The main ways and forms of adaptation of living organisms to environmental conditions. Photoperiodism. Physiological adaptation of animals, plants and humans: definition, types, mechanisms and examples What types of adaptation exist behavioral

Grand inventions human mind never cease to amaze, there are no limits to imagination. But what nature has created for many centuries surpasses the most creative ideas and plans. Nature has created more than one and a half million species of living individuals, each of which is individual and unique in its forms, physiology, and adaptability to life. Examples of adaptation of organisms to constantly changing living conditions on the planet are examples of the wisdom of the creator and a constant source of problems for biologists to solve.

Adaptation means adaptability or habituation. This is the process of gradual degeneration of the physiological, morphological or psychological functions of a creature in a changed environment. Both individuals and entire populations undergo changes.

A striking example of direct and indirect adaptation is the survival of flora and fauna in a zone of increased radiation around Chernobyl nuclear power plant. Direct adaptability is characteristic of those individuals that managed to survive, get used to it and begin to reproduce; some did not survive the test and died (indirect adaptation).

Since the conditions of existence on Earth are constantly changing, the processes of evolution and adaptation in living nature are also a continuous process.

A recent example of adaptation is a change in the habitat of a colony of green Mexican aratinga parrots. Recently, they changed their usual habitat and settled in the very mouth of the Masaya volcano, in an environment constantly saturated with highly concentrated sulfur gas. Scientists have not yet provided an explanation for this phenomenon.

Types of adaptation

A change in the entire form of existence of an organism is a functional adaptation. An example of adaptation, when a change in conditions leads to mutual adaptation of living organisms to each other, is a correlative adaptation or co-adaptation.

Adaptation can be passive, when the functions or structure of the subject occur without his participation, or active, when he consciously changes his habits to match the environment (examples of people adapting to natural conditions or society). There are cases when a subject adapts the environment to suit his needs - this is objective adaptation.

Biologists divide types of adaptation according to three criteria:

• Morphological.
• Physiological.
• Behavioral or psychological.

Examples of adaptation of animals or plants in their pure form are rare; most cases of adaptation to new conditions occur in mixed species.

Morphological adaptations: examples

Morphological changes are changes in the shape of the body, individual organs, or the entire structure of a living organism that occurred during the process of evolution.

Below are morphological adaptations, examples from the animal and plant world, which we consider as a matter of course:

• Degeneration of leaves into spines in cacti and other plants of arid regions.
• Turtle shell.
• Streamlined body shapes of inhabitants of reservoirs.

Physiological adaptations: examples

A physiological adaptation is a change in a number of chemical processes occurring inside the body.

• The release of a strong odor by flowers to attract insects contributes to dust.
• The state of suspended animation that simple organisms are capable of entering allows them to maintain vital activity after many years. The oldest bacteria capable of reproducing is 250 years old.
• Accumulation of subcutaneous fat, which is converted into water, in camels.

Behavioral (psychological) adaptations

Examples of human adaptation are more related to the psychological factor. Behavioral characteristics are common to flora and fauna. Thus, in the process of evolution, changes in temperature conditions cause some animals to hibernate, birds to fly south to return in the spring, trees to shed their leaves and slow down the movement of sap. The instinct to choose the most suitable partner for procreation drives the behavior of animals during the mating season. Some northern frogs and turtles freeze completely during the winter and thaw and come to life when the weather gets warmer.

Factors driving the need for change

Any adaptation process is a response to environmental factors that lead to environmental change. Such factors are divided into biotic, abiotic and anthropogenic.

Biotic factors are the influence of living organisms on each other, when, for example, one species disappears, which serves as food for another.

Abiotic factors are changes in the environment inanimate nature when the climate, soil composition, water availability, and solar activity cycles change. Physiological adaptations, examples of the influence of abiotic factors - equatorial fish that can breathe both in water and on land. They have adapted well to conditions where drying up of rivers is a common occurrence.

Anthropogenic factors - influence human activity that changes the environment.

Adaptations to the environment

• Illumination. In plants, these are separate groups that differ in their need for sunlight. Light-loving heliophytes live well in open spaces. In contrast to them are sciophytes: plants of forest thickets that feel good in shaded places. Among the animals there are also individuals that are designed for an active lifestyle at night or underground.
• Air temperature. On average, for all living things, including humans, the optimal temperature environment is considered to be from 0 to 50 o C. However, life exists in almost all climatic regions of the Earth.

Contrasting examples of adaptation to abnormal temperatures are described below.

Arctic fish do not freeze thanks to the production of a unique antifreeze protein in the blood, which prevents the blood from freezing.

The simplest microorganisms have been found in hydrothermal vents, where the water temperature exceeds boiling degrees.

Hydrophyte plants, that is, those that live in or near water, die even with a slight loss of moisture. Xerophytes, on the contrary, are adapted to live in arid regions and die in high humidity. Among animals, nature has also worked to adapt to aquatic and non-aquatic environments.

Human adaptation

Man's ability to adapt is truly enormous. The secrets of human thinking are far from fully revealed, and the secrets of people's adaptive ability will remain a mysterious topic for scientists for a long time. The superiority of Homo sapiens over other living beings lies in the ability to consciously change their behavior to suit the demands of the environment or, conversely, the world around them to suit their needs.

The flexibility of human behavior manifests itself every day. If you give the task: “give examples of people’s adaptation,” the majority begins to remember exceptional cases of survival in these rare cases, and in new circumstances it is typical for a person every day. We try on a new environment at the moment of birth, in kindergarten, school, in a team, when moving to another country. It is this state of acceptance of new sensations by the body that is called stress. Stress is a psychological factor, but nevertheless, many physiological functions change under its influence. In the case when a person accepts a new environment as positive for himself, the new state becomes habitual, otherwise stress threatens to become protracted and lead to a number of serious diseases.

Human coping mechanisms

There are three types of human adaptation:

• Physiological. The simplest examples are acclimatization and adaptation to changes in time zones or daily work patterns. In the process of evolution, they formed Various types people, depending on their territorial place of residence. Arctic, alpine, continental, desert, equatorial types differ significantly in physiological indicators.
• Psychological adaptation. This is a person’s ability to find moments of understanding with people of different psychotypes, in a country with a different level of mentality. Homo sapiens tend to change their established stereotypes under the influence new information, special occasions, stress.
• Social adaptation. A type of addiction that is unique to humans.

All adaptive types are closely related to each other; as a rule, any change in habitual existence causes in a person the need for social and psychological adaptation. Under their influence, mechanisms of physiological changes come into play, which also adapt to new conditions.

This mobilization of all body reactions is called adaptation syndrome. New reactions of the body appear in response to sudden changes in the environment. At the first stage - anxiety - there is a change in physiological functions, changes in the functioning of metabolism and systems. Next, protective functions and organs (including the brain) are activated and begin to turn on their protective functions and hidden capabilities. The third stage of adaptation depends on individual characteristics: a person either becomes involved in new life and returns to normal (in medicine, recovery occurs during this period), or the body does not accept stress, and the consequences take on a negative form.

Phenomena of the human body

Nature has a huge reserve of strength in man, which is used in Everyday life only to a small extent. It manifests itself in extreme situations and is perceived as a miracle. In fact, the miracle lies within us. Example of adaptation: the ability of people to adapt to normal life after removal of a significant part of the internal organs.

Natural innate immunity throughout life can be strengthened by a number of factors or, conversely, weakened due to an incorrect lifestyle. Unfortunately, passion bad habits- This is also the difference between humans and other living organisms.

A special case of cryptic coloring is coloring based on the countershadow principle. U aquatic organisms it appears more often, because Light in an aquatic environment falls only from above. The principle of counter-shadow assumes a darker color on the upper part of the body and a lighter color on the lower part (a shadow falls on it).

Dismembering coloration Dismembering coloration is also a special case of protective coloration, although a slightly different strategy is used. In this case, there are bright, contrasting stripes or spots on the body. From afar, it is very difficult for a predator to distinguish the boundaries of the body of a potential victim.

Warning coloration This type of protective coloration is characteristic of protected animals (such as this nudibranch, which uses nitric acid to protect itself from enemies). Poison, sting or other methods of defense make the animal inedible for the predator, and the coloring serves to ensure that the appearance of the object is retained in the memory of the predator in combination with the unpleasant sensations that he experienced when trying to eat the animal.

Threatening coloring Unlike warning coloring, threatening coloring is inherent in unprotected organisms that are edible from the point of view of a predator. This coloring is not visible all the time, unlike the warning color, it is suddenly shown to the attacking predator in order to disorient it. It is believed that the “eyes” on the wings of many butterflies serve precisely this purpose.

Mimicry The term “mimicry” covers a whole range of different forms protective colors, which have in common a similarity, organisms, imitation of the color of some creatures by others. Types of mimicry: 4 Classical mimicry Batesian mimicry 4 Classical mimicry, or Batesian mimicry - the imitation of an unprotected organism by a protected one; 4 Müller's mimicry 4 Müller's mimicry - similar coloring (“advertising”) in a number of species of protected organisms; 4 Mimesia 4 Mimesia - imitation of inanimate objects; 4 Collective mimicry 4 Collective mimicry is the creation of a common image by a group of organisms; 4 Aggressive mimicry 4 Aggressive mimicry - elements of imitation by a predator in order to attract prey.

Classical mimicry, or Batesian mimicry (Batesian mimicry) An unprotected (already edible) organism imitates the color of a protected (inedible) one. In this way, the imitator exploits the stereotype formed in the predator’s memory by contact with the model (protected organism). The photo shows a hoverfly, imitating a wasp in color and body shape.

Müllerian mimicry (Müllerian mimicry) In this case, a number of protected, inedible species have similar colors (“one advertisement for all”). In this way, the following effect is achieved: on the one hand, the predator does not need to try one organism of each species; the general image of one mistakenly eaten animal will be quite firmly imprinted. On the other hand, the predator will not have to remember dozens of different variants of the bright warning colors of different species. An example is the similar coloration of a number of species of the Order Hymenoptera.

Aggressive mimicry In aggressive mimicry, a predator has adaptations that allow it to attract potential prey. An example is the clown fish, which has projections on its head that resemble worms and are also capable of moving. The slave herself lies on the bottom (she has a magnificent cryptic coloring!) and waits for the approach of the victim, who is busy searching for food.

Relative nature of fitness Each of the given protective colors is adaptive, i.e. useful for organisms only under certain environmental conditions. If these conditions change (for example, the background color for a protective coloring), it can even become maladaptive and harmful. Think about the situations in which the relative nature of fitness will manifest itself with: 4p4warning coloring; 4m4Bates mimicry; 4k4collective mimicry?

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

Adaptation is a genetically determined process of the formation of protective systems that ensure increased stability and the course 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 changed conditions of existence. The better an organism is adapted to a certain 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 norm. It is controlled by the genotype and is characteristic of all living organisms. Most modifications that occur within the normal range of reaction have adaptive significance. They correspond to changes in the environment and ensure better plant survival under fluctuating environmental conditions. In this regard, such modifications have evolutionary significance. The term “reaction norm” was introduced by V.L. Johannsen (1909).

The greater the ability of a species or variety to be modified in accordance with the environment, the wider its reaction rate and the higher its ability to adapt. This property distinguishes resistant varieties of crops. As a rule, slight and short-term changes in environmental factors do not lead to significant disturbances in the physiological functions of plants. This is due to their ability to maintain relative dynamic equilibrium internal environment and stability of basic physiological functions in a changing external environment. At the same time, sudden 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 contribute to increased stability and contribute to the survival of the species.

1.Anatomical and morphological devices. 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, pubescent leaves, and the transformation of leaves into spines reduce water loss, which is very important in conditions of lack of moisture.

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

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

In mountainous regions with large daily temperature fluctuations, plants often have the form of spread out pillows with numerous stems densely spaced. This allows you to maintain 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 parts of the plant immersed in water.

2. Physiological-biochemical adaptations. In succulents, an adaptation for growing in desert and semi-desert conditions is the assimilation of CO 2 during photosynthesis via the CAM pathway. These plants have stomata that are closed during the day. Thus, the plant preserves its 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 CO 2 in the photosynthetic cycle occurs during the day when the stomata are closed.

Physiological and biochemical adaptations include the ability of stomata to open and close, depending on external conditions. Synthesis in cells of abscisic acid, proline, protective proteins, phytoalexins, phytoncides, 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 increasing plant resistance to unfavorable 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 reactions in a much wider temperature range compared to each individual isoenzyme. This allows the plant to successfully perform vital functions in changing temperature conditions.

3. Behavioral adaptations, or avoidance of an unfavorable factor. An example is ephemera and ephemeroids (poppy, chickweed, crocuses, tulips, snowdrops). They go through their entire development cycle in the spring in 1.5-2 months, even before the onset of heat and drought. Thus, they seem to leave, or avoid falling under the influence of the stressor. Similarly, early ripening varieties of agricultural crops form a harvest before the onset of unfavorable weather conditions. seasonal phenomena: August fogs, rains, frosts. Therefore, the selection of many agricultural crops is aimed at creating early ripening varieties. Perennial plants overwinter in the form of 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 an individual cell to a phytocenosis. The higher the level of organization (cell, organism, population), the greater the number of mechanisms simultaneously involved in plant adaptation to stress.

Regulation of metabolic and adaptation processes inside the cell is carried out using systems: metabolic (enzymatic); genetic; membrane These systems are closely interconnected. 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 at the genetic level, while at the same time enzymes regulate nucleic acid metabolism in the cell.

On organismal level new ones are added to the cellular mechanisms of adaptation, reflecting the interaction of organs. In unfavorable conditions, plants create and retain such an amount of fruit elements that are sufficiently provided with the necessary substances to form full-fledged seeds. For example, in the inflorescences of cultivated cereals and in the crowns fruit trees in unfavorable conditions, more than half of the established ovaries may fall off. Such changes are based on competitive relationships between organs for physiologically active substances and nutrients.

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

Mechanisms for regeneration of lost organs operate. For example, the surface of a wound is covered with secondary integumentary tissue (wound periderm), a wound on a trunk or branch is healed with nodules (calluses). When the apical shoot is lost, dormant buds awaken in plants and side shoots intensively develop. The regeneration of leaves in the spring instead of those that fell in the fall is also an example of natural organ regeneration. Regeneration as a biological device that provides vegetative propagation of plants by segments of roots, rhizomes, thallus, stem and leaf cuttings, isolated cells, individual protoplasts, is of great practical importance for plant growing, fruit growing, forestry, ornamental horticulture, etc.

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

On population level selection is added, which leads to the emergence 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 uneven emergence of seedlings on saline soil and the increase in variation in germination timing with increasing stressors.

A species in the modern concept consists of a large number of biotypes - smaller ecological units that are genetically identical, but exhibit different resistance to environmental factors. Under different conditions, not all biotypes are equally viable, and as a result of competition, only those that best meet the given conditions remain. That is, the resistance of a population (variety) to one or another factor is determined by the resistance of the organisms that make up the population. Resistant varieties include a set of biotypes that provide good productivity even in unfavorable conditions.

At the same time, during long-term cultivation of varieties, the composition and ratio of biotypes in the population changes, 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 unfavorable environmental conditions (anatomical, morphological, physiological, biochemical, behavioral, population, etc.)

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

In the event of a sudden action of an extreme factor, the response cannot be delayed; it must follow immediately to avoid irreversible damage to the plant. With prolonged exposure to a small force, adaptive changes occur gradually, and the choice of possible strategies increases.

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

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

In the process of evolution, each plant species has developed certain needs for living conditions and adaptability to the ecological niche it occupies, a stable adaptation of the organism to its habitat. Moisture and shade tolerance, heat resistance, cold resistance and other ecological characteristics of specific plant species were formed as a result of long-term exposure to appropriate conditions. Thus, heat-loving and short-day plants are characteristic of southern latitudes, while less demanding heat-loving 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-lying root system, shedding leaves and transition to a dormant state, and other adaptations.

In this regard, varieties of agricultural plants exhibit resistance precisely to those environmental factors against the background of which breeding and selection of productive forms is carried out. If 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 bred at the Research Institute of Agriculture of the South-East (Saratov) are more resistant to drought than the varieties created in the breeding centers of the Moscow region. In the same way, in ecological zones with unfavorable soil-climatic conditions, resistant local plant varieties were formed, and endemic plant species are resistant precisely to the stressor that is expressed in their habitat.

Characteristics of resistance of spring wheat varieties from the collection of the All-Russian Institute of Plant Growing (Semyonov et al., 2005)

In a natural setting, 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 this kind of adaptation takes a relatively long time, which is why 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 photosynthetic pathway under conditions of water deficiency caused by drought, salinity, low temperatures and other stressors.

This adaptation is associated with the induction of the expression of “inactive” in normal conditions the phosphoenolpyruvate carboxylase gene and the genes of other enzymes of the CAM pathway of CO 2 assimilation, with the biosynthesis of osmolytes (proline), with the activation of antioxidant systems and changes in the daily rhythms of stomatal movements. All this leads to very economical consumption of water.

In field crops, for example, corn, aerenchyma is absent under normal growing conditions. But under conditions of flooding and a lack of oxygen in the tissues of 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 aboveground part of the plant to root system. The signal for cell death is ethylene synthesis.

Urgent adaptation occurs with rapid and intense changes in living conditions. It is based on the formation and functioning of shock defense 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 influence of a damaging factor and thereby 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 a factor exceeds the protective and reparation 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 nonspecific (general) plant responses to stressors.

Nonspecific reactions do not depend on nature active factor. They are the same under the influence of high and low temperatures, lack or excess of moisture, high concentration of salts in the soil or harmful gases in the air. In all cases, the permeability of membranes in plant cells increases, respiration is impaired, the hydrolytic breakdown 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 various factors external environment.

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

Based on the data in the table, it can be seen that plant resistance 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 and others) have shown that short-term heat treatment of cotton plants is accompanied by an increase in their resistance to subsequent salinity. 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 subsequent drought and, conversely, during drought the body's resistance to high temperatures increases. Short-term exposure to high temperatures increases resistance to heavy metals and UV-B irradiation. Previous drought promotes plant survival in salinity or cold conditions.

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 general (nonspecific) mechanisms of resistance, the response of plants to factors that cause water deficiency in plants: salinity, drought, low and high temperatures, and some others is of great interest. At the level of the whole organism, all plants respond to water deficiency in the same way. Characterized by inhibition of shoot growth, increased growth of the root system, abscisic acid synthesis, and decreased stomatal conductance. After some time, the lower leaves age rapidly 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- These are reactions to the action of any one stress factor. Thus, phytoalexins (substances with antibiotic properties) are synthesized in plants in response to contact with pathogens.

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

The manifestation of specific and nonspecific plant responses depends on the strength of stress and the speed of its development. Specific responses occur more often if stress develops slowly, and the body has time to rebuild and adapt to it. Nonspecific reactions usually occur with a shorter and stronger 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 ontogenesis. The most stable plants and plant organs are 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 under stress conditions growth processes are damaged first. The second critical period is the period of gamete formation and fertilization. Stress during this period leads to a decrease in the reproductive function of plants and a decrease in yield.

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

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

To prevent disruptions in plant life under the influence of unfavorable factors, the principles of redundancy, heterogeneity of functionally equivalent components, systems for repairing lost structures.

Redundancy of structures and functionality is one of the main ways to ensure system reliability. Redundancy and redundancy have diverse manifestations. At the subcellular level, the redundancy and duplication of genetic material contribute to increasing the reliability of the plant organism. This is ensured, for example, by the double helix of DNA and an increase in ploidy. The reliability of the functioning of a plant organism under changing conditions is also supported by the presence of various messenger RNA molecules and the formation of heterogeneous polypeptides. These include isoenzymes that catalyze the same reaction, but differ in their physicochemical 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 portion of the available chloroplasts is sufficient to provide the plant with photosynthetic products. The remaining chloroplasts seem to remain in reserve. The same applies to the total chlorophyll content. Redundancy is also manifested in the large accumulation of precursors for the biosynthesis of many compounds.

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

Reparation systems also operate at different levels - molecular, cellular, organismal, population and biocenotic. Reparative processes occur with the expenditure of energy and plastic substances, therefore, repair is possible only if sufficient metabolic rate is maintained. If metabolism stops, repair also stops. In extreme environmental conditions, maintaining respiration is especially important, since it is respiration that provides energy for repair processes.

The restorative 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 due to 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 the associated repair processes depend on the stability and ability of the photosynthetic apparatus to recover after damage. To maintain photosynthesis under extreme conditions in plants, the synthesis of thylakoid membrane components is activated, lipid oxidation is inhibited, and the ultrastructure of plastids is restored.

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

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In the process of evolution, as a result of natural selection and the struggle for existence, 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 changes in body structure. For example, the appearance of membranes between the toes in waterfowl (amphibians, birds, etc.), thick fur in northern mammals, long legs And long neck in wading birds, a flexible body in burrowing predators (for example, weasels), etc. In warm-blooded animals, when moving north, an increase in average body size is observed (Bergmann's rule), which reduces the relative surface and heat transfer. Benthic fish develop a flat body (rays, flounder, etc.). In plants in northern latitudes and in high mountain areas, creeping and cushion-shaped forms are common, 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 it, animals become less noticeable in the area. 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. Patronizing coloring have bottom-dwelling fish, most insects and many other animal species. In the north, white or light colors are more common, helping to camouflage in the snow ( polar bears, polar owls, arctic foxes, baby pinnipeds - squirrels, etc.). A number of animals have acquired 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, sika deer, etc.). Some animals are capable of changing color very quickly depending on conditions (chameleons, octopuses, flounder, etc.).

Disguise

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

Warning or threatening coloring

Some types of insects that have poisonous or odorous glands have bright warning colors. Therefore, predators that once encounter them remember this coloring 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 imitate their poisonous counterparts. For example, some don't Poisonous 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 a restructuring of metabolism in organisms. For example, the emergence of warm-bloodedness and thermoregulation in birds and mammals. In more simple 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 changes in behavior in certain conditions. For example, caring for offspring leads to better survival of young animals and increases the stability of their populations. IN mating seasons many animals form separate families, and in winter they unite in flocks, which makes it easier for them to feed or protect (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 (shedding of leaves, winter or summer diapauses of animals, etc.), animal migrations caused by seasonal changes, etc.

Adaptations to extreme living conditions

Plants and animals living in deserts and polar regions also acquire a number of specific adaptations. In cacti, the leaves have been transformed into spines (reducing evaporation and protecting them from being eaten by animals), and the stem has turned into a photosynthetic organ and reservoir. Desert plants have long root systems that allow them to obtain water from great depths. Desert lizards can survive without water by eating insects and obtaining water by hydrolyzing their fats. In addition to thick fur, northern animals also have a large supply of subcutaneous fat, which reduces body cooling.

Relative nature of adaptations

All devices are appropriate only for certain conditions in which they were developed. If these conditions change, adaptations may lose their value or even cause harm to the organisms that have them. The white coloration of hares, which protects them well in the snow, becomes dangerous during winters with little snow or severe thaws.

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

Behavioral adaptations - these are behaviors developed in the process of evolution of individuals that allow them to adapt and survive in specific environmental conditions.

Typical example- a bear's winter sleep.

Examples can also be 1) creation of shelters, 2) movement in order to select optimal temperature conditions, especially in extreme temperatures. 3) the process of tracking and pursuing prey in predators, and in victims - in operational responses (for example, hiding).

Common for animals way of adapting to unfavorable periods- migration (saiga antelopes annually go for the winter to the southern semi-deserts with little snow, where winter grasses are more nutritious and accessible due to the dry climate. However, in the summer, semi-desert grass stands quickly burn out, so for the breeding season saigas move to the wetter northern steppes).

Examples: 4) behavior when searching for food and a sexual partner, 5) mating, 6) feeding offspring, 7) avoiding danger and protecting life in case of threat, 8) aggression and threatening poses, 9) caring for the offspring, which increases the likelihood of survival of the cubs, 10) joining in packs, 11) simulating injury or death in the event of a threat of attack.

21.Life forms as a result of the adaptation of organisms to the action of a complex of environmental factors. Classification of life forms of plants according to K. Raunkier, I.G. Serebryakov, animals according to D.N. Kashkarov.

The term “life form” was introduced in the 80s by E. Warming. He understood life form as “the form in which the vegetative body of the plant (individual) is in harmony with external environment throughout his entire life, from the cradle to the grave, from seed to death.” This is a very deep definition.

Life forms as types of adaptive structures demonstrate 1) a variety of ways of adaptation of different plant species even to the same conditions,

2) the possibility of similarity of these pathways in completely unrelated plants belonging to different species, genera, and families.

->The classification of life forms is based on the structure of vegetative organs and reflects the convergent paths of ecological evolution.

According to Raunkier: applied his system to elucidate the relationship between plant life forms and climate.

He identified an important feature that characterizes the adaptation of plants to endure unfavorable seasons - cold or dry.

This sign is the position of renewal buds on the plant in relation to the level of the substrate and snow cover. Raunkier linked this to protecting the kidneys during unfavorable times of the year.

1)phanerophytes- the buds overwinter or endure the dry period “openly”, high above the ground (trees, shrubs, woody vines, epiphytes).

-> they are usually protected by special bud scales, which have a number of devices for preserving the growth cone and young leaf primordia enclosed in them from loss of moisture.

2)chamephytes- buds are located almost at the soil level or no higher than 20-30 cm above it (shrubs, subshrubs, creeping plants). In cold and cold climates, these buds very often receive additional protection in winter, in addition to their own bud scales: they overwinter under the snow.

3)cryptophytes- 1) geophytes - buds are located in the ground at a certain depth (they are divided into rhizomatous, tuberous, bulbous),

2) hydrophytes - buds overwinter under water.

4)hemicryptophytes- usually herbaceous plants; their renewal buds are at the soil level or are buried very shallowly, in the litter formed by leaf litter - another additional “cover” for the buds. Among the hemicryptophytes, Raunkier distinguishes “ irotogeiicryptophytes» with elongated shoots that die annually to the base, where renewal buds are located, and rosette hemicryptophytes, in which shortened shoots can overwinter entirely at the soil level.

5)therophytes- special group; these are annuals in which all vegetative parts die off by the end of the season and there are no overwintering buds left - these plants are renewed the next year from seeds that overwinter or survive a dry period on or in the soil.

According to Serebryakov:

Having used and generalized the classifications proposed at different times, he proposed calling a unique habitus a life form - (characteristic form, appearance org-ma) specific groups of plants that arise as a result of growth and development in specific conditions - as an expression of adaptability to these conditions.

The basis of its classification is a sign of the life span of the entire plant and its skeletal axes.

A. woody plants

1.Trees

2.Shrubs

3. Shrubs

B. Semi-woody plants

1.Subshrubs

2.Subshrubs

B. Terrestrial herbs

1.Polycarpic herbs (perennial herbs, bloom many times)

2.Monocarpic herbs (live for several years, bloom once and die)

G. Aquatic herbs

1.Amphibian grasses

2.Floating and underwater grasses

The life form of a tree turns out to be an adaptation to conditions most favorable for growth.

IN forests of the humid tropics- most tree species (up to 88% in the Amazon region of Brazil), and in the tundra and highlands there are no real trees. In area taiga forests trees are represented by only a few species. No more than 10–12% of the total number of species are trees and in the flora of the temperate forest zone of Europe.

According to Kashkarov:

I. Floating forms.

1. Purely aquatic: a) nekton; b) plankton; c) benthos.

2. Semi-aquatic:

a) diving; b) not diving; c) only those that extract food from water.

II. Burrowing forms.

1. Absolute diggers (spending their entire lives underground).

2.Relative excavators (coming to the surface).

III. Ground forms.

1. Those who do not make holes: a) running; b) jumping; c) crawling.

2. Making holes: a) running; b) jumping; c) crawling.

3. Animals of the rocks.

IV. Woody climbing forms.

1. Not coming down from trees.

2.Only those who climb trees.

V. Air forms.

1. Foraging for food in the air.

2.Looking for food from the air.

In appearance In birds, their association with specific types of habitats and the nature of their movement when obtaining food are manifested.

1) woody vegetation;

2) open spaces of land;

3) swamps and shallows;

4) water spaces.

In each of these groups there are specific forms:

a) obtain food by climbing (pigeons, parrots, woodpeckers, passerines)

b) foraging for food in flight (long-winged birds, in forests - owls, nightjars, above water - tubenoses);

c) feeding while moving on the ground (in open spaces - cranes, ostriches; forest - most chickens; in swamps and shallows - some passerines, flamingos);

d) obtaining food by swimming and diving (loons, copepods, geese, penguins).

22. The main environments of life and their characteristics: ground-air and water.

Ground-air- most animals and plants live there.
It is characterized by 7 main abiotic factors:

1.Low air density makes it difficult to maintain the shape of the body and provokes an image of the support system.

EXAMPLE: 1. aquatic plants do not have mechanical tissues: they appear only in terrestrial forms. 2. Animals necessarily have a skeleton: a hydroskeleton (in roundworms), or an external skeleton (in insects), or an internal skeleton (in mammals).

The low density of the environment facilitates the movement of animals. Many terrestrial species are capable of flight.(birds and insects, but there are also mammals, amphibians and reptiles). Flight is associated with searching for prey or settling. Land dwellers live only on the Earth, which serves as their support and attachment point. Due to active flight in such organisms modified forelimbs And pectoral muscles are developed.

2) Mobility air masses

*provides the essence of aeroplankton. It includes pollen, seeds and fruits of plants, small insects and arachnids, spores of fungi, bacteria and lower plants.

This ecological group of organisms adapted due to a large variety of wings, outgrowths, webs, or due to its very small size.

* way of pollinating plants by wind - anemophily- har-n for birch, spruce, pine, nettle, cereals and sedges.

*dispersal by wind: poplar, birch, ash, linden, dandelion, etc. The seeds of these plants have parachutes (dandelions) or wings (maple).

3) Low pressure, norm=760 mm. Pressure differences, compared with aquatic habitats, are very small; Thus, at h=5800 m it is only half of its normal value.

=>almost all land inhabitants are sensitive to strong pressure changes, i.e. they are stenobionts in relation to this factor.

Upper limit life for most vertebrates -6000 m, because pressure decreases with altitude, which means the solubility of o in the blood decreases. To maintain a constant concentration of O 2 in the blood, the respiratory rate must increase. However, we exhale not only CO 2, but also water vapor, so frequent breathing should invariably lead to dehydration of the body. This simple dependence is not typical only for rare species organisms: birds and some invertebrates, mites, spiders and springtails.

4) Gas composition It is characterized by a high content of O 2: it is more than 20 times higher than in the aquatic environment. This allows animals to have very high level metabolism. Therefore, only on land could it arise homeothermicity- the ability to maintain a constant t of the body due to internal energy. Thanks to homeothermy, birds and mammals can maintain vital activity in the harshest conditions

5) Soil and relief are very important, first of all, for plants. For animals, the structure of the soil is more important than its chemical composition.

*For ungulates that perform long migrations on dense ground, adaptation is a decrease in the number of fingers and a => decrease in the amount of support.

*Inhabitants of quicksand typically require an increase in the support surface (fan-toed gecko).

*Soil density is also important for burrowing animals: prairie dogs, marmots, gerbils and others; some of them develop digging limbs.

6) Significant water shortage on land provokes the development of various adaptations aimed to save water in the body:

Development of respiratory organs capable of absorbing O2 from the air of the integument (lungs, trachea, pulmonary sacs)

Development of waterproof covers

The change will highlight the system and metabolic products (urea and uric acid)

Internal fertilization.

In addition to providing water, precipitation also plays an ecological role.

*Snow reduces temperature fluctuations to a depth of 25 cm. Deep snow protects plant buds. For black grouse, hazel grouse and tundra partridges, snowdrifts are a place to spend the night, that is, at 20–30 o frost at a depth of 40 cm, it remains ~0 ° C.

7) Temperature more variable than aquatic. ->many land dwellers eurybiont to this factor, i.e. they are capable of beings in a wide range of temperatures and demonstrate very different methods of thermoregulation.

Many species of animals that live in areas with snowy winters molt in the fall, changing the color of their fur or feathers to white. Perhaps this seasonal molt birds and animals are also an adaptation - camouflage coloring, which is typical for the snowshoe hare, weasel, arctic fox, tundra partridge and others. However, not all white animals change color seasonally, which reminds us of the indefinability and impossibility of considering all properties of the body as beneficial or harmful.

Water. Water covers 71% of the earth's S or 1370 m3. The main mass of water is in the seas and oceans – 94-98%, in polar ice contains about 1.2% water and a very small proportion - less than 0.5%, in fresh waters of rivers, lakes and swamps.

The aquatic environment is home to about 150,000 species of animals and 10,000 plants, which is only 7 and 8% of the total number of species on Earth. Thus, evolution on land was much more intense than in water.

In the seas and oceans, as in the mountains, it is expressed vertical zoning.

All inhabitants of the aquatic environment can be divided into three groups.

1) Plankton- countless accumulations of tiny organisms that cannot move on their own and are carried by currents in the upper layer of sea water.

It consists of plants and living organisms - copepods, eggs and larvae of fish and cephalopods, +unicellular algae.

2) Nekton- a large number of organizations floating freely in the depths of the world's oceans. The largest of them are blue whales And giant shark feeding on plankton. But among the inhabitants of the water column there are also dangerous predators.

3) Benthos- inhabitants of the bottom. Some deep-sea inhabitants lack vision, but most can see in dim light. Many inhabitants lead an attached lifestyle.

Adaptations of hydrobionts to high water density:

Water has high density (800 times the density of air) and viscosity.

1) Plants have very poorly developed or absent mechanical tissues“The water itself is their support. Most are characterized by buoyancy. Characteristic is active vegetative reproduction, development of hydrochory - removal of flower stalks above the water and distribution of pollen, seeds and spores by surface currents.

2) The body has a streamlined shape and is lubricated with mucus, which reduces friction when moving. Developed devices to increase buoyancy: accumulations of fat in tissues, swim bladders in fish.

Passively swimming animals have outgrowths, spines, appendages; the body is flattened, and skeletal organs are reduced.

Different modes of transportation: bending of the body, with the help of flagella, cilia, reactive mode of movement (cephalomolluscs).

In benthic animals, the skeleton disappears or is poorly developed, body size increases, vision reduction is common, and tactile organs develop.

Adaptations of hydrobionts to water mobility:

Mobility is determined by ebbs and flows, sea currents, storms, and different elevation levels of river beds.

1) In flowing waters, plants and animals are firmly attached to stationary underwater objects. The bottom surface is primarily a substrate for them. These are green and diatom algae, water mosses. From animals - gastropods, barnacles + hide in crevices.

2) Different body shapes. Fish that live in flowing waters have a round body in diameter, while fish that live near the bottom have a flat body.

Adaptations of hydrobionts to water salinity:

Natural bodies of water have a certain chemical composition. (carbonates, sulfates, chlorides). In fresh water bodies, the salt concentration is not >0.5 g/, in the seas - from 12 to 35 g/l (ppm). With a salinity of more than 40 ppm, the reservoir is called g hyperhaline or oversalted.

1) *IN fresh water(hypotonic environment) osmoregulation processes are well expressed. Hydrobionts are forced to constantly remove water that penetrates them, they homoiosmotic.

*In salt water (isotonic environment), the concentration of salts in the bodies and tissues of hydrobionts is the same as the concentration of salts dissolved in water - they poikiloosmotic. ->inhabitants of salt water bodies have not developed osmoregulatory functions, and they were unable to populate fresh water bodies.

2) Aquatic plants are able to absorb water and nutrients from water - “broth”, with their entire surface Therefore, their leaves are strongly dissected and their conducting tissues and roots are poorly developed. The roots serve to attach to the underwater substrate.

Typically maritime and typically freshwater species – stenohaline, cannot tolerate changes in water salinity. Euryhaline species A little. They are common in brackish waters (pike, bream, mullet, coastal salmon).

Adaptation of hydrobionts to the composition of gases in water:

In water O2 is the most important environmental factor. Its source is the atmosphere and photosynthetic plants.

When stirring the water and decreasing t, the O2 content increases. *Some fish are very sensitive to O2 deficiency (trout, minnow, grayling) and therefore prefer cold mountain rivers and streams.

*Other fish (crucian carp, carp, roach) are unpretentious to O2 content and can live at the bottom of deep reservoirs.

*Many aquatic insects, mosquito larvae, and pulmonate mollusks are also tolerant of the O2 content in water, because from time to time they rise to the surface and swallow fresh air.

There is enough carbon dioxide in water - almost 700 times more than in air. It is used in plant photosynthesis and goes into the formation of calcareous skeletal structures of animals (mollusk shells).