biological characteristics and physical parameters of the environment that determine the conditions for the existence of a particular species, its transformation of energy, the exchange of information with environment and others like them.

The concept of an ecological niche is usually used when using the relationships of ecologically close species belonging to the same trophic level. The term "ecological niche" was proposed by J. Grinnell in 1917 to characterize the spatial distribution of species, that is, the ecological niche was defined as a concept close to the habitat. C. Elton defined an ecological niche as the position of a species in a community, emphasizing the particular importance of trophic relationships. A niche can be thought of as part of an imaginary multi-dimensional space (hypervolume), the individual dimensions of which correspond to the factors necessary for the species. The more the parameter varies, i.e. the adaptability of a species to a certain environmental factor, the wider its niche. The niche can also increase in the case of weakened competition.

habitat of the species- this is the physical space occupied by a species, organism, community, it is determined by the totality of the conditions of the abiotic and biotic environment that provide the entire development cycle of individuals of the same species.

The habitat of the species can be designated as "spatial niche".

The functional position in the community, in the ways of processing matter and energy in the process of nutrition, is called trophic niche.

Figuratively speaking, if a habitat is, as it were, the address of organisms of a given species, then a trophic niche is a profession, the role of an organism in its habitat.

The combination of these and other parameters is commonly called an ecological niche.

ecological niche(from the French niche - a recess in the wall) - this is the place occupied by a biological species in the biosphere, includes not only its position in space, but also its place in trophic and other interactions in the community, as if the "profession" of the species.

Niche ecological fundamental(potential) is an ecological niche in which a species can exist in the absence of competition from other species.

Ecological niche realized (real) – ecological niche, part of a fundamental (potential) niche that a species can defend in competition with other species.

According to the relative position of the niches of the two types, they are divided into three types: non-contiguous ecological niches; contiguous but not overlapping niches; contiguous and overlapping niches.

Man is one of the representatives of the animal kingdom, a biological species of the class of mammals. Despite the fact that it has many specific properties (mind, articulate speech, labor activity, biosociality, etc.), it has not lost its biological essence and all the laws of ecology are valid for it to the same extent as for other living organisms. . Man has his own, only his own, ecological niche. The space in which the human niche is localized is very limited. As a biological species, humans can only live on land equatorial belt(tropics, subtropics), where the family of hominids arose.

  1. Formulate the fundamental law of Gause. What is a "life form"? What ecological (or life) forms are distinguished among the inhabitants of the aquatic environment?

Both in the plant and in the animal world, interspecific and intraspecific competition is very widespread. There is a fundamental difference between them.

Rule (or even law) Gause: two species cannot occupy the same ecological niche at the same time and therefore necessarily crowd out each other.

In one of the experiments, Gause bred two types of ciliates - Paramecium caudatum and Paramecium aurelia. As food, they regularly received one of the types of bacteria that does not multiply in the presence of paramecium. If each type of ciliate was cultivated separately, then their populations grew according to a typical sigmoid curve (a). At the same time, the number of paramecia was determined by the amount of food. But when coexisting, paramecia began to compete, and P. aurelia completely replaced its competitor (b).

Rice. Competition between two closely related species of ciliates occupying a common ecological niche. a - Paramecium caudatum; b - P. aurelia. 1. - in one culture; 2. - in a mixed culture

With the joint cultivation of ciliates, after a while only one species remained. At the same time, ciliates did not attack individuals of another type and did not emit harmful substances. The explanation lies in the fact that the studied species differed in unequal growth rates. In the competition for food, the fastest breeding species won.

When breeding P. caudatum and P. bursaria no such displacement occurred, both species were in equilibrium, the latter being concentrated on the bottom and walls of the vessel, and the former in free space, i.e., in a different ecological niche. Experiments with other types of ciliates have demonstrated the regularity of the relationship between prey and predator.

Gauze principle is called the principle elimination competitions. This principle leads either to the ecological separation of closely related species, or to a decrease in their density where they are able to coexist. As a result of competition, one of the species is ousted. The Gause principle plays a huge role in the development of the concept of a niche, and also forces ecologists to look for answers to a number of questions: How do similar species coexist? How big must be the differences between species so that they can coexist? How do you avoid competitive exclusion?

The life form of the species it is a historically developed complex of its biological, physiological and morphological properties, which determines a certain reaction to the influence of the environment.

Among the inhabitants of the aquatic environment (hydrobionts), the classification distinguishes the following life forms.

1.Neuston(from the Greek neuston - able to swim) – collection of marine and freshwater organisms that live in water surface, for example, mosquito larvae, many protozoa, water strider bugs, and from plants, the well-known duckweed.

2. Closer to the surface of the water inhabits plankton.

Plankton(from Greek planktos - soaring) - floating organisms capable of making vertical and horizontal movements mainly in accordance with the movement of water masses. Allocate phytoplankton photosynthetic free-swimming algae and zooplankton- small crustaceans, larvae of mollusks and fish, jellyfish, small fish.

3.Nekton(from the Greek nektos - floating) - free-floating organisms capable of independent vertical and horizontal movement. Nekton lives in the water column - these are fish, in the seas and oceans, amphibians, large aquatic insects, crustaceans, and reptiles ( sea ​​snakes and turtles) and mammals: cetaceans (dolphins and whales) and pinnipeds (seals).

4. Periphyton(from the Greek peri - around, about, phyton - plant) - animals and plants attached to the stems of higher plants and rising above the bottom (molluscs, rotifers, bryozoans, hydras, etc.).

5. Benthos ( from the Greek benthos - depth, bottom) - benthic organisms leading an attached or free lifestyle, including: living in the thickness of the bottom sediment. These are mainly mollusks, some lower plants, crawling insect larvae, worms. The bottom layer is inhabited by organisms that feed mainly on decaying remains.

  1. What is biocenosis, biogeocenosis, agrocenosis? The structure of biogeocenosis. Who is the founder of the doctrine of biocenosis? Examples of biogeocenoses.

Biocenosis(from the Greek koinos - common bios - life) is a community of interacting living organisms, consisting of plants (phytocenosis), animals (zoocenosis), microorganisms (microbocenosis) adapted to cohabitation in a given territory.

The concept of "biocenosis" - conditional, since organisms cannot live outside the environment of existence, but it is convenient to use it in the process of studying ecological relationships between organisms. Depending on the area, the attitude towards human activity, degree of saturation, usefulness, etc. there are biocenoses of land, water, natural and anthropogenic, saturated and unsaturated, full-membered and non-full-membered.

Biocenoses, like populations - this is a supra-organismal level of life organization, but of a higher rank.

The sizes of biocenotic groups are different- these are also large communities of lichen pillows on tree trunks or a rotting stump, but this is also a population of steppes, forests, deserts, etc.

The community of organisms is called biocenosis, and the science that studies the community of organisms - biocenology.

V.N. Sukachev the term has been proposed (and generally accepted) to refer to communities biogeocenosis(from Greek bios - life, geo - Earth, cenosis - community) - is a collection of organisms natural phenomena characteristic of a given geographic area.

The structure of biogeocenosis includes two components biotic - community of living plant and animal organisms (biocenosis) - and abiotic - a set of non-living environmental factors (ecotope, or biotope).

Space with more or less homogeneous conditions, which occupies a biocenosis, is called a biotope (topis - place) or ecotope.

Ecotop includes two main components: climatetop- the climate in all its diverse manifestations and edaphotop(from the Greek edafos - soil) - soil, relief, water.

Biogeocenosis\u003d biocenosis (phytocenosis + zoocenosis + microbocenosis) + biotope (climatotop + edaphotop).

Biogeocenoses - these are natural formations (they contain the element "geo" - the Earth ) .

Examples biogeocenoses there may be a pond, a meadow, a mixed or single-species forest. At the level of biogeocenosis, all processes of transformation of energy and matter in the biosphere take place.

Agrocenosis(from Latin agraris and Greek koikos - common) - a community of organisms created by man and artificially supported by him with increased productivity (productivity) of one or more selected plant or animal species.

Agrocenosis differs from biogeocenosis main components. It cannot exist without human support, as it is an artificially created biotic community.

  1. The concept of "ecosystem". Three principles of functioning of ecosystems.

ecological system- one of the most important concepts of ecology, abbreviated as an ecosystem.

Ecosystem(from the Greek oikos - dwelling and system) - this is any community of living beings, together with their habitat, connected inside by a complex system of relationships.

Ecosystem - these are supraorganismal associations, including organisms and inanimate (inert) environment, which are in interaction, without which it is impossible to maintain life on our planet. This is a community of plant and animal organisms and an inorganic environment.

Based on the interaction of living organisms that form an ecosystem, with each other and with their habitat, in any ecosystem, interdependent aggregates are distinguished biotic(living organisms) and abiotic(oblique or inanimate nature) components, as well as environmental factors (such as solar radiation, humidity and temperature, Atmosphere pressure), anthropogenic factors and others.

To abiotic components of ecosystems are not organic matter- carbon, nitrogen, water, atmospheric carbon dioxide, minerals, organic substances found mainly in the soil: proteins, carbohydrates, fats, humic substances, etc., which entered the soil after the death of organisms.

To the biotic components of the ecosystem include producers, autotrophs (plants, chemosynthetics), consumers (animals) and detritophages, decomposers (animals, bacteria, fungi).

  • Kazan physiological school. F.V. Ovsyannikov, N.O. Kovalevsky, N.A. Mislavsky, A.V. Kibyakov