Abiotic, biotic and anthropogenic factors. Characteristics of abiotic environmental factors

The environment that surrounds living beings consists of many elements. They affect the life of organisms in different ways. The latter react differently to various environmental factors. Individual elements of the environment that interact with organisms are called environmental factors. Living conditions are a set of vital environmental factors, without which living organisms cannot exist. In relation to organisms, they act as environmental factors.

Classification of environmental factors.

All environmental factors accepted classify(distribute) into the following main groups: abiotic, biotic And anthropic. V Abiotic (abiogenic) factors are physical and chemical factors of inanimate nature. Biotic, or biogenic, factors are the direct or indirect influence of living organisms both on each other and on the environment. Anthropogenic (anthropogenic) In recent years, factors have been identified as a separate group of biotic factors due to their great importance. These are factors of direct or indirect impact of man and his economic activities on living organisms and the environment.

Abiotic factors.

Abiotic factors include elements of inanimate nature that act on a living organism. Types of abiotic factors are presented in table. 1.2.2.

Table 1.2.2. Main types of abiotic factors

Climatic factors.

All abiotic factors manifest themselves and act within the three geological shells of the Earth: atmosphere, hydrosphere And lithosphere. Factors that manifest themselves (act) in the atmosphere and during the interaction of the latter with the hydrosphere or with the lithosphere are called climatic. their manifestation depends on the physical and chemical properties of the geological shells of the Earth, on the amount and distribution of solar energy penetrating and reaching them.

Solar radiation.

Among the variety of environmental factors, solar radiation is of greatest importance. (solar radiation). This is a continuous flow of elementary particles (speed 300-1500 km/s) and electromagnetic waves (speed 300 thousand km/s), which carries a huge amount of energy to the Earth. Solar radiation is the main source of life on our planet. Under the continuous flow of solar radiation, life arose on Earth, went through a long path of evolution and continues to exist and depend on solar energy. The main properties of the radiant energy of the Sun as an environmental factor are determined by the wavelength. Waves passing through the atmosphere and reaching the Earth are measured in the range of 0.3 to 10 microns.

Based on the nature of the impact on living organisms, this spectrum of solar radiation is divided into three parts: ultraviolet radiation, visible light And infrared radiation.

Short-wave ultraviolet rays are almost completely absorbed by the atmosphere, namely its ozone screen. A small amount of ultraviolet rays penetrates the surface of the earth. Their wavelength lies in the range of 0.3-0.4 microns. They account for 7% of solar radiation energy. Short-wave rays have a detrimental effect on living organisms. They can cause changes in hereditary material - mutations. Therefore, in the process of evolution, organisms that have been exposed to solar radiation for a long time have developed adaptations to protect against ultraviolet rays. Many of them produce additional amounts of black pigment in their integument - melanin, which protects against the penetration of unwanted rays. This is why people get a tan by being outdoors for a long time. In many industrial regions there is a so-called industrial melanism- darkening of the color of animals. But this does not happen under the influence of ultraviolet radiation, but due to pollution by soot and environmental dust, the elements of which usually become darker. Against such a dark background, darker forms of organisms survive (are well camouflaged).

Visible light appears within wavelengths from 0.4 to 0.7 µm. It accounts for 48% of solar radiation energy.

It also adversely affects living cells and their functions in general: it changes the viscosity of the protoplasm, the magnitude of the electrical charge of the cytoplasm, disrupts the permeability of membranes and changes the movement of the cytoplasm. Light affects the state of protein colloids and the course of energy processes in cells. But despite this, visible light was, is and will continue to be one of the most important sources of energy for all living things. Its energy is used in the process photosynthesis and accumulates in the form of chemical bonds in the products of photosynthesis, and is then transmitted as food to all other living organisms. In general, we can say that all living things in the biosphere, and even humans, depend on solar energy, on photosynthesis.

Light for animals is a necessary condition for the perception of information about the environment and its elements, vision, visual orientation in space. Depending on their living conditions, animals have adapted to varying degrees of illumination. Some animal species are diurnal, while others are most active at dusk or at night. Most mammals and birds lead a twilight lifestyle, have difficulty distinguishing colors and see everything in black and white (canines, cats, hamsters, owls, nightjars, etc.). Living in twilight or low light conditions often leads to eye hypertrophy. Relatively huge eyes, capable of capturing tiny fractions of light, characteristic of nocturnal animals or those that live in complete darkness and are guided by the luminescent organs of other organisms (lemurs, monkeys, owls, deep-sea fish, etc.). If, in conditions of complete darkness (in caves, underground in burrows) there are no other sources of light, then the animals living there, as a rule, lose their organs of vision (European proteus, mole rat, etc.).

Temperature.

The sources of the temperature factor on Earth are solar radiation and geothermal processes. Although the core of our planet is characterized by extremely high temperatures, its influence on the surface of the planet is insignificant, except for zones of volcanic activity and the release of geothermal waters (geysers, fumaroles). Consequently, the main source of heat within the biosphere can be considered solar radiation, namely infrared rays. Those rays that reach the Earth's surface are absorbed by the lithosphere and hydrosphere. The lithosphere, as a solid body, heats up faster and cools just as quickly. The hydrosphere has a higher heat capacity than the lithosphere: it heats up slowly and cools down slowly, and therefore retains heat for a long time. The surface layers of the troposphere are heated due to the radiation of heat from the hydrosphere and the surface of the lithosphere. The Earth absorbs solar radiation and radiates energy back into airless space. And yet, the Earth's atmosphere helps retain heat in the surface layers of the troposphere. Thanks to its properties, the atmosphere transmits short-wave infrared rays and blocks long-wave infrared rays emitted by the heated surface of the Earth. This atmospheric phenomenon has a name greenhouse effect. It was thanks to him that life became possible on Earth. The greenhouse effect helps retain heat in the surface layers of the atmosphere (where most organisms are concentrated) and smoothes out temperature fluctuations during the day and night. On the Moon, for example, which is located in almost the same space conditions as the Earth, and which has no atmosphere, daily temperature fluctuations at its equator appear in the range from 160 ° C to + 120 ° C.

The range of temperatures available in the environment reaches thousands of degrees (hot magma of volcanoes and the lowest temperatures of Antarctica). The limits within which life known to us can exist are quite narrow and are equal to approximately 300 ° C, from -200 ° C (freezing in liquefied gases) to + 100 ° C (the boiling point of water). In fact, most species and most of their activity are confined to an even narrower range of temperatures. The general temperature range of active life on Earth is limited to the following temperature values ​​(Table 1.2.3):

Table 1.2.3 Temperature range of life on Earth

Plants adapt to different temperatures and even extreme ones. Those that tolerate high temperatures are called heat-stimulating plants. They are able to tolerate overheating up to 55-65° C (some cacti). Species growing in high temperatures tolerate them more easily due to a significant shortening of the size of the leaves, the development of a tomentose (hairy) or, conversely, waxy coating, etc. Plants can withstand prolonged exposure to low temperatures (from 0 to -10°C) without harming their development C), are called cold-resistant.

Although temperature is an important environmental factor affecting living organisms, its effect is highly dependent on its combination with other abiotic factors.

Humidity.

Humidity is an important abiotic factor, which is determined by the presence of water or water vapor in the atmosphere or lithosphere. Water itself is a necessary inorganic compound for the life of living organisms.

Water in the atmosphere is always present in the form water couples. The actual mass of water per unit volume of air is called absolute humidity, and the percentage of vapor relative to the maximum amount that air can contain is relative humidity. Temperature is the main factor affecting the ability of air to hold water vapor. For example, at a temperature of +27°C, air can contain twice as much moisture as at a temperature of +16°C. This means that the absolute humidity at 27°C is 2 times higher than at 16°C, while the relative humidity in both cases will be 100%.

Water as an ecological factor is extremely necessary for living organisms, because without it metabolism and many other processes associated with it cannot take place. Metabolic processes of organisms take place in the presence of water (in aqueous solutions). All living organisms are open systems, so they constantly experience water loss and always have a need to replenish its reserves. For normal existence, plants and animals must maintain a certain balance between the flow of water into the body and its loss. Large loss of water from the body (dehydration) lead to a decrease in his vital activity, and subsequently to death. Plants satisfy their water needs through precipitation and air humidity, and animals also through food. The resistance of organisms to the presence or absence of moisture in the environment varies and depends on the adaptability of the species. In this regard, all terrestrial organisms are divided into three groups: hygrophilic(or moisture-loving), mesophilic(or moderately moisture-loving) and xerophilic(or dry-loving). Regarding plants and animals separately, this section will look like this:

1) hygrophilic organisms:

- hygrophytes(plants);

- hygrophiles(animal);

2) mesophilic organisms:

- mesophytes(plants);

- mesophiles(animal);

3) xerophilic organisms:

- xerophytes(plants);

- xerophiles, or hygrophobias(animals).

Need most moisture hygrophilic organisms. Among plants, these will be those that live on excessively moist soils with high air humidity (hygrophytes). In the conditions of the middle zone, they are among the herbaceous plants that grow in shaded forests (oxalis, ferns, violets, gap-grass, etc.) and in open places (marigold, sundew, etc.).

Hygrophilic animals (hygrophiles) include those ecologically associated with the aquatic environment or with waterlogged areas. They need a constant presence of large amounts of moisture in the environment. These are animals of tropical rainforests, swamps, and wet meadows.

Mesophilic organisms require moderate amounts of moisture and are usually associated with moderately warm conditions and good mineral nutrition. These can be forest plants and plants of open areas. Among them there are trees (linden, birch), shrubs (hazel, buckthorn) and even more herbs (clover, timothy, fescue, lily of the valley, hoofed grass, etc.). In general, mesophytes are a broad ecological group of plants. To mesophilic animals (mesophiles) belongs to the majority of organisms that live in temperate and subarctic conditions or in certain mountainous regions of land.

Xerophilic organisms - This is a fairly diverse ecological group of plants and animals that have adapted to arid living conditions through the following means: limiting evaporation, increasing water production, and creating water reserves for long periods of lack of water supply.

Plants that live in dry conditions cope with them in different ways. Some do not have the structural arrangements to cope with the lack of moisture. their existence is possible in arid conditions only due to the fact that at a critical moment they are in a state of rest in the form of seeds (ephemeri) or bulbs, rhizomes, tubers (ephemeroids), very easily and quickly switch to active life and completely disappear in a short period of time annual development cycle. Ephemery mainly distributed in deserts, semi-deserts and steppes (stonefly, spring ragwort, turnip, etc.). Ephemeroids(from Greek ephemeral And to look like)- these are perennial herbaceous, mainly spring, plants (sedges, cereals, tulip, etc.).

Very unique categories of plants that have adapted to tolerate drought conditions are succulents And sclerophytes. Succulents (from Greek. juicy) are able to accumulate large amounts of water and gradually waste it. For example, some cacti of North American deserts can contain from 1000 to 3000 liters of water. Water accumulates in the leaves (aloe, sedum, agave, young) or stems (cacti and cactus-like milkweeds).

Animals obtain water in three main ways: directly by drinking or absorbing through the integument, with food, and as a result of metabolism.

Many species of animals drink water and in fairly large quantities. For example, Chinese oak silkworm caterpillars can drink up to 500 ml of water. Certain species of animals and birds require regular consumption of water. Therefore, they choose certain springs and regularly visit them as watering places. Desert bird species fly daily to oases, drink water there and bring water to their chicks.

Some animal species that do not consume water by direct drinking can consume it by absorbing it through the entire surface of the skin. Insects and larvae that live in soil moistened with tree dust have their integuments permeable to water. The Australian moloch lizard absorbs moisture from precipitation through its skin, which is extremely hygroscopic. Many animals get moisture from succulent food. Such succulent food can be grass, juicy fruits, berries, bulbs and plant tubers. The steppe tortoise, which lives in the Central Asian steppes, consumes water only from succulent food. In these regions, in areas where vegetables are planted or in melon fields, turtles cause great damage by feeding on melons, watermelons, and cucumbers. Some predatory animals also obtain water by eating their prey. This is typical, for example, of the African fennec fox.

Species that feed exclusively on dry food and do not have the opportunity to consume water obtain it through metabolism, that is, chemically during the digestion of food. Metabolic water can be formed in the body due to the oxidation of fats and starch. This is an important way of obtaining water, especially for animals that inhabit hot deserts. Thus, the red-tailed gerbil sometimes feeds only on dry seeds. There are known experiments where, in captivity, a North American deer mouse lived for about three years, eating only dry barley grains.

Food factors.

The surface of the Earth's lithosphere constitutes a separate living environment, which is characterized by its own set of environmental factors. This group of factors is called edaphic(from Greek edaphos- soil). Soils have their own structure, composition and properties.

Soils are characterized by a certain moisture content, mechanical composition, content of organic, inorganic and organomineral compounds, and a certain acidity. Many properties of the soil itself and the distribution of living organisms in it depend on the indicators.

For example, certain species of plants and animals love soils with a certain acidity, namely: sphagnum mosses, wild currants, and alder grow on acidic soils, and green forest mosses grow on neutral ones.

Beetle larvae, terrestrial mollusks and many other organisms also react to a certain acidity of the soil.

The chemical composition of the soil is very important for all living organisms. For plants, the most important are not only those chemical elements that they use in large quantities (nitrogen, phosphorus, potassium and calcium), but also those that are rare (microelements). Some of the plants selectively accumulate certain rare elements. Cruciferous and umbelliferous plants, for example, accumulate sulfur in their bodies 5-10 times more than other plants.

Excessive content of certain chemical elements in the soil can negatively (pathologically) affect animals. For example, in one of the valleys of Tuva (Russia) it was noticed that sheep were suffering from some specific disease, which manifested itself in hair loss, deformed hooves, etc. Later it turned out that in this valley there was increased selenium content. When this element entered the body of sheep in excess, it caused chronic selenium toxicosis.

The soil has its own thermal regime. Together with moisture, it affects soil formation and various processes occurring in the soil (physicochemical, chemical, biochemical and biological).

Due to their low thermal conductivity, soils are able to smooth out temperature fluctuations with depth. At a depth of just over 1 m, daily temperature fluctuations are almost imperceptible. For example, in the Karakum Desert, which is characterized by a sharply continental climate, in the summer, when the soil surface temperature reaches +59°C, in the burrows of gerbil rodents at a distance of 70 cm from the entrance the temperature was 31°C lower and amounted to +28°C. In winter, during a frosty night, the temperature in the gerbils’ burrows was +19°C.

Soil is a unique combination of physical and chemical properties of the surface of the lithosphere and the living organisms that inhabit it. It is impossible to imagine soil without living organisms. No wonder the famous geochemist V.I. Vernadsky called soils bioinert body.

Orographic factors (relief).

Relief does not relate to such directly acting environmental factors as water, light, heat, soil. However, the nature of the relief in the life of many organisms has an indirect effect.

c Depending on the size of the forms, the relief of several orders is quite conventionally distinguished: macrorelief (mountains, lowlands, intermountain depressions), mesorelief (hills, ravines, ridges, etc.) and microrelief (small depressions, unevenness, etc.). Each of them plays a certain role in the formation of a complex of environmental factors for organisms. In particular, relief affects the redistribution of factors such as moisture and heat. Thus, even minor drops of several tens of centimeters create conditions of high humidity. Water flows from elevated areas to lower ones, where favorable conditions are created for moisture-loving organisms. The northern and southern slopes have different lighting and thermal conditions. In mountainous conditions, significant altitude amplitudes are created in relatively small areas, which leads to the formation of various climatic complexes. In particular, their typical features are low temperatures, strong winds, changes in humidification, gas composition of the air, etc.

For example, with a rise above sea level, the air temperature decreases by 6 ° C for every 1000 m. Although this is a characteristic of the troposphere, due to the relief (hills, mountains, mountain plateaus, etc.), terrestrial organisms may find themselves in conditions not similar to those in neighboring regions. For example, the Kilimanjaro volcanic mountain range in Africa is surrounded by savannas at the foot, and higher up the slopes there are plantations of coffee, bananas, forests and alpine meadows. The peaks of Kilimanjaro are covered with eternal snow and glaciers. If the air temperature at sea level is +30° C, then negative temperatures will appear already at an altitude of 5000 m. In temperate zones, a decrease in temperature for every 6° C corresponds to a movement of 800 km towards high latitudes.

Pressure.

Pressure manifests itself in both air and water environments. In atmospheric air, pressure changes seasonally, depending on weather conditions and altitude. Of particular interest are the adaptations of organisms that live in conditions of low pressure and rarefied air in the highlands.

The pressure in the aquatic environment changes depending on the depth: it increases by approximately 1 atm for every 10 m. For many organisms, there are limits to the change in pressure (depth) to which they have adapted. For example, abyssal fish (fish from the depths of the world) are able to withstand great pressure, but they never rise to the surface of the sea, because for them this is fatal. Conversely, not all marine organisms are capable of diving to great depths. The sperm whale, for example, can dive to a depth of up to 1 km, and seabirds - up to 15-20 m, where they get their food.

Living organisms on land and in the aquatic environment clearly respond to changes in pressure. At one time it was noted that fish can perceive even minor changes in pressure. their behavior changes when atmospheric pressure changes (for example, before a thunderstorm). In Japan, some fish are specially kept in aquariums and changes in their behavior are used to judge possible changes in the weather.

Terrestrial animals, perceiving minor changes in pressure, can predict changes in weather conditions through their behavior.

Uneven pressure, which is the result of uneven heating by the Sun and heat distribution both in water and in atmospheric air, creates conditions for mixing water and air masses, i.e. formation of currents. Under certain conditions, flow is a powerful environmental factor.

Hydrological factors.

Water, as a component of the atmosphere and lithosphere (including soils), plays an important role in the life of organisms as one of the environmental factors called humidity. At the same time, water in a liquid state can be a factor that forms its own environment - aqueous. Due to its properties, which distinguish water from all other chemical compounds, it, in a liquid and free state, creates a complex of conditions in the aquatic environment, the so-called hydrological factors.

Such characteristics of water as thermal conductivity, fluidity, transparency, salinity, manifest themselves differently in reservoirs and are environmental factors, which in this case are called hydrological. For example, aquatic organisms have adapted differently to varying degrees of water salinity. There are freshwater and marine organisms. Freshwater organisms do not amaze with their species diversity. Firstly, life on Earth originated in sea waters, and secondly, fresh water bodies occupy a tiny part of the earth’s surface.

Marine organisms are more diverse and numerically more numerous. Some of them have adapted to low salinity and live in desalinated areas of the sea and other brackish water bodies. In many species of such reservoirs, a decrease in body size is observed. For example, the valves of mollusks, the edible mussel (Mytilus edulis) and the Lamarck's mussel (Cerastoderma lamarcki), which live in the bays of the Baltic Sea at a salinity of 2-6%o, are 2-4 times smaller than the individuals that live in the same sea, only at a salinity of 15%o. The crab Carcinus moenas in the Baltic Sea is small in size, whereas in desalinated lagoons and estuaries it is much larger. Sea urchins grow smaller in lagoons than in the sea. The brine shrimp (Artemia salina) at a salinity of 122%o has dimensions of up to 10 mm, but at 20%o it grows to 24-32 mm. Salinity can also affect life expectancy. The same Lamarck's heartfish lives up to 9 years in the waters of the North Atlantic, and 5 in the less salty waters of the Sea of ​​Azov.

The temperature of water bodies is a more constant indicator than the temperature of land. This is due to the physical properties of water (heat capacity, thermal conductivity). The amplitude of annual temperature fluctuations in the upper layers of the ocean does not exceed 10-15° C, and in continental reservoirs - 30-35° C. What can we say about the deep layers of water, which are characterized by a constant thermal regime.

Biotic factors.

Organisms that live on our planet require not only abiotic conditions for their life, they interact with each other and are often very dependent on each other. The set of factors in the organic world that influence organisms directly or indirectly are called biotic factors.

Biotic factors are very diverse, but despite this, they also have their own classification. According to the simplest classification, biotic factors are divided into three groups, which are caused by: plants, animals and microorganisms.

Clements and Shelford (1939) proposed their classification, which takes into account the most typical forms of interaction between two organisms - co-actions. All co-actions are divided into two large groups, depending on whether organisms of the same species or two different ones interact. Types of interactions between organisms belonging to the same species are homotypic reactions. Heterotypic reactions call the forms of interaction between two organisms of different species.

Homotypic reactions.

Among the interactions of organisms of the same species, the following coactions (interactions) can be distinguished: group effect, mass effect And intraspecific competition.

Group effect.

Many living organisms that can live alone form groups. Often in nature you can observe how some species grow in groups plants. This gives them the opportunity to accelerate their growth. Animals also form groups. Under such conditions they survive better. When living together, it is easier for animals to defend themselves, obtain food, protect their offspring, and survive adverse environmental factors. Thus, the group effect has a positive impact for all group members.

The groups into which animals are united can vary in size. For example, cormorants, which form huge colonies on the coasts of Peru, can exist only if there are at least 10 thousand birds in the colony, and there are three nests per 1 square meter of territory. It is known that for the survival of African elephants, a herd must consist of at least 25 individuals, and a herd of reindeer - from 300-400 animals. A pack of wolves can number up to a dozen individuals.

Simple aggregations (temporary or permanent) can develop into complex groups consisting of specialized individuals that perform their inherent function in that group (families of bees, ants or termites).

Mass effect.

A mass effect is a phenomenon that occurs when a living space is overpopulated. Naturally, when combining into groups, especially large ones, some overpopulation also occurs, but there is a big difference between group and mass effects. The first gives advantages to each member of the association, while the other, on the contrary, suppresses the life activity of everyone, that is, it has negative consequences. For example, the mass effect occurs when vertebrate animals gather together. If a large number of experimental rats are kept in one cage, then their behavior will manifest acts of aggressiveness. When animals are kept in such conditions for a long time, the embryos of pregnant females dissolve, aggressiveness increases so much that the rats gnaw off each other's tails, ears, and limbs.

The mass effect of highly organized organisms leads to a stressful state. In humans, this can cause mental disorders and nervous breakdowns.

Intraspecific competition.

There is always a kind of competition between individuals of the same species to obtain the best living conditions. The greater the population density of a particular group of organisms, the more intense the competition. Such competition between organisms of the same species for certain conditions of existence is called intraspecific competition.

Mass effect and intraspecific competition are not identical concepts. If the first phenomenon occurs for a relatively short time and subsequently ends with a rarefaction of the group (mortality, cannibalism, decreased fertility, etc.), then intraspecific competition exists constantly and ultimately leads to a wider adaptation of the species to environmental conditions. The species becomes more ecologically adapted. As a result of intraspecific competition, the species itself is preserved and does not destroy itself as a result of such struggle.

Intraspecific competition can manifest itself in anything that organisms of the same species can claim. In plants that grow densely, competition may occur for light, mineral nutrition, etc. For example, an oak tree, when it grows separately, has a spherical crown; it is quite spreading, since the lower side branches receive a sufficient amount of light. In oak plantings in the forest, the lower branches are shaded by the upper ones. Branches that do not receive enough light die. As the oak grows in height, the lower branches quickly fall off, and the tree takes on a forest shape - a long cylindrical trunk and a crown of branches at the top of the tree.

In animals, competition arises for a certain territory, food, nesting sites, etc. It is easier for active animals to avoid tough competition, but it still affects them. As a rule, those that avoid competition often find themselves in unfavorable conditions; they are also forced, like plants (or attached species of animals), to adapt to the conditions with which they have to be content.

Heterotypic reactions.

Table 1.2.4. Forms of interspecific interactions

0 - interaction between species does not produce gains and does not cause damage to either side;

Interactions between species produce positive consequences; --interaction between species produces negative consequences.

Neutralism.

The most common form of interaction occurs when organisms of different species, occupying the same territory, do not affect each other in any way. The forest is home to a large number of species and many of them maintain neutral relationships. For example, a squirrel and a hedgehog inhabit the same forest, but they have a neutral relationship, like many other organisms. However, these organisms are part of the same ecosystem. They are elements of one whole, and therefore, upon detailed study, one can still find not direct, but indirect, rather subtle and at first glance, invisible connections.

Eat. Doom, in his “Popular Ecology,” gives a humorous but very apt example of such connections. He writes that in England, old single women support the power of the king's guards. And the connection between guardsmen and women is quite simple. Single women, as a rule, breed cats, and cats hunt mice. The more cats, the fewer mice in the fields. Mice are the enemies of bumblebees because they destroy their burrows where they live. The fewer mice, the more bumblebees. Bumblebees, as you know, are not the only pollinators of clover. More bumblebees in the fields means a larger clover harvest. Horses are grazed on clover, and the guards like to eat horse meat. Behind this example in nature you can find many hidden connections between different organisms. Although in nature, as can be seen from the example, cats have a neutral relationship with horses or dzhmels, they are indirectly related to them.

Comensalism.

Many types of organisms enter into relationships that benefit only one party, while the other does not suffer from this and nothing is useful. This form of interaction between organisms is called commensalism. Comensalism often manifests itself as the coexistence of different organisms. Thus, insects often live in mammal burrows or bird nests.

You can often observe such a joint settlement when sparrows build nests in the nests of large birds of prey or storks. For birds of prey, the proximity of sparrows does not interfere, but for the sparrows themselves it is reliable protection of their nests.

In nature, there is even a species called the commensal crab. This small, graceful crab willingly settles in the mantle cavity of oysters. By doing this, he does not disturb the mollusk, but he himself receives shelter, fresh portions of water and nutrient particles that reach him with the water.

Protocooperation.

The next step in the joint positive coaction of two organisms of different species is protocooperation, in which both species benefit from interaction. Naturally, these species can exist separately without any losses. This form of interaction is also called primary cooperation, or cooperation.

In the sea, this mutually beneficial, but not obligatory, form of interaction arises when crabs and gutters come together. Anemones, for example, often settle on the dorsal side of crabs, camouflaging and protecting them with their stinging tentacles. In turn, the sea anemones receive pieces of food from the crabs that are left over from their meal, and use the crabs as a means of transport. Both crabs and sea anemones are able to exist freely and independently in a reservoir, but when they are nearby, the crab even uses its claw to transplant the sea anemone onto itself.

Joint nesting of birds of different species in the same colony (herons and cormorants, waders and terns of different species, etc.) is also an example of cooperation in which both parties benefit, for example, in protection from predators.

Mutualism.

Mutualism (or obligate symbiosis) is the next stage of mutually beneficial adaptation of different species to each other. It differs from protocooperation in its dependence. If in protocooperation the organisms that enter into communication can exist separately and independently of each other, then in mutualism the existence of these organisms separately is impossible.

This type of coaction often occurs in quite different organisms, systematically distant, with different needs. An example of this is the relationship between nitrogen-fixing bacteria (vesicle bacteria) and leguminous plants. Substances secreted by the root system of legumes stimulate the growth of vesicular bacteria, and waste products of bacteria lead to deformation of root hairs, which begins the formation of vesicles. The bacteria have the ability to assimilate atmospheric nitrogen, which is deficient in soil but an essential macronutrient for plants, which in this case greatly benefits leguminous plants.

In nature, the relationship between fungi and plant roots is quite common, called mycorrhiza. The mycelium, interacting with the root tissues, forms a kind of organ that helps the plant more efficiently absorb minerals from the soil. From this interaction, fungi obtain the products of plant photosynthesis. Many types of trees cannot grow without mycorrhiza, and certain types of fungi form mycorrhiza with the roots of certain types of trees (oak and porcini mushroom, birch and boletus, etc.).

A classic example of mutualism is lichens, which combine a symbiotic relationship between fungi and algae. The functional and physiological connections between them are so close that they are considered as separate group organisms. The fungus in this system provides the algae with water and mineral salts, and the algae, in turn, provides the fungus with organic substances that it itself synthesizes.

Amensalism.

In the natural environment, not all organisms have a positive effect on each other. There are many cases when, in order to ensure their livelihoods, one species harms another. This form of co-action, in which one type of organism suppresses the growth and reproduction of an organism of another species without losing anything, is called amensalism (antibiosis). A depressed look in a couple that interacts is called amensalom, and the one who suppresses - inhibitor.

Amensalism is best studied in plants. During their life, plants release chemicals into the environment, which are factors influencing other organisms. Regarding plants, amensalism has its own name - allelopathy. It is known that due to the release of toxic substances by its roots, Nechuyviter volokhatenki displaces other annual plants and forms continuous single-species thickets over large areas. In fields, wheatgrass and other weeds crowd out or suppress cultivated plants. Walnut and oak suppress herbaceous vegetation under their crowns.

Plants can secrete alelopathic substances not only from their roots, but also from the aboveground part of their body. Volatile alelopathic substances released into the air by plants are called phytoncides. Basically, they have a destructive effect on microorganisms. Everyone is well aware of the antimicrobial preventive effect of garlic, onions, and horseradish. Coniferous trees produce a lot of phytoncides. One hectare of common juniper plantings produces more than 30 kg of phytoncides per year. Coniferous trees are often used in populated areas to create sanitary protection strips around various industries, which helps purify the air.

Phytoncides negatively affect not only microorganisms, but also animals. Various plants have long been used in everyday life to control insects. So, baglitsa and lavender are good means for fighting moths.

Antibiosis is also known in microorganisms. It was first discovered. Babesh (1885) and rediscovered by A. Fleming (1929). Penicillin mushrooms have been shown to secrete a substance (penicillin) that inhibits the growth of bacteria. It is widely known that some lactic acid bacteria acidify their environment so that putrefactive bacteria, which require an alkaline or neutral environment, cannot exist in it. Alelopathic chemicals from microorganisms are known as antibiotics. Over 4 thousand antibiotics have already been described, but only about 60 of their varieties are widely used in medical practice.

Animals can also be protected from enemies by secreting substances that have an unpleasant odor (for example, among reptiles - vulture turtles, snakes; birds - hoopoe chicks; mammals - skunks, ferrets).

Predation.

Theft in the broad sense of the word is considered a way of obtaining food and feeding animals (sometimes plants), in which they catch, kill and eat other animals. Sometimes this term is understood as any consumption of some organisms by others, i.e. such relationships between organisms in which some use others as food. With this understanding, the hare is a predator in relation to the grass it consumes. But we will use a narrower understanding of predation, in which one organism feeds on another, which is close to the first in systematic terms (for example, insects that feed on insects; fish that feed on fish; birds that feed on reptiles, birds and mammals; mammals that that feed on birds and mammals). The extreme case of predation, in which a species feeds on organisms of its own species, is called cannibalism.

Sometimes a predator selects prey in such numbers that it does not negatively affect its population size. By doing this, the predator contributes to the better condition of the prey population, which has also already adapted to the pressure of the predator. The birth rate in prey populations is higher than that required to normally maintain its population. Figuratively speaking, the prey population takes into account what the predator should select.

Interspecific competition.

Between organisms of different species, as well as between organisms of the same species, interactions arise through which they try to obtain the same resource. Such co-actions between different species are called interspecific competition. In other words, we can say that interspecific competition is any interaction between populations of different species that adversely affects their growth and survival.

The consequences of such competition may be the displacement of one organism by another from a certain ecological system (the principle of competitive exclusion). At the same time, competition promotes the emergence of many adaptations through the process of selection, which leads to the diversity of species that exist in a particular community or region.

Competitive interaction may concern space, food or nutrients, light and many other factors. Interspecific competition, depending on what it is based on, can lead either to the establishment of equilibrium between two species, or, with more severe competition, to the replacement of a population of one species by a population of another. Also, the result of competition may be that one species displaces another to another place or forces it to switch to other resources.

All life on Earth is associated with a habitat, which includes diverse geographic areas and the communities of living organisms that inhabit them. According to the nature of the action, the connections of the organism with the environment can be abiotic(this includes factors of inanimate nature - physical and chemical environmental conditions) and biotic(factors of living nature - interspecific and intraspecific relationships).

The life of organisms is impossible without a constant flow of energy from outside. Its source is the Sun. The rotation of the Earth around its axis leads to an uneven distribution of the Sun's energy and its thermal radiation. In this regard, the atmosphere over land and ocean heats up unequally, and differences in local temperature and pressure cause movement of air masses, changes in air humidity, which affects the course of chemical reactions, physical transformations and directly or indirectly - all biological phenomena (the nature of the distribution of life , biorhythms, etc.). The regulating influence on the density of life is exerted by a complex of factors: light, temperature, water, mineral nutrients, etc. The evolution of life was carried out in the direction of effective adaptation to these factors: “fluctuations in humidity, lighting, temperature, wind, gravity, etc. The relationships of organisms between science studies ourselves and our environment ecologists I. Let's consider the importance of individual environmental factors.

Light- the main source of energy on Earth. The nature of light is dual: on the one hand, it is a stream of elementary physical particles - corpuscles, or photons that do not have a charge, on the other hand, it has wave properties. The shorter the photon wavelength, the higher its energy, and vice versa. The energy of photons serves as a source of meeting the energy needs of plants during photosynthesis, so a green plant cannot exist without light.

Light (illumination) is a powerful stimulus for the activity of organisms - photoperiodism in the life of plants (growth, flowering, leaf fall) and animals (molting, accumulation of fat, migration and reproduction of birds and mammals, the onset of the resting stage - diapause, behavioral reactions, etc.). The length of daylight hours depends on geographic latitude. This is associated with the existence of long-day plants, the flowering of which occurs when the daylight period lasts 12 hours or more (potatoes, rye, oats, wheat, etc.), and short-day plants with a photoperiod of 12 hours or less (most tropical flowering plants, soybeans , millet, hemp, corn and many other plants of the temperate zone). But there are plants whose flowering does not depend on the length of the day (tomatoes, dandelion, etc.). Rhythms of illumination cause different activity in animals during the day and night or at dusk, as well as seasonal phenomena: in the spring - preparation for reproduction, in the fall - for hibernation, molting.

The sun's short-wave radiation (290 nm) is ultraviolet rays (UV). Most of them are absorbed by the ozone layer in the upper atmosphere; UV rays with lower energy (300-400 nm) penetrate the Earth, which are destructive for many microorganisms and their spores; in the human and animal body, these rays activate the synthesis of vitamin D from cholesterol and the formation of skin and eye pigments. Mid-wave radiation (600-700 nm) is the orange part of the spectrum and is absorbed by the plant during photosynthesis.

As a manifestation of adaptive reactions to the change of day and night in animals and humans, daily rhythmicity in metabolic rate, respiratory rate, heart rate and blood pressure levels, body temperature, cell division, etc. is observed. More than a hundred physiological processes of a biorhythmological nature have been identified in humans, thanks to which healthy people observe coordination of various functions. The study of biorhythms is of great importance for the development of measures that facilitate human adaptation to new conditions during long-distance flights and the relocation of people to areas of Siberia, the Far East, the North, and Antarctica.

It is believed that violation of regulatory mechanisms to maintain the internal environment of the body (homeostasis) is a consequence of urbanization and industrialization: how The longer the body is isolated from external climatic factors and is in comfortable indoor microclimate conditions, the more noticeably its adaptive reactions to changes in weather factors decrease, the ability to thermoregulate is impaired, and disorders of cardiovascular activity occur more often.

Biological effect photons is that their energy in the animal body causes an excited state of electrons in pigment molecules (porphyrins, carotenoids, flavins), which transfer the resulting excess of their energy to other molecules, and in this way a chain of chemical transformations is started. Proteins and nucleic acids absorb UV rays with a wavelength of 250-320 nm, which can cause genetic effects (gene mutations); rays of shorter wavelengths (200 nm or less) not only excite molecules, but can also destroy them.

In recent years, much attention has been paid to the study of the process of photoreactivation - the ability of microorganism cells to weaken and completely eliminate the damaging effect of UV irradiation of DNA, if the irradiated cells are then grown not in the dark, but in visible light. Photoreactivation is a universal phenomenon, carried out with the participation of specific cellular enzymes, the action of which is activated by light quanta of a certain wavelength.

Temperature has a regulatory effect on many life processes of plants and animals, changing the intensity of metabolism. The activity of cellular enzymes ranges from 10 to 40 ° C; at low temperatures, reactions proceed slowly, but when the optimal temperature is reached, enzyme activity is restored. The endurance limits of organisms in relation to the temperature factor for most species do not exceed 40-45 ° C; low temperatures have a less adverse effect on the body than high temperatures. The vital activity of the body is carried out within the range from -4 to 45 °C. However, a small group of lower organisms are able to live in hot springs at a temperature of 85 ° C (sulfur bacteria, blue-green algae, some roundworms), many lower organisms can easily withstand very low temperatures (their resistance to freezing is explained by the high concentration of salts and organic substances in the cytoplasm) .

Each species of animals, plants and microorganisms has developed the necessary adaptations to both high and low temperatures. Thus, when cold weather sets in, many insects hide in the soil, under the bark of trees, in rock cracks, frogs burrow into the silt at the bottom of reservoirs, and some terrestrial animals hibernate and become torpor. Adaptation from overheating in the hot season in plants is expressed in increased evaporation of water through the stomata, in animals - in the form of evaporation of water through the respiratory system and skin. Animals that do not have an active thermoregulation system (cold-blooded or poikilothermic) do not tolerate fluctuations in external temperature well, so their habitats on land are relatively limited (amphibians, reptiles). With the onset of cold weather, their metabolism, food and oxygen consumption decrease, they hibernate or go into a state of depression. state of suspended animation(a sharp slowdown in life processes while maintaining the ability to revive), and under favorable weather conditions they awaken and begin an active life again. Spores and seeds of plants, and among animals - ciliates, rotifers, bedbugs, mites, etc. - can remain in a state of suspended animation for many years. Warm-bloodedness in mammals and birds allows them to endure adverse conditions in an active state, using shelters, so they are less dependent on the environment. During the period of excessive temperature rise in desert conditions, animals adapted to endure the heat by immersion into summer hibernation. Plants of deserts and semi-deserts in the spring complete their growing season in a very short time and, after the seeds ripen, shed their leaves, entering the dormant phase (tulips, bluegrass bulbous, rose of Jericho, etc.).

Water. With the energy of the Sun, water rises from the surface of the seas and oceans and returns to Earth in the form of various precipitation, having a diverse effect on organisms. Water is the most important component of the cell, accounting for 60-80% of its mass. The biological significance of water is determined by its physicochemical properties. The water molecule is polar, so it is able to be attracted to various other molecules and weaken the intensity of the interaction between the charges of these molecules, forming hydrates with them, i.e. act as a solvent. Many substances enter into various chemical reactions only in the presence of water.

Dielectric properties and the presence of bonds between molecules determine the high heat capacity of water, which creates a “thermal buffer” in living systems, protecting unstable cell structures from damage during local short-term release of thermal energy. By absorbing heat during the transition from liquid to gaseous state, water produces cooling; the effect of evaporation used by organisms to regulate body temperature. Due to its large heat capacity, water plays the role of the main climate thermoregulator. Its slow heating and cooling regulate the temperature fluctuations of oceans and lakes: in summer and during the day they accumulate heat, which they release in winter and at night. Climate stabilization is also facilitated by the constant exchange of carbon dioxide between the air and water shells of the globe and rocks, as well as flora and fauna. Water plays a transport role in moving soil substances from top to bottom and in the opposite direction. In the soil they serve as a habitat for unicellular organisms (amoebas, flagellates, ciliates, algae).

Depending on the moisture regime of plants in places and their usual growth, they are divided into hygrophyte plants excessive wet areas, mesophyte plants sufficiently moist places and xerophytes - plants of dry habitats. There is also a group of aquatic flowering plants - hydrophytes, that live in the aquatic environment (arrowhead, elodea, hornwort). Lack of moisture serves as a limiting factor that determines the boundaries of life and its zonal distribution. When there is a lack of water, animals and plants develop adaptations to obtain and conserve it. One of the functions of leaf fall is an adaptation against excess water loss. Plants in arid areas have small leaves, sometimes in the form of scales (in this case, the stem takes on the function of photosynthesis); The distribution of stomata on the leaf serves the same purpose, which can reduce water evaporation. Animals in conditions of very low humidity are active at night to avoid water loss; during the day they hide in burrows and even fall into torpor or hibernation. Rodents do not drink water, but replenish it with plant foods. A unique reservoir of water for desert animals is fat deposits (the hump of a camel, subcutaneous fat deposits of rodents, the fat body of insects), from which comes water formed in the body during oxidative reactions during the breakdown of fat. Thus, all the facts of the adaptation of organisms to living conditions are a clear illustration of expediency in living nature, which arose under the influence of natural selection.

Ionizing radiation. Very high energy radiation that can produce pairs of positive and negative ions is called ionizing. His the source is radioactive substances, contains huddling in rocks; Moreover, it comes from space. Of the three types of ionizing radiation that have important environmental significance, two are corpuscular radiation (alpha and beta particles), and the third is electromagnetic (gamma radiation and related X-ray radiation). Gamma radiation easily penetrates living tissue; this radiation can pass through the body without having any effect, or it can cause ionization along a large portion of its path.

In general, ionizing radiation has the most destructive effect on more highly developed and complex organisms; the person is particularly sensitive.
Pollutants. These substances can be divided into two groups: natural compounds, which are waste products from technological processes, and artificial compounds, which are not found in nature.

Group 1 includes sulfur dioxide, carbon dioxide, oxides of nitrogen, carbon, hydrocarbons, compounds of copper, zinc and mercury, etc., mineral fertilizers.

The 2nd group includes artificial substances that have special properties that satisfy human needs: pesticides, used to control animal pests of agricultural crops, antibiotics used in medicine and veterinary medicine to treat infectious diseases. Pesticides include insecticides - means to combat harmful insects and herbicides --. weed control products.

All of them have a certain toxicity (poisonous) to humans.

Abiotic factors also include atmospheric gases, minerals, barometric pressure, movement of air masses and hydrosphere (current), mineral base of the soil, salinity of water and soil.

Let's dwell on the meaning mineral elements. A number of inorganic substances are found in the body as salts, and upon dissociation they form ions (cations and anions): Na+, Mg2+, PO43-, Cl-, K+, Ca2+, CO32-, NO3-. The importance of the ionic composition in a cell is revealed in many aspects of its life activity. For example, potassium selectively interacts with the contractile protein of muscles - myosin, reducing the viscosity of cell sap and causing muscle relaxation. Calcium increases the viscosity of the cytoplasm and stimulates muscle contraction, reduces the threshold of nerve excitability and is released from the membrane system during muscle contraction. Large doses of calcium are consumed by mollusks and vertebrates, which need it for the growth of shells and bones. In animals there is a lot of sodium, mainly in the extracellular fluid, and potassium - inside the cell; their mutual movement creates a difference in electrical potential between the fluids inside and outside the cells, which underlies the transmission of nerve impulses.

Magnesium ions affect ribosome aggregation: when their concentration decreases, the ribosome breaks into two parts. Magnesium is part of the chlorophyll molecule and some enzymes. To carry out photosynthesis, plants need Mn, Fe, Cl, Zn; for nitrogen metabolism - Mo, B, Co, Cu, Si. The hemoglobin molecule contains iron and the thyroid hormone. Noah glands - iodine. Zinc is involved in many hydrolysis reactions, breaking the bonds between carbon and oxygen atoms. Absence or deficiency of Na+, Mg2+, K+, Ca2+ , leads to loss of cell excitability and death.
Under natural conditions, a lack of certain microelements leads to the development of endemic (specific only to a certain area) human diseases: endemic goiter (lack of iodine in drinking water), fluorosis and mottling of teeth (excessive intake of fluoride into the body), etc. Lack of copper in herbs, growing on swampy and peaty soils, leads to anemia in cattle, digestive system disorders, damage to the central nervous system, changes in coat color, etc.

An excess of microelements is also undesirable. In particular, in some areas, strontium rickets and chronic molybdenum toxicosis in animals are known (diarrhea in cattle, drop in milk yield, change in coat color). Many questions about the role of microelements in the occurrence of certain physiological disorders have not yet been sufficiently studied.

The most important abiotic factors and adaptation of living organisms to them

Describe light as an abiotic factor. Give a classification of ecological classes of plants in relation to light.

Describe temperature as an abiotic factor. Explain the ecological meaning of Bergman and Allen's rules (give examples).

What is the difference between poikilothermic and homeothermic organisms?

How is A. Hopkins' bioclimatic law formulated? Give it an ecological explanation.

Describe moisture as an abiotic factor. Give examples of moisture- and dry-loving plants and animals, as well as those that prefer moderate humidity.

Among the main abiotic factors, let us consider light, temperature And humidity.

Light.
At one time, the French astronomer Camille Flammarion (1842-1925) wrote: “We don’t think about it, but everything that walks, moves, lives on our planet is a child of the Sun” .

Indeed, only under the influence of light does the most important process of photosynthesis take place in the biosphere, which in general can be represented as follows:

Where A is an electron donor.

In green plants (higher plants and algae), the electron donor is water (oxygen), therefore oxygen is formed as a result of photosynthesis:

In bacteria, the role of electron donor can be performed, for example, by hydrogen sulfide (sulfur) and organic substances. So, in green and purple sulfur bacteria the following process occurs:

With regard to light, organisms face a dilemma: on the one hand, direct exposure to light on a cell can be fatal to the organism, on the other hand, light serves as a primary source of energy, without which life is impossible.

Visible light has a mixed effect on organisms: red rays have a thermal effect; blue and violet rays - change the speed and direction of biochemical reactions. In general, light affects the rate of growth and development of plants, the intensity of photosynthesis, the activity of animals, causes changes in humidity and temperature of the environment, and is an important factor ensuring daily and seasonal biological cycles. Each habitat is characterized by a certain light regime, determined intensity (strength), quantity and quality of light.

Intensity (strength) light is measured by energy per unit area per unit time: J/m2Hs; J/cm2Hs. This factor is strongly influenced by terrain features. Direct light is the most intense, but plants use diffused light more fully.

Amount of light determined by total radiation. From the poles to the equator the amount of light increases. To determine the light regime, it is necessary to take into account the amount of reflected light, the so-called albedo. Albedo (from Latin albus - white) - the reflectivity of the surfaces of various bodies - is expressed as a percentage of the total radiation and depends on the angle of incidence of the rays and the properties of the reflecting surface. For example, the albedo of pure snow is 85%, polluted snow is 40-50%, chernozem soil is 5-14%, light sand is 35-45%, forest canopy is 10-18%, green maple leaves are 10%, yellowed autumn leaves - 28%.

In relation to light as an environmental factor, the following groups of plants are distinguished: heliophytes (from the Greek helios - sun, phyton - plant), sciophytes (from the Greek skia - shadow) and shade-tolerant plants (facultative heliophytes).

Light plants (heliophytes)- live in open places with good lighting and are rare in the forest zone. The process of photosynthesis begins to dominate over the respiration process only in high light conditions (wheat, pine, larch). The flowers of light-loving plants such as sunflower, salsify, and string turn to follow the sun.

Shade plants (sciophytes)- do not tolerate strong lighting and live under the forest canopy in constant shade (these are mainly forest grasses, ferns, mosses, and oxalis). In clearings under strong light, they show obvious signs of oppression and often die.

Shade-tolerant plants (facultative heliophytes)- can live in good light, but can easily tolerate dark places (most forest plants, meadow plants, forest herbs and shrubs).

Shade-tolerant tree species and shady herbaceous plants are distinguished by a mosaic arrangement of leaves. Eucalyptus leaves have their edges facing the light. In trees, light and shadow leaves (located respectively on the surface and inside the crown) - well-lit and shaded - have anatomical differences. Light leaves are thicker and rougher, and are sometimes shiny, which helps reflect light. Shade leaves are usually matte, hairless, thin, with a very delicate cuticle or without it at all (the cuticle is the outer film covering the epidermis).

In the forest, shade-tolerant trees form densely closed stands. Even more shade-tolerant trees and shrubs grow under their canopy, and below that grow shady shrubs and herbs. The picture shows two pine trees: one of them grew in an open space with good lighting (1), and the other in a dense forest (2).

Light is of greatest importance as a means of orientation in the life of animals. Already in the simplest organisms light-sensitive organelles appear. Thus, green euglena reacts to the degree of illumination in the environment with the help of a light-sensitive “eye”. Starting with the coelenterates, almost all animals develop light-sensitive organs - eyes, which have one structure or another.

Bioluminescence called the ability of living organisms to glow. This occurs as a result of the oxidation of complex organic compounds with the participation of catalysts, usually in response to irritations coming from the external environment. Light signals emitted by fish, cephalopods and other aquatic organisms, as well as some organisms of the terrestrial-air environment (for example, beetles of the firefly family), serve to attract individuals of the opposite sex, lure prey or scare away predators, orientate themselves in a school, etc.

An important environmental factor is temperature.

Temperature.
One of the most important factors determining the existence, development and distribution of organisms around the globe is temperature. Not only the absolute amount of heat is important, but also its temporal distribution, i.e. the thermal regime.
Plants do not have their own body temperature: their anatomical, morphological and physiological mechanisms of thermo-
Regulations are aimed at protecting the body from the harmful effects of unfavorable temperatures.

In the zone of high temperatures with low humidity (tropical and subtropical deserts), a unique morphological type of plants with an insignificant leaf surface or with a complete absence of leaves was historically formed. Many desert plants develop whitish pubescence, which helps reflect sunlight and protects them from overheating (sandy acacia, angustifolia oleagin).

Physiological adaptations of plants that mitigate the harmful effects of high temperatures may include: evaporation intensity - transpiration (from Latin trans - through, spiro- I breathe, I exhale), the accumulation of salts in cells that change the temperature of plasma coagulation, the property of chlorophyll to prevent the penetration of sunlight.

In the animal world, certain morphological adaptations are observed that are aimed at protecting organisms from the unfavorable effects of temperatures. This can be evidenced by the well-known Bergman's rule(1847), according to which Within a species or fairly homogeneous group of closely related species, warm-blooded organisms with larger body sizes are common in colder areas.

Let's try to explain this rule from the standpoint of thermodynamics: heat loss is proportional to the surface of the body of the organism, and not to its mass. The larger the animal and the more compact its body, the easier it is to maintain a constant temperature (less specific energy consumption), and vice versa, the smaller the animal, the greater its relative surface area and heat loss and the higher the specific level of its basal metabolism, i.e. the amount of energy expended by the body of an animal (or human) with complete muscle rest at an ambient temperature at which thermoregulation is most pronounced.

In animals with a constant body temperature in cold climatic zones, there is a tendency to reduce the area of ​​​​protruding parts of the body (Allen's rule, 1877).

Allen's rule is clearly manifested, for example, when comparing the ear sizes of ecologically similar species: the Arctic fox - an inhabitant of the tundra; common fox - typical for temperate latitudes; Fenech - an inhabitant of the deserts of Africa.
The reaction of animals to the thermal regime is also manifested in changes in the proportions of individual organs and the body (the stoat from the northern regions has an enlarged heart, kidneys, liver and adrenal glands compared to the same animals in areas with higher temperatures). There are exceptions to the rules of Bergman and Allen.

Depending on the type of heat exchange, two ecological types of animals are distinguished: poikilothermic and homeothermic.

Poikilothermic organisms (from Greek poikilos- diverse) - animals with an unstable level of metabolism, inconsistent body temperature and an almost complete absence of heat regulation mechanisms (cold-blooded). These include invertebrates, fish, reptiles, amphibians, i.e. most animals, with the exception of birds and mammals.

Their body temperature changes with changes in ambient temperature.

Homeothermic organisms (from Greek homoios- identical) - animals with a higher and more stable level of metabolism, during which thermoregulation is carried out and a relatively constant body temperature is ensured (warm-blooded). These include birds and mammals. Body temperature is maintained at a relatively constant level.

In turn, poikilothermic animals can be divided into eurythermic animals, which lead an active lifestyle in a relatively wide temperature range, and stenothermic animals, which cannot tolerate significant temperature fluctuations.

Thermoregulation mechanisms are chemical and physical.

The chemical mechanism is determined by the intensity of reactions in the body and is carried out by reflex:

The physical mechanism of thermoregulation is provided by heat-insulating covers (fur, feathers, fat layer), the activity of sweat glands, the evaporation of moisture during breathing, and vascular regulation of blood circulation.

In poikilothermic animals, the metabolic rate is directly proportional to the external temperature; in homeothermic animals, on the contrary, when it decreases, heat loss increases and, in response, metabolic processes are activated and heat production increases. The intensity of metabolism (metabolic processes) during homeothermy is inversely proportional to external temperatures. However, this pattern can be traced only within certain limits. An increase or decrease in temperature relative to a threshold value causes overheating or hypothermia of the animal and ultimately its death.

Heterothermic animals occupy an intermediate position between poikilothermic and homeothermic animals. In the active state, they maintain a relatively high and constant body temperature, and in the inactive state, the body temperature differs little from the external one. In these animals, during hibernation or deep sleep, the metabolic rate drops, and the body temperature only slightly exceeds the ambient temperature. Typical representatives of heterothermic animals are ground squirrels, hedgehogs, bats, bears, swifts, platypuses, echidnas, and kangaroos.

Let's consider an example with insects, representatives of poikilothermic animals (see figure).

Curve of P. I. Bakhmetyev

At t° +10°C, insects become torpid, at t° 0°C - hypothermia. It continues until the water crystallizes, which is accompanied by a temperature jump. After its sharp increase, processes begin that lead to a deterioration in the physiological state of the body. The physiological state of the insect during the cooling process depends on the rate of temperature decrease. With slow cooling, ice crystals form in the cells, which break their shell. With very rapid cooling, crystallization centers do not have time to form, and a glassy structure is formed. As a result, the cytoplasm is not damaged. Thus, deep but very rapid cooling causes a temporary, reversible suspension of all vital processes of the body. A similar condition, called suspended animation, is observed in viruses, bacteria, invertebrates, amphibians, reptiles, lichens, and mosses. The phenomenon of suspended animation was first discovered and described by A. Leeuwenhoek (1701).

The study of suspended animation gave impetus to the development of various cryotechnology(from Greek kryos- cold, frost), for example, cryopreservation. This method is widely used in biology, medicine, agriculture, in the practice of long-term storage of canned blood, sperm for artificial insemination of farm animals, various tissues and organs for transplantation (from the Latin transplantatio - transplantation), cultures, bacteria, viruses.

The temperature factor is important in the distribution of living organisms on Earth and thereby determines their population of different natural zones. In 1918 A. Hopkins formed regulated the bioclimatic law . He established that there is a natural, close connection between the development of phenological (seasonal) phenomena and the latitude, longitude and altitude of the area above sea level.
He calculated that As you move north, east and into the mountains, the onset of periodic phenomena in the life of organisms is delayed by 4 days for each degree of latitude, 5 degrees of longitude and approximately 100 m of altitude.

One of the important patterns in the distribution of modern organisms is their bipolarity - the geographical distribution of terrestrial and marine flora and fauna, in which the same species lives in cold and temperate latitudes of both hemispheres, but is absent in the tropical zone (toothless whales, eared seals, etc. .).

An equally important environmental factor is humidity.

Humidity.
Water is the most important environmental factor in the life of living organisms and their permanent component. All living things on Earth include water, for example, jellyfish contain 95-99% water, corn 70%, cereals 87%. Even the granary weevil, which feeds on dry grain, contains 46% water. The human embryo contains 97% water, after birth - 64-77%. In men aged 18 to 50 years, the body contains ~61% water, in women it is 54%.

During his life, a person drinks up to 50-77 m3 of water (per day ~ 2.5-3 liters). In general, a person loses 2-2.5 liters of water per day: 800-

1300 ml in urine, about 200 ml in feces and 600 ml from the surface of the body and during breathing. With the loss of 1-1.5 liters of water, a person becomes thirsty; when 6-8% of moisture from body weight is consumed, he falls into a semi-fainting state; with a deficit of 10-12%, death occurs.

At different periods of development, the need of plants for water is not the same, especially among different species; It also varies depending on climate and soil type. For example, cereals need less moisture during seed germination and ripening than during their intensive growth. For each phase of growth and stage of development of any type of plant, a critical period can be identified when the lack of water has a particularly negative effect on its life. Environmental humidity is often a factor limiting the number and distribution of organisms around the globe. For example, beech can live on relatively dry soil, but it needs fairly high air humidity. In animals, the permeability of the integument and the mechanisms regulating water metabolism play a very important role.

There is a distinction between absolute air humidity, which is the amount of gaseous water (steam) in grams per 1 m3 of air, and relative humidity. Relative humidity characterizes the degree of saturation of air with water vapor at a certain temperature and is expressed as a percentage as the ratio of absolute humidity to maximum humidity (the mass of water vapor in grams capable of creating complete saturation in 1 m3 of air)

where: r - relative humidity, %;
m is the mass of steam actually contained in 1 m3 of air (absolute humidity), g;
msat - mass of 1 m3 of saturated steam at a given temperature, g.

Of great importance for organisms is the deficiency of air saturation with water vapor, i.e. the difference between maximum and absolute humidity at a given temperature:

d = mus - m.

At different temperatures, the deficiency of air saturation with water vapor is not the same at the same humidity. The higher the temperature, the drier the air, and the more intense transpiration occurs in it (evaporation of water from leaves and other parts of plants).

The seasonal distribution of moisture throughout the year, as well as its daily fluctuations, is also extremely important for the life of organisms.

In relation to the water regime, the following ecological groups of plants and animals are distinguished: moisture-loving, dry-loving and preferring moderate humidity. Among the plants there are:

Among terrestrial animals there are:

Hydrophiles - moisture-loving animals (woodlice, springtails, mosquitoes, terrestrial planarians, terrestrial mollusks and amphibians).

Mesophiles - live in areas with moderate humidity (winter armyworm, many insects, birds, mammals).

Xerophiles - these are dry-loving animals that cannot tolerate high humidity (camels, desert rodents and reptiles).

For example, the elephant turtle stores water in the bladder; some mammals avoid moisture deficiency by depositing fats, the oxidation of which produces metabolic water. Many insects, camels, fat-tailed sheep, fat-tailed jerboas, etc. live on metabolic water.

Abiotic factors are components of inanimate nature. These include: climatic (light, temperature, water, wind, atmosphere, etc.), acting on all habitats of living organisms: water, air, soil, the body of another organism. Their action is always cumulative.

Light- one of the most important biotic factors, it is the source of life for all life on earth. In the life of organisms, not only visible rays are important, but also others that reach the earth’s surface: ultraviolet, infrared, electromagnetic. The most important process that occurs in plants on Earth with the participation of solar energy: photosynthesis. On average, 1-5% of the light incident on a plant is used for photosynthesis and is transferred further along the food chain in the form of accumulated energy.

Photoperiodism– adaptation of plants and animals to a certain length of the day.

In plants: light-loving and shade-tolerant species are distinguished. Some species grow in illuminated areas (cereals, birch, sunflower), others with a lack of light (forest grasses, ferns), shade-tolerant species can grow in different conditions, but at the same time change their appearance. A pine tree that grows alone has a thick, wide crown; in a tree stand, the crown is formed in the upper part, and the trunk is bare. There are short-day and long-day plants.

Among animals, light is a means of orientation in space. Some are adapted to live in sunlight, while others are nocturnal or twilight. There are animals, such as moles, that do not require sunlight.

Temperature The temperature range at which life is possible is very small. For most organisms it is determined from 0 to +50C.

The temperature factor has pronounced seasonal and daily fluctuations. Temperature determines the speed of biochemical processes in the cell. It determines the appearance of the organism and the breadth of its geographical distribution. Organisms that can withstand a wide range of temperatures are called eurythermal. Stenothermic organisms live in a narrow range of temperatures.

Some organisms are better adapted to tolerate unfavorable (high or low) air temperatures, while others are better able to tolerate soil temperatures. There is a large group of warm-blooded organisms that are capable of

maintain body temperature at a stable level. The ability of organisms to suspend their vital functions at unfavorable temperatures is called suspended animation.

Water There are no living organisms on earth that do not contain water in their tissues. The water content in the body can reach 60-98%. The amount of water required for normal development varies depending on age. Organisms are especially sensitive to water deficiency during the breeding season.

In relation to the water regime, plants are divided into 3 large groups:

Hygrophytes– plants of damp places. They cannot tolerate water shortages.

Mesophytes– plants of moderately humid habitats. They are able to tolerate soil and air drought for a short period. These are the majority of agricultural crops and meadow grasses.

Xerophytes– plants of dry habitats. They are adapted to withstand a lack of water for a long time due to special devices. Leaves turn into spines or, for example, in succulents, the cells grow to enormous sizes, storing water. There is also a similar classification for animals. Only the ending of the phyta changes to phyla: hygrophiles, mesophylls, xerophiles.

Atmosphere The layered atmosphere covering the earth and the ozone layer, located at an altitude of 10-15 km, protect all living things from powerful ultraviolet radiation and cosmic radiation. The gas composition of the modern atmosphere is 78% nitrogen, 21% oxygen, 0.3-3% water vapor, 1% comes from other chemical elements.

Soil or edaphic factors. Soil is a bioinert natural body, formed under the influence of living and inanimate nature. She has fertility. Plants consume nitrogen, phosphorus, potassium, calcium, magnesium, boron and other microelements from soils. The growth, development and biological productivity of plants depends on the availability of nutrients in the soil. Both deficiency and excess of nutrients can become a limiting factor. Some plant species have adapted to an excess of an element, such as calcium, and are called calciumphylls.

The soil is characterized by a certain structure, which depends on humus - a product of the vital activity of microorganisms and fungi. Soil contains air and water, which interact with other elements of the biosphere.

When wind, water or other erosion occurs, the soil cover is destroyed, which leads to loss of soil fertility.

Orographic factors - terrain. Terrain is not a direct factor, but is of great ecological importance as an indirect factor that redistributes climatic and other abiotic factors. The most striking example of the influence of relief is the vertical zoning characteristic of mountainous regions.

There are:

nanorelief – these are heaps near animal burrows, hummocks in swamps, etc.;

microrelief – small funnels, dunes;

mesorelief – ravines, ravines, river valleys, hills, depressions;

macrorelief – plateaus, plains, mountain ranges, i.e. significant geographical boundaries that have a significant impact on the movement of air masses.

Biotic factors. Living organisms are influenced not only by abiotic factors, but also by the living organisms themselves. The group of these factors includes: phytogenic, zoogenic and anthropogenic.

The influence of biotic factors on the environment is very diverse. In one case, when different species influence each other, they have no effect (0); in another case, the effects are favorable (+) or unfavorable (-).

Types of species relationships

Neutralism (0,0) – species do not influence each other;

Competition (-,-) – each type has an adverse effect, suppressing the other and displacing the weaker one;

Mutualism (+,+) – one of the species can develop normally only in the presence of another species (symbiosis of plants and fungi);

Protocooperation (+,+) – cooperation, mutually beneficial influence, not as strict as with mutualism;

Commensalism (+, 0) one species benefits from coexistence;

Amensalism (0,-) – one species is oppressed, the other species is not oppressed;

Anthropogenic influence fits into this classification of species relationships. Among biotic factors, this is the most powerful. It can be direct or indirect, positive or negative. The anthropogenic impact on the abiotic and biotic environment is further discussed in the manual from the point of view of nature conservation.