The adaptation of an organism to its environment is called adaptation. From the standpoint of ecology, it can be considered that the formation and existence, the diversity of organisms, their variability and conservation in nature are the result of environmental influences and adaptation. In nature, adaptations of organisms always develop under the influence of three main factors: variability, heredity and natural selection. The totality of adaptations gives the structure and life of organisms features of expediency. The adaptability of a species to any permanent environment is a prerequisite for its long-term stable existence.
The biological meaning of the adaptation process is to ensure that this individual survives under adverse conditions and left offspring. The means can be very different. For example, by the onset of winter cold, some animals grow a thick and warm fur coat, which also changes color, others form a thick subcutaneous layer of fat, while others, having fattened themselves over the summer, hibernate. Trees shed their leaves, their buds become covered with a thick layer of wax, and so on. These are various biological reactions in response to changes in environmental conditions, which are sometimes complex and long-term changes in the structure and functions of organisms, sometimes relatively simple and easily reversible reactions. For example, off the coast of Antarctica, the Trematotus fish acquired the ability to synthesize protein compounds in the blood. Acting as antifreeze, they prevent ice crystals from forming. All this allows the fish to survive at temperatures below -2 °C. Some types of insects also have some kind of antifreeze in their bodies. So, the larva of the Alaskan gall midge can freeze and thaw several times without any harm to itself.
The ability to adapt is one of the main properties of life on our planet. Adaptations provide the possibility of existence, survival and reproduction of organisms.
Bergmann's climate rule, formulated in 1847, states: within a species or a fairly homogeneous group of related species, animals with larger body sizes are common in colder areas of their range or in the mountains. This rule reflects the adaptation of animals to maintaining a constant body temperature in different climatic conditions. In the south, in a warm climate, small varieties of the same species are found. In the north live the most big bears, wolves, moose. So, polar bear The Arctic has a weight of up to 1000 kg, Brown bear from Alaska weighs about 700 kg, and the Malayan bear does not reach even up to 70 kg. The large king penguin of Antarctica has a height of up to 120 cm, and the equatorial Galapagos penguin is up to 40 cm.
It should be noted that, according to modern data, Bergman's rule is not as comprehensive as previously assumed. Perhaps the exceptions even prevail. However, despite this, the rule retains its value. An increase in body size in cold regions is characteristic to a certain extent even of invertebrates. Often the same dependence is found when comparing closely related species.
According to Allen's rule(1877) than colder conditions in the range, the shorter the limbs of warm-blooded animals and the shorter and more compact body. Many protruding parts of the body (limbs, tail, ears) become smaller and shorter, and the body becomes more massive than colder climate. This pattern can be traced when comparing species of hares in their habitats in the direction from Central America to North. Thus, a comparison of Allen's hares, the black-tailed (California) hare, the American hare and the polar hare demonstrates a gradual decrease in the length of the ears and limbs. The wings of birds become finer and sharper, the hair of mammals is longer, the undercoat is thicker. Finally, in northern birds, the migratory instinct is more pronounced, the size of the clutch increases and, accordingly, the number of chicks in the brood.
As an example of the manifestation of Allen's rule, we can cite the ratio of the length of the tail to the length of the body in the field vole (Microtus agrestis) from various regions of Europe: Portugal - 39%, Central Europe- 33%, Sweden - 29%.
In Hamburg, the shortest-tailed mice were grown in special refrigerators; the tails were also shortened in individuals who, under experimental conditions, were regularly given drugs that reduce body temperature. Mice that grew up in the warmth were long-tailed and long-eared.
Allen's rule is also confirmed in interspecific comparisons. So, in a Mexican hare, the length of the ears reaches 189% of the length of the head, while in the hare in Greenland - only 96%.
Birds on the islands have longer beaks than on the continents. Animals - inhabitants of hot places ( African elephant, American desert hare) have huge ears that serve them for heat dissipation.
To be fair, it should be noted that Allen's rule also has exceptions.
Gloger's rule(1833) explains the fact that animal species living in more humid and cooler climates have darker body pigmentation. So, the black raven living in the ice of Greenland has a blacker color than the one living in the deserts of the Sahara, where its plumage has acquired a brown tint. Southern birds tend to be brighter and more colorful.
Another climatic rule: in the direction from the poles to the equator, the freshwater fauna as a whole reveals more and more similarities with the marine one. What is the reason? It is known that in the tropics, marine fish penetrate rivers more easily than in middle latitudes. This is probably determined by the fact that under conditions of more favorable climate rather, the level of metabolism necessary for the transition of the body to fresh water can be reached. By the way, real freshwater forms do not live on oceanic islands at all.
Adaptations – various adaptations to the environment developed by organisms in the process of evolution. Adaptations appear in different levels organization of living matter: from molecular to biocenotic. The ability to adapt is one of the main properties of living matter, which ensures the possibility of its existence. Adaptations develop under the influence of three main factors: heredity, variability and natural (as well as artificial) selection.
There are three main ways that organisms adapt to environmental conditions: the active way, the passive way, and the avoidance of adverse effects.
active path – strengthening of resistance, development of regulatory processes that allow to carry out all the vital functions of the body, despite the deviation of the factor from the optimum. For example, maintaining a constant body temperature in warm-blooded animals (birds and mammals), which is optimal for the flow of biochemical processes in cells.
Avoidance of adverse effects – the body's production of life cycles and behaviors that avoid adverse effects. For example, seasonal migrations animals.
passive way – the subordination of the vital functions of the body to changes in environmental factors Rest can be different in depth and duration, many functions of the body are weakened or not performed at all, since the level of metabolism falls under the influence of external and internal factors. With a deep suppression of metabolism, organisms may not show visible signs of life at all. The complete temporary suspension of life is called suspended animation . In a state of anabiosis, organisms become resistant to various influences. In a dry state, when no more than 2% of water remained in the cells in a chemically bound form, such organisms as rotifers, tardigrades, small nematodes, seeds and spores of plants, spores of bacteria and fungi survived in liquid oxygen (-218.4 ° C ), liquid hydrogen (-259.4 °С), liquid helium (-269.0 °С). All metabolism is stopped. Anabiosis is a rather rare phenomenon and is an extreme state of rest in wildlife, the state of anabiosis is possible only with almost complete dehydration of organisms. Much more widespread in nature are other forms of dormancy associated with a state of reduced vital activity as a result of partial inhibition of metabolism. Forms of rest in a state of reduced vital activity are divided into hypobiosis (compelled rest) and cryptobiosis (physiological rest) . At hypobiosis inhibition of activity, or torpor, occurs under the direct pressure of unfavorable conditions (with a lack of heat, water, oxygen, etc.) and stops almost immediately after these conditions return to normal (some frost-resistant species of arthropods (springtails, a number of flies, ground beetles, etc.) hibernate in a state of stupor, quickly thawing and turning to activity under the rays of the sun, and then again lose mobility when the temperature drops). Cryptobiosis- a fundamentally different type of rest, it is associated with a complex of physiological changes that occur in advance, before the onset of adverse seasonal changes, and organisms are ready for them. Cryptobiosis is widespread in wildlife (typical, for example, for plant seeds, cysts and spores of various microorganisms, fungi, algae, hibernation of mammals, deep dormancy of plants). The states of hypobiosis, cryptobiosis and anabiosis ensure the survival of species in natural conditions of different latitudes, often extreme ones, allow organisms to survive for long unfavorable periods, settle in space and in many ways push the boundaries of the possibility and spread of life in general.
Usually, the adaptation of a species to the environment is carried out by one or another combination of all three possible ways of adaptation.
The main mechanisms of adaptation at the level of the organism:
Biochemical adaptations - changes in intracellular processes (for example, a change in the work of enzymes or a change in their number).
Morpho-anatomical adaptations – changes in the structure of the organism (for example, the modification of a leaf into a thorn in cacti to reduce water loss, the bright color of flowers to attract pollinators, etc.). Morphological adaptations in plants and animals lead to the formation of certain life forms.
Physiological adaptations - changes in the physiology of the body (for example, the ability of a camel to provide the body with moisture by oxidizing fat reserves, the presence of cellulose-degrading enzymes in cellulose-destroying bacteria, etc.).
Ethological (behavioral) adaptations – behavioral changes (e.g. seasonal migrations of mammals and birds, hibernation during winter period, mating games in birds and mammals during the breeding season, etc.). Ethological adaptations are characteristic of animals.
Adaptation of a person to a new environment for him is a complex socio-biological process, which is based on a change in the systems and functions of the body, as well as habitual behavior. Human adaptation refers to the adaptive reactions of his body to changing environmental factors. Adaptation manifests itself at different levels of organization of living matter: from molecular to biocenotic. Adaptation develops under the influence of three factors: heredity, variability, natural / artificial selection. There are three main ways that organisms adapt to their environment: the active way, the passive way, and the avoidance of adverse effects.
active path- strengthening of resistance, development of regulatory processes that allow to carry out all the vital functions of the body, despite the deviation of the environmental factor from the optimum. For example, maintaining a constant body temperature in warm-blooded animals (birds, humans), optimal for the flow of biochemical processes in cells.
passive way- subordination of the vital functions of the organism to changes in environmental factors. For example, under unfavorable environmental conditions, transition to a state of anabiosis ( hidden life), when the metabolism in the body almost completely stops (winter dormancy of plants, preservation of seeds and spores in the soil, stupor of insects, hibernation, etc.).
Avoidance of adverse conditions- development by the body of such life cycles and behaviors that allow avoiding adverse effects. For example, seasonal migrations of animals.
Usually, the adaptation of a species to the environment takes place by one or another combination of all three possible ways of adaptation.
Adaptations can be divided into three main types: morphological, physiological, ethological.
Morphological adaptations- changes in the structure of the organism (for example, the modification of a leaf into a thorn in cacti to reduce water loss, bright colors of flowers to attract pollinators, etc.). Morphological adaptations in animals lead to the formation of certain life forms.
Physiological adaptations- changes in the physiology of the body (for example, the ability of a camel to provide the body with moisture by oxidizing fat reserves, the presence of cellulose-degrading enzymes in cellulose-destroying bacteria, etc.).
Ethological (behavioral) adaptations- changes in behavior (for example, seasonal migrations of mammals and birds, hibernation in winter, mating games in birds and mammals during the breeding season, etc.). Ethological adaptations are characteristic of animals.
Living organisms are well adapted to periodic factors. Non-periodic factors can cause disease and even death of a living organism. A person uses this by applying antibiotics and other non-periodic factors. However, the duration of their exposure can also cause adaptation to them.
The environment has a huge impact on a person. In this regard, the problem of adapting a person to his environment is becoming increasingly important. In social ecology, this problem is of paramount importance. At the same time, adaptation is First stage, which is dominated by reactive forms of human behavior. The person does not stop at this stage. He shows physical, intellectual, moral, spiritual activity, transforms (for worse or worse) his environment.
Human adaptation is divided into genotypic and phenotypic. Genotypic adaptation: a person outside of his consciousness can adapt to changing environmental conditions (temperature changes, food taste, etc.), that is, if the adaptation mechanisms are already in the genes. Phenotypic adaptation is understood as the inclusion of consciousness, one's personal qualities of a person in order to adapt the body to a new environment, to maintain balance in new conditions.
The main types of adaptation include physiological, adaptation to activity, adaptation to society. Let's focus on physiological adaptation. Under the physiological adaptation of a person is understood the process of maintaining the functional state of the body as a whole, ensuring its preservation, development, performance, maximum life expectancy. Great importance in physiological adaptation attached to acclimation and acclimatization. It is clear that a person's life in the Far North differs from his life at the equator, since these are different climatic zones. Moreover, a southerner, having lived for a certain time in the north, adapts to it and can live there permanently and vice versa. Acclimation is the initial, urgent stage of acclimatization under changing climatic and geographical conditions. In some cases, a synonym for physiological adaptation is acclimatization, that is, the adaptation of plants, animals and humans to new climatic conditions for them. Physiological acclimatization occurs when a person, with the help of adaptive reactions, increases working capacity, improves well-being, which can deteriorate sharply during the period of acclimation. When new conditions are replaced by old ones, the body can return to its previous state. Such changes are called acclimatization. The same changes that, in the process of adapting to a new environment, have passed into the genotype and are inherited, are called adaptive.
Adaptation of the body to living conditions (city, village, other locality). not limited to climatic conditions. A person can live in the city and in the countryside. Many people prefer the metropolis with its noise, pollution, frantic pace of life. Objectively live in a village where fresh air, calm measured rhythm, more favorable to people.
The same area of adaptation includes moving, for example, to another country. Some quickly adapt, overcome the language barrier, find a job, others with great difficulty, others, having adapted outwardly, experience a feeling called nostalgia.
We can highlight the adaptation to the activity. Different kinds human activities impose different requirements on the individual (some require perseverance, diligence, punctuality, others require speed of reaction, the ability to make decisions independently, etc.). However, a person can cope with these and other types of activity quite successfully. There is an activity that is contraindicated for a person, but he can perform it, as adaptation mechanisms work, which is called the development of an individual style of activity.
Particular attention should be paid to adaptation to society, other people, and the team. A person can adapt to a group by assimilating its norms, rules of behavior, values, etc. The mechanisms of adaptation here are suggestibility, tolerance, conformity as forms of submissive behavior, and on the other hand, the ability to find one’s place, find a face, and show determination.
We can talk about adaptation to spiritual values, to things, to states, for example, to stressful ones, and to many other things. In 1936, the Canadian physiologist Selye published the message "Syndrome caused by various damaging elements", in which he described the phenomenon of stress - a general non-specific reaction of the body aimed at mobilizing its defenses under the influence of irritating factors. In the development of stress, 3 stages were distinguished: 1. stage of anxiety, 2. stage of resistance, 3. stage of exhaustion. G. Selye formulated the theory of the General Adaptation Syndrome (GAS) and adaptive diseases as a consequence of the adaptive reaction, according to which GAS manifests itself whenever a person feels danger to himself. The visible causes of stress can be injuries, postoperative conditions, etc., changes in abiotic and biotic environmental factors. In recent decades, the number of anthropogenic environmental factors with a high stress effect has significantly increased (chemical pollution, radiation, exposure to computers during systematic work with them, etc.). The stress factors of the environment should also include negative changes in modern society: increase, change in the ratio of urban and rural population, rising unemployment, crime.
The grandiose inventions of the human mind never cease to amaze, there is no limit to fantasy. But what nature has been creating for many centuries surpasses the most creative ideas and designs. Nature has created more than one and a half million species of living individuals, each of which is individual and unique in its forms, physiology, adaptability to life. Examples of organisms adapting to constantly changing living conditions on the planet are examples of the wisdom of the creator and a constant source of problems for biologists to solve.
Adaptation means adaptability or habituation. This is a process of gradual rebirth of the physiological, morphological or psychological functions of a creature in a changed environment. Both individual individuals and entire populations undergo changes.
A striking example of direct and indirect adaptation is the survival of flora and fauna in the zone of increased radiation around Chernobyl nuclear power plant. Direct adaptability is characteristic of those individuals who managed to survive, get used to it and begin to reproduce, some did not stand the test and died (indirect adaptation).
Since the conditions of existence on Earth are constantly changing, the processes of evolution and fitness in living nature are also a continuous process.
A recent example of adaptation is changing the habitat of a colony of green Mexican arating parrots. FROM recently they changed their habitual habitat and settled in the very mouth of the Masaya volcano, in an environment constantly saturated with high concentration sulfuric gas. Scientists have not yet given an explanation for this phenomenon.
A change in the whole form of an organism's existence is a functional adaptation. An example of adaptation, when changing conditions lead to mutual adaptation of living organisms to each other, is a correlative adaptation or co-adaptation.
Adaptation can be passive, when the functions or structure of the subject occur without his participation, or active, when he consciously changes his habits to match the environment (examples of people adapting to natural conditions or society). There are cases when the subject adapts the environment to his needs - this is an objective adaptation.
Biologists divide the types of adaptation according to three criteria:
Examples of adaptation of animals or plants in their pure form are rare, most cases of adaptation to new conditions occur in mixed forms.
Morphological changes are changes in the shape of the body, individual organs or the entire structure of a living organism that have occurred in the process of evolution.
The following are morphological adaptations, examples from the animal and flora, which we take for granted:
Physiological adaptation is a change in a number of chemical processes occurring inside the body.
Examples of human adaptation are more associated with the psychological factor. Behavioral characteristics are characteristic of flora and fauna. So, in the process of evolution, a change in the temperature regime causes some animals to hibernate, birds fly south to return in the spring, trees shed their leaves and slow down the movement of juices. The instinct to choose the most suitable partner for procreation drives the behavior of animals during the mating season. Some northern frogs and turtles freeze completely for the winter and thaw, reviving with the onset of heat.
Any adaptation processes are a response to environmental factors that lead to a change in the environment. Such factors are divided into biotic, abiotic and anthropogenic.
Biotic factors are the influence of living organisms on each other, when, for example, one species disappears, which serves as food for another.
Abiotic factors are changes in the environment inanimate nature when the climate changes, soil composition, water supply, cycles of solar activity. Physiological adaptations, examples of the influence of abiotic factors - equatorial fish that can breathe both in water and on land. They are well adapted to the conditions when the drying up of rivers is a frequent occurrence.
Anthropogenic factors - the influence of human activity that changes the environment.
Opposite examples of adaptation to abnormal temperatures are described below.
Arctic fish do not freeze due to the production of a unique anti-freeze protein in the blood, which prevents the blood from freezing.
The simplest microorganisms are found in hydrothermal springs, the water temperature in which exceeds the boiling point.
Hydrophyte plants, that is, those that live in or near water, die even with a slight loss of moisture. Xerophytes, on the contrary, are adapted to live in arid regions, and die in high humidity. Among animals, nature has also worked on adapting to aquatic and non-aquatic environments.
Man's ability to adapt is truly enormous. The secrets of human thinking are far from being fully revealed, and the secrets of the adaptive ability of people will remain a mysterious topic for scientists for a long time to come. The superiority of Homo sapiens over other living beings is in the ability to consciously change their behavior to the requirements of the environment or, conversely, the world according to your needs.
The flexibility of human behavior is manifested daily. If you give the task: "give examples of people's adaptation", the majority begins to recall exceptional cases of survival in this rare cases, and in new circumstances is characteristic of a person every day. We try on a new environment at the moment of birth, in kindergarten, school, in a team, when moving to another country. It is this state of accepting new sensations by the body that is called stress. Stress is a psychological factor, but nevertheless, many physiological functions change under its influence. In the case when a person accepts a new environment as positive for himself, the new state becomes habitual, otherwise stress threatens to become protracted and lead to a number of serious diseases.
There are three types of human adaptation:
All adaptive types are closely related to each other, as a rule, any change in habitual existence causes a need in a person for social and psychological adaptation. Under their influence, the mechanisms of physiological changes come into action, which also adapt to new conditions.
Such a mobilization of all body reactions is called an adaptation syndrome. New body reactions appear in response to sudden changes in the environment. At the first stage - anxiety - there is a change in physiological functions, changes in the work of metabolism and systems. Next connect protective functions and organs (including the brain) begin to turn on their protective functions and hidden capabilities. The third stage of adaptation depends on individual characteristics: a person is either included in new life and enters the usual course (in medicine, recovery occurs during this period), or the body does not take stress, and the consequences are already taking a negative form.
In man, nature has a huge margin of safety, which is used in Everyday life only to a small extent. It appears in extreme situations and is seen as a miracle. In fact, the miracle is inherent in ourselves. An example of adaptation: the ability of people to adapt to a normal life after the removal of a significant part of the internal organs.
Natural innate immunity throughout life can be strengthened by a number of factors or, conversely, weakened by an incorrect lifestyle. Unfortunately, passion bad habits This is also the difference between humans and other living organisms.
Adaptations are various adaptations to the environment developed by organisms in the process of evolution. .
There are three main ways that organisms adapt to environmental conditions: the active way, the passive way, and the avoidance of adverse effects.
Active path - strengthening of resistance, development of regulatory processes that allow to carry out all the vital functions of the body, despite the deviation of the factor from the optimum. For example, maintaining a constant body temperature in warm-blooded animals (birds and mammals), which is optimal for the flow of biochemical processes in cells.
The passive path is the subordination of the vital functions of the body to changes in environmental factors. For example, the transition under adverse environmental conditions to a state of anabiosis (hidden life), when the metabolism in the body almost completely stops (winter dormancy of plants, preservation of seeds and spores in the soil, stupor of insects, hibernation of vertebrates).
Avoidance of adverse effects is the development by the body of such life cycles and behaviors that allow avoiding adverse effects. For example, seasonal migrations of animals.
Adaptations can be divided into three main types: morphological, physiological and ethological.
Morphological adaptations - changes in the structure of the body (for example, the modification of a leaf into a thorn in cacti to reduce water loss, the bright color of flowers to attract pollinators). Morphological adaptations in plants and animals lead to the formation of certain life forms.
Physiological adaptations - changes in the physiology of the body (for example, the ability of a camel to provide the body with moisture by oxidizing fat reserves, the presence of cellulose-degrading enzymes in cellulose-degrading bacteria).
Ethological (behavioral) adaptations - changes in behavior (for example, seasonal migrations of mammals and birds, hibernation in winter, mating games in birds and mammals during the breeding season).
15. The aquatic environment of life and its characteristics. Classification of hydrobionts
Hydrobionts - (from the Greek hydor - water and bios - life) organisms that live in the aquatic environment.
Diversity of hydrobionts
Pelagic organisms (plants or animals that live in the water column or on the surface)
Neuston - a set of microorganisms living near the surface film of water on the border of aquatic and air environments.
Pleuston - plant or animal organisms that live on the surface of the water, or semi-submerged in water.
Rheophylls are animals that have adapted to living in flowing waters.
Nekton - a set of aquatic actively swimming organisms that can resist the force of the current.
Plankton are heterogeneous, mostly small organisms, freely drifting in the water column and unable to resist the flow.
Benthos (a set of organisms that live on the ground and in the soil of the bottom of water bodies)
The hydrosphere as an aquatic environment of life occupies about 71% of the area and 1/800 of the volume of the globe. The main amount of water, more than 94%, is concentrated in the seas and oceans. AT fresh waters rivers, lakes, the amount of water does not exceed 0.016% of the total volume of fresh water.
In the ocean with its constituent seas, two ecological regions are primarily distinguished: the water column - the pelagial and the bottom - the benthal. Depending on the depth, the benthal is divided into the sublittoral zone - the area of a smooth decrease in land to a depth of 200 m, the bathyal - the region of a steep slope and the abyssal zone - the ocean floor with an average depth of 3-6 km. The deeper benthal regions corresponding to the depressions of the oceanic bed (6-10 km) are called the ultra-abyssal. The edge of the coast, flooded during high tides, is called the littoral. The part of the coast above the level of the tides, moistened by the splashes of the surf, is called the superlittoral.
The open waters of the oceans are also divided into vertical zones corresponding to the benthal zones: epipeligial, bathypeligial, abyssopegial.
Approximately 150,000 animal species, or about 7% of their total number, and 10,000 plant species (8%) live in the aquatic environment.
Specific gravity rivers, lakes and swamps, as noted earlier, compared with the seas and oceans is negligible. However, they create a supply of fresh water necessary for plants, animals and humans.
characteristic feature of the aquatic environment is its mobility, especially in flowing, fast-flowing streams and rivers. In the seas and oceans, ebbs and flows, powerful currents, and storms are observed. In lakes, water moves under the influence of temperature and wind.
16. Ground-air environment of life, its characteristics and forms of adaptation to it
Life on land required such adaptations that were possible only in highly organized living organisms. The ground-air environment is more difficult for life, it is characterized by a high oxygen content, a small amount of water vapor, low density, etc. This greatly changed the conditions of respiration, water exchange and movement of living beings.
The low air density determines its low lifting force and insignificant bearing capacity. Organisms in the air must have their own support system supporting the body: plants - a variety of mechanical tissues, animals - a solid or hydrostatic skeleton. In addition, all the inhabitants of the air environment are closely connected with the surface of the earth, which serves them for attachment and support.
Low air density provides low movement resistance. Therefore, many land animals have acquired the ability to fly. 75% of all terrestrial creatures, mainly insects and birds, have adapted to active flight.
Due to air mobility, vertical and horizontal flows existing in the lower layers of the atmosphere air masses passive flight of organisms is possible. In this regard, many species have developed anemochory - resettlement with the help of air currents. Anemochory is characteristic of spores, seeds and fruits of plants, protozoan cysts, small insects, spiders, etc. Organisms passively transported by air currents are collectively called aeroplankton.
Terrestrial organisms exist in relatively low pressure due to low air density. Normally it is equal to 760 mm mercury column. As altitude increases, pressure decreases. Low pressure may limit the distribution of species in the mountains. For vertebrates, the upper limit of life is about 60 mm. A decrease in pressure entails a decrease in oxygen supply and dehydration of animals due to an increase in the respiratory rate. Approximately the same limits of advance in the mountains have higher plants. Somewhat more hardy are the arthropods that can be found on glaciers above the vegetation line.
Gas composition of air. Except physical properties of the air environment, its chemical properties are very important for the existence of terrestrial organisms. The gas composition of the air in surface layer atmosphere is quite homogeneous in terms of the content of the main components (nitrogen - 78.1%, oxygen - 21.0%, argon - 0.9%, carbon dioxide - 0.003% by volume).
The high oxygen content contributed to an increase in the metabolism of terrestrial organisms compared to primary aquatic ones. It was in the terrestrial environment, on the basis of the high efficiency of oxidative processes in the body, that animal homeothermia arose. Oxygen, due to its constant high content in the air, is not a limiting factor for life in the terrestrial environment.
Content carbon dioxide can vary in certain areas of the surface air layer within fairly significant limits. Increased air saturation with CO? occurs in areas volcanic activity, near thermal springs and other underground outlets of this gas. In high concentrations, carbon dioxide is toxic. In nature, such concentrations are rare. Low CO2 content slows down the process of photosynthesis. Under indoor conditions, you can increase the rate of photosynthesis by increasing the concentration of carbon dioxide. This is used in the practice of greenhouses and greenhouses.
Air nitrogen for most inhabitants of the terrestrial environment is an inert gas, but individual microorganisms (nodule bacteria, nitrogen bacteria, blue-green algae, etc.) have the ability to bind it and involve it in the biological cycle of substances.
Moisture deficiency is one of the essential features of the ground-air environment of life. The whole evolution of terrestrial organisms was under the sign of adaptation to the extraction and conservation of moisture. The modes of environmental humidity on land are very diverse - from the complete and constant saturation of air with water vapor in some areas of the tropics to their almost complete absence in the dry air of deserts. Also significant is the daily and seasonal variability water vapor content in the atmosphere. The water supply of terrestrial organisms also depends on the mode of precipitation, the presence of reservoirs, soil moisture reserves, the proximity of groundwater, and so on.
This led to the development of adaptations in terrestrial organisms to various water supply regimes.
Temperature regime. next hallmark air-ground environment are significant temperature fluctuations. In most land areas, daily and annual temperature amplitudes are tens of degrees. The resistance to temperature changes in the environment of terrestrial inhabitants is very different, depending on the particular habitat in which they live. However, in general, terrestrial organisms are much more eurythermic than aquatic organisms.
The conditions of life in the ground-air environment are complicated, in addition, by the existence of weather changes. Weather - continuously changing states of the atmosphere near the borrowed surface, up to a height of about 20 km (troposphere boundary). Weather variability is manifested in the constant variation of the combination of such environmental factors as temperature, air humidity, cloudiness, precipitation, wind strength and direction, etc. The long-term weather regime characterizes the climate of the area. The concept of "Climate" includes not only average values meteorological phenomena, but also their annual and daily course, deviation from it and their recurrence. The climate is determined by the geographical conditions of the area. Main climatic factors- temperature and humidity - measured by the amount of precipitation and saturation of the air with water vapor.
For most terrestrial organisms, especially small ones, the climate of the area is not so much important as the conditions of their immediate habitat. Very often, local elements of the environment (relief, exposure, vegetation, etc.) change the regime of temperatures, humidity, light, air movement in a particular area in such a way that it differs significantly from the climatic conditions of the area. Such modifications of the climate, which take shape in the surface layer of air, are called the microclimate. In each zone, the microclimate is very diverse. Microclimates of very small areas can be distinguished.
The light regime of the ground-air environment also has some features. The intensity and amount of light here are the greatest and practically do not limit the life of green plants, as in water or soil. On land, the existence of extremely photophilous species is possible. For the vast majority of terrestrial animals with diurnal and even nocturnal activity, vision is one of the main ways of orientation. Land animals have vision importance to search for prey, many species even have color vision. In this regard, the victims develop such adaptive features as a defensive reaction, masking and warning coloration, mimicry, etc. At aquatic life such adaptations are much less developed. The emergence of brightly colored flowers of higher plants is also associated with the peculiarities of the apparatus of pollinators and, ultimately, with the light regime of the environment.
The relief of the terrain and the properties of the soil are also the conditions for the life of terrestrial organisms and, first of all, plants. Properties earth's surface that have an ecological impact on its inhabitants are united by "edaphic environmental factors" (from the Greek "edafos" - "soil").
In relation to different properties of soils, a number of environmental groups plants. So, according to the reaction to the acidity of the soil, they distinguish:
acidophilic species - grow on acidic soils with a pH of at least 6.7 (plants of sphagnum bogs);
neutrophilic - tend to grow on soils with a pH of 6.7-7.0 (most cultivated plants);
basiphilic - grow at a pH of more than 7.0 (mordovnik, forest anemone);
indifferent - can grow on soils with different pH values (lily of the valley).
Plants also differ in relation to soil moisture. Certain species are confined to different substrates, for example, petrophytes grow on stony soils, and pasmophytes inhabit free-flowing sands.
The terrain and the nature of the soil affect the specifics of the movement of animals: for example, ungulates, ostriches, bustards living in open spaces, hard ground, to enhance repulsion when running. In lizards that live in loose sands, the fingers are fringed with horny scales that increase support. For terrestrial inhabitants digging holes, dense soil is unfavorable. The nature of the soil in certain cases affects the distribution of terrestrial animals that dig holes or burrow into the ground, or lay eggs in the soil, etc.
17. Soil as a living environment. Classification of soil animals, form of adaptation
The soil is a surface layer of land, consisting of a mixture of minerals obtained from the decay rocks, and organic matter resulting from the decomposition of plant and animal remains by microorganisms. They live in the surface layers of the soil various organisms destroyers of the remains of dead organisms (fungi, bacteria, worms, small arthropods, etc.). The vigorous activity of these organisms contributes to the formation of a fertile soil layer suitable for the existence of many living beings. The soil is characterized by high density, slight temperature fluctuations, moderate moisture, insufficient oxygen content and high concentration of carbon dioxide. Its porous structure allows the penetration of gases and water, which creates favorable conditions for soil organisms such as algae, fungi, protozoa, bacteria, arthropods, mollusks and other invertebrates.
