Introduction

1. Light as an environmental factor. The role of light in the life of organisms

2. Temperature as an environmental factor

3. Humidity as an environmental factor

4. Edaphic factors

5. Various living environments

Conclusion

List of used literature

Introduction

On Earth, there is a huge variety of living environment conditions, which ensures a variety of ecological niches and their "settlement". However, despite this diversity, there are four qualitatively different living environments that have a specific set of environmental factors, and therefore require a specific set. adaptations. These are the environments of life: ground-air (land); water; the soil; other organisms.

Each species is adapted to a specific set of environmental conditions for it - an ecological niche.

Each species is adapted to its specific environment, to certain food, predators, temperature, water salinity and other elements of the outside world, without which it cannot exist.

For the existence of organisms, a complex of factors is required. The body's need for them is different, but each to a certain extent limits its existence.

The absence (lack) of some environmental factors can be compensated for by other close (similar) factors. Organisms are not "slaves" of environmental conditions - to a certain extent, they themselves adapt and change environmental conditions in such a way as to alleviate the lack of certain factors.

The absence of physiologically necessary factors (light, water, carbon dioxide, nutrients) in the environment cannot be compensated (replaced) by others.

1. Light as an environmental factor. The role of light in the life of organisms

Light is one form of energy. According to the first law of thermodynamics, or the law of conservation of energy, energy can change from one form to another. According to this law, organisms are a thermodynamic system constantly exchanging energy and matter with the environment. Organisms on the surface of the Earth are exposed to the flow of energy, mainly solar energy, as well as long-wave thermal radiation from cosmic bodies. Both of these factors determine the climatic conditions of the environment (temperature, water evaporation rate, air and water movement). Sunlight with an energy of 2 cal falls on the biosphere from space. per 1 cm 2 in 1 min. This so-called solar constant. This light, passing through the atmosphere, is attenuated and no more than 67% of its energy can reach the Earth's surface on a clear noon, i.e. 1.34 cal. per cm 2 in 1 min. Passing through cloud cover, water and vegetation, sunlight is further weakened, and the distribution of energy in it in different parts of the spectrum changes significantly.

The degree of attenuation of sunlight and cosmic radiation depends on the wavelength (frequency) of the light. Ultraviolet radiation with a wavelength of less than 0.3 microns almost does not pass through the ozone layer (at an altitude of about 25 km). Such radiation is dangerous for a living organism, in particular for protoplasm.

In wildlife, light is the only source of energy; all plants, except bacteria, photosynthesize, i.e. synthesize organic substances from inorganic substances (i.e. from water, mineral salts and CO 2 - using radiant energy in the process of assimilation). All organisms depend for food on terrestrial photosynthesizers i.e. chlorophyll-bearing plants.

Light as an environmental factor is divided into ultraviolet with a wavelength of 0.40 - 0.75 microns and infrared with a wavelength greater than these greatness.

The effect of these factors depends on the properties of organisms. Each type of organism is adapted to one or another spectrum of wavelengths of light. Some species of organisms have adapted to ultraviolet, while others to infrared.

Some organisms are able to distinguish the wavelength. They have special light-perceiving systems and have color vision, which are of great importance in their life. Many insects are sensitive to shortwave radiation, which humans do not perceive. Night butterflies perceive ultraviolet rays well. Bees and birds accurately determine their location and navigate the terrain even at night.

Organisms also react strongly to light intensity. According to these characteristics, plants are divided into three ecological groups:

1. Light-loving, sun-loving or heliophytes - which are able to develop normally only under the sun's rays.

2. Shade-loving, or sciophytes, are plants of the lower tiers of forests and deep-sea plants, for example, lilies of the valley and others.

As light intensity decreases, photosynthesis also slows down. All living organisms have threshold sensitivity to light intensity, as well as to other environmental factors. Different organisms have different threshold sensitivity to environmental factors. For example, intense light inhibits the development of Drosophyll flies, even causing their death. They do not like light and cockroaches and other insects. In most photosynthetic plants, at low light intensity, protein synthesis is inhibited, while in animals, biosynthesis processes are inhibited.

3. Shade-tolerant or facultative heliophytes. Plants that grow well in both shade and light. In animals, these properties of organisms are called light-loving (photophiles), shade-loving (photophobes), euryphobic - stenophobic.

2. Temperature as an environmental factor

Temperature is the most important environmental factor. Temperature has a huge impact on many aspects of the life of organisms, their geography of distribution, reproduction and other biological properties of organisms that depend mainly on temperature. Range, i.e. the temperature limits at which life can exist range from about -200°C to +100°C, sometimes the existence of bacteria is found in hot springs at a temperature of 250°C. In fact, most organisms can survive within an even narrower range of temperatures.

Some types of microorganisms, mainly bacteria and algae, are able to live and multiply in hot springs at temperatures close to the boiling point. The upper temperature limit for hot spring bacteria lies around 90°C. Temperature variability is very important from an ecological point of view.

Any species is able to live only within a certain range of temperatures, the so-called maximum and minimum lethal temperatures. Beyond these critical extreme temperatures, cold or hot, death of the organism occurs. Somewhere between them is the optimum temperature at which the vital activity of all organisms, living matter as a whole, is active.

According to the tolerance of organisms to the temperature regime, they are divided into eurythermal and stenothermic, i.e. capable of withstanding wide or narrow temperature fluctuations. For example, lichens and many bacteria can live at different temperatures, or orchids and other heat-loving plants of tropical zones are stenothermic.

Some animals are able to maintain a constant body temperature, regardless of the ambient temperature. Such organisms are called homeothermic. In other animals, body temperature changes depending on the ambient temperature. They are called poikilotherms. Depending on the way organisms adapt to the temperature regime, they are divided into two ecological groups: cryophylls - organisms adapted to cold, to low temperatures; thermophiles - or heat-loving.

3. Humidity as an environmental factor

Initially, all organisms were aquatic. Having conquered land, they did not lose their dependence on water. Water is an integral part of all living organisms. Humidity is the amount of water vapor in the air. Without humidity or water, there is no life.

Humidity is a parameter that characterizes the content of water vapor in the air. Absolute humidity is the amount of water vapor in the air and depends on temperature and pressure. This amount is called relative humidity (i.e. the ratio of the amount of water vapor in the air to the saturated amount of vapor under certain conditions of temperature and pressure.)

In nature, there is a daily rhythm of humidity. Humidity fluctuates both vertically and horizontally. This factor, along with light and temperature, plays an important role in regulating the activity of organisms and their distribution. Humidity also changes the effect of temperature.

Air drying is an important environmental factor. Especially for terrestrial organisms, the drying effect of air is of great importance. Animals adapt by moving to protected areas and are active at night.

Plants absorb water from the soil and almost completely (97-99%) evaporate through the leaves. This process is called transpiration. Evaporation cools the leaves. Thanks to evaporation, ions are transported through the soil to the roots, transport of ions between cells, etc.

A certain amount of moisture is essential for terrestrial organisms. Many of them need a relative humidity of 100% for normal life, and vice versa, an organism in a normal state cannot live for a long time in absolutely dry air, because it constantly loses water. Water is an essential part of living matter. Therefore, the loss of water in a certain amount leads to death.

Plants of a dry climate adapt to morphological changes, reduction of vegetative organs, especially leaves.

Land animals also adapt. Many of them drink water, others suck it up through the integument of the body in a liquid or vapor state. For example, most amphibians, some insects and mites. Most of the desert animals never drink; they satisfy their needs at the expense of water supplied with food. Other animals receive water in the process of fat oxidation.

Water is essential for living organisms. Therefore, organisms spread throughout the habitat depending on their needs: aquatic organisms live in water constantly; hydrophytes can only live in very humid environments.

From the point of view of ecological valence, hydrophytes and hygrophytes belong to the group of stenogigers. Humidity greatly affects the vital functions of organisms, for example, 70% relative humidity was very favorable for field maturation and fecundity of migratory locust females. With favorable reproduction, they cause enormous economic damage to the crops of many countries.

For an ecological assessment of the distribution of organisms, an indicator of the dryness of the climate is used. Dryness serves as a selective factor for the ecological classification of organisms.

Thus, depending on the characteristics of the humidity of the local climate, the species of organisms are distributed into ecological groups:

1. Hydatophytes are aquatic plants.

2. Hydrophytes are terrestrial-aquatic plants.

3. Hygrophytes - terrestrial plants living in conditions of high humidity.

4. Mesophytes are plants that grow with medium moisture

5. Xerophytes are plants growing with insufficient moisture. They, in turn, are divided into: succulents - succulent plants (cacti); sclerophytes are plants with narrow and small leaves, and folded into tubules. They are also divided into euxerophytes and stipaxerophytes. Euxerophytes are steppe plants. Stipaxerophytes are a group of narrow-leaved turf grasses (feather grass, fescue, thin-legged, etc.). In turn, mesophytes are also divided into mesohygrophytes, mesoxerophytes, etc.

Yielding in its value to temperature, humidity is nevertheless one of the main environmental factors. For most of the history of wildlife, the organic world was represented exclusively by water norms of organisms. An integral part of the vast majority of living beings is water, and for the reproduction or fusion of gametes, almost all of them need an aquatic environment. Land animals are forced to create in their body an artificial aquatic environment for fertilization, and this leads to the fact that the latter becomes internal.

Humidity is the amount of water vapor in the air. It can be expressed in grams per cubic meter.

4. Edaphic factors

The edaphic factors include the whole set of physical and chemical properties of the soil that can have an ecological impact on living organisms. They play an important role in the life of those organisms that are closely related to the soil. Plants are especially dependent on edaphic factors.

The main soil properties that affect the life of organisms include its physical structure, i.e. slope, depth and granulometry, the chemical composition of the soil itself and the substances circulating in it - gases (in this case, it is necessary to find out the conditions for its aeration), water, organic and mineral substances in the form of ions.

The main characteristic of the soil, which is of great importance for both plants and burrowing animals, is the size of its particles.

Ground soil conditions are determined by climatic factors. Even at a shallow depth in the soil, complete darkness reigns, and this property is a characteristic feature of the habitat of those species that avoid light. As they sink into the soil, temperature fluctuations become less and less significant: daily changes quickly fade, and, starting from a known depth, its seasonal differences smooth out. Daily temperature differences disappear already at a depth of 50 cm. As the soil sinks, the oxygen content in it decreases, and CO 2 increases. At a considerable depth, conditions approach anaerobic conditions, where some anaerobic bacteria live. Already earthworms prefer an environment with a higher content of CO 2 than in the atmosphere.

Soil moisture is an extremely important characteristic, especially for plants growing on it. It depends on numerous factors: the rainfall regime, the depth of the layer, as well as the physical and chemical properties of the soil, the particles of which, depending on their size, the content of organic matter, etc. The flora of dry and wet soils is not the same, and the same crops cannot be grown on these soils. Soil fauna is also very sensitive to soil moisture and generally cannot tolerate too much dryness. Well-known examples are earthworms and termites. The latter are sometimes forced to supply their colonies with water by making underground galleries at great depths. However, too high a water content in the soil kills insect larvae in large numbers.

Minerals necessary for plant nutrition are found in the soil in the form of ions dissolved in water. At least traces of over 60 chemical elements can be found in the soil. CO 2 and nitrogen are present in large quantities; the content of others, such as nickel or cobalt, is extremely small. Some ions are poisonous to plants, others, on the contrary, are vital. The concentration of hydrogen ions in the soil - pH - is on average close to neutral. The flora of such soils is especially rich in species. Calcareous and saline soils have an alkaline pH of the order of 8-9; on sphagnum peatlands, acidic pH can drop to 4.

Some ions are of great ecological importance. They can cause the elimination of many species and, conversely, contribute to the development of very peculiar forms. Soils lying on limestones are very rich in the Ca +2 ion; specific vegetation develops on them, called calcephyte (in the mountains, edelweiss; many types of orchids). In contrast to this vegetation, there is calcephobic vegetation. It includes chestnut, bracken fern, most heather. Such vegetation is sometimes called flint, because soils poor in calcium contain correspondingly more silicon. In fact, this vegetation does not directly prefer silicon, but simply avoids calcium. Some animals have an organic need for calcium. It is known that chickens stop laying eggs in hard shells if the chicken coop is located in an area whose soil is poor in calcium. The limestone zone is abundantly populated by shell gastropods (snails), which are widely represented here in terms of species, but they almost completely disappear on granite massifs.

On soils rich in 0 3 ion, a specific flora also develops, called nitrophilic. Organic residues containing nitrogen that are often found on them are decomposed by bacteria first to ammonium salts, then to nitrates, and finally to nitrates. Plants of this type form, for example, dense thickets in the mountains near cattle pastures.

The soil also contains organic matter formed during the decomposition of dead plants and animals. The content of these substances decreases with increasing depth. In the forest, for example, an important source of their income is the litter of fallen leaves, and the litter of deciduous species is richer in this respect than coniferous. It feeds on destructor organisms - saprophyte plants and saprophage animals. Saprophytes are represented mainly by bacteria and fungi, but among them you can also find higher plants that have lost chlorophyll as a secondary adaptation. Such, for example, orchids.

5. Various living environments

According to the majority of authors studying the origin of life on Earth, it was the aquatic environment that was the evolutionary primary environment for life. We find quite a few indirect confirmations of this position. First of all, most organisms are not capable of active life without water entering the body, or at least without maintaining a certain amount of fluid inside the body.

Perhaps the main distinguishing feature of the aquatic environment is its relative conservatism. For example, the amplitude of seasonal or daily temperature fluctuations in the aquatic environment is much less than in the ground-air one. The bottom relief, the difference in conditions at different depths, the presence of coral reefs, and so on. create a variety of conditions in the aquatic environment.

Features of the aquatic environment stem from the physicochemical properties of water. Thus, the high density and viscosity of water are of great ecological importance. The specific gravity of water is commensurate with that of the body of living organisms. The density of water is about 1000 times that of air. Therefore, aquatic organisms (especially actively moving ones) face a large force of hydrodynamic resistance. For this reason, the evolution of many groups of aquatic animals went in the direction of the formation of a body shape and types of movement that reduce drag, which leads to a decrease in energy consumption for swimming. Thus, the streamlined shape of the body is found in representatives of various groups of organisms that live in water - dolphins (mammals), bony and cartilaginous fish.

The high density of water is also the reason that mechanical vibrations (vibrations) propagate well in the aquatic environment. This was important in the evolution of the sense organs, orientation in space and communication between aquatic inhabitants. Four times greater than in air, the speed of sound in the aquatic environment determines the higher frequency of echolocation signals.

Due to the high density of the aquatic environment, its inhabitants are deprived of the obligatory connection with the substrate, which is characteristic of terrestrial forms and is associated with the forces of gravity. Therefore, there is a whole group of aquatic organisms (both plants and animals) that exist without the obligatory connection with the bottom or other substrate, "floating" in the water column.

The ground-air environment is characterized by a huge variety of living conditions, ecological niches and organisms inhabiting them.

The main features of the ground-air environment are the large amplitude of changes in environmental factors, the heterogeneity of the environment, the action of the forces of gravity, and low air density. The complex of physiographic and climatic factors inherent in a certain natural zone leads to the evolutionary formation of morphophysiological adaptations of organisms to life in these conditions, a variety of life forms.

Atmospheric air is characterized by low and variable humidity. This circumstance largely limited (restricted) the possibilities of mastering the ground-air environment, and also directed the evolution of water-salt metabolism and the structure of the respiratory organs.

The soil is the result of the activities of living organisms.

An important feature of the soil is also the presence of a certain amount of organic matter. It is formed as a result of the death of organisms and is part of their excretions (excretions).

The conditions of the soil habitat determine such properties of the soil as its aeration (that is, air saturation), humidity (the presence of moisture), heat capacity and thermal regime (daily, seasonal, year-to-year temperature variation). The thermal regime, in comparison with the ground-air environment, is more conservative, especially at great depths. In general, the soil is characterized by fairly stable living conditions.

Vertical differences are also characteristic of other soil properties, for example, the penetration of light, of course, depends on depth.

Soil organisms are characterized by specific organs and types of movement (burrowing limbs in mammals; the ability to change body thickness; the presence of specialized head capsules in some species); body shapes (rounded, wolf-shaped, worm-shaped); durable and flexible covers; reduction of eyes and disappearance of pigments. Among the soil inhabitants, saprophagy is widely developed - eating the corpses of other animals, rotting remains, etc.

Conclusion

The output of one of the environmental factors beyond the limits of the minimum (threshold) or maximum (extreme) values ​​(typical for the type of tolerance zone) threatens the death of the organism even with an optimal combination of other factors. Examples are: the appearance of an oxygen atmosphere, the ice age, drought, pressure changes during the ascent of divers, etc.

Each environmental factor affects different types of organisms differently: the optimum for some may be the pessimum for others.

Organisms on the surface of the Earth are exposed to the flow of energy, mainly solar energy, as well as long-wave thermal radiation from cosmic bodies. Both of these factors determine the climatic conditions of the environment (temperature, water evaporation rate, air and water movement).

Temperature is the most important environmental factor. Temperature has a huge impact on many aspects of the life of organisms, their geography of distribution, reproduction and other biological properties of organisms that depend mainly on temperature.

Air drying is an important environmental factor. Especially for terrestrial organisms, the drying effect of air is of great importance.

Yielding in its value to temperature, humidity is nevertheless one of the main environmental factors. For most of the history of wildlife, the organic world was represented exclusively by water norms of organisms.

The edaphic factors include the whole set of physical and chemical properties of the soil that can have an ecological impact on living organisms. They play an important role in the life of those organisms that are closely related to the soil. Plants are especially dependent on edaphic factors.

List of used literature

1. Dedyu I.I. Ecological encyclopedic dictionary. - Chisinau: ITU Publishing House, 1990. - 406 p.

2. Novikov G.A. Fundamentals of general ecology and nature conservation. - L .: Publishing house Leningrad. un-ta, 1979. - 352 p.

3. Radkevich V.A. Ecology. - Minsk: Higher School, 1983. - 320 p.

4. Reimers N.F. Ecology: theory, laws, rules, principles and hypotheses. -M.: Young Russia, 1994. - 367 p.

5. Riklefs R. Fundamentals of general ecology. - M.: Mir, 1979. - 424 p.

6. Stepanovskikh A.S. Ecology. - Kurgan: GIPP "Zauralye", 1997. - 616 p.

7. Khristoforova N.K. Fundamentals of ecology. - Vladivostok: Dalnauka, 1999. -517 p.

Moisture is the most important environmental factor for all living organisms.

Water is the main environment of the cell, where the biochemical and physiological processes that underlie its life activity are carried out, and itself is a participant in the most important of them: photosynthesis, respiration, growth. The special role of water for terrestrial organisms is the need for constant replenishment due to losses during evaporation.

Water is the main component of living organisms, its content varies over a very wide range: from 10-11% in seeds to 98% in algae. Without water, plant growth is impossible, since after cell division, the turgor pressure created by water causes the membranes to stretch. That is why in dry years, plants practically do not grow in height. Therefore, watering when there is not enough rainfall is of great importance for plant growth.

According to the availability of water, the surface of the Earth is usually divided into zones:

• arid, or dry, in which the amount of evaporated moisture exceeds the amount of precipitation;
• humid, or wet, in which the amount of evaporated moisture is less than the amount of precipitation.

The temperature and the movement of air masses - the wind - have a great influence on the water regime of the area. At high temperatures and wind, the air and soil become drier, which causes an increase in water loss from terrestrial organisms.

Of exceptional importance is the seasonal pattern of precipitation throughout the year, as well as daily fluctuations.

Air humidity and precipitation determine the periodicity of the active life of organisms, their distribution by habitat, affect mortality, fertility, etc. rain.

Rains are the main suppliers of moisture for terrestrial plants during the growing season and drinking water for animals. Of great importance for the water regime are the timing of rainfall, their frequency and duration. The nature of the rain is also important. During heavy rains, the soil does not have time to absorb water, which leads to the development of water erosion. The crowns of deciduous trees hold precipitation very well, worse - conifers. In light rains, water does not get under the crown of deciduous tree species at all. When it enters the soil, rain moisture is most accessible to trees. Only very heavy rains can bring harm. They cause mechanical damage to plants and create high soil moisture, displacing from it the air necessary for the respiration of the roots. In this case, the roots die, and the plants are said to "get wet".

Snow. First of all, this is the supply of available water, but the degree of its availability depends on the rate of melting, and the supply depends on the thickness of the snow cover. With intensive melting, surface runoff rushes into reservoirs, washing away the fertile layer, which can lead to soil erosion. Snow protects soil and vegetation from freezing.

The effect of snow on animals is ambiguous. For small rodents, deep snow cover is a good protection against low temperatures. For ungulates, such a cover is detrimental: it makes movement difficult, and sometimes makes it impossible, as the animals hang in the snow and die of hunger.

Ice as a form of moisture has a negative meaning rather than a positive one. When ice occurs in the intercellular spaces of plant tissues, cell death occurs. The formation of ice on the surface of the soil causes the crops to rot, and at a shallow depth - their bulging. Freezing of reservoirs contributes to a sharp deterioration in air exchange, and the entire population of reservoirs experiences a lack of oxygen. Long-term stay of a reservoir under ice and freezing of shallow reservoirs to the bottom, as happened in the cold winter of 1995-1996, leads to mass death of fish.

Precipitation in the form of hoarfrost, hail, hoarfrost, fog, to one degree or another, can be both harmful and beneficial. The destructive effect of hail on plants is well known.

For living organisms, not only the amount of moisture is important, but also its distribution over the seasons, as well as daily fluctuations. The need of plants for water in different periods of development is not the same, it also changes depending on the climate and soil type.

According to the method of regulating their water regime, plants are divided into several ecological groups:

• poikilohydric - not capable of actively regulating the water regime (in plants that do not have stomata, the water content depends on fluctuations in its amount in the external environment, like in lichens);
• homoiohydric - most of the plants that can actively regulate the water regime (the presence of stomata, cuticles, hairs).

According to the confinement of plants to habitat conditions, they distinguish:

• hydrophytes - plants of places of excessive moisture and semi-submerged aquatic plants that do not have adaptations for regulating the water regime (touchy, oxalis, arrowhead, plantain chastuha, etc.);
• mesophytes - plants of places of moderate moisture. They have a well-developed root system and a number of devices for regulating the water regime. These include meadow and many forest grasses, deciduous trees, most agricultural crops;
• xerophytes - plants of dry habitats, adapted to the lack of moisture. Some of them have a powerful root system, getting water from deep layers (camel thorn); others have well-developed pubescence, mechanical tissues and other adaptive features (many cereals, wormwood).

Many plants store water in stems or leaves (succulents). These include cacti, agaves, aloe.

Animals get water in three main ways: through drinking, along with food and as a result of metabolism, that is, due to the oxidation and breakdown of fats, proteins and carbohydrates.

Like plants, land animals also inhabit habitats with different water regimes. Animals of wet habitats - hygrophiles - do not have mechanisms for regulating water metabolism. These include wood lice, mosquitoes, snakes, crocodiles, terrestrial gastropods and amphibians.

Mesophiles are the majority of animals.

Animals of dry habitats - xerophiles - have well-developed mechanisms for the regulation of water metabolism and adaptation to water retention in the body. So, many desert insects never drink water and are content with moisture coming from food. A number of animals have adapted to live off the metabolic water formed in the process of oxidation of accumulated fat reserves (camel, fat-tailed jerboas, clothes moth caterpillars, rice and granary weevils). Most xerophilous animals have a number of adaptations for water retention, such as waterproof integuments, absence of skin glands, excretion of the end products of nitrogen metabolism in the form of uric acid, increased reabsorption of water in the tubules of the nephrons of the kidneys, and reduced sweating. A variety of adaptive behavioral responses play an important role: digging into the ground, digging holes, going into the shade, appropriate orientation of the body in relation to the sun's rays, and summer hibernation. For actively moving animals, movement to water bodies is important as water sources.

1. Geographical variability of populations and its adaptive nature. Clines, isophenes.

Geographical variability of populations- this is the phenotypic and genotypic dissimilarity of spatially separated populations of the same species. Geographical variability is an inevitable consequence of the geographical variability of the environment. Signs and phenotypes change in different parts of the range due to a change in living conditions - due to a change in the directions of natural selection.

Populations from generation to generation are subjected to continuous selection by habitat conditions for maximum adaptability to the conditions of that part of the range, the ecosystem in which the population exists. The greater the spatial separation between the compared populations, the more they differ in the frequency of signs, the more significantly the populations differ in phenol appearance.

For example, in populations located in different natural zones of the downy birch in the Cis-Urals, the frequency of individuals with a certain leaf shape changes. Individuals with diamond-shaped leaves in the tundra - 4%, in the middle taiga - 8%, in the southern taiga - 28%, in broad-leaved forests - 21%, in the forest-steppe - 20%, in the steppe - 16%. Geographically distant or isolated populations (or groups of populations) have such a changed frequency of occurrence of characters and such a specific set of them that they are defined as geographical populations, or subspecies. This is especially true for species with a wide range. In this case, the species consists of a system of separate vicarious (lat. vicarius - replacing), replacing geographical populations. Thus, in the range of the field bumblebee, which lives in Europe, 25 geographical populations have been identified.

With geographical variability, different populations of the same species in different parts of its range naturally differ from each other in certain characters. Very often one can observe such geographical variability of any trait, in which the frequency of its occurrence or the degree of expression gradually decrease or, conversely, increase, sometimes even throughout the entire length of the range. This type of change is called clinal, and the curve depicting the nature of the change in the trait - to w and n o th.

Wedges may have different directions and different lengths. The steepness of the wedge can vary greatly in different parts of the range. If we mark on the map points in which a given feature is expressed to the same degree, and connect them with lines, then the latter will be located at right angles to the direction of the wedge and will be parallel to each other. Such lines connecting points with the same degree of development of the trait are called isophenes. According to isophenes, one can clearly trace the regularity of geographical variability. Thus, the percentage of individuals with white coloration in the swede butterfly naturally decreases in the direction from south to north.

The study of the geographical variability of animal traits led to the establishment of some general patterns formulated in the form of special rules. Of these, some rules relating to warm-blooded animals are widely known.

Bergman's rule. In the warmer parts of the range, the species are represented by smaller individuals, and in the colder parts, by larger individuals. Thus, in a hare in the conditions of the Black Sea coast, the skull length is less than 8 cm, while at the northern border of the range it exceeds 10 cm. The average length of the skull in a hare in Scotland is 7 cm, and in Scandinavia and Greenland - 9 cm .

Allen's rule. According to this rule, the protruding parts of the body in mammals and birds (tails, ears, limbs) in the colder parts of the range are somewhat shorter.

Gloger's rule. The amount of black pigments (eumelanins) increases in warm and humid parts of the distribution area of ​​the species, while reddish and yellowish-brown pigments (pheomelanins) predominate in dry areas. Thus, in the brown-headed tit (Parus atricapillus), according to the microscopic analysis of plumage pigments, the amount of pheomelanins naturally increases from north to south. A similar relationship between the development of a particular pigment and climatic conditions has also been established for ladybugs, some butterflies and other insects.

1. Energy concept of the ecosystem. Lindemann's law.

Life on Earth exists due to solar energy.

Light is the only food resource on Earth, the energy of which, in combination with carbon dioxide and water, gives rise to the process of photosynthesis. Photosynthetic plants create organic matter that herbivores feed on, carnivores feed on them, etc., in the end, plants “feed” the rest of the living world, that is, solar energy through plants is, as it were, transmitted to all organisms.

Energy is transferred from organism to organism, creating a food or trophic chain: from autotrophs, producers (creators) to heterotrophs, consumers (devourers) and so on 4-6 times from one trophic level to another.

Trophic level is the place of each link in the food chain. The first trophic level is producers, all the rest are consumers. The second trophic level is herbivorous consumers; the third - carnivorous consumers feeding on herbivorous forms; the fourth - consumers consuming other carnivores, etc. Therefore, it is possible to divide consumers according to levels: consumers of the first, second, third, etc. orders.

Only consumers who specialize in a certain type of food are clearly divided by levels. However, there are species that feed on meat and plant foods (humans, bears, etc.), which can be included in food chains at any level.

The food absorbed by the consumer is not completely absorbed - from 12 to 20% in some herbivores, up to 75% or more in carnivores. Energy costs are associated primarily with the maintenance of metabolic processes, which are called breathing costs, estimated by the total amount of CO2 excreted by the body. A much smaller part goes to the formation of tissues and a certain supply of nutrients, i.e., to growth. The rest of the food is excreted in the form of excrement. In addition, a significant part of the energy is dissipated in the form of heat during chemical reactions in the body and especially during active muscular work. Ultimately, all the energy used for metabolism is converted into heat and dissipated in the environment.

Thus, most of the energy in the transition from one trophic level to another, higher one, is lost.

Approximately, the losses are about 90%: no more than 10% of the energy from the previous level is transferred to each next level. So, if the caloric content of the producer is 1000 J, then when it enters the body of the phytophage, 100 J remains, in the body of the predator it is already 10 J, and if this predator is eaten by another, then only 1 J, i.e. 0.1% from the calorie content of plant foods.

However, such a strict picture of energy transition from level to level is not entirely realistic, since the trophic chains of ecosystems are intricately intertwined, forming food webs. But the end result: the dissipation and loss of energy, which, in order for life to exist, must be renewed.

We must not forget also dead organic matter, which feeds on a significant part of heterotrophs. Among them there are saprophages and saprophytes (mushrooms) that use the energy contained in detritus. Therefore, two types of trophic chains are distinguished: grazing chains, or pasture chains, which begin with the eating of photosynthetic organisms, and detrital decomposition chains, which begin with the remains of dead plants, corpses and animal excrement.

Thus, entering the ecosystem, the flow of radiant energy is divided into two parts, spreading through two types of food webs, but the source of energy is the same - sunlight.

Lindemann's Law (R. Lindemann, 1942)

No more than 10% of energy passes from one trophic level of the ecological pyramid to another trophic level.

1. Spatial structure of ecosystems, continuum and discreteness. Ecotone and edge effect.

Spatial structure of the ecosystem. Populations of different species in an ecosystem are distributed in a certain way - they form a spatial structure. There are vertical and horizontal structures of the ecosystem.

Vegetation forms the basis of the vertical structure.

The plant community determines, as a rule, the appearance of the ecosystem. Plants largely influence the conditions for the existence of other species. In the forest, these are large trees, in the meadows and in the steppes - perennial grasses, and in the tundra, mosses and shrubs dominate.

Living together, plants of the same height create a kind of floors - tiers. In the forest, for example, tall trees make up the first (upper) tier, the second tier is formed from young trees of the upper tier and from mature trees that are smaller in height. The third tier consists of shrubs, the fourth - of tall grasses. The lowest tier, where very little light enters, is made up of mosses and undersized grasses.

Layering is also observed in herbaceous communities (meadows, steppes, savannahs). There is also an underground layering, which is associated with different depths of penetration into the soil of the root systems of plants: in some, the roots go deep into the soil, reach the groundwater level, while others have a surface root system that captures water and nutrients from the upper soil layer.

Due to the tiered arrangement, plants use the light flux most efficiently, while competition is reduced: light-loving plants occupy the upper tier, and shade-tolerant ones develop under their canopy.

Animals are also adapted to life in one or another plant layer (some do not leave their layer at all). For example, among insects, there are: underground, living in the soil (bear, burrowing spider); terrestrial, surface (ant, stink bug); inhabitants of the herbage (grasshopper, aphid, ladybug) and inhabitants of higher tiers (various flies, dragonflies, butterflies).

Due to the heterogeneity of the relief, soil properties, and various biological characteristics, plants are also located in the horizontal direction in microgroups that differ in species composition. This phenomenon is called mosaicism. Mosaic vegetation is a kind of "ornament" formed by clusters of plants of different species.

Thanks to the vertical and horizontal structures, the organisms living in the ecosystem more efficiently use soil minerals, moisture, and light flux.

An important consequence of the principle of the individuality of species ecology is the gradual change in the composition of plant communities and ecosystems along environmental gradients. Such gradual changes are called continuum (continuity). For this reason, specific communities and ecosystems are distinguished in the same conditional way as ecological groups of species.

The concept of the continuum was formulated at the beginning of the 20th century. independently by two scientists - Russian L.G. Ramensky and American H. Gleason. In the second half of the twentieth century. The greatest contribution to its development was made by R. Whittaker, J. Curtis, R. McIntosh and M. Austin.

There are two types of continua: ecocline and ecotone. An ecocline is an absolute continuum within which no zones of fast and slow changes in the species composition of communities are distinguished on the gradient. This type of continuum prevails in those cases when the change in the composition of communities occurs without a change in the life form of plants, i.e. grass or forest vegetation changes. An example of an ecocline is shown in fig. 7, it is obvious from it that the change of plant communities on the gradient occurs gradually and it is possible to draw the boundaries of communities corresponding to different conditions of soil salinity only conditionally.

Rice. Fig. 7. Ecocline of herbaceous vegetation of the lower Volga floodplain along the gradient of total salinity (the list of species is shortened, after Golub and Mirkin, 1986). 1 - Phalaroides arundinacea, 2 - Bolboschoenus borodinii, 6 - Argusia sibirica, 7 - Atriplex litoralis, 8 - Tripolium vulgare.

Ecotone - this is a type of continuum in which more or less homogeneous communities are formed on the gradient, connected by a zone of fast and visible transition. A typical example of an ecotone is the vegetation of the edge (Fig. 8), i.e. zones of contact between forest and grassland (meadows or steppes).

Rice. Fig. 8. Ecotope effect in the vegetation of the forest edge (according to Kucherova, 2001). Number of species: 1 - common, 2 - grasslands, 3 - forest, 4 - edge.
Similar continuums of ecocline and ecotone types are also manifested in the nature of changes in heterotrophic biota, primarily insects and soil animals. The ecotone is characterized by species richness and is a transitional zone.

1. Evolution of the biosphere. Geochronological scale of the development of the organic world. The Gaia hypothesis.

One of the most important areas in the study of evolution is the study of the development of life forms. There are several stages here:

1. Cells without a nucleus, but having strands of DNA (reminiscent of today's bacteria and blue-green algae). The age of such most ancient organisms is more than 3 billion years. Their properties: 1) mobility; 2) nutrition and the ability to store food and energy; 3) protection from unwanted influences; 4) reproduction; 5) irritability; 6) adaptation to changing external conditions; 7) the ability to grow.

2. At the next stage (approximately 2 billion years ago), a nucleus appears in the cell. Single-celled organisms with a nucleus are called protozoa. There are 25-30 thousand of them. The simplest of them are amoeba. Ciliates also have cilia. The nucleus of protozoa is surrounded by a double membrane with pores and contains chromosomes and nucleoli. Fossil protozoa - radiolarians and foraminifers - are the main parts of sedimentary rocks. Many protozoa have complex locomotor apparatus.

3. Approximately 1 billion years ago, multicellular organisms appeared. As a result of plant activity - photosynthesis - organic matter was created from carbon dioxide and water using solar energy captured by chlorophyll. The emergence and spread of vegetation led to a fundamental change in the composition of the atmosphere, which initially had very little free oxygen. Plants, assimilating carbon from carbon dioxide, created an atmosphere containing free oxygen - not only an active chemical agent, but also a source of ozone, blocking the path of short ultraviolet rays to the Earth's surface.

L. Pasteur identified the following two important points in the evolution of the biosphere: 1) the moment when the level of oxygen in the Earth's atmosphere reached approximately 1% of the current one. Since that time, aerobic life has become possible. Geochronologically, it is Archaean. It is assumed that the accumulation of oxygen proceeded spasmodically and took no more than 20 thousand years: 2) the achievement of the oxygen content in the atmosphere of about 10% of the current one. This led to the emergence of prerequisites for the formation of the ozonosphere. As a result, life became possible in shallow water, and then on land.

Paleontology, which deals with the study of fossil remains, confirms the fact of an increase in the complexity of organisms. In the most ancient rocks, organisms of a few types with a simple structure are found. Gradually the variety and complexity grows. Many species that appear at any stratigraphic level then disappear. This is interpreted as the emergence and extinction of species.

In accordance with paleontological data, it can be considered that bacteria, algae, primitive invertebrates appeared in the Proterozoic geological era (700 million years ago); in the Paleozoic (365 million years ago) - land plants, amphibians; in the Mesozoic (185 million years ago) - mammals, birds, conifers; into the Cenozoic (70 million years ago) - modern groups. Of course, it should be borne in mind that the paleontological record is incomplete.

For centuries, the accumulated remains of plants formed in the earth's crust enormous energy reserves of organic compounds (coal, peat), and the development of life in the oceans led to the creation of sedimentary rocks consisting of skeletons and other remains of marine organisms.

Important properties of living systems include:

1. Compactness. 5 ? 10-15 g of DNA contained in a fertilized whale egg contains information for the vast majority of signs of an animal that weighs 5? 107g (the mass increases by 22 orders of magnitude).

2. The ability to create order from the chaotic thermal motion of molecules and thereby counteract the increase in entropy. Living things consume negative entropy and work against thermal equilibrium, increasing, however, the entropy of the environment. The more complex the living matter is, the more hidden energy and entropy it has.

3. Exchange with the environment of matter, energy and information.

The living being is able to assimilate substances received from outside, i.e., rebuild them, likening them to its own material structures and, due to this, reproduce them many times.

4. Feedback loops formed during autocatalytic reactions play an important role in metabolic functions. “While in the inorganic world feedback between the ‘effects’ (end products) of nonlinear reactions and the ‘causes’ that give rise to them is relatively rare, in living systems feedback (as established by molecular biology), on the contrary, is the rule rather than the exception. "(I. Prigogine, I. Stengers. Order out of chaos. M., 1986, p. 209). Autocatalysis, cross-catalysis and autoinhibition (the process opposite to catalysis, if a given substance is present, it is not formed during the reaction) take place in living systems. To create new structures, positive feedback is needed; for sustainable existence, negative feedback is needed.

5. Life is qualitatively superior to other forms of existence of matter in terms of the diversity and complexity of chemical components and the dynamics of transformations occurring in living things. Living systems are characterized by a much higher level of order and asymmetry in space and time. The structural compactness and energy efficiency of living things are the result of the highest orderliness at the molecular level.

6. In the self-organization of non-living systems, the molecules are simple, and the reaction mechanisms are complex; in the self-organization of living systems, on the contrary, the reaction schemes are simple, and the molecules are complex.

7. Living systems have a past. The non-living have none. “The integral structures of atomic physics consist of a certain number of elementary cells, an atomic nucleus and electrons and do not show any change in time, unless they are disturbed from the outside. In the event of such an external disturbance, it is true that they somehow react to it, but if the disturbance was not too great, they return to their original position when it ceases. But organisms are not static formations. The ancient comparison of a living being with a flame suggests that living organisms, like a flame, are a form through which matter passes in a certain sense as a stream ”(W. Heisenberg. Physics and Philosophy. Part and Whole. M., 1989, p. 233).

8. The life of an organism depends on two factors - heredity, determined by the genetic apparatus, and variability, depending on environmental conditions and the individual's reaction to them. It is interesting that now life on Earth could not have arisen due to the oxygen atmosphere and the opposition of other organisms. Once born, life is in the process of constant evolution.

9. Ability to excessive self-reproduction. “The progression of reproduction is so high that it leads to a struggle for life and its consequences - natural selection” (Ch. Darwin. Soch. T. 3. M.-L., 1939, p. 666).

The Gaia hypothesis was put forward by the English scientist James Lovelock, who worked at NASA in the early 1960s, at a time when the search for life in the solar system was just beginning. Based on the fact that the earth's atmosphere is significantly different from the atmospheres of lifeless planets, Lovelock argued that our planet and its biosphere are a kind of living organism. He said: "The earth is more than just a house, it is a living organism, and we are part of it."

The significance of the hypothesis lies in the fact that it contributed to the development of a systematic approach to the study of the Earth, in which the planet is considered as a single whole, and not as a set of separate parts.

1. Temperature as the main environmental factor. adaptation to low and high temperatures.

Poikilothermic animals are able to adapt to high temperatures. This also happens in different ways: heat transfer can occur due to evaporation of moisture from the surface of the body or from the mucous membrane of the upper respiratory tract, as well as due to subcutaneous vascular regulation (for example, in lizards, the rate of blood flow through the vessels of the skin increases with increasing temperature).

The most perfect thermoregulation is observed in birds and mammals - homoiothermal animals. In the process of evolution, they acquired the ability to maintain a constant body temperature due to the presence of a four-chambered heart and one aortic arch, which ensured complete separation of arterial and venous blood flow; high metabolism; feather or hairline; regulation of heat transfer; well-developed nervous system acquired the ability to live actively at different temperatures. In most birds, the body temperature is slightly above 40 o C, while in mammals it is somewhat lower. Not only the ability to thermoregulate, but also adaptive behavior, the construction of special shelters and nests, the choice of a place with a more favorable temperature, etc., is of great importance for animals. They are also able to adapt to low temperatures in several ways: in addition to feather or hair, warm-blooded animals reduce heat loss with the help of trembling (microcontractions of apparently immobile muscles); when brown adipose tissue is oxidized in mammals, additional energy is generated that supports metabolism.

The adaptation of warm-blooded animals to high temperatures is in many ways similar to similar adaptations of cold-blooded ones - sweating and evaporation of water from the mucous membrane of the mouth and upper respiratory tract, in birds - only the last way, since they do not have sweat glands; expansion of blood vessels located close to the surface of the skin, which enhances heat transfer (in birds, this process occurs in non-feathered areas of the body, for example, through a comb). Temperature, as well as the light regime on which it depends, naturally changes throughout the year and in connection with geographic latitude. Therefore, all adaptations are more important for living at low temperatures.

1. Demographic structure of populations.

All chemical processes occurring in the body depend on temperature. Changes in thermal conditions, often observed in nature, are deeply reflected in the growth, development and other manifestations of the vital activity of animals and plants. There are organisms with a variable body temperature - poikilothermic and organisms with a constant body temperature - homeothermic. Poikilothermic animals are completely dependent on the ambient temperature, while homeothermic animals are able to maintain a constant body temperature regardless of changes in ambient temperature. The vast majority of terrestrial plants and animals in a state of active life cannot tolerate negative temperatures and die. The upper temperature limit of life is not the same for different species - rarely above 40-45 °C. Some cyanobacteria and bacteria live at temperatures of 70-90 °C, and some mollusks can live in hot springs (up to 53 °C). For most terrestrial animals and plants, the optimum temperature conditions fluctuate within rather narrow limits (15-30 °C). The upper threshold of life temperature is determined by the temperature of protein coagulation, since irreversible protein coagulation (breakdown of protein structure) occurs at a temperature of about 60 oC.

Poikilothermic organisms in the process of evolution have developed various adaptations to changing environmental temperature conditions. The main source of thermal energy in poikilothermic animals is external heat. Poikilothermic organisms have developed various adaptations to low temperatures. Some animals, for example, arctic fish, living constantly at a temperature of -1.8 o C, contain substances (glycoproteins) in the tissue fluid that prevent the formation of ice crystals in the body; insects accumulate glycerol for these purposes. Other animals, on the contrary, increase the heat production of the body due to the active contraction of the muscles - this is how they increase the body temperature by several degrees. Still others regulate their heat exchange by exchanging heat between the vessels of the circulatory system: the vessels leaving the muscles are in close contact with the vessels coming from the skin and carrying cooled blood (this phenomenon is characteristic of cold-water fish). Adaptive behavior is seen in the fact that many insects, reptiles and amphibians choose places in the sun for heating or change different positions to increase the heating surface.

In a number of cold-blooded animals, body temperature can vary depending on the physiological state: for example, in flying insects, the internal body temperature can rise by 10-12 o C or more due to increased muscle work. Social insects, especially bees, have developed an effective way of maintaining temperature through collective thermoregulation (the hive can be maintained at a temperature of 34-35 o C, which is necessary for the development of larvae).

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Humidity as an environmental factor

Humidity is also one of the most important environmental factors. Being the most common substance on Earth, water plays an important role for living organisms, is a necessary condition for life, and its quantity can be a limiting environmental factor. Water is the main component of cells, a solvent, a vehicle for the transfer of nutrients, with its participation biochemical reactions occur in organisms. water biochemical humidity

As a physical body, water has a number of anomalous properties due to its molecular structure. For example, when water freezes, it does not compress, like most liquids, but expands. Therefore, the density of ice is less than the density of water (the maximum density of water at + 4 ° C) prevents freezing of reservoirs to the bottom. In addition, water has a high dielectric constant, i.e., a highly polar solvent, and a high heat capacity, so it is an important temperature regulator. In summer, water bodies absorb heat, in winter they release it to the environment. Therefore, in areas in which large reservoirs are located, there are no sharp fluctuations in temperature in winter and summer, day and night.

Since water is a habitat for many organisms, its properties such as density, content of dissolved gases, transparency, acidity, etc. are important. The content of oxygen dissolved in water can be a limiting factor and it depends on a number of factors, in particular temperature, pressure , currents, etc..

Plants are especially sensitive to changes in humidity and water content. If necessary, the following ecological groups of plants are distinguished in water:

Hydratophytes that live only in water, they are completely or almost completely submerged in water. Without water, they quickly die; Hydrophytes are terrestrial-aquatic plants that can be partially submerged in water, for example, they grow on the banks of reservoirs, swamps, etc.;

Hygrophytes are terrestrial plants that can exist in conditions of high humidity and on moist soils;

Mesophytes that withstand a short and not very strong drought. These plants are quite numerous and widespread;

Xerophytes that can tolerate prolonged drought while active due to their ability to regulate water metabolism, such as desert plants, etc.

Animals are also sensitive to the amount of water that is in their body. Water enters the body of animals during drinking, with food and as a result of metabolic processes, in particular as a result of fat oxidation. In the case when less water enters the animal's body than it is spent, it feels a water deficit. Dehydration of the body can lead to its death. So water has not only a direct impact on the physiology of organisms, but also changes other environmental factors, such as temperature, soil aeration, the assimilation of nutrients by plants, etc. In addition, water is the habitat of a significant number of organisms.

There is a huge amount of water in nature. The totality of all water is called the aquatic environment or hydrosphere So, the hydrosphere is a continuous water shell of the Earth, which is a collection of oceans, seas, continental waters and ice layers. The hydrosphere, which is one of the most important elements of the environment, plays a decisive role in many processes occurring in nature. Water plays an important role in the history of the development of our planet, since the origin and development of living matter, and, as a result, the entire biosphere is associated with it.

If we consider the constituent parts of the hydrosphere, (Then the seas and oceans (World Ocean) occupy about 71% of the earth's surface, they contain 1.37 x 109 km3 of water, which is 94% of the entire hydrosphere. The total area of ​​\u200b\u200ball continental water bodies is ~ 3% of the area ~ 1.7% of the reserves of the hydrosphere are accumulated in continental glaciers, and their area is about 10% of the area of ​​the continents Significant amounts of water, about (SW) x 103 km3, is an integral part of living organisms that inhabit the Earth.

Water in nature is in circulation. The water cycle is a process of continuous, interconnected movement of water on Earth, which takes place under the influence of solar energy, gravity, vital activity of living organisms and human economic activity.

Under the action of the thermal energy of the Sun, ~ 525x103 km3 of water evaporates annually from the surface of the ocean and continents, which corresponds to 1030 mm of atmospheric precipitation per year. Part of the water returns to the World Ocean in the form of precipitation, forming a link in the small water cycle in nature. The second part of the water in the form of precipitation is transported by air masses to the continents, forming a link in the large water cycle in nature, where evaporation from the land surface and precipitation, as well as river runoff, partially returns to the World Ocean. Large and small water cycles in nature ensure the unity of all water in the hydrosphere.

Although different parts of the hydrosphere are connected with each other by the processes of the water cycle in nature, however, the rate of their natural renewal is not the same. The available data on various parts of the hydrosphere and their water balance made it possible to calculate the activity of water exchange, which takes place in the process of the water cycle. The activity of water exchange is understood as the rate of renewal of individual water resources of the hydrosphere. It is expressed in terms of the number of years required for their complete renewal.

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In the life of organisms, water acts as the most important environmental factor. It is the main part of the protoplasm of cells, tissues, plant and animal juices. All biochemical processes of assimilation and dissimilation, gas exchange in the body are carried out with sufficient water supply. Water with substances dissolved in it determines the osmotic pressure of cell and tissue fluids, including intercellular exchange. During the period of active life of plants and animals, the water content in their organisms, as a rule, is quite high.

In the inactive state of the body, the amount of water can significantly decrease, however, even during the rest period, it does not completely disappear. For example, in dry mosses and lichens, the water content of the total mass is 5-7%, and in air-dry grains of cereals - at least 12-14%. Terrestrial organisms, due to the constant loss of water, need regular replenishment. Therefore, in the process of evolution, they have developed adaptations that regulate water exchange and ensure the economical use of moisture. Adaptations are anatomical, morphological, physiological and behavioral in nature. The need for different types of plants in water for periods of development is not the same. It changes depending on the climate and soil. Thus, cereal crops during periods of seed germination and maturation require less moisture than during the most intensive growth. In addition to the humid tropics, plants experience almost everywhere

belt water shortage. drought. At high temperatures in summer, atmospheric drought is often manifested, as well as soil drought (with a decrease in soil moisture available to the plant). Lack or deficiency of moisture reduces the growth of plants, can cause their short stature, infertility due to underdevelopment of generative organs.

Of paramount importance in all manifestations of life is water exchange between the body and the external environment. Humidity of the environment is often a factor that limits the distribution and abundance of organisms on Earth. For example, steppe and especially forest plants require a high content of moisture vapor in the air, while desert plants have adapted to low humidity.

Humidity determines the frequency of active life of organisms, the seasonal dynamics of life cycles, affects the duration of development, fertility and their mortality. For example, such plant species as spring veronica, sandy forget-me-not, desert beetroot, etc., using spring moisture, have time to germinate in a very short time (12-30 days), develop generative shoots, bloom, form fruits and seeds. These annual plants are called ephemers (from the Greek "ephemeros" - fleeting, one-day). Adaptation to the seasonal rhythm of humidity is also shown by individual species of perennial plants, called ephemeroids or geoephemeroids. Under unfavorable humidity conditions, they can delay their development until it becomes optimal, or, like ephemera, go through its entire cycle in extremely short early spring terms. This includes typical plants of the southern steppes - steppe hyacinth, poultry, tulips, etc.

Animals can also be ephemera. These are insects, crustaceans (shieldworms that appear in large numbers in forest puddles in spring) and even fish that live in small reservoirs, puddles, for example, African notobranchs and afio-semions from the carp-tooth-like order.

In relation to humidity, euryhygrobiont and stenohygrobiont organisms are distinguished.

Euryhygrobiont organisms have adapted to live with various fluctuations in humidity. For stenohygrobiont organisms, the humidity must be strictly defined: high, medium or low. The development of animals is no less closely related to humidity.

environment. However, animals, unlike plants, have the ability to actively seek conditions with optimal humidity, and have more advanced mechanisms for regulating water metabolism.

The humidity of the environment affects the water content in the tissues of the animal and hence is directly related to its behavior and survival. However, it can also have an indirect effect.

through food and other factors. For example, during droughts, with a strong burnout of vegetation, the number of phytophagous animals decreases. The development of animals in phases requires strictly defined conditions for humidity. With a lack of moisture in the air or food of animals, fertility is sharply reduced, and first of all, moisture-loving forms. An insufficient amount of water in the feed reduces the growth rate in most animals, slows down their development, shortens life expectancy, and increases mortality.

Consequently, the water regime, i.e. successive changes in the inflow, state and content of water in the external environment (rain, snow, fog, air vapor saturation, groundwater level, soil moisture) have a significant impact on life

living organisms.

Depending on the habitat among terrestrial plants, the following ecological groups are distinguished:

hygrophytes,

mesophytes,

xerophytes.

Hygrophytes(from the Greek "hygros" - wet, "phyton" - plants) - plants that live in humid places, do not tolerate water deficiency and have low drought resistance. On the whole, with a rather large variety of habitats, features of the water regime, and anatomical and morphological features of all hygrophytes, they are united by the absence of adaptations that limit water flow and the inability to endure its slight loss.

Mesophytes- These are plants of moderately humid habitats. They have a well-developed root system. Mesophytes include many meadow grasses (red clover, timothy), most forest plants (lily of the valley, etc.), a significant part of deciduous trees (aspen, birch, linden), many field (rye, cabbage, etc.), fruit and berry crops (apple, currants, raspberries, cherries, etc.) and weeds.

Xerophytes(from the Greek "xeros" - dry, "phyton" - plant) - these are plants of dry habitats that can tolerate a significant lack of moisture - soil and atmospheric drought. Xerophytes are most abundant and diverse in areas with a hot and dry climate. These include plant species of deserts, dry steppes, savannahs, and dry subtropics. To overcome the lack of moisture, there can be different ways: increasing its absorption and reducing consumption, as well as the ability to tolerate large losses of water.

In the process of evolution, plants and animals developed various adaptations to the water regime (Table 2).

Table 2

Adaptation to dry conditions in plants and animals (according to N. Green et al., 1993)

Reducing water loss
Leaves are turned into needles or	Euphorbia, coniferous trees
submerged stomata	Pinus, Ammophila
Leaves rolled into a cylinder
Thick waxy cuticle	leaves of the majority
	xerophytes, insects
Thick stem with a large ratio	Cactaceae, Euphorbiaceae (bough-
volume reduction to the surface
pubescent leaves	Many alpine plants
Dropping leaves during drought	Fouguieria splendens
Stomata open at night and closed	Crassula
Efficient CO2 fixation at night with	C-4 - plants, e.g. Zea
Not fully open stomata
Excretion of nitrogen in the form of urine	Insects, birds and some
	reptiles
Elongated loop of Henle in the kidney	desert mammals,
	e.g. camel, desert
Fabrics are resistant to high
	Many desert plants.
temperatures due to a decrease
sweating or transpiration.
Animals hide in burrows.	Many small desert
	mammals, for example
Breathing holes are covered	desert rat
	many insects
valves
Increase water absorption
Extensive superficial root	Some, such as Cactaceae,
long roots	Opuntia and Euphorbiaceae
	Many alpine plants
Digging passages to the water	(edelweiss)

water storage In mucous cells and in cell walls In a specialized bladder In the form of fat (water is a product of fat oxidation)	Cactaceae and EuphorbiceaeDesert FrogDesert Rat
Physiological resistance to water loss Visible dehydration remains viable Loss of a significant part of the body weight and its rapid recovery with the presence of available water	Some epiphytic ferns and club mosses, many bryophytes and lichens, sedge Earthworm (loses up to 70% of mass), camel (loses up to 30% of mass)
"Problem Avoidance" Survive an unfavorable period in the form of seeds Survive an unfavorable period in the form of bulbs and tubers Disperse seeds in the hope that some of them will fall into favorable conditions Behavioral avoidance reactions Summer hibernation in a cocoon	Eschscholzia californiaSome liliesDifferent plants Soil organisms, mites, earthwormsEarthworms, lungfish

Temperature and humidity are the leading climatic factors and are closely interrelated.

With a constant amount of water in the air, relative humidity increases as the temperature drops. If the air cools below its saturation point (100%), condensation occurs and precipitation occurs. When heated, its relative humidity drops. The combination of temperature and humidity often plays a decisive role in the distribution of vegetation and animals. The interaction of temperature and humidity depends not only on their relative, but also on their absolute value. For example, temperature has a more pronounced effect on organisms under conditions of humidity close to critical, i.e. if the humidity is very high or very low. Humidity also plays a more critical role at temperature,

close to limit values. Hence the same species of organisms b different geographical areas prefer different habitats.

Light, temperature and humidity as environmental factors

test

3. Humidity as an environmental factor

Initially, all organisms were aquatic. Having conquered land, they did not lose their dependence on water. Water is an integral part of all living organisms. Humidity is the amount of water vapor in the air. Without humidity or water, there is no life.

Humidity is a parameter that characterizes the content of water vapor in the air. Absolute humidity is the amount of water vapor in the air and depends on temperature and pressure. This amount is called relative humidity (i.e. the ratio of the amount of water vapor in the air to the saturated amount of vapor under certain conditions of temperature and pressure.)

In nature, there is a daily rhythm of humidity. Humidity fluctuates both vertically and horizontally. This factor, along with light and temperature, plays an important role in regulating the activity of organisms and their distribution. Humidity also changes the effect of temperature.

Air drying is an important environmental factor. Especially for terrestrial organisms, the drying effect of air is of great importance. Animals adapt by moving to protected areas and are active at night.

Plants absorb water from the soil and almost completely (97-99%) evaporate through the leaves. This process is called transpiration. Evaporation cools the leaves. Thanks to evaporation, ions are transported through the soil to the roots, transport of ions between cells, etc.

A certain amount of moisture is essential for terrestrial organisms. Many of them need a relative humidity of 100% for normal life, and vice versa, an organism in a normal state cannot live for a long time in absolutely dry air, because it constantly loses water. Water is an essential part of living matter. Therefore, the loss of water in a certain amount leads to death.

Plants of a dry climate adapt to morphological changes, reduction of vegetative organs, especially leaves.

Land animals also adapt. Many of them drink water, others suck it up through the integument of the body in a liquid or vapor state. For example, most amphibians, some insects and mites. Most of the desert animals never drink; they satisfy their needs at the expense of water supplied with food. Other animals receive water in the process of fat oxidation.

Water is essential for living organisms. Therefore, organisms spread throughout the habitat depending on their needs: aquatic organisms live in water constantly; hydrophytes can only live in very humid environments.

From the point of view of ecological valence, hydrophytes and hygrophytes belong to the group of stenogigers. Humidity greatly affects the vital functions of organisms, for example, 70% relative humidity was very favorable for field maturation and fecundity of migratory locust females. With favorable reproduction, they cause enormous economic damage to the crops of many countries.

For an ecological assessment of the distribution of organisms, an indicator of the dryness of the climate is used. Dryness serves as a selective factor for the ecological classification of organisms.

Thus, depending on the characteristics of the humidity of the local climate, the species of organisms are distributed into ecological groups:

1. Hydatophytes are aquatic plants.

2. Hydrophytes are terrestrial-aquatic plants.

3. Hygrophytes - terrestrial plants living in conditions of high humidity.

4. Mesophytes are plants that grow with average moisture

5. Xerophytes are plants growing with insufficient moisture. They, in turn, are divided into: succulents - succulent plants (cacti); sclerophytes are plants with narrow and small leaves, and folded into tubules. They are also divided into euxerophytes and stipaxerophytes. Euxerophytes are steppe plants. Stipaxerophytes are a group of narrow-leaved turf grasses (feather grass, fescue, thin-legged, etc.). In turn, mesophytes are also divided into mesohygrophytes, mesoxerophytes, etc.

Yielding in its value to temperature, humidity is nevertheless one of the main environmental factors. For most of the history of wildlife, the organic world was represented exclusively by water norms of organisms. An integral part of the vast majority of living beings is water, and for the reproduction or fusion of gametes, almost all of them need an aquatic environment. Land animals are forced to create in their body an artificial aquatic environment for fertilization, and this leads to the fact that the latter becomes internal.

Humidity is the amount of water vapor in the air. It can be expressed in grams per cubic meter.

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