The ability of organisms to adapt to changing environmental conditions. Environmental environmental factors

Levels of adaptation of the body to changing conditions. How do organisms adapt to environmental conditions? There are several levels at which this process occurs. The cellular level is one of the most important.

Let us consider, as an example, how a single-celled organism, Escherichia coli, adapts to environmental conditions. It is known that it grows and reproduces well in a medium containing the only sugar - glucose. When living in such an environment, its cells do not need the enzymes needed to convert other sugars, such as lactose, into glucose. But if bacteria are grown in a medium containing lactose, then intensive synthesis of enzymes that convert lactose into glucose immediately begins in the cells (remember § 17). Consequently, E. coli is able to rearrange its vital activity in order to adapt to new environmental conditions. The above example applies to all other cells, including cells of higher organisms.

Another level at which organisms adapt to environmental conditions is the tissue level. Training leads to the development of tissues and organs: weightlifters have powerful muscles; people who scuba dive have highly developed lungs; Excellent shooters and hunters have special visual acuity. Many qualities of the body can be developed to a large extent by training. For some diseases, especially when huge pressure falls on the liver, a sharp increase in its size is observed. Thus, individual organs and tissues are able to respond to changing living conditions.

Self-regulation. The body is a complex system capable of self-regulation. Self-regulation allows the body to effectively adapt to environmental changes. The ability for self-regulation is highly expressed in higher vertebrates, especially in mammals. This is achieved thanks to the powerful development of the nervous, circulatory, immune, endocrine and digestive systems.

Changing conditions inevitably entail a restructuring of their work. For example, a lack of oxygen in the air leads to intensification of the circulatory system, the pulse quickens, and the amount of hemoglobin in the blood increases. As a result, the body adapts to changed conditions.

The constancy of the internal environment under systematically changing environmental conditions is created by the joint activity of all body systems. In higher animals this is expressed in maintaining a constant body temperature, constant chemical, ionic and gas composition, blood pressure, respiratory rate and heart rate, constant synthesis of necessary substances and destruction of harmful ones.

Maintaining a relative constancy of the internal environment of the body is called homeostasis. Homeostasis - most important property whole organism.

Metabolism - required condition and a way to maintain the stability of the organization of living things. Without metabolism, the existence of a living organism is impossible. The exchange of substances and energy between the body and the external environment is an integral property of living things.

The immune (protective) system plays a special role in maintaining the constancy of the internal environment. The Russian scientist I. I. Mechnikov was one of the first biologists to prove its enormous importance. Cells of the immune system synthesize special proteins - antibodies, which detect and destroy everything foreign to a given organism.

The influence of external conditions on early development organisms. The ability to self-regulate and resist harmful environmental influences does not arise immediately in organisms. During embryonic and postembryonic development, when many protective systems have not yet been formed, organisms are especially vulnerable to the action of damaging factors. Therefore, in both animals and plants, the embryo is protected by special membranes or by the mother’s body itself. It is either equipped with special nourishing tissue or receives nutrients directly from the mother's body. Nevertheless, changes in external conditions can accelerate the development of the embryo or slow it down and even cause various disorders.

Parental use of alcohol, drugs, and smoking tobacco has a harmful effect on the development of the human embryo. Alcohol and nicotine inhibit cellular respiration. Insufficient oxygen supply leads to the fact that fewer cells are formed in the developing organs, and the organs are underdeveloped. Nerve tissue is especially sensitive to lack of oxygen. The future mother's use of alcohol, drugs, smoking tobacco, and drug abuse often lead to irreversible damage to the embryo and the subsequent birth of children with mental retardation or congenital deformities. No less dangerous for the development of the embryo is pollution of the habitat with various chemicals or exposure to ionizing radiation.

During the postembryonic period, developing organisms are also very sensitive to harmful environmental influences. This is explained by the fact that the formation of systems for maintaining homeostasis continues after birth. Therefore, alcohol, nicotine, and drugs, which are poisons for the adult body, are especially dangerous for children. These substances inhibit the growth and development of the entire organism, and especially the brain, which leads to mental retardation, serious illnesses and even death.

The biological clock. Organisms do not always strictly maintain the characteristics of their internal environment at the same level. Often external changes entail a restructuring of the internal environment. An example of this is the change in the physiological state of organisms depending on changes in day length throughout the year, or, as they say, changes in photoperiodic conditions.

For many animals and plants living in temperate climates, the breeding season coincides with increasing daylight hours. Changes in photoperiodic conditions in this case are the leading factor. Seasonal rhythms are most clearly manifested in the change of cover of trees in deciduous forests, the change in the plumage of birds and the hair of mammals, in the periodic stops and resumption of plant growth, etc.

The study of the phenomena of daily, seasonal and lunar periodicity in living organisms has shown that all eukaryotes (unicellular and multicellular) have a so-called biological clock. In other words, organisms have the ability to measure daily, lunar, and seasonal cycles.

It is known that tidal currents in the ocean are caused by the influence of the Moon. During lunar days the water rises (and recedes) either twice or once, depending on the area of ​​the Earth. Marine animals living in such periodically changing conditions are able to measure the time of high and low tides using biological clocks. Locomotor activity, oxygen consumption and many physiological processes in crabs, sea anemones, hermit crabs and other inhabitants of coastal areas of the seas naturally change during the lunar day.

The course of the biological clock can be restructured depending on changed conditions. An example of such a process is a change in the rhythms of many physiological functions: body temperature, blood pressure, phases of motor activity and rest in a person who has flown from Moscow to Kamchatka, where the Sun rises 9 hours earlier. When flying quickly over long distances, the adjustment of the biological clock does not occur immediately, but over several days.

The daily rhythms of life of many organisms are determined by the alternation of light and darkness: the beginning of dawn or dusk. An hour before sunset, starlings gather in flocks for 10-30 minutes and fly away to roosting sites tens of kilometers away. They are never late thanks to their biological clock, which adjusts to the Sun. In general, daily periodicity results from the coordination of many rhythms, both internal and external.

In some cases, the cause of periodic fluctuations in the internal environment lies in the body itself. Experiments on animals have shown that under conditions of absolute darkness and sound insulation, periods of rest and wakefulness alternate sequentially, falling within a period of time close to 24 hours.

So, fluctuations in the characteristics of the internal environment of the body can be considered as one of the factors that maintain its constancy.

Anabiosis. Often organisms find themselves in environmental conditions in which the continuation of normal life processes is impossible. In such cases, some organisms may fall into suspended animation (from the Greek “ana” - again, “bios” - life), i.e. a condition characterized by a sharp decrease or even temporary cessation of metabolism. Anabiosis is an important adaptation of many species of living beings to unfavorable conditions a habitat. Microbial spores, plant seeds, animal eggs are examples of an anabiotic state. In some cases, suspended animation can last hundreds or even thousands of years, after which the seeds do not lose their viability. Deep freezing of sperm and eggs of especially valuable farm animals for their long-term storage and subsequent widespread use is an example of the use of suspended animation in human practice.

1. Give examples confirming the adaptability of organisms to environmental conditions at the cellular and tissue levels.
2. Why are alcohol, nicotine, and drugs especially harmful to the embryo?
3. Do you think the ability of organisms to measure time and fall into a state of suspended animation can be considered examples of self-regulation? Justify your answer.
4. How do you think we can use knowledge about the biological clock and suspended animation in practical activities?

The ultimate goal of nature conservation is to ensure favorable conditions for the life of present and subsequent generations of people, development National economy, science and culture of all peoples inhabiting our planet.

It is essential for young people in education to understand the seriousness of the problems facing conservation. It is necessary to realize that even if all environmental protection measures are taken at industrial enterprises, humanity will have a negative impact on nature. Replacement of complex biocenoses with agrocenoses, construction of cities and various structures that reduce the bioproductivity of vast territories, chemicalization of agriculture, local changes in the hydrothermal regime of water areas and territories, industrial use All more species of animals and plants - these and many other impacts have, and will have, an increasingly stronger impact on nature, even if all conceivable precautions are taken. According to Academician S.S. Schwartz, the struggle for a “healthy biosphere” should be waged in two directions: by minimizing the immediate harmful effects of industrial pressure on nature and by developing measures that ensure the normal functioning of the biosphere and its constituent biocenoses in new conditions. Konstantinov V.M., Chelidze Yu.B. Ecological foundations of environmental management: Textbook. A manual for student institutions. prof. education. - M.: Mastery, 2002. pp. 22-23

The first is considered to be the crisis of the appropriating economy: gathering and primitive hunting. It is believed that it arose due to the depletion of natural reserves of fruits and edible plants, and the extermination of small animals in the habitats of ancient people. The crisis was overcome by switching to collective hunting for large animals using more advanced tools: bow, spear, harpoon and division of labor between the participants in the hunt. A new environmental crisis is believed to have arisen at the end of ice age, when large animals began to disappear - the woolly rhinoceros, the cave bear, the mammoth. This crisis is associated with the overhunting of large animals by very skilled hunters, whose increased numbers could not be provided by the natural food supply. The way out of this crisis was found in the transition from an appropriating to a producing economy. The development of animal husbandry and agriculture determined the progress of mankind for several millennia.

The next crisis arose in arid regions - places of ancient irrigated agriculture. This was facilitated by the complete deforestation and the excessive load of primitive agriculture on the soils, which caused their accelerated erosion and salinization. Now in these areas of North Africa, the Middle East, Central and Central Asia there are deserts. Overgrazing of livestock also contributed to desertification of arid regions. The processes of expansion of desert territories due to overgrazing and unsustainable farming continue in our time. In many areas they have acquired the character of major regional environmental disasters.

The growth of the modern environmental crisis in the relationship between nature and society is associated with the scientific and technological revolution. At the same time, regional crisis situations arising due to depletion natural resources, are successfully resolved by improving the technologies of search, extraction, transportation, processing of traditional natural resources, the use of new resources and the production of synthetic materials.

More ominous evidence of growing crisis situations in the relationship between society and nature in different regions is associated with the degradation of natural ecosystems caused by excessive load on biocenoses, population growth and environmental pollution.

IN last years Due to human fault, environmental disasters caused by chemical and radioactive pollution are becoming more frequent. More than 50 years have passed since the atomic bombing of the Japanese cities of Hiroshima and Nagasaki, but even now the lists of those who died from radiation sickness are growing every year. The consequences of wind-borne radioactive dust and waste at the Mayak enterprise in Chelyabinsk region in 1957 Accident at the 4th power unit Chernobyl nuclear power plant in 1986 it became the worst environmental disaster of the 20th century. Environmental disasters of various scales arise as a result of chemical pollution of the environment. All medical and environmental reference books include information about Minamata disease, which arose in the population as a result of environmental pollution with mercury compounds. Catastrophic consequences arise as a result of pollution by industrial emissions and vehicle exhaust gases and the formation of toxic fogs - smog in large cities.

Medicinal plants. Recently, despite the advances in chemistry and the abundance of synthetic drugs, interest in plant medicines has increased. The point of view is becoming increasingly popular that drugs of natural origin are more effective because active substances in a plant they are usually found in a complex.

The demand for medicinal raw materials is increasing. However, one should not increase the removal of plants from nature, but should conduct farming in nature: sowing plants, alternating collection sites, creating temporary reserves, etc. Currently, several reserves have already been created.

Adaptation– this is the adaptation of the organism to environmental conditions due to a complex of morphological, physiological, and behavioral characteristics.

Different organisms adapt to different environmental conditions, and as a result, moisture-loving hydrophytes and "dry-bearers" - xerophytes(Fig. 6); plants of saline soils – halophytes; shade tolerant plants ( sciophytes), and requiring full sunlight for normal development ( heliophytes); animals that live in deserts, steppes, forests or swamps are nocturnal or diurnal. Groups of species with a similar relationship to environmental conditions (that is, living in the same ecotopes) are called environmental groups.

The ability of plants and animals to adapt to unfavorable conditions differs. Due to the fact that animals are mobile, their adaptations are more diverse than those of plants. Animals can:

– avoid unfavorable conditions (birds fly to warmer regions due to lack of food and cold in winter, deer and other ungulates wander in search of food, etc.);

– fall into suspended animation – a temporary state in which life processes are so slow that their visible manifestations are almost completely absent (numbness of insects, hibernation of vertebrates, etc.);

– adapt to life in unfavorable conditions (they are saved from frost by their fur and subcutaneous fat, desert animals have adaptations for economical use of water and cooling, etc.). (Fig. 7).

Plants are inactive and lead an attached lifestyle. Therefore, only the last two adaptation options are possible for them. Thus, plants are characterized by a decrease in the intensity of vital processes during unfavorable periods: they shed their leaves, overwinter in the form of dormant organs buried in the soil - bulbs, rhizomes, tubers, and remain in the state of seeds and spores in the soil. In bryophytes, the entire plant has the ability to undergo anabiosis, which can survive for several years in a dry state.

Plant resistance to adverse factors is increased due to special physiological mechanisms: changing the osmotic pressure in cells, regulating the intensity of evaporation using stomata, using “filter” membranes for selective absorption of substances, etc.

Adaptations develop at different rates in different organisms. They arise most quickly in insects, which in 10–20 generations can adapt to the action of a new insecticide, which explains the failures chemical control density of insect pest populations. The process of developing adaptations in plants or birds occurs slowly, over centuries.

Observed changes in the behavior of organisms are usually associated with hidden characteristics that they had, as it were, “in reserve,” but under the influence of new factors they emerged and increased the stability of the species. Such hidden characteristics explain the resistance of some tree species to industrial pollution (poplar, larch, willow) and some weed species to herbicides.

The same ecological group often includes organisms that are not similar to each other. This is due to the fact that to the same environmental factor different types organisms can adapt in different ways.

For example, they experience the cold differently warm-blooded(they are called endothermic, from the Greek words endon - inside and terme - heat) and cold-blooded (ectothermic, from the Greek ektos - outside) organisms. (Fig. 8.)

The body temperature of endothermic organisms does not depend on the ambient temperature and is always more or less constant, its fluctuations do not exceed 2–4 o even in the most severe frosts and extreme heat. These animals (birds and mammals) maintain body temperature by internal heat generation based on intensive metabolism. They retain their body heat through warm “coats” made of feathers, wool, etc.

Physiological and morphological adaptations are complemented by adaptive behavior (choosing sheltered places to spend the night, building burrows and nests, group overnight stays with rodents, close groups of penguins keeping each other warm, etc.). If the ambient temperature is very high, then endothermic organisms are cooled due to special devices, for example, by evaporation of moisture from the surface of the mucous membranes of the oral cavity and upper respiratory tract. (For this reason, in hot weather, the dog’s breathing quickens and he sticks out his tongue.)

The body temperature and mobility of ectothermic animals depends on the ambient temperature. In cool weather, insects and lizards become lethargic and inactive. Many species of animals have the ability to choose a place with favorable conditions of temperature, humidity and sunlight (lizards bask on illuminated rock slabs).

However, absolute ectothermism is observed only in very small organisms. Most cold-blooded organisms are still capable of weak regulation of body temperature. For example, in actively flying insects - butterflies, bumblebees, body temperature is maintained at 36–40 o C even at air temperatures below 10 o C.

Similarly, species of one ecological group in plants differ in their appearance. They can also adapt to the same environmental conditions in different ways. Thus, different types of xerophytes save water in different ways: some have thick cell membranes, others have pubescence or a waxy coating on the leaves. Some xerophytes (for example, from the family Lamiaceae) emit vapors of essential oils that envelop them like a “blanket”, which reduces evaporation. The root system of some xerophytes is powerful, goes into the soil to a depth of several meters and reaches the groundwater level (camel thorn), while others have a superficial but highly branched one, which allows them to collect precipitation water.

Among the xerophytes there are shrubs with very small hard leaves that can be shed in the driest time of the year (caragana shrub in the steppe, desert shrubs), turf grasses with narrow leaves (feather grass, fescue), succulents(from the Latin succulentus - succulent). Succulents have succulent leaves or stems that store water, and can easily tolerate high air temperatures. Succulents include American cacti and saxaul, which grows in Central Asian deserts. They have a special type of photosynthesis: the stomata open briefly and only at night; during these cool hours, plants store carbon dioxide, and during the day they use it for photosynthesis with closed stomata. (Fig. 9.)

A variety of adaptations to surviving unfavorable conditions on saline soils is also observed in halophytes. Among them there are plants that are capable of accumulating salts in their bodies (saltweed, swede, sarsazan), secreting excess salts onto the surface of the leaves with special glands (kermek, tamarix), “not allowing” salts into their tissues due to the “root barrier” impermeable to salts "(wormwood). In the latter case, the plants have to be content with a small amount of water and they have the appearance of xerophytes.

For this reason, one should not be surprised that in the same conditions there are plants and animals that are dissimilar to each other, which have adapted to these conditions in different ways.

Control questions

1. What is adaptation?

2. How can animals and plants adapt to unfavorable environmental conditions?

2. Give examples of ecological groups of plants and animals.

3. Tell us about the different adaptations of organisms to surviving the same unfavorable environmental conditions.

4. What is the difference between adaptations to low temperatures in endothermic and ectothermic animals?

A wide range of tolerance of a species in relation to environmental factors is indicated by adding the prefix “eury-” (from the Greek eurys - wide) to the name of the factor, and the low ecological valency of the species is characterized by the prefix “steno-” (from the Greek stenos - narrow). For example, animals that can tolerate significant temperature fluctuations are called eurythermic, and if they are unable to do this they are called stenothermic. Small changes in temperature have little effect on eurythermal organisms, but can be disastrous for stenothermic organisms. Ecologically non-plastic, i.e. low-hardy species, the existence of which requires strictly defined environmental conditions, are called stenobiotic, and more hardy species that adapt to ecological situation with a wide range of parameter changes, - eurybiotic.

The ability of an organism to adapt to the action of environmental factors and to survive in changing environmental conditions due to evolutionarily emerging morphological, physiological, biochemical and behavioral adaptations is called adaptation(from Latin adaptatio - device).

Different organisms are characterized by different environmental valence, but the range of tolerance of an organism can change even during the transition from one stage of development to another - for example, young organisms are often more vulnerable and more demanding of environmental conditions than adults.

Any organism simultaneously experiences the influence of a whole complex of environmental factors that are interconnected and influence each other, and therefore the boundaries of the range of tolerance of the organism in relation to any environmental factor can shift depending on the combination in which other factors act (for example , heat and cold are easier to bear in dry rather than humid air). As a result of the interaction of environmental factors, their partial compensation may occur, but it is impossible to completely replace one of the factors with another, despite the most favorable combinations of other conditions.

If all environmental conditions are favorable, with the exception of one environmental factor, then it is this factor that becomes decisive for the life of specific organisms (populations), limiting (limiting) their development, and therefore it is called limiting factor. Back in the middle of the 19th century, the German organic chemist J. Liebig experimentally proved that the development of living organisms is limited by the lack of any component (for example, mineral salts, moisture, light, etc.) and called this phenomenon law of the minimum. However, as the American zoologist V. Shelford later found out, who formulated law of tolerance, the limiting factor can be not only a deficiency (minimum), but also an excess (maximum) of an environmental factor, the range between which determines the amount of endurance (tolerance limit) or the ecological valence of the organism to a given factor.

Each type of organism arose in a certain environment, adapted to one degree or another to its fluctuations and changes, and the further existence of the species is possible only in this or a similar environment that corresponds to its genetic adaptation capabilities. A sharp and rapid change in environmental factors can lead to the fact that the genetic capabilities of a species will be insufficient to adapt to new conditions, which is why radical transformations of nature by man can be dangerous for many species of living organisms, including himself.

Different organisms are characterized by different amounts of tolerance.

Environmental factors are interconnected and influence each other.

Conclusion: There is an ecological balance between living organisms and their habitat:

One of the main factors in ecology is chemical factor.

Environmental chemistry- a new branch of chemistry that deals with chemical composition and interactions between the main components and pollutants of inorganic and organic origin in the atmosphere, hydrosphere, lithosphere and their impact on the environment and the biosphere as a whole.

System– a set of elements (substances, bodies, living and inanimate nature) with connections between them, mentally or actually isolated from the surrounding space.

Distinguish chemical systems, physical systems, biological (living) systems, ecological systems and others.

Biological system is an ordered set of interdependent living components that dynamically interact with the inanimate environment. The following main levels of organization of biological systems are distinguished: molecular (gene), cellular, organ, organismal, population-species and ecosystem.

The hierarchical organization of biosystems, the simpler of which are part of more complexly organized ones, is manifested in emergence(from English emergent– suddenly arising), when, as they combine into larger systems of the next level, they acquire qualitatively new properties that were absent at the previous one.

Ecological system (ecosystem)– a system in which organisms and their habitat are combined into a single functional whole through metabolism and energy; any collection of organisms and their environment. An ecosystem is the basic functional unit in ecology.

More specific, ecosystem is a community of living organisms - biocenosis(from Greek bios- life and koinos- general) and its habitat - biotope(from Greek topos- place) , combined into a single functional whole. The exchange of matter, energy and information connects the biotic and abiotic components of an ecosystem in such a way that it remains stable over time.

To the term " ecosystem", proposed in 1935 by the English biologist A. Tansley to define the basic functional unit of living nature, is very close to the term " biogeocenosis", which was proposed in 1940 by V.N. Sukachev, and which largely reflects the structural characteristics of the geographical space in which the biocenosis develops.

Chemical system- a set of substances between which chemical reactions occur with the formation of new substances - reaction products.

Physical system – a set of bodies (substances) between which no chemical interactions occur; system characterized by the absence chemical reactions.

Cybernetic system– a system capable of receiving, storing and processing information, as well as exchanging it with other systems.

General ecology studies biological systems starting from the organismal level and, depending on the dimension of these systems, the following sections are distinguished: autecology(level of individual organisms), demecology(population level) and synecology(ecosystem level).

A population is a collection of organisms of the same species exchanging genetic information and inhabiting a certain limited space for many generations. A population is characterized by a number of characteristics inherent to the group as a whole, and not to its individual individuals: number, density, birth rate, mortality, age structure, spatial distribution, biotic potential, etc.

Number– the number of individuals in a population, which depends on the biological potential of the species and external conditions and can vary significantly over time.

Density– the number of individuals per unit area or volume. Optimal density is a level of density that combines the rational use of territory and the implementation of intrapopulation functions. Maintaining optimal density is a complex process of biological regulation based on the feedback principle.

Sex structure of the population– the ratio of female and male individuals in a population, closely related to its genetic and age structure.

Age structure of the population– the ratio of different individuals in a population age groups. The growth rate of a population is determined by the proportion of sexually mature individuals in it. If the percentage of immatures is high, this indicates a potential increase in population size.

Genetic structure of the population– the ratio of different genes in populations. It reflects the richness of the population’s gene pool (the totality of the genes of all individuals in the population), which determines the general species properties, as well as the features that arose in the order of the population’s adaptation to certain environmental conditions.

Spatial population structure– this is the distribution of individuals within the range, depending on the characteristics of the organisms and their habitat. It may be uniform(characterized by equal distance of individuals from each other), diffuse(individuals are distributed randomly across the territory) or mosaic(individuals are distributed in groups at a certain distance from each other).

Fertility– the number of new individuals appearing in the population per unit of time as a result of reproduction.

Mortality– the number of individuals who died in a population per unit of time from all causes.

Population growth rate– change in population size per unit of time. In the absence of limiting environmental factors, the specific growth rate (the ratio of the population growth rate to the initial size) is called biotic potential. In nature, under the influence of limiting factors, which are the so-called medium resistance, biotic potential is never fully realized, making up the difference between fertility and mortality in a population.

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Ecology

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Ecology
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Atomic and molecular particles
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Atmosphere
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Features of chemical processes in the atmosphere
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Hydrosphere
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Natural water
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Basic elemental composition of the earth's crust
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Accumulation by living matter
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The main functions of living matter in the biosphere
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Types of mineral raw materials and their reserves
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Pollution and environmental pollutants
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The ability of living organisms to adapt to their environment is called adaptation. Adaptation of an organism to the environment is one of the main properties of life, since this ensures the possibility of existence, survival and reproduction of organisms.

Along with nutrition, movement and reproduction, a mandatory property of any organism is their ability to protect themselves from the effects of adverse environmental factors, regardless of their nature (abiotic or biotic).

Environmental environmental factors can act as:

1) irritants (which provide adaptive changes in physiological and biochemical functions in the body);

2) limiters (causing the impossibility of the organism’s existence under given conditions);

3) modifiers (promote anatomical and morphological changes in the body);

4) signals (indicating changes in other environmental factors).

In the process of adaptation to unfavorable environmental conditions, organisms were able to develop following paths avoiding them.

Active path– a path that helps strengthen resistance and develop regulatory processes that allow all vital functions of the body to be carried out, despite unfavorable external factors. For example, warm-blooded animals - mammals and birds, living in conditions of variable temperatures, maintain a constant temperature within themselves, which is optimal for the passage of biochemical processes in the cells of the body. This active resistance influence of the surrounding external environment requires large energy costs, which must be constantly replenished, as well as special adaptations in the external and internal structure of the body.

The passive path is closely related to the subordination of the vital functions of the body to changes in environmental factors. For example, a lack of heat in the body leads to suppression of vital functions and a decrease in the level of metabolism, which allows for economical use of energy reserves. When environmental conditions sharply deteriorate, organisms of different species can suspend their vital activity and enter a state of so-called hidden life. Some small organisms can dry out completely in the air and then return to active life after being in water. This state of imaginary death is called suspended animation. The transition to a state of deep anabiosis, in which metabolism almost completely stops, significantly expands the survival capabilities of organisms in the most extreme conditions. For example, dried seeds and spores of many plants, when moistened, sprout even after several years. This also applies to small animals. For example, rotifers and nematodes are capable of withstanding temperatures down to minus 2000C in a state of suspended animation. Examples of hidden life are the torpor of insects, the winter dormancy of perennial plants, the hibernation of vertebrates, the preservation of seeds and spores in the soil, and small organisms in drying up reservoirs. Some bacteria and viruses, including pathogenic ones, can remain in an inactive state for an indefinitely long time until favorable conditions arise for their “awakening” and subsequent active reproduction. This is a phenomenon in which there is temporary physiological rest in individual development In some animals and plants, caused by unfavorable environmental factors, is called diapause.

Avoidance of Adverse Effects- this is the development by the body of such life cycles in which the most vulnerable stages of its development are completed during the most favorable periods of the year in terms of temperature and other conditions. The common way for animals to adapt to unfavorable periods is migration . For example, in Kazakhstan, steppe saigas go annually for the winter to the southern semi-deserts with little snow, where winter grasses are more nutritious and accessible due to the dry climate. In summer, the grassland of semi-deserts quickly dries out due to the dry climate; therefore, saigas migrate to wetter northern areas during breeding. Most often, adaptation of a species to its environment is carried out by a certain combination of all three possible ways their devices.

Living organisms, over the course of long evolution, have developed a variety of devices (adaptations) that allow them to regulate metabolism when the ambient temperature changes. This is achieved by: a) various biochemical and physiological changes in the body, which include changes in the concentration and activity of enzymes, dehydration, lowering the freezing point of solutions present in the body, etc.; b) maintaining body temperature at a more stable temperature level than the temperature of the surrounding habitat, which allows maintaining the course of biochemical reactions that has developed for a given species.

Morphological adaptation- this is the presence of such features of the external structure that contribute to the survival and successful functioning of organisms in their usual conditions. An example of such adaptations is that developed in the process of long evolution external structure organisms that live in the aquatic environment. In particular, adaptations for high-speed swimming in many fish, squids and soaring in water in planktonic organisms. Plants that live in the desert are devoid of leaves (instead of wide traditional leaves, they have formed prickly needles), and their structure is best adapted to maximum accumulation and minimal loss of moisture at high temperatures (cacti). The morphological type of adaptation of an animal or plant, in which they have an external form that reflects the way they interact with their environment, called the life form of a species. Moreover, different species can have a similar life form if they lead a similar lifestyle. Examples in this case include a whale (mammal), a penguin (bird), and a shark (fish).

If in an individual individual adaptation to the environment is achieved due to its physiological mechanisms, then it called physiological adaptation.

Physiological regulation may be insufficient to withstand unfavorable environmental conditions. Sometimes prolonged strain on physiological functions (stress) leads to depletion of the body's resources and can lead to negative consequences. Therefore, in many cases, when environmental conditions persistently deviate from the biological optimum, changes in physiological regulation occur that increase its effectiveness and at the same time reduce the overall functional stress of the body. Such changes are also called acclimation . The acclimation of plants, animals and humans is of great ecological importance. Physiological adaptations are manifested in the characteristics of the enzymatic set in the digestive tract of animals, determined by the composition of food. An example is the camel, which is able to provide the body with the required amount of moisture through the biochemical oxidation of its own fat. Or changes in the body of animals and humans due to lack of oxygen. Low partial pressure of oxygen at high altitudes causes the condition hypoxia – oxygen starvation of cells. The body's immediate response to hypoxia is to increase ventilation of the lungs and intensify blood circulation, but this cannot last for a long time, as it requires energy expenditure and additional oxygen supply. In this regard, changes occur in various systems of the body aimed at reducing hypoxic stress and sufficiently supplying tissues with oxygen when its content in the environment is low. First of all, hematopoiesis is stimulated: the number of red blood cells in the blood increases and the relative content of a special form of hemoglobin, which has an increased affinity for oxygen, increases in them. In this regard, the oxygen capacity and oxygen transport function of the blood increase significantly. Then morphological changes occur in the circulatory system: the arteries of the heart and brain expand, the capillary network in the tissues thickens - all this facilitates the delivery of oxygen to the cells. In the cells themselves, due to an increase in the activity of oxidative enzymes, the affinity for oxygen also increases, and at the same time the relative level of temporary oxygen-free energy supply - anaerobic glycolysis - increases. All these processes of acclimation to hypoxia, occurring over several hours or days, help relieve functional stress from the respiratory and circulatory systems.

IN natural conditions the importance of physiological adaptation is associated with natural changes living conditions, this is mainly due to seasonal changes in temperature, humidity, availability of food in habitats, etc. Everyone is well aware of the autumn increase in thermal insulation in many mammals and birds due to molting, the appearance of winter plumage of the body (down, feathers, fur) and the accumulation of subcutaneous fat. During food-free times, the diet and quality of nutrition changes, physiological functions are aimed at economical expenditure of energy. Seasonal migrations of birds and fish are prepared by a complex of physiological and morphological changes and behavioral changes. All these changes are ensured by specific species-specific programs of physiological adaptation. However, the new physiological qualities of the organism acquired during acclimation are not highly stable; when the season changes and when conditions return to optimal, they are lost and are not inherited. This distinguishes acclimation from species-specific genetic adaptation.

If adaptation in a population of organisms (species) is achieved due to the mechanism of genetic variability and heredity, then its called genetic adaptation . Genetic adaptation occurs over a number of generations and is associated with the process of speciation and the emergence of new life forms of organisms.

Adaptive rhythms of life. Due to the axial rotation of the Earth and its movement around the Sun, the development of life on the planet occurred and occurs under conditions of a regular change of day and night, as well as the alternation of seasons. Such rhythmicity, in turn, creates periodicity, that is, repeatability of conditions in the life of most species. At the same time, the action quite naturally changes large number environmental factors: illumination, temperature, humidity, pressure atmospheric air, all weather components. There is a regularity in the repetition of both periods critical for survival and favorable ones. Circadian rhythms adapt organisms to the cycle of day and night. For example, in humans, about a hundred physiological characteristics are subject to the daily cycle: blood pressure, body temperature, heart rate, breathing rhythm, hormone secretion and many others.

Annual rhythms adapt organisms to seasonal changes in conditions. Thanks to this, the most vulnerable processes for many species of reproduction and rearing of young animals occur during the most favorable season. It should be especially emphasized that the main ecological period to which organisms respond in their annual cycles is not a random change in weather, but photoperiod , that is, changes in the ratio of day and night.

It is known that the length of daylight hours changes naturally throughout the year, and this is what serves as a very accurate signal of the approach of spring, summer, autumn and winter. The ability of organisms to respond to changes in day length is called photoperiodism. Plant photoperiodism, the response to the ratio of light (length of day) and dark (length of night) periods of the day, expressed in changes in the processes of growth and development, is associated with the adaptation of ontogenesis to seasonal changes in external conditions. Day length serves as an indicator of the season for plants and an external signal for the transition to flowering or preparation for an unfavorable season. One of the main manifestations of photoperiodism is the photoperiodic flowering reaction. The organ of photoperiod perception is the leaf, in which, as a result of light and dark reactions, a hormonal complex is formed that stimulates flowering. According to the photoperiod that causes flowering, plants are divided into long-day (cereals, etc.), short-day (rice, millet, hemp, soybeans, etc.) and neutral (buckwheat, peas, etc.). Long-day plants are distributed mainly in temperate and subpolar latitudes, while short-day plants are found closer to the subtropics. Photoperiodism significantly affects the formation (tubers, bulbs, heads of cabbage, stems) and physiological (intensity and form of growth, the onset of the dormant period, leaf fall, etc.) processes. Plant species differ in their belonging to one or another photoperiodic group, and varieties and lines differ in the degree of severity of the photoperiodic reaction. This is taken into account when zoning varieties, as well as in light culture and when growing plants in closed ground.

In animals, photoperiodism controls the timing of the mating season, fertility, autumn and spring molting, egg production, etc., and is genetically associated with biological rhythms. Using the photoperiodic reaction, it is possible to control the development of farm animals and their fertility.

Phototropism(from the Greek word tropos - turn, direction) these are growth movements of plant organs in response to the unilateral directed action of any environmental factor. Tropism is a phenomenon of irritability that causes redistribution of phytohormones in plant tissues. As a result of this, cells on one side of the stem, leaf or root grow faster than on the other, and the organ bends from the stimulus ( positive tropism) or from him ( negative). Thus, the seedling bends towards the light source ( phototropism ), the root grows vertically downward under the influence of gravity ( geotropism), plant roots grow towards a more humid environment ( hydrotropism) . Under the influence of touch and friction, the tendrils of climbing plants wrap around the support ( haptotropism ), in poorly aerated soil, the roots of some mangrove trees grow upward towards a source of oxygen ( aerotropism ), pollen tubes grow towards the ovule, which secretes certain chemical substances (chemotropism) . Tropism is an adaptive reaction that allows a plant to make full use of environmental factors or protect itself from their adverse effects.

In the process of evolution, characteristic time cycles have developed with a certain sequence and duration of periods of reproduction, growth, preparation for winter, that is biological rhythms vital activity of organisms in certain environmental conditions. Tidal rhythms. Species of organisms living in the coastal or bottom part of shallow water (littoral zone), into which light penetrates to the bottom, are in conditions of a very complex periodicity of the external environment. Superimposed on the 24-hour cycle of fluctuations in illumination and other factors is the alternation of ebbs and flows. During the lunar day (24 hours 50 minutes) there are 2 high tides and two low tides. Twice a month (new moon and full moon) the strength of the tides reaches its maximum value. The life of organisms is subject to this complex rhythm. coastal zone. For example, female fish smeltweed at the highest tide they lay their eggs at the water's edge, rolling them into the sand. When the tide goes out, the caviar remains to mature in it. The hatching of the fry occurs after half a month, coinciding with the time of the next high tide.

In addition to adaptation, plants and animals have developed defensive responses to certain environmental changes and impacts on them. For example, in plants, protection from unfavorable environmental factors can be provided by:

• features of the anatomical structure (formation of a cuticle, crust, thickening of waxy plaque or mechanical tissue, etc.);
• special defense organs (formation of burning hairs, spines);
• motor and physiological reactions;
• production of protective substances (synthesis of resins, phytoncides, phytoalexins, toxins, protective proteins, etc.).

It is known that each organism survives and reproduces only in a specific environment, characterized by a relatively narrow range of temperatures, precipitation, soil conditions, etc. The geographic range of any species corresponds to the geographic distribution of environmental conditions suitable for a given organism (temperature, humidity, light, atmospheric and water pressure).

Therefore, it is important to have information about the essence of the phenomena caused, the connections and dependencies that have developed between organisms, populations, biocenoses and environmental factors. Their theoretical basis constitutes the law of unity of the organism and the environment, according to which, in the opinion
IN AND. Vernadsky, life develops as a result of constant exchange of matter and information based on energy flows in the total unity of the environment and the organisms inhabiting it.

In the process of conjugate evolution, various types plants and animals have developed mutual adaptations to each other, that is co-adaptation : they are sometimes so strong that living separately in modern conditions They can’t anymore. This is where unity comes into play. organic world. Coadaptation of insect-pollinated plants and
Insect pollinators are an example of mutual adaptations that have historically emerged. In particular, a consequence of joint evolution is the attachment of various groups of animals to certain groups of plants and their places of growth.

When considering the relationship of organisms with the environment, ecology must, first of all, take into account the criteria of survival and reproduction. They mainly determine the ecological chances of persistence of individual species in a given environment or in a particular ecosystem. Currently, the following definitions (concepts) of the environment have emerged (Fig. 3.1).

Environment– it is the space, matter and energy that surrounds organisms and affects them both positively and negatively.

Fig.3.1. Classification of the concept “environment” (N.F. Reimers, 1990)

Natural environment is a set of natural abiotic (inanimate nature) and biotic (living nature) factors in relation to plant and animal organisms, regardless of contact with humans.

Built environment it is a natural environment modified by human activity. It includes " quasi-natural environment(cultivated landscapes, agrocenoses and other objects incapable of self-sustaining); " artificial" environment (artificial structures, buildings, asphalt roads in combination with natural elements - soil, vegetation, air, etc.); the human environment – ​​a set of abiotic, biotic and social factors in combination with “quasi-natural” and “arte-natural” environments. In factorial ecology, the habitat and conditions of existence of organisms are distinguished.

There is also a specific spatial understanding of the environment as the immediate surroundings of the organism - habitat. It includes only those elements of the environment with which a given organism enters into direct and indirect relationships, that is, everything that surrounds it.

Each organism reacts to its environment in accordance with its genetic constitution. Matching Rule environmental conditions of the genetic predetermination of the organism says: “ As long as the environment surrounding a certain type of organism corresponds to the genetic capabilities of this species to adapt to its fluctuations and changes, this species can exist.” According to this rule, one or another species of living things arose in a certain environment and, to one degree or another, was able to adapt to it. Its further existence is possible only in it or in a close environment. A sharp and rapid change in environmental conditions can lead to the fact that the genetic apparatus of a species will not be able to adapt to new living conditions. This can fully be applied to humans. Each organism reacts to its environment in accordance with its genetic constitution.