Adaptation of the body to different living conditions

The concept of adaptation – conditions of existence – technogenic conditions – forms of adaptation – phenotypic adaptation – short-term and long-term adaptation – social conditions of human adaptation

Adaptation (from lat. adaptatio- adapt, adapt) is a set of morphophysiological, behavioral, population and other characteristics of a species, providing the possibility of existence in certain environmental conditions.

The concept of "adaptation" includes:

– processes, with the help of which the body adapts to the environment;

– state of balance between the organism and the environment;

– implementation of the reaction norm under specific environmental conditions by changing the phenotype;

– the result of the evolutionary process– adaptationogenesis (selection and fixation of genes encoding information about developed changes).

The phenomenon of biological adaptation is inherent in all living organisms, and especially in such a highly organized one as human beings. The conditions for the existence of any living organism can be:

– adequate(those that currently allow the body to carry out all vital processes within the normal reaction limits);

– inadequate(those that do not correspond to the range of properties of the organism determined by the reaction norm).

In adequate conditions, the body experiences a state of comfort, i.e. optimal level of operation of all systems. In inadequate conditions, the body has to turn on additional mechanisms to ensure a state of stability (resistance) and activate all processes. This condition is called "tension". If, with the help of tension, the body has not reached a state of stability, then a state of “pre-disease” and then “disease” develops. States of comfort, tension and adaptation constitute a state of health (but not pathology); the state of adaptation is a normal physiological reaction.

Modern anthropogenic (technogenic) conditions include, as a rule, not one unfavorable factor, but a whole complex of factors to which the body must adapt. Therefore, the body’s response must be not only multicomponent, but also integrated. This integration is created by the interconnected and interdependent work of the regulatory, energetic and nonspecific components of adaptation and constitutes adaptation strategy.

Adaptation is based on a number of general patterns of reactions in the body. Depending on which systems are involved in creating the state of adaptation and the extent of this process, its two main forms are distinguished:

– evolutionary(or genotypic) adaptation; this process is the basis of evolution, since the existing complex of species hereditary characteristics becomes the starting point for changes introduced by environmental conditions and fixed at the genotype level; this process takes thousands and millions of years;

– phenotypic adaptation (arising during the individual development of the organism, as a result of which the organism acquires resistance to certain environmental factors).

Phenotypic adaptation is also determined by a genetic program, but not in the form of a preprogrammed adaptation, but in the form of a reaction norm, i.e. the range of metabolic processes, the potential for ensuring the body’s response to changes in environmental conditions. At the same time, turning such potential opportunities into real ones, i.e. ensuring the body's response to environmental demands is also impossible without activating the genetic apparatus (increasing the synthesis of nucleic acids, proteins and other compounds). This phenomenon is called structural trace of adaptation. At the same time, the mass of membrane structures responsible for signal perception, ion transport, and energy supply also increases. After the cessation of the environmental factor, the activity of the genetic apparatus decreases and the structural trace of adaptation disappears. This indicates that in ensuring the state of adaptation, the relationship between functions and the genetic apparatus is a key link. It must also be emphasized that metabolic changes aimed at ensuring a state of phenotypic adaptation constitute biochemical adaptation strategy, which is one of the main components of the overall adaptation strategy.

There are two forms of phenotypic adaptation: short-term (including immediate, urgent) and long-term (acclimatization).

Short-term (urgent) adaptation:

– occurs immediately after the action of a stimulus;

– is carried out due to ready-made, previously formed structures and physiological mechanisms. This means that: a) the body always has a certain amount of reserve structural elements, for example mitochondria, lysosomes, ribosomes; b) the work of cells and tissues can be carried out according to the type of duplication; c) there is a certain amount of ready-made substances: hormones, nucleic acids, proteins, ATP, enzymes, vitamins, etc.; this is the so-called structural adaptation reserve, which can provide immediate response. Due to the fact that this reserve is small, the body’s activity occurs at the limit of physiological capabilities.

For urgent adaptation:

– the leading factors are the activity of nonspecific components and the formation of a stereotypical response, regardless of the nature of the stimulus;

– acute adaptation syndrome develops (Hans Selye called it “stress”, which translated from English means “tension”) in this case:

The hypothalamic-pituitary system is activated;

The production of adrenocorticotropic hormone (ACTH) increases;

The synthesis of glucocorticoids and adrenaline by the adrenal glands is enhanced;

The thymus and spleen shrink;

Energy and structural resources are mobilized;

The state of adaptation is achieved quickly, but it will be stable only if the factor has ceased to act; if the factor continues to operate, then adaptation turns out to be imperfect, since the reserves are exhausted and need to be replenished.

Urgent adaptation is manifested by generalized motor reactions or emotional behavior (for example, an animal's flight in response to pain; an increase in heat production in response to cold; an increase in heat loss in response to heat; an increase in pulmonary ventilation and minute volume in response to a lack of oxygen).

Long-term adaptation develops on the basis of the implementation of the stage of urgent adaptation, when the systems that respond to a given stimulus are activated, but do not provide a stable state, or if the stimulus continues to act.

For long-term adaptation:

– higher regulatory centers activate the hormonal system and specific adaptation components come into play;

– mobilization of the body’s energy and structural resources occurs; this is possible only with the activation of the genetic apparatus, which ensures enhanced biosynthesis of structures on the molecular (induction of the synthesis of hormones, enzymes, RNA, protein, etc.), organoid (biosynthesis and hyperplasia of cell organelles), cellular (increased cell reproduction), tissue and organ (increase in organ and tissue components) levels;

– the biochemical strategy of adaptation is carried out through the synthesis of necessary substances, coordination of their quantities and mutual transformations;

– the leading role in ensuring long-term adaptation is played by the central nervous system, hormonal system, and genetic apparatus;

– the resulting structural trace of adaptation (due to the biogenesis of structures) gradually disappears when the enhanced activity of the genetic apparatus ceases; the state of stability is achieved due to the existence of positive and negative feedback;

– the result of the adaptation process is the organism achieving a state of stability, which provides the organism with the opportunity to exist in new conditions.

If the intensity of the factor exceeds the adaptive capabilities of the organism and the state of stability does not occur, then the organism goes into a state of exhaustion (its structures, systems, functions are depleted); then follows the state of pre-illness and illness.

When discussing the issue of adaptation features in humans, it is necessary to emphasize that humans have both a biological and a social nature. Therefore, the mechanisms for achieving a state of adaptation in humans are more complex than in other species of living beings. On the one hand, a person, as a biological being, has all the adaptive processes determined by the norm of reaction and aimed at achieving the stability of the organism. At the same time, the human body, which in the process of evolution has achieved the highest specialization of its organs and systems, the highest level of development of the nervous system, is most capable of adapting to changing environmental conditions. At the same time, the social nature of man has created a number of features of adaptation processes that are unique to humans:

– the number of anthropogenic environmental factors has increased sharply in recent decades, while adaptation systems have been formed over millions of years in the absence of these factors or their significantly lower intensity and therefore are not effective enough in modern environmental conditions;

– a person is less connected with nature, less dependent on it; is subject to social rhythms, regulates its behavior with consciousness; sometimes consciously chooses inappropriate behavior;

– a person has additional (social) adaptation mechanisms (clothing, shoes, housing, work organization, medicine, physical education, art, etc.);

– the second signaling system plays a leading role in human adaptation.

The history of environmental knowledge goes back many centuries. Already primitive people needed to have certain knowledge about plants and animals, their way of life, relationships with each other and with the environment. As part of the general development of the natural sciences, there was also an accumulation of knowledge that now belongs to the field of environmental science. Ecology emerged as an independent discipline in the 19th century.

The term Ecology (from the Greek eco - house, logos - teaching) was introduced into science by the German biologist Ernest Haeckel.

In 1866, in his work “General Morphology of Organisms,” he wrote that this is “... the sum of knowledge related to the economics of nature: the study of the entire set of relationships between an animal and its environment, both organic and inorganic, and, above all, its friendly or hostile relations with those animals and plants with which it directly or indirectly comes into contact.” This definition classifies ecology as a biological science. At the beginning of the 20th century. the formation of a systematic approach and the development of the doctrine of the biosphere, which is a vast field of knowledge, including many scientific areas of both the natural and humanitarian cycles, including general ecology, led to the spread of ecosystem views in ecology. The main object of study in ecology has become the ecosystem.

An ecosystem is a collection of living organisms that interact with each other and with their environment through the exchange of matter, energy and information in such a way that this single system remains stable for a long time.

The ever-increasing human impact on the environment has made it necessary to once again expand the boundaries of environmental knowledge. In the second half of the 20th century. Scientific and technological progress has entailed a number of problems that have received global status, thus, in the field of view of ecology, the issues of comparative analysis of natural and man-made systems and the search for ways of their harmonious coexistence and development have clearly emerged.

Accordingly, the structure of environmental science differentiated and became more complex. Now it can be represented as four main branches, further divided: Bioecology, geoecology, human ecology, applied ecology.

Thus, we can define ecology as a science about the general laws of functioning of ecosystems of various orders, a set of scientific and practical issues of the relationship between man and nature.

2. Environmental factors, their classification, types of effects on organisms

Any organism in nature experiences the influence of a wide variety of environmental components. Any properties or components of the environment that influence organisms are called environmental factors.

Classification of environmental factors. Environmental factors (ecological factors) are diverse, have different natures and specific actions. The following groups of environmental factors are distinguished:

1. Abiotic (factors of inanimate nature):

a) climatic - lighting conditions, temperature conditions, etc.;

b) edaphic (local) - water supply, soil type, terrain;

c) orographic - air (wind) and water currents.

2. Biotic factors are all forms of influence of living organisms on each other:

Plants Plants. Plants Animals. Plants Mushrooms. Plants Microorganisms. Animals Animals. Animals Mushrooms. Animals Microorganisms. Mushrooms Mushrooms. Fungi Microorganisms. Microorganisms Microorganisms.

3. Anthropogenic factors are all forms of activity of human society that lead to changes in the habitat of other species or directly affect their lives. The impact of this group of environmental factors is rapidly increasing from year to year.

Types of impact of environmental factors on organisms. Environmental factors have various impacts on living organisms. They may be:

Stimuli that contribute to the appearance of adaptive physiological and biochemical changes (hibernation, photoperiodism);

Limiters that change the geographical distribution of organisms due to the impossibility of existence in given conditions;

Modifiers that cause morphological and anatomical changes in organisms;

Signals indicating changes in other environmental factors.

General patterns of action of environmental factors:

Due to the extreme diversity of environmental factors, different types of organisms, experiencing their influence, respond to it differently, however, it is possible to identify a number of general laws (patterns) of the action of environmental factors. Let's look at some of them.

1. Law of optimum

2. The law of ecological individuality of species

3. Law of the limiting (limiting) factor

4. The law of ambiguous action

3. Patterns of action of environmental factors on organisms

1) Optimum rule. For an ecosystem, an organism or a certain stage of it

development there is a range of the most favorable value of the factor. Where

factors are favorable; population density is maximum. 2) Tolerance.

These characteristics depend on the environment in which the organisms live. If she

stable in its own way

yours, it has a greater chance for organisms to survive.

3) Rule of interaction of factors. Some factors may enhance or

mitigate the effect of other factors.

4) Rule of limiting factors. A factor that is deficient or

excess negatively affects organisms and limits the possibility of manifestation. strength

the action of other factors. 5) Photoperiodism. Under photoperiodism

understand the body's reaction to the length of the day. Reaction to changes in light.

6) Adaptation to the rhythm of natural phenomena. Adaptation to daily and

seasonal rhythms, tidal phenomena, solar activity rhythms,

lunar phases and other phenomena that repeat with strict frequency.

Ek. valence (plasticity) - ability to org. adapt to dep. environmental factors environment.

Patterns of the action of environmental factors on living organisms.

Environmental factors and their classification. All organisms are potentially capable of unlimited reproduction and dispersal: even species leading an attached lifestyle have at least one developmental phase in which they are capable of active or passive dispersal. But at the same time, the species composition of organisms living in different climatic zones does not mix: each of them is characterized by a certain set of species of animals, plants, and fungi. This is explained by the limitation of excessive reproduction and dispersal of organisms by certain geographical barriers (seas, mountain ranges, deserts, etc.), climatic factors (temperature, humidity, etc.), as well as relationships between individual species.

Depending on the nature and characteristics of the action, environmental factors are divided into abiotic, biotic and anthropogenic (anthropic).

Abiotic factors are components and properties of inanimate nature that directly or indirectly affect individual organisms and their groups (temperature, light, humidity, gas composition of air, pressure, salt composition of water, etc.).

A separate group of environmental factors includes various forms of human economic activity that change the state of the habitat of various species of living beings, including humans themselves (anthropogenic factors). Over the relatively short period of human existence as a biological species, its activities have radically changed the appearance of our planet, and this impact on nature is increasing every year. The intensity of the action of some environmental factors can remain relatively stable over long historical periods of development of the biosphere (for example, solar radiation, gravity, salt composition of sea water, gas composition of the atmosphere, etc.). Most of them have variable intensity (temperature, humidity, etc.). The degree of variability of each environmental factor depends on the characteristics of the organisms’ habitat. For example, the temperature on the soil surface can vary significantly depending on the time of year or day, weather, etc., while in reservoirs at depths of more than several meters there are almost no temperature differences.

Changes in environmental factors can be:

Periodic, depending on the time of day, time of year, the position of the Moon relative to the Earth, etc.;

Non-periodic, for example, volcanic eruptions, earthquakes, hurricanes, etc..;

Directed over significant historical periods of time, for example, changes in the Earth's climate associated with a redistribution of the ratio of land areas and the World Ocean.

Each of the living organisms constantly adapts to the entire complex of environmental factors, that is, to the habitat, regulating life processes in accordance with changes in these factors. Habitat is a set of conditions in which certain individuals, populations, or groupings of organisms live.

Patterns of influence of environmental factors on living organisms. Despite the fact that environmental factors are very diverse and different in nature, some patterns of their influence on living organisms, as well as the reactions of organisms to the action of these factors, are noted. Adaptations of organisms to environmental conditions are called adaptations. They are produced at all levels of organization of living matter: from molecular to biogeocenotic. Adaptations are not constant because they change during the historical development of individual species depending on changes in the intensity of environmental factors. Each type of organism is adapted to certain living conditions in a special way: there are no two close species that are similar in their adaptations (the rule of ecological individuality). Thus, the mole (Insectivorous series) and the mole rat (Rodents series) are adapted to exist in the soil. But the mole digs passages with the help of its forelimbs, and the mole rat digs with its incisors, throwing the soil out with its head.

Good adaptation of organisms to a certain factor does not mean the same adaptation to others (the rule of relative independence of adaptation). For example, lichens, which can settle on substrates poor in organic matter (such as rock) and withstand dry periods, are very sensitive to air pollution.

There is also the law of optimum: each factor has a positive effect on the body only within certain limits. The intensity of influence of an environmental factor that is favorable for organisms of a certain type is called the optimum zone. The more the intensity of the action of a certain environmental factor deviates from the optimal one in one direction or another, the more pronounced its inhibitory effect on organisms will be (pessimum zone). The intensity of the impact of an environmental factor, due to which the existence of organisms becomes impossible, is called the upper and lower limits of endurance (critical points of maximum and minimum). The distance between the limits of endurance determines the ecological valency of a certain species relative to a particular factor. Consequently, environmental valency is the range of intensity of the impact of an environmental factor in which the existence of a certain species is possible.

The broad ecological valency of individuals of a certain species relative to a specific environmental factor is denoted by the prefix “eur-”. Thus, arctic foxes are classified as eurythermic animals, since they can withstand significant temperature fluctuations (within 80°C). Some invertebrates (sponges, serpentines, echinoderms) belong to eurybatherous organisms, and therefore settle from the coastal zone to great depths, withstanding significant pressure fluctuations. Species that can live in a wide range of fluctuations of various environmental factors are called eurybiontnyms. Narrow ecological valence, that is, the inability to withstand significant changes in a certain environmental factor, is denoted by the prefix “stenothermic” (for example, stenothermic, stenobiontny, etc.).

The optimum and limits of the body's endurance relative to a certain factor depend on the intensity of the action of others. For example, in dry, windless weather it is easier to withstand low temperatures. So, the optimum and limits of endurance of organisms in relation to any environmental factor can shift in a certain direction depending on the strength and in what combination other factors act (the phenomenon of interaction of environmental factors).

But the mutual compensation of vital environmental factors has certain limits and none can be replaced by others: if the intensity of the action of at least one factor goes beyond the limits of endurance, the existence of the species becomes impossible, despite the optimal intensity of the action of others. Thus, a lack of moisture inhibits the process of photosynthesis even with optimal illumination and CO2 concentration in the atmosphere.

A factor whose intensity of action exceeds the limits of endurance is called limiting. Limiting factors determine the territory of distribution of a species (area). For example, the spread of many animal species to the north is hampered by a lack of heat and light, and to the south by a similar lack of moisture.

Thus, the presence and prosperity of a certain species in a given habitat is determined by its interaction with a whole range of environmental factors. Insufficient or excessive intensity of action of any of them makes it impossible for the prosperity and very existence of individual species.

Environmental factors are any components of the environment that affect living organisms and their groups; they are divided into abiotic (components of inanimate nature), biotic (various forms of interaction between organisms) and anthropogenic (various forms of human economic activity).

Adaptations of organisms to environmental conditions are called adaptations.

Any environmental factor has only certain limits of positive influence on organisms (the law of optimum). The limits of the intensity of the action of a factor at which the existence of organisms becomes impossible are called the upper and lower limits of endurance.

The optimum and limits of endurance of organisms in relation to any environmental factor can vary in a certain direction depending on the intensity and in what combination other environmental factors act (the phenomenon of interaction of environmental factors). But their mutual compensation is limited: not a single vital factor can be replaced by others. An environmental factor that goes beyond the limits of endurance is called limiting, it determines the range of a certain species.

ecological plasticity of organisms

Ecological plasticity of organisms (ecological valence) is the degree of adaptability of a species to changes in environmental factors. It is expressed by the range of values ​​of environmental factors within which a given species maintains normal life activity. The wider the range, the greater the environmental plasticity.

Species that can exist with small deviations of the factor from the optimum are called highly specialized, and species that can withstand significant changes in the factor are called broadly adapted.

Environmental plasticity can be considered both in relation to a single factor and in relation to a complex of environmental factors. The ability of species to tolerate significant changes in certain factors is indicated by the corresponding term with the prefix “every”:

Eurythermic (plastic to temperature)

Eurygolinaceae (salinity of water)

Euryphotic (plastic to light)

Eurygygric (plastic to humidity)

Euryoic (plastic to habitat)

Euryphagous (plastic to food).

Species adapted to slight changes in this factor are designated by the term with the prefix “steno”. These prefixes are used to express the relative degree of tolerance (for example, in a stenothermic species, the ecological temperature optimum and pessimum are close together).

Species that have broad ecological plasticity in relation to a complex of environmental factors are eurybionts; species with low individual adaptability are stenobionts. Eurybiontism and isthenobiontism characterize various types of adaptation of organisms to survival. If eurybionts develop for a long time in good conditions, then they can lose ecological plasticity and develop the traits of stenobionts. Species that exist with significant fluctuations in the factor acquire increased ecological plasticity and become eurybionts.

For example, there are more stenobionts in the aquatic environment, since its properties are relatively stable and the amplitudes of fluctuations of individual factors are small. In a more dynamic air-ground environment, eurybionts predominate. Warm-blooded animals have a broader ecological valency than cold-blooded animals. Young and old organisms tend to require more uniform environmental conditions.

Eurybionts are widespread, and stenobiontism narrows their ranges; however, in some cases, due to their high specialization, stenobionts own vast territories. For example, the fish-eating bird osprey is a typical stenophage, but in relation to other environmental factors it is a eurybiont. In search of the necessary food, the bird is able to fly long distances, so it occupies a significant range.

Plasticity is the ability of an organism to exist in a certain range of environmental factor values. Plasticity is determined by the reaction norm.

According to the degree of plasticity in relation to individual factors, all types are divided into three groups:

Stenotopes are species that can exist in a narrow range of environmental factor values. For example, most plants of moist equatorial forests.

Eurytopes are broadly flexible species capable of colonizing various habitats, for example, all cosmopolitan species.

Mesotopes occupy an intermediate position between stenotopes and eurytopes.

It should be remembered that a species can be, for example, a stenotopic according to one factor and a eurytopic according to another and vice versa. For example, a person is a eurytope in relation to air temperature, but a stenotop in terms of the oxygen content in it.

1. Abiotic factors. This category of factors includes all physical and chemical characteristics of the environment. These are light and temperature, humidity and pressure, the chemistry of water, atmosphere and soil, the nature of the relief and the composition of rocks, and wind conditions. The most potent group of factors is united as climatic factors. They depend on the latitude and position of the continents. There are many secondary factors. Latitude has the greatest effect on temperature and photoperiod. The position of the continents is the reason for the dryness or humidity of the climate. The internal regions are drier than the peripheral ones, which greatly influences the differentiation of animals and plants on the continents. Wind regime, as one of the components of the climatic factor, plays an extremely important role in the formation of life forms of plants.

Global climate is the climate of the planet that determines the functioning and Biodiversity of the biosphere. Regional climate is the climate of continents and oceans, as well as their large topographic subdivisions. Local climate – climate of subordinates landscape-regional socio-geographical structures: climate of Vladivostok, climate of the Partizanskaya river basin. Microclimate (under a stone, outside a stone, grove, clearing).

The most important climatic factors: light, temperature, humidity.

Lightis the most important source of energy on our planet. If for animals light is inferior in importance to temperature and humidity, then for photosynthetic plants it is the most important.

The main source of light is the Sun. The main properties of radiant energy as an environmental factor are determined by the wavelength. Radiation includes visible light, ultraviolet and infrared rays, radio waves, and penetrating radiation.

Orange-red, blue-violet and ultraviolet rays are important for plants. Yellow-green rays are either reflected by plants or absorbed in small quantities. Reflected rays give plants their green color. Ultraviolet rays have a chemical effect on living organisms (they change the speed and direction of biochemical reactions), and infrared rays have a thermal effect.

Many plants have a phototropic response to light. Tropism– this is the directional movement and orientation of plants, for example, a sunflower “follows” the sun.

In addition to the quality of the light rays, the amount of light falling on the plant is also of great importance. The intensity of illumination depends on the geographic latitude of the area, the season, time of day, cloudiness and local dustiness of the atmosphere. The dependence of thermal energy on latitude shows that light is one of the climatic factors.

The life of many plants depends on photoperiod. Day gives way to night and plants stop synthesizing chlorophyll. The polar day is replaced by the polar night and plants and many animals stop actively functioning and freeze (hibernation).

In relation to light, plants are divided into three groups: light-loving, shade-loving and shade-tolerant. Photophilous They can develop normally only with sufficient lighting; they do not tolerate or do not tolerate even slight darkening. Shade-loving found only in shaded areas and never found in high light conditions. Shade-tolerant plants are characterized by a wide ecological amplitude in relation to the light factor.

Temperature is one of the most important climatic factors. The level and intensity of metabolism, photosynthesis and other biochemical and physiological processes depend on it.

Life on earth exists in a wide range of temperatures. The most acceptable temperature range for life is from 0 0 to 50 0 C. For most organisms, these are lethal temperatures. Exceptions: many northern animals, where there is a change in seasons, are able to withstand winter temperatures below freezing. Plants are able to tolerate sub-zero winter temperatures, when their active activity stops. Under experimental conditions, some seeds, spores and pollen of plants, nematodes, rotifers, protozoan cysts tolerated temperatures of - 190 0 C and even - 273 0 C. But still, the majority of living creatures are able to live at temperatures between 0 and 50 0 C. This is determined properties of proteins and enzyme activity. One of the adaptations to endure unfavorable temperatures is anabiosis– suspension of the body’s vital processes.

On the contrary, in hot countries, fairly high temperatures are the norm. A number of microorganisms are known that can live in sources with temperatures above 70 0 C. Spores of some bacteria can withstand short-term heating up to 160–180 0 C.

Eurythermic and stenothermic organisms– organisms whose functioning is associated with wide and narrow temperature gradients, respectively. The abyssal environment (0˚) is the most constant environment.

Biogeographical zoning(arctic, boreal, subtropical and tropical zones) largely determines the composition of biocenoses and ecosystems. An analogue of climatic distribution based on the latitudinal factor can be mountain zones.

Based on the relationship between the body temperature of the animal and the ambient temperature, organisms are divided into:

– poikilothermic organisms are cold-water with variable temperatures. The body temperature approaches the ambient temperature;

– homeothermic– warm-blooded organisms with a relatively constant internal temperature. These organisms have great advantages in using the environment.

In relation to the temperature factor, species are divided into the following ecological groups:

species that prefer cold are cryophiles And cryophytes.

species with optimum activity in the area of ​​high temperatures belong to thermophiles And thermophytes.

Humidity. All biochemical processes in organisms occur in an aquatic environment. Water is necessary to maintain the structural integrity of cells throughout the body. It is directly involved in the process of formation of the primary products of photosynthesis.

Humidity is determined by the amount of precipitation. The distribution of precipitation depends on geographic latitude, the proximity of large bodies of water, and the terrain. The amount of precipitation is unevenly distributed throughout the year. In addition, it is necessary to take into account the nature of precipitation. Summer drizzle moisturizes the soil better than rain, carrying streams of water that do not have time to soak into the soil.

Plants living in areas with different moisture availability adapt differently to a lack or excess of moisture. Regulation of water balance in the body of plants in arid regions is carried out due to the development of a powerful root system and the suction power of root cells, as well as a decrease in the evaporating surface. Many plants shed leaves and even entire shoots (saxaul) during the dry period; sometimes partial or even complete reduction of leaves occurs. A peculiar adaptation to a dry climate is the rhythm of development of some plants. Thus, ephemerals, using spring moisture, manage to germinate in a very short time (15-20 days), develop leaves, bloom and form fruits and seeds; with the onset of drought they die. The ability of many plants to accumulate moisture in their vegetative organs - leaves, stems, roots - also helps withstand drought..

In relation to humidity, the following ecological groups of plants are distinguished. Hydrophytes, or hydrobionts, are plants for which water is their living environment.

Hygrophytes- plants living in places where the air is saturated with water vapor and the soil contains a lot of droplet-liquid moisture - in flooded meadows, swamps, in damp shady places in forests, on the banks of rivers and lakes. Hygrophytes evaporate a lot of moisture due to stomata, which are often located on both sides of the leaf. The roots are sparsely branched, the leaves are large.

Mesophytes– plants of moderately humid habitats. These include meadow grasses, all deciduous trees, many field crops, vegetables, fruits and berries. They have a well-developed root system, large leaves with stomata on one side.

Xerophytes- plants that have adapted to life in places with arid climates. They are common in steppes, deserts and semi-deserts. Xerophytes are divided into two groups: succulents and sclerophytes.

Succulents(from lat. succulentus- juicy, fat, thick) are perennial plants with juicy fleshy stems or leaves in which water is stored.

Sclerophytes(from Greek skleros– hard, dry) – these are fescue, feather grass, saxaul and other plants. Their leaves and stems do not contain a supply of water, they seem rather dry, due to the large amount of mechanical tissue, their leaves are hard and tough.

Other factors may also be important in plant distribution, e.g. nature and properties of the soil. Thus, there are plants for which the determining environmental factor is the salt content in the soil. This halophytes. A special group consists of lovers of calcareous soils - calciphiles. The same “soil-associated” species are plants that live on soils containing heavy metals.

Environmental factors that influence the life and distribution of organisms also include the composition and movement of air, the nature of the relief, and many, many others.

The basis of intraspecific selection is intraspecific struggle. That is why, as Charles Darwin believed, more young organisms are born than reach adulthood. At the same time, the predominance of the number of organisms born over the number of organisms surviving to maturity compensates for the high mortality rate in the early stages of development. Therefore, as noted by S.A. Severtsov, the magnitude of fertility is related to the persistence of the species.

Thus, intraspecific relationships are aimed at the reproduction and dispersal of the species.

In the world of animals and plants, there are a large number of devices that facilitate contact between individuals or, conversely, prevent their collision. Such mutual adaptations within a species were called S.A. Severtsov congruences . Thus, as a result of mutual adaptations, individuals have a characteristic morphology, ecology, and behavior that ensure the meeting of the sexes, successful mating, reproduction and raising of offspring. Five groups of congruences have been established:

– embryos or larvae and parental individuals (marsupials);

– individuals of different sexes (genital apparatus of males and females);

– individuals of the same sex, mainly males (horns and teeth of males, used in fights for the female);

– brothers and sisters of the same generation in connection with the herd lifestyle (spots that facilitate orientation when fleeing);

– polymorphic individuals in colonial insects (specialization of individuals to perform certain functions).

The integrity of the species is also expressed in the unity of the breeding population, the homogeneity of its chemical composition and the unity of its impact on the environment.

Cannibalism– this type of intraspecific relationships is not uncommon in broods of birds of prey and animals. The weakest are usually destroyed by the stronger, and sometimes by their parents.

Self-draining plant populations. Intraspecific competition influences the growth and distribution of biomass within plant populations. As individuals grow, they increase in size, their needs increase and, as a result, competition between them increases, which leads to death. The number of surviving individuals and their growth rate depend on population density. A gradual decrease in the density of growing individuals is called self-thinning.

A similar phenomenon is observed in forest plantations.

Interspecies relationships. The most important and frequently occurring forms and types of interspecific relationships can be called:

Competition. This type of relationship determines Gause's rule. According to this rule, two species cannot simultaneously occupy the same ecological niche and therefore necessarily displace each other. For example, spruce displaces birch.

Allelopathy- this is the chemical effect of some plants on others through the release of volatile substances. The carriers of allelopathic action are the active substances - Colin. Due to the influence of these substances, the soil can be poisoned, the nature of many physiological processes can change, and at the same time, plants recognize each other through chemical signals.

Mutualism– an extreme degree of association between species in which each benefits from its association with the other. For example, plants and nitrogen-fixing bacteria; cap mushrooms and tree roots.

Commensalism– a form of symbiosis in which one of the partners (comensal) uses the other (the owner) to regulate its contacts with the external environment, but does not enter into close relationships with him. Comensalism is widely developed in coral reef ecosystems - this is housing, protection (tentacles of sea anemones protect fish), living in the body of other organisms or on its surface (epiphytes).

Predation- this is a way of obtaining food by animals (less often plants), in which they catch, kill and eat other animals. Predation occurs in almost all types of animals. During evolution, predators have well developed nervous systems and sensory organs that allow them to detect and recognize prey, as well as means of capturing, killing, eating and digesting prey (sharp retractable claws in cats, poisonous glands of many arachnids, stinging cells of sea anemones, enzymes that break down proteins and other). The evolution of predators and prey occurs in tandem. During this process, predators improve their methods of attack, and victims improve their methods of defense.

Identifying limiting factors is of great practical importance. Primarily for growing crops: applying the necessary fertilizers, liming soils, land reclamation, etc. allow you to increase productivity, increase soil fertility, and improve the existence of cultivated plants.

1. What do the prefixes “evry” and “steno” mean in the name of the species? Give examples of eurybionts and stenobionts.

Wide range of species tolerance in relation to abiotic environmental factors, they are designated by adding the prefix to the name of the factor "every. The inability to tolerate significant fluctuations in factors or a low limit of endurance is characterized by the prefix "stheno", for example, stenothermic animals. Small changes in temperature have little effect on eurythermal organisms and can be disastrous for stenothermic organisms. A species adapted to low temperatures is cryophilic(from the Greek krios - cold), and to high temperatures - thermophilic. Similar patterns apply to other factors. Plants can be hydrophilic, i.e. demanding on water and xerophilic(dry-tolerant).

In relation to content salts in the habitat they distinguish eurygals and stenogals (from the Greek gals - salt), to illumination – euryphotes and stenophotes, in relation to to the acidity of the environment– euryionic and stenoionic 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 eury – and stenobionts. Many terrestrial animals living in continental climates are able to withstand significant fluctuations in temperature, humidity, and solar radiation.

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

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

Eurybionts include 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 environmental organisms, expressed in changes in their external and internal characteristics.

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

Types of adaptation: morphological, physiological and behavioral adaptation.

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

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

2.Physiological adaptations lie in the peculiarities of the enzymatic set in the digestive tract of animals, determined by the composition of the food. For example, inhabitants of dry deserts are able to meet their moisture needs through the biochemical oxidation of fats.

3.Behavioral (ethological) adaptations appear in a wide 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 manifest itself in the creation of shelters, movements in the direction of more favorable, preferred temperature conditions, and selection of places with optimal humidity or light. Many invertebrates are characterized by a selective attitude towards light, manifested in approaches or distances from the source (taxis). Daily and seasonal movements of mammals and birds are known, including migrations and flights, as well as intercontinental movements of fish.

Adaptive behavior can manifest itself in predators during the hunt (tracking and pursuing prey) and in their victims (hiding, confusing the trail). The behavior of animals during the mating season and during feeding of offspring is extremely specific.

There are two types of adaptation to external factors. Passive way of adaptation– this adaptation according to the type of tolerance (tolerance, endurance) consists in the emergence of a certain degree of resistance to a given 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-tissue level. The second type of device is active. In this case, the body, with the help of specific adaptive mechanisms, compensates for changes caused by the influencing factor in such a way that the internal environment remains relatively constant. Active adaptations are adaptations of the resistant type (resistance) that maintain the homeostasis of the internal environment of the body. An example of a tolerant type of adaptation is poikilosmotic animals, an example of a resistant type is homoyosmotic animals. .

1. Define 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 interacting with each other and jointly inhabiting a common territory. The main characteristics of the population are as follows:

1. Abundance - the total number of individuals in a certain territory.

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

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

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

5. Population growth is the difference between birth and death rates.

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

The population is characterized by a certain organization, the distribution of individuals over the territory, the ratio of groups by sex, age, and behavioral characteristics. It is formed, on the one hand, on the basis of the general biological properties of the species, and on the other, under the influence of abiotic environmental factors and the population of other species.

The population structure 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 changes 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, third world countries); More often, there is an excess of birth rates over deaths and the population size 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 cite the population of Western European countries).

Declining (dying) population is a population in which the mortality rate exceeds the birth rate . A declining or dying population is a population in which older individuals predominate. An example is Russia in the 90s of the 20th century.

However, it also cannot shrink indefinitely.. At a certain population level, the mortality rate begins to fall and fertility begins to increase . Ultimately, a declining population, having reached a certain minimum size, turns into its opposite - a growing population. The birth rate in such a population gradually increases and at a certain point equalizes the mortality rate, that is, the population becomes stable for a short period of time. In declining populations, old individuals predominate, no longer able to reproduce intensively. This age structure indicates unfavorable conditions.

1. Ecological niche of an organism, concepts and definitions. Habitat. Mutual arrangement of ecological niches. Human ecological niche.

Any type of animal, plant, or microbe is capable of normally living, feeding, and reproducing only in the place where evolution has “prescribed” it for many millennia, starting with its ancestors. To designate this phenomenon, biologists borrowed term from architecture - the word “niche” and they began to say that each type of living organism occupies its own ecological niche in nature, unique to it.

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 entire set of many biological characteristics and physical parameters of the environment that determine the conditions of existence of a particular species, its transformation of energy, exchange of information with environment and others like them.

The concept of ecological niche is usually used when using the relationships of ecologically similar 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 special importance of trophic relationships. A niche can be imagined as part of an imaginary multidimensional 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 specific environmental factor, the wider its niche. A 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 conditions of the abiotic and biotic environment that ensure 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 pathways of processing matter and energy during 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 usually called an ecological niche.

Ecological niche(from the French niche - a recess in the wall) - this 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.

Fundamental ecological niche(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 the fundamental (potential) niche that a species can defend in competition with other species.

Based on the relative position, the niches of the two species are divided into three types: non-adjacent ecological niches; niches touching but not overlapping; touching 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 (intelligence, 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 . The man has his own, inherent only to him, ecological niche. The space in which a person’s niche is localized is very limited. As a biological species, humans can only live within the landmass of the equatorial belt (tropics, subtropics), where the hominid family arose.

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

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

Gause's rule (or even law): two species cannot simultaneously occupy the same ecological niche and therefore necessarily displace each other.

In one of the experiments, Gause bred two types of ciliates - Paramecium caudatum and Paramecium aurelia. They regularly received as food a type of bacteria that does not reproduce in the presence of paramecium. If each type of ciliate was cultivated separately, then their populations grew according to a typical sigmoid curve (a). In this case, the number of paramecia was determined by the amount of food. But when they coexisted, 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

When ciliates were grown together, after some time only one species remained. At the same time, the ciliates did not attack individuals of another type and did not emit harmful substances. The explanation is that the species studied had different growth rates. The fastest reproducing species won the competition for food.

When breeding P. caudatum and P. bursaria no such displacement occurred; both species were in equilibrium, with the latter 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 pattern of relationships between prey and predator.

Gauseux's principle is called the principle exception 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 displaced. Gause's principle plays a huge role in the development of the niche concept, and also forces ecologists to seek answers to a number of questions: How do similar species coexist? How large must the differences between species be for them to coexist? How can competitive exclusion be avoided?

Life form of the species – this is a historically developed complex of its biological, physiological and morphological properties, which determines a certain response to environmental influences.

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

1.Neuston(from Greek neuston - capable of swimming) – a collection of marine and freshwater organisms that live near the surface of the water , for example, mosquito larvae, many protozoa, water strider bugs, and among plants, the well-known duckweed.

2. Lives closer to the surface of the water plankton.

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

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

1. What is biocenosis, biogeocenosis, agrocenosis? 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 living together in a given territory.

The concept of “biocenosis” – conditional, since organisms cannot live outside their environment, but it is convenient to use in the process of studying ecological connections between organisms. Depending on the area, the attitude towards human activity, the degree of saturation, usefulness, etc. distinguish biocenoses of land, water, natural and anthropogenic, saturated and unsaturated, complete and incomplete.

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

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

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

V.N. Sukachev the term was proposed (and generally accepted) to denote communities biogeocenosis(from Greek bios – life, geo – Earth, cenosis – community) - This is a collection of organisms and natural phenomena characteristic of a given geographical area.

The structure of biogeocenosis includes two components biotic – community of living plant and animal organisms (biocenosis) – and abiotic - a set of inanimate 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- climate in all its diverse manifestations and edaphotope(from the Greek edaphos - soil) - soils, relief, water.

Biogeocenosis= biocenosis (phytocenosis+zoocenosis+microbocenosis)+biotope (climatope+edaphotope).

Biogeocenoses – these are natural formations (they contain the element “geo” - Earth ) .

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

Agrocenosis(from the Latin agraris and the Greek koikos - general) - a community of organisms created by man and artificially maintained by him with increased yield (productivity) of one or more selected species of plants or animals.

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

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

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

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

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

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

To the abiotic components of ecosystems These include inorganic substances - carbon, nitrogen, water, atmospheric carbon dioxide, minerals, organic substances found mainly in the soil: proteins, carbohydrates, fats, humic substances, etc., which enter the soil after the death of organisms.

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

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

Environmental factors is a complex of environmental conditions affecting living organisms. Distinguish inanimate factors— abiotic (climatic, edaphic, orographic, hydrographic, chemical, pyrogenic), wildlife factors— biotic (phytogenic and zoogenic) and anthropogenic factors (impact of human activity). Limiting factors include any factors that limit the growth and development of organisms. The adaptation of an organism to its environment is called adaptation. The external appearance of an organism, reflecting its adaptability to environmental conditions, is called life form.

The concept of environmental environmental factors, their classification

Individual components of the environment that affect living organisms, to which they respond with adaptive reactions (adaptations), are called environmental factors, or ecological factors. In other words, the complex of environmental conditions affecting the life of organisms is called environmental environmental factors.

All environmental factors are divided into groups:

1. include components and phenomena of inanimate nature that directly or indirectly affect living organisms. Among the many abiotic factors, the main role is played by:

• climatic(solar radiation, light and light regime, temperature, humidity, precipitation, wind, atmospheric pressure, etc.);
• edaphic(mechanical structure and chemical composition of the soil, moisture capacity, water, air and thermal conditions of the soil, acidity, humidity, gas composition, groundwater level, etc.);
• orographic(relief, slope exposure, slope steepness, elevation difference, altitude above sea level);
• hydrographic(water transparency, fluidity, flow, temperature, acidity, gas composition, content of mineral and organic substances, etc.);
• chemical(gas composition of the atmosphere, salt composition of water);
• pyrogenic(exposure to fire).

2. - the totality of relationships between living organisms, as well as their mutual influences on the habitat. The effect of biotic factors can be not only direct, but also indirect, expressed in the adjustment of abiotic factors (for example, changes in soil composition, microclimate under the forest canopy, etc.). Biotic factors include:

• phytogenic(the influence of plants on each other and on the environment);
• zoogenic(the influence of animals on each other and on the environment).

3. reflect the intense influence of humans (directly) or human activities (indirectly) on the environment and living organisms. Such factors include all forms of human activity and human society that lead to changes in nature as a habitat for other species and directly affect their lives. Every living organism is influenced by inanimate nature, organisms of other species, including humans, and in turn has an impact on each of these components.

The influence of anthropogenic factors in nature can be either conscious, accidental, or unconscious. Man, plowing virgin and fallow lands, creates agricultural land, breeds highly productive and disease-resistant forms, spreads some species and destroys others. These influences (conscious) are often negative, for example, the thoughtless resettlement of many animals, plants, microorganisms, the predatory destruction of a number of species, environmental pollution, etc.

Biotic environmental factors are manifested through the relationships of organisms belonging to the same community. In nature, many species are closely interrelated, and their relationships with each other as components of the environment can be extremely complex. As for the connections between the community and the surrounding inorganic environment, they are always two-way, reciprocal. Thus, the nature of the forest depends on the corresponding type of soil, but the soil itself is largely formed under the influence of the forest. Similarly, temperature, humidity and light in the forest are determined by vegetation, but the prevailing climatic conditions in turn affect the community of organisms living in the forest.

Impact of environmental factors on the body

The impact of the environment is perceived by organisms through environmental factors called environmental. It should be noted that the environmental factor is only a changing element of the environment, causing in organisms, when it changes again, adaptive ecological and physiological reactions that are hereditarily fixed in the process of evolution. They are divided into abiotic, biotic and anthropogenic (Fig. 1).

They name the entire set of factors in the inorganic environment that influence the life and distribution of animals and plants. Among them there are: physical, chemical and edaphic.

Physical factors - those whose source is a physical state or phenomenon (mechanical, wave, etc.). For example, temperature.

Chemical factors- those that originate from the chemical composition of the environment. For example, water salinity, oxygen content, etc.

Edaphic (or soil) factors are a set of chemical, physical and mechanical properties of soils and rocks that affect both the organisms for which they are a habitat and the root system of plants. For example, the influence of nutrients, humidity, soil structure, humus content, etc. on plant growth and development.

Rice. 1. Scheme of the impact of the habitat (environment) on the body

— human activity factors affecting the natural environment (hydrosphere, soil erosion, forest destruction, etc.).

Limiting (limiting) environmental factors These are factors that limit the development of organisms due to a lack or excess of nutrients compared to the need (optimal content).

Thus, when growing plants at different temperatures, the point at which maximum growth occurs will be optimum. The entire temperature range, from minimum to maximum, at which growth is still possible is called range of stability (endurance), or tolerance. The points limiting it, i.e. the maximum and minimum temperatures suitable for life are the limits of stability. Between the optimum zone and the limits of stability, as it approaches the latter, the plant experiences increasing stress, i.e. we're talking about about stress zones, or zones of oppression, within the stability range (Fig. 2). As you move further down and up the scale from the optimum, not only does stress intensify, but when the limits of the body's resistance are reached, its death occurs.

Rice. 2. Dependence of the action of an environmental factor on its intensity

Thus, for each species of plant or animal there is an optimum, stress zones and limits of stability (or endurance) in relation to each environmental factor. When the factor is close to the limits of endurance, the organism can usually exist only for a short time. In a narrower range of conditions, long-term existence and growth of individuals is possible. In an even narrower range, reproduction occurs, and the species can exist indefinitely. Typically, somewhere in the middle of the resistance range there are conditions that are most favorable for life, growth and reproduction. These conditions are called optimal, in which individuals of a given species are the most fit, i.e. leave the greatest number of descendants. In practice, it is difficult to identify such conditions, so the optimum is usually determined by individual vital signs (growth rate, survival rate, etc.).

Adaptation consists in adapting the body to environmental conditions.

The ability to adapt is one of the main properties of life in general, ensuring the possibility of its existence, the ability of organisms to survive and reproduce. Adaptations manifest themselves at different levels - from the biochemistry of cells and the behavior of individual organisms to the structure and functioning of communities and ecological systems. All adaptations of organisms to existence in various conditions have been developed historically. As a result, groupings of plants and animals specific to each geographical zone were formed.

Adaptations may be morphological, when the structure of an organism changes until a new species is formed, and physiological, when changes occur in the functioning of the body. Closely related to morphological adaptations is the adaptive coloration of animals, the ability to change it depending on the light (flounder, chameleon, etc.).

Widely known examples of physiological adaptation are winter hibernation of animals, seasonal migrations of birds.

Very important for organisms are behavioral adaptations. For example, instinctive behavior determines the action of insects and lower vertebrates: fish, amphibians, reptiles, birds, etc. This behavior is genetically programmed and inherited (innate behavior). This includes: the method of building a nest in birds, mating, raising offspring, etc.

There is also an acquired command, received by an individual in the course of his life. Education(or learning) - the main way of transmitting acquired behavior from one generation to another.

The ability of an individual to manage his cognitive abilities to survive unexpected changes in his environment is intelligence. The role of learning and intelligence in behavior increases with the improvement of the nervous system—an increase in the cerebral cortex. For humans, this is the defining mechanism of evolution. The ability of species to adapt to a particular range of environmental factors is denoted by the concept ecological mystique of the species.

The combined effect of environmental factors on the body

Environmental factors usually act not one at a time, but in a complex manner. The effect of one factor depends on the strength of the influence of others. The combination of different factors has a noticeable impact on the optimal living conditions of the organism (see Fig. 2). The action of one factor does not replace the action of another. However, with the complex influence of the environment, one can often observe a “substitution effect”, which manifests itself in the similarity of the results of the influence of different factors. Thus, light cannot be replaced by excess heat or an abundance of carbon dioxide, but by influencing temperature changes, it is possible to stop, for example, plant photosynthesis.

In the complex influence of the environment, the impact of various factors on organisms is unequal. They can be divided into main, accompanying and secondary. The leading factors are different for different organisms, even if they live in the same place. The role of a leading factor at different stages of an organism’s life can be played by one or another element of the environment. For example, in the life of many cultivated plants, such as cereals, the leading factor during the germination period is temperature, during the heading and flowering period - soil moisture, and during the ripening period - the amount of nutrients and air humidity. The role of the leading factor may change at different times of the year.

The leading factor may be different for the same species living in different physical and geographical conditions.

The concept of leading factors should not be confused with the concept of. A factor whose level in qualitative or quantitative terms (deficiency or excess) turns out to be close to the limits of endurance of a given organism, called limiting. The effect of the limiting factor will also manifest itself in the case when other environmental factors are favorable or even optimal. Both leading and secondary environmental factors can act as limiting factors.

The concept of limiting factors was introduced in 1840 by the chemist 10. Liebig. Studying the influence of the content of various chemical elements in the soil on plant growth, he formulated the principle: “The substance found in the minimum controls the yield and determines the size and stability of the latter over time.” This principle is known as Liebig's law of the minimum.

The limiting factor can be not only a deficiency, as Liebig pointed out, but also an excess of factors such as, for example, heat, light and water. As noted earlier, organisms are characterized by ecological minimums and maximums. The range between these two values ​​is usually called the limits of stability, or tolerance.

In general, the complexity of the influence of environmental factors on the body is reflected by V. Shelford’s law of tolerance: the absence or impossibility of prosperity is determined by a deficiency or, conversely, an excess of any of a number of factors, the level of which may be close to the limits tolerated by a given organism (1913). These two limits are called tolerance limits.

Numerous studies have been carried out on the “ecology of tolerance”, thanks to which the limits of existence of many plants and animals have become known. Such an example is the effect of air pollutants on the human body (Fig. 3).

Rice. 3. The influence of air pollutants on the human body. Max - maximum vital activity; Additional - permissible vital activity; Opt is the optimal (not affecting vital activity) concentration of a harmful substance; MPC is the maximum permissible concentration of a substance that does not significantly change vital activity; Years - lethal concentration

The concentration of the influencing factor (harmful substance) in Fig. 5.2 is indicated by the symbol C. At concentration values ​​of C = C years, a person will die, but irreversible changes in his body will occur at significantly lower values ​​of C = C MPC. Consequently, the range of tolerance is limited precisely by the value C MPC = C limit. Hence, Cmax must be determined experimentally for each pollutant or any harmful chemical compound and its Cmax must not be exceeded in a specific habitat (living environment).

In protecting the environment, it is important upper limits of body resistance to harmful substances.

Thus, the actual concentration of the pollutant C actual should not exceed C maximum permissible concentration (C fact ≤ C maximum permissible value = C lim).

The value of the concept of limiting factors (Clim) is that it gives the ecologist a starting point when studying complex situations. If an organism is characterized by a wide range of tolerance to a factor that is relatively constant, and it is present in the environment in moderate quantities, then such a factor is unlikely to be limiting. On the contrary, if it is known that a particular organism has a narrow range of tolerance to some variable factor, then it is this factor that deserves careful study, since it may be limiting.