Extreme sports in the animal world. Extreme sportsmen in the animal world Most often use seven general criteria for the species

Extremophiles are organisms that live and thrive in habitats where life is impossible for most other organisms. The suffix (-phil) in Greek means love. Extremophiles “love” to live in extreme conditions. They have the ability to withstand conditions such as high radiation, high or low pressure, high or low pH, lack of light, extreme heat or cold, and extreme drought.

Most extremophiles are microorganisms such as, and. Larger organisms such as worms, frogs, and insects can also live in extreme habitats. There are different classes of extremophiles based on the type of environment in which they thrive. Here are some of them:

• Acidophilus is an organism that thrives in an acidic environment with pH levels of 3 and below.
• Alkaliphile is an organism that thrives in alkaline environments with pH levels of 9 and above.
• Barophil is an organism that lives in high pressure environments such as deep sea habitats.
• A halophile is an organism that lives in habitats with extremely high salt concentrations.
• A hyperthermophile is an organism that thrives in environments with extremely high temperatures (80° to 122° C).
• Psychrophile/cryophile - an organism that lives in extremely cold conditions and low temperatures (from -20° to +10° C).
• Radioresistant organisms are organisms that thrive in environments with high levels of radiation, including ultraviolet and nuclear radiation.
• A xerophile is an organism that lives in extremely dry conditions.

Tardigrades

Tardigrades, or water bears, can tolerate several types of extreme conditions. They live in hot springs Antarctic ice, as well as in deep environments, on mountain tops and even in. Tardigrades are commonly found in lichens and mosses. They feed on plant cells and tiny invertebrates such as nematodes and rotifers. Aquatic bears reproduce, although some reproduce through parthenogenesis.

Tardigrades can survive in a variety of extreme conditions because they are able to temporarily shut down their metabolism when conditions are not suitable for survival. This process is called cryptobiosis and allows aquatic bears to enter a state that allows them to survive in conditions of extreme aridity, lack of oxygen, extreme cold, low pressure and high toxicity or radiation. Tardigrades can remain in this state for several years and exit it when the environment becomes habitable.

Artemia ( Artemia salina)

Artemia is a species of small crustacean that can live in conditions with extremely high salt concentrations. These extremophiles live in salt lakes, salt marshes, seas and rocky shores. Their main food source is green algae. Artemia have gills that help them survive in salty environments by absorbing and releasing ions and producing concentrated urine. Like tardigrades, brine shrimp reproduce sexually and asexually (via parthenogenesis).

Helicobacter pylori bacteria ( Helicobacter pylori)

Helicobacter pylori- a bacterium that lives in the extremely acidic environment of the stomach. These bacteria secrete the enzyme urease, which neutralizes hydrochloric acid. It is known that other bacteria are not able to withstand the acidity of the stomach. Helicobacter pylori are spiral-shaped bacteria that can burrow into the stomach wall and cause ulcers or even stomach cancer in humans. Most people in the world have this bacteria in their stomachs, but they typically rarely cause illness, according to the Centers for Disease Control and Prevention (CDC).

Cyanobacteria Gloeocapsa

Gloeocapsa- a genus of cyanobacteria that usually live on wet rocks of rocky shores. These bacteria contain chlorophyll and are capable of... Cells Gloeocapsa surrounded by gelatinous membranes that can be brightly colored or colorless. Scientists have discovered that they are able to survive in space for a year and a half. Samples rocks containing Gloeocapsa, were placed outside the International space station, and these microorganisms were able to withstand the extreme conditions of space, such as temperature fluctuations, vacuum exposure and radiation exposure.

In boiling water at a temperature of 100°C, all forms of living organisms die, including bacteria and microbes, which are known for their persistence and vitality - this is a fact widely known and generally accepted. But it turns out to be wrong!

In the late 1970s, with the advent of the first deep-sea vehicles, hydrothermal vents, from which streams of extremely hot, highly mineralized water continuously flowed. The temperature of such streams reaches an incredible 200-400°C. At first, no one could have imagined that life could exist at a depth of several thousand meters from the surface, in eternal darkness, and even at such a temperature. But she existed there. Moreover, not primitive single-celled life, but entire independent ecosystems consisting of previously unknown known to science species.

A hydrothermal vent found at the bottom of the Cayman Trench at a depth of about 5,000 meters. Such springs are called black smokers due to the eruption of black, smoke-like water.

The basis of ecosystems living near hydrothermal vents are chemosynthetic bacteria - microorganisms that obtain the necessary nutrients by oxidizing various chemical elements; in a particular case by oxidation of carbon dioxide. All other representatives of thermal ecosystems, including filter-feeding crabs, shrimp, various mollusks and even huge marine worms, depend on these bacteria.

This black smoker is completely enveloped in white sea anemones. Conditions that mean death for others marine organisms, are the norm for these creatures. White anemones obtain their nutrition by ingesting chemosynthetic bacteria.

Organisms that live in black smokers"are completely dependent on local conditions and are not able to survive in the habitat familiar to the vast majority of marine life. For this reason for a long time It was not possible to raise a single creature to the surface alive; they all died when the water temperature dropped.

Pompeian worm (lat. Alvinella pompejana) - this inhabitant of underwater hydrothermal ecosystems received a rather symbolic name.

Raise first living creature succeeded underwater unmanned aerial vehicle ISIS is run by British oceanographers. Scientists have found that temperatures below 70°C are deadly for these amazing creatures. This is quite remarkable, since a temperature of 70°C is lethal for 99% of organisms living on Earth.

The discovery of underwater thermal ecosystems was extremely important for science. First, the limits within which life can exist have been expanded. Secondly, the discovery led scientists to a new version of the origin of life on Earth, according to which life originated in hydrothermal vents. And thirdly, this discovery in once again made us understand that we know negligibly little about the world around us.

Some organisms have a special advantage that allows them to withstand the most extreme conditions where others simply cannot cope. Such abilities include resistance to enormous pressure, extreme temperatures, and others. These ten creatures from our list will give odds to anyone who dares to claim the title of the most resilient organism.

10. Himalayan jumping spider

The Asian wild goose is famous for flying at altitudes of over 6.5 kilometers, while the highest human settlement is at 5,100 meters in the Peruvian Andes. However, the high-altitude record does not belong to geese, but to the Himalayan jumping spider (Euophrys omnisuperstes). Living at an altitude of over 6,700 meters, this spider feeds mainly on small insects carried there by gusts of wind. The key feature of this insect is the ability to survive in almost complete absence oxygen.

9. Giant Kangaroo Jumper


Usually, when we think about the animals that can survive the longest without water, the camel immediately comes to mind. But camels can survive without water in the desert for only 15 days. Meanwhile, you will be surprised to learn that there is an animal in the world that can live its entire life without drinking a drop of water. The giant kangaroo hopper is a close relative of beavers. Their average lifespan is usually between 3 and 5 years. They usually obtain moisture from food, eating various seeds. In addition, these rodents do not sweat, thereby avoiding additional water loss. These animals usually live in Death Valley, and are currently endangered.

8. Heat-tolerant worms


Since heat in water is more efficiently transferred to organisms, a water temperature of 50 degrees Celsius will be much more dangerous than the same air temperature. For this reason, predominantly bacteria thrive in underwater hot springs, which cannot be said about multicellular life forms. However, there is special kind worms called paralvinella sulfincola, which happily make their home in areas where the water reaches temperatures of 45-55 degrees. Scientists conducted an experiment where one of the walls of the aquarium was heated, as a result it turned out that the worms preferred to stay in this particular place, ignoring cooler places. It is believed that this feature was developed by the worms so that they could feast on the bacteria found in abundance in hot springs. Because they didn't have it before natural enemies, bacteria were relatively easy prey.

7. Greenland shark


The Greenland shark is one of the largest and least studied sharks on the planet. Despite the fact that they swim quite slowly (any amateur swimmer can overtake them), they are extremely rarely seen. This is due to the fact that this type of shark usually lives at a depth of 1200 meters. In addition, this shark is one of the most resistant to cold. She usually prefers to stay in water whose temperature ranges between 1 and 12 degrees Celsius. Because these sharks live in cold waters, they have to move extremely slowly to minimize their energy expenditure. They are indiscriminate in food and eat everything that comes their way. There are rumors that their lifespan is about 200 years, but no one has yet been able to confirm or deny it.

6. Devil's Worm


For many decades, scientists believed that only single-celled organisms could survive at great depths. In their opinion, high blood pressure, lack of oxygen and extreme temperatures stood in the way of multicellular creatures. But then microscopic worms were discovered at a depth of several kilometers. Named halicephalobus mephisto, after a demon from German folklore, it was discovered in water samples 2.2 kilometers below the surface of a cave in South Africa. They managed to survive extreme conditions environment, which made it possible to assume that life is possible on Mars and on other planets in our galaxy.

5. Frogs

Some species of frogs are widely known for their ability to literally freeze completely. winter period and come to life with the arrival of spring. IN North America Five species of such frogs have been found, the most common of which is the common tree frog. Since tree frogs are not very strong burrowers, they simply hide under fallen leaves. They have a substance like antifreeze in their veins, and although their hearts eventually stop, it is temporary. The basis of their survival technique is the huge concentration of glucose entering the blood from the frog's liver. What is even more surprising is the fact that frogs are able to demonstrate their ability to freeze not only in natural environment, but also in laboratory conditions, allowing scientists to reveal their secrets.

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4. Deep Sea Microbes


We all know that the deepest point in the world is the Mariana Trench. Its depth reaches almost 11 kilometers, and the pressure there exceeds atmospheric pressure 1100 times. Several years ago, scientists managed to discover giant amoebas there, which they managed to photograph using a camera with high resolution and protected by a glass sphere from the enormous pressure that reigns at the bottom. Moreover, a recent expedition sent by James Cameron himself showed that in the depths Mariana Trench There may be other forms of life. Samples of bottom sediments were obtained, which proved that the depression was literally teeming with microbes. This fact amazed scientists, because the extreme conditions prevailing there, as well as the enormous pressure, are far from a paradise.

3. Bdelloidea


Rotifers of the species Bdelloidea are incredibly tiny female invertebrates, usually found in fresh water. Since their discovery, no males of the species have been found, and rotifers themselves reproduce asexually, which in turn destroys their own DNA. They restore their native DNA by eating other types of microorganisms. Thanks to this ability, rotifers can withstand extreme dehydration, in fact, they are able to withstand levels of radiation that would kill most living organisms on our planet. Scientists believe that their ability to repair their DNA came about as a result of their need to survive in extremely arid environments.

2. Cockroach


There is a myth that cockroaches will be the only living organisms that will survive a nuclear war. In fact, these insects can live without water and food for several weeks, and what's more, they can live for weeks without a head. Cockroaches have been around for 300 million years, outliving even the dinosaurs. The Discovery Channel conducted a series of experiments that were supposed to show whether cockroaches would survive or not under powerful nuclear radiation. As a result, it turned out that almost half of all insects were able to survive radiation of 1000 rads (such radiation can kill an adult healthy person in just 10 minutes of exposure), moreover, 10% of cockroaches survived exposure to radiation of 10,000 rads, which is equal to radiation at nuclear explosion in Hiroshima. Unfortunately, none of these small insects survived the 100,000 rad radiation dose.

1. Tardigrades


Tiny aquatic organisms called tardigrades have proven to be the hardiest organisms on our planet. These seemingly cute animals are able to survive almost any extreme conditions, be it heat or cold, enormous pressure or high radiation. They are able to survive for some time even in space. In extreme conditions and in a state of extreme dehydration, these creatures are able to remain alive for several decades. They come to life as soon as you place them in a pond.

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, which depend mainly on temperature. Range, i.e. The temperature limits in which life can exist range from approximately -200°C to +100°C, and bacteria have sometimes been found to exist in hot springs at temperatures of 250°C. In reality, most organisms can survive in an even narrower range of temperatures.

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

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

According to the tolerance of organisms to temperature conditions they are divided into eurythermic and stenothermic, i.e. able to tolerate temperature fluctuations within wide or narrow limits. For example, lichens and many bacteria can live in 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 varies depending on the ambient temperature. They are called poikilothermic. Depending on the method of adaptation of organisms to temperature conditions, they are divided into two environmental groups: cryophylls are organisms adapted to cold and low temperatures; thermophiles - or heat-loving.

Allen's rule- an ecogeographical rule established by D. Allen in 1877. According to this rule, among related forms of homeothermic (warm-blooded) animals leading a similar lifestyle, those that live in colder climates have relatively smaller protruding body parts: ears, legs, tails, etc.

Reducing the protruding parts of the body leads to a decrease in the relative surface of the body and helps to save heat.

An example of this rule are representatives of the Canine family from various regions. The smallest (relative to body length) ears and less elongated muzzle in this family are found in the Arctic fox (area: Arctic), and the largest ears and narrow, elongated muzzle are found in the fennec fox (area: Sahara).

This rule also applies to human populations: the shortest (relative to body size) nose, arms and legs are characteristic of the Eskimo-Aleut peoples (Eskimos, Inuit), and long arms and legs for furs and tootsies.

Bergman's rule- an ecogeographical rule formulated in 1847 by the German biologist Karl Bergmann. The rule states that among similar forms of homeothermic (warm-blooded) animals, the largest are those that live in colder climates - in high latitudes or in the mountains. If there are closely related species (for example, species of the same genus) that do not differ significantly in their feeding patterns and lifestyle, then larger species are also found in more severe (cold) climates.

The rule is based on the assumption that the total heat production in endothermic species depends on the volume of the body, and the rate of heat transfer depends on its surface area. As the size of organisms increases, the volume of the body grows faster than its surface. This rule was experimentally tested for the first time on dogs. different sizes. It turned out that heat production in small dogs is higher per unit mass, but regardless of size it remains almost constant per unit surface area.

Indeed, Bergmann's rule is often fulfilled both within the same species and among closely related species. For example, the Amur form of a tiger with Far East larger than the Sumatran from Indonesia. Northern wolf subspecies are on average larger than southern ones. Among the closely related species of the bear genus, the largest ones live in northern latitudes ( polar bear, brown bears with o. Kodiak), and the smallest species (for example, the spectacled bear) are found in areas with warm climates.

At the same time, this rule was often criticized; it was noted that it cannot be of a general nature, since the size of mammals and birds is influenced by many other factors besides temperature. In addition, adaptations to harsh climates at the population and species level often occur not due to changes in body size, but due to changes in the size of internal organs (increase in the size of the heart and lungs) or due to biochemical adaptations. Taking into account this criticism, it is necessary to emphasize that Bergman’s rule is statistical in nature and manifests its effect clearly, all other things being equal.

Indeed, there are many exceptions to this rule. So, the smallest race woolly mammoth known from the polar island of Wrangel; many forest subspecies of wolves are larger than tundra wolves (for example, an extinct subspecies from the Kenai Peninsula; it is assumed that their large size could give these wolves an advantage when hunting large moose inhabiting the peninsula). The Far Eastern subspecies of leopard living on the Amur is significantly smaller than the African one. In the examples given, the compared forms differ in lifestyle (island and continental populations; tundra subspecies, feeding on smaller prey, and forest subspecies, feeding on larger prey).

In relation to humans, the rule is applicable to a certain extent (for example, pygmy tribes apparently appeared repeatedly and independently in different areas with a tropical climate); however, differences in local diets and customs, migration, and genetic drift between populations place limits on the applicability of this rule.

Gloger's Rule is that among forms related to each other ( different races or subspecies of the same species, related species) homeothermic (warm-blooded) animals, those that live in warm and humid climates are brighter in color than those that live in cold and dry climates. Established in 1833 by Konstantin Gloger (Gloger C. W. L.; 1803-1863), a Polish and German ornithologist.

For example, most desert bird species are duller in color than their subtropical and subtropical relatives. tropical forests. Gloger's rule can be explained both by considerations of camouflage and by the influence of climatic conditions on the synthesis of pigments. To a certain extent, Gloger's rule also applies to hypokilothermic (cold-blooded) animals, in particular insects.

Humidity as an environmental factor

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

Humidity is a parameter characterizing 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 vertically and horizontally. This factor, along with light and temperature, plays a large role in regulating the activity of organisms and their distribution. Humidity also modifies the effect of temperature.

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

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

A certain amount of moisture is absolutely necessary for terrestrial organisms. Many of them require a relative humidity of 100% for normal functioning, and on the contrary, 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 in dry climates adapt through morphological changes and reduction of vegetative organs, especially leaves.

Land animals also adapt. Many of them drink water, others absorb it through the body in liquid or vapor form. For example, most amphibians, some insects and mites. Most desert animals never drink; they satisfy their needs from water supplied with food. Other animals obtain water through the process of fat oxidation.

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

From the point of view of ecological valency, hydrophytes and hygrophytes belong to the group of stenogyrs. Humidity greatly affects the vital functions of organisms, for example, 70% relative humidity was very favorable for field maturation and fertility of female migratory locusts. When propagated successfully, they cause enormous economic damage to crops in many countries.

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

Thus, depending on the humidity characteristics of the local climate, 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 that grow with insufficient moisture. They, in turn, are divided into: succulents - succulent plants (cacti); sclerophytes are plants with narrow and small leaves, and rolled into tubes. They are also divided into euxerophytes and stypaxerophytes. Euxerophytes are steppe plants. Stypaxerophytes are a group of narrow-leaved turf grasses (feather grass, fescue, tonkonogo, etc.). In turn, mesophytes are also divided into mesohygrophytes, mesoxerophytes, etc.

Although inferior in importance to temperature, humidity is nevertheless one of the main environmental factors. For most of the history of living nature, the organic world was represented exclusively by aquatic organisms. An integral part of the vast majority of living beings is water, and almost all of them require an aquatic environment to reproduce or fuse gametes. Land animals are forced to create an artificial aquatic environment in their bodies for fertilization, and this leads to the latter becoming internal.

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

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

Light is one of the forms 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 a flow of energy, mainly solar energy, as well as long-wave thermal radiation from cosmic bodies.

Both of these factors determine climatic conditions environment (temperature, rate of water evaporation, movement of air and water). Sunlight with an energy of 2 cal falls on the biosphere from space. by 1 cm 2 in 1 min. This is the so-called solar constant. This light, passing through the atmosphere, is weakened 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 across different parts of the spectrum changes significantly.

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

In living nature, light is the only source of energy; all plants, except bacteria, photosynthesize, i.e. synthesize organic matter from inorganic substances(i.e., from water, mineral salts and CO-In living nature, light is the only source of energy; all plants, except bacteria 2, use radiant energy in the process of assimilation). All organisms depend for nutrition on terrestrial photosynthetic organisms, 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 magnitudes.

The action of these factors depends on the properties of the organisms. Each type of organism is adapted to a particular wavelength of light. Some types of organisms have adapted to ultraviolet radiation, while others have adapted to infrared radiation.

Some organisms are able to distinguish between wavelengths. They have special light-perceiving systems and have color vision, which are of great importance in their life. Many insects are sensitive to short-wave radiation, which humans cannot perceive. Moths 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. Based on 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 plants, 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. U various organisms threshold sensitivity to environmental factors varies. For example, intense light inhibits the development of Drosophila flies, even causing their death. Cockroaches and other insects do not like light. In most photosynthetic plants, at low light intensity, protein synthesis is inhibited, and 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.

Environmental valence

the degree of adaptability of a living organism to changes in environmental conditions. E.v. represents a species property. It is expressed quantitatively by the range of environmental changes within which this type maintains normal functioning. E.v. can be considered both in relation to the reaction of a species to individual environmental factors, and in relation to a complex of factors.

In the first case, species that tolerate wide changes in the strength of the influencing factor are designated by a term consisting of the name of this factor with the prefix “eury” (eurythermal - in relation to the influence of temperature, euryhaline - in relation to salinity, eurybatherous - in relation to depth, etc.); species adapted only to small changes of this factor are denoted by a similar term with the prefix “steno” (stenothermic, stenohaline, etc.). Species with broad E. v. in relation to a complex of factors, they are called eurybionts (See Eurybionts) in contrast to stenobionts (See Stenobionts), which have low adaptability. Since eurybiontism makes it possible to populate a variety of habitats, and stenobiontism sharply narrows the range of habitats suitable for the species, these two groups are often called eury- or stenotopic, respectively.

Eurybionts, animal and plant organisms capable of existing under significant changes in environmental conditions. For example, the inhabitants of the marine littoral zone endure regular drying during low tide, strong heating in summer, and cooling and sometimes freezing in winter (eurythermal animals); The inhabitants of river estuaries can withstand it. fluctuations in water salinity (euryhaline animals); a number of animals exist in a wide range of hydrostatic pressure (eurybates). Many land dwellers temperate latitudes able to withstand large seasonal temperature fluctuations.

The eurybiontism of a species increases with its ability to tolerate unfavorable conditions in a state of suspended animation (many bacteria, spores and seeds of many plants, adult perennial plants of cold and temperate latitudes, wintering buds of freshwater sponges and bryozoans, eggs of branchial crustaceans, adult tardigrades and some rotifers, etc.) or hibernation (some mammals).

CHETVERIKOV'S RULE As a rule, according to Krom, in nature all types of living organisms are represented not by individual isolated individuals, but in the form of aggregates of numbers (sometimes very large) of individuals-populations. Bred by S. S. Chetverikov (1903).

View- this is a historically established set of populations of individuals, similar in morpho-physiological properties, capable of freely interbreeding with each other and producing fertile offspring, occupying a certain area. Each species of living organisms can be described by a set of characteristic features and properties, which are called characteristics of the species. Characteristics of a species by which one species can be distinguished from another are called species criteria.

The most commonly used are seven general criteria of the form:

1. Specific type of organization: aggregate characteristic features, allowing to distinguish individuals of a given species from individuals of another.

2. Geographical certainty: the existence of individuals of a species in a specific place on globe; range - the area where individuals of a given species live.

3. Ecological certainty: individuals of a species live in a specific range of values ​​of physical environmental factors, such as temperature, humidity, pressure, etc.

4. Differentiation: a species consists of smaller groups of individuals.

5. Discreteness: individuals of a given species are separated from individuals of another by a gap - hiatus. Hiatus is determined by the action of isolating mechanisms, such as discrepancies in the timing of reproduction, the use of specific behavioral reactions, sterility of hybrids, etc.

6. Reproducibility: reproduction of individuals can be carried out asexually (the degree of variability is low) and sexually (the degree of variability is high, since each organism combines the characteristics of the father and mother).

7. A certain level of numbers: numbers undergo periodic (waves of life) and non-periodic changes.

Individuals of any species are distributed extremely unevenly in space. For example, stinging nettle, within its range, is found only in moist, shady places with fertile soil, forming thickets in the floodplains of rivers, streams, around lakes, along the edges of swamps, in mixed forests and thickets of bushes. Colonies of the European mole, clearly visible on the mounds of earth, are found on forest edges, meadows and fields. Suitable for life
Although habitats are often found within the range, they do not cover the entire range, and therefore individuals of this species are not found in other areas of the range. There is no point in looking for nettles in pine forest or a mole in a swamp.

Thus, the uneven distribution of a species in space is expressed in the form of “islands of density”, “condensations”. Areas with a relatively high distribution of this species alternate with areas with low abundance. Such “density centers” of the population of each species are called populations. A population is a collection of individuals of a given species over a long period of time ( large number generations) inhabiting a certain space (part of the area), and isolated from other similar populations.

Free crossing (panmixia) practically takes place within the population. In other words, a population is a group of individuals freely joining together, living for a long time in a certain territory, and relatively isolated from other similar groups. A species, therefore, is a collection of populations, and a population is a structural unit of a species.

Difference between a population and a species:

1) individuals of different populations interbreed freely with each other,

2) individuals of different populations differ little from each other,

3) there is no gap between two neighboring populations, that is, there is a gradual transition between them.

The process of speciation. Let us assume that a given species occupies a certain habitat determined by its feeding pattern. As a result of divergence between individuals, the range increases. The new habitat will contain areas with different food plants, physical and chemical properties, etc. Individuals that find themselves in different parts of the habitat form populations. In the future, as a result of the ever-increasing differences between individuals of populations, it will become increasingly clear that individuals of one population differ in some way from individuals of another population. A process of population divergence is taking place. Mutations accumulate in each of them.

Representatives of any species in the local part of the range form a local population. The totality of local populations associated with areas of the range that are homogeneous in terms of living conditions is ecological population. So, if a species lives in a meadow and forest, then they speak of its gum and meadow populations. Populations within a species' range that are associated with specific geographic boundaries are called geographic populations.
Population sizes and boundaries can change dramatically. During outbreaks of mass reproduction, the species spreads very widely and giant populations arise.

A set of geographical populations with persistent signs, the ability to interbreed and produce fertile offspring is called a subspecies. Darwin said that the formation of new species occurs through varieties (subspecies).

However, it should be remembered that in nature often some element is missing.
Mutations occurring in individuals of each subspecies cannot by themselves lead to the formation of new species. The reason lies in the fact that this mutation will wander throughout the population, since individuals of the subspecies, as we know, are not reproductively isolated. If a mutation is beneficial, it increases the heterozygosity of the population; if it is harmful, it will simply be rejected by selection.

As a result of the constantly ongoing mutation process and free crossing, mutations accumulate in populations. According to the theory of I. I. Shmalhausen, a reserve of hereditary variability is created, i.e., the vast majority of mutations that arise are recessive and do not manifest themselves phenotypically. Once a high concentration of mutations in the heterozygous state is reached, crossing of individuals carrying recessive genes becomes possible. In this case, homozygous individuals appear in which the mutations already manifest themselves phenotypically. In these cases, mutations are already under the control of natural selection.
But this is not yet decisive for the process of speciation, because natural populations are open and foreign genes from neighboring populations are constantly introduced into them.

There is a gene flow sufficient to maintain a high similarity of gene pools (the totality of all genotypes) of all local populations. It is estimated that the replenishment of the gene pool due to foreign genes in a population consisting of 200 individuals, each of which has 100,000 loci, is 100 times greater than due to mutations. As a consequence, no population can change dramatically as long as it is subject to the normalizing influence of gene flow. The resistance of a population to changes in its genetic composition under the influence of selection is called genetic homeostasis.

As a result of genetic homeostasis in a population, the formation of a new species is very difficult. One more condition must be met! Namely, it is necessary to isolate the gene pool of the daughter population from the maternal gene pool. Isolation can come in two forms: spatial and temporal. Spatial isolation occurs due to various geographical barriers, such as deserts, forests, rivers, dunes, and floodplains. Most often, spatial isolation occurs due to a sharp reduction in the continuous range and its disintegration into separate pockets or niches.

Often a population becomes isolated as a result of migration. In this case, an isolate population arises. However, since the number of individuals in an isolate population is usually small, there is a danger of inbreeding - degeneration associated with inbreeding. Speciation based on spatial isolation is called geographic.

The temporary form of isolation includes changes in the timing of reproduction and shifts in the entire life cycle. Speciation based on temporary isolation is called ecological.
The decisive thing in both cases is the creation of a new, incompatible with the old, genetic system. Evolution is realized through speciation, which is why they say that a species is an elementary evolutionary system. A population is an elementary evolutionary unit!

Statistical and dynamic characteristics of populations.

Species of organisms enter the biocenosis not as individuals, but as populations or parts thereof. A population is a part of a species (consists of individuals of the same species), occupying a relatively homogeneous space and capable of self-regulation and maintaining a certain number. Each species within the occupied territory breaks up into populations. If we consider the impact of environmental factors on an individual organism, then at a certain level of the factor (for example, temperature), the individual under study will either survive or die. The picture changes when studying the effect of the same factor on a group of organisms of the same species.

Some individuals will die or reduce their vital activity at one specific temperature, others - at a lower temperature, and others - at a higher temperature. Therefore, we can give another definition of a population: all living organisms, in order to survive and give offspring, must, under dynamic environmental conditions factors exist in the form of groups, or populations, i.e. a collection of cohabiting individuals with similar heredity. The most important feature of a population is the total territory it occupies. But within a population there may be groups that are more or less isolated for various reasons.

Therefore, it is difficult to give an exhaustive definition of the population due to the blurred boundaries between individual groups of individuals. Each species consists of one or more populations, and a population is thus the form of existence of a species, its smallest evolving unit. For populations various types There are acceptable limits for reducing the number of individuals, beyond which the existence of the population becomes impossible. There are no exact data on critical values ​​of population numbers in the literature. The given values ​​are contradictory. However, the fact remains undoubted that the smaller the individuals, the higher the critical values ​​of their numbers. For microorganisms this is millions of individuals, for insects - tens and hundreds of thousands, and for large mammals - several dozen.

The number should not decrease below the limits beyond which the probability of meeting sexual partners sharply decreases. The critical number also depends on other factors. For example, some organisms have a specific way of life (colonies, flocks, herds). Groups within a population are relatively isolated. There may be cases when the population size as a whole is still quite large, and the number separate groups reduced below critical limits.

For example, a colony (group) of the Peruvian cormorant must have a population of at least 10 thousand individuals, and the herd reindeer- 300 - 400 heads. To understand the mechanisms of functioning and solve issues of using populations great value have information about their structure. There are gender, age, territorial and other types of structure. In theoretical and applied terms, the most important data is on the age structure - the ratio of individuals (often combined into groups) of different ages.

Animals are divided into the following age groups:

Juvenile group (children) senile group (senile group, not involved in reproduction)

Adult group (individuals engaged in reproduction).

Typically, normal populations are characterized by the greatest viability, in which all ages are represented relatively evenly. In a regressive (endangered) population, senile individuals predominate, which indicates the presence of negative factors that disrupt reproductive functions. Urgent measures are required to identify and eliminate the causes of this condition. Invading populations are represented mainly by young individuals. Their vitality usually does not cause concern, but there is a high probability of outbreaks of excessively high numbers of individuals, since trophic and other connections have not been formed in such populations.

It is especially dangerous if it is a population of species that were previously absent from the area. In this case, populations usually find and occupy a free ecological niche and realize their reproduction potential, intensively increasing their numbers. If the population is in a normal or close to normal state, a person can remove from it the number of individuals (in animals) or biomass (in plants), which increases over the period of time between withdrawals. First of all, individuals of post-productive age (who have completed reproduction) should be removed. If the goal is to obtain a certain product, then age, gender and other characteristics of populations are adjusted taking into account the task.

Exploitation of populations plant communities(for example, to obtain wood), usually coincides with the period of age-related slowdown in growth (accumulation of production). This period usually coincides with the maximum accumulation of woody mass per unit area. The population is also characterized by a certain sex ratio, and the ratio of males and females is not equal to 1:1. There are known cases of a sharp predominance of one sex or another, alternation of generations with the absence of males. Each population can also have a complex spatial structure (divided into more or less large hierarchical groups - from geographical to elementary (micropopulations).

Thus, if the mortality rate does not depend on the age of individuals, then the survival curve is a decreasing line (see figure, type I). That is, the death of individuals occurs evenly in this type, the mortality rate remains constant throughout life. Such a survival curve is characteristic of species whose development occurs without metamorphosis with sufficient stability of the born offspring. This type is usually called the hydra type - it is characterized by a survival curve approaching a straight line. In species for which the role external factors in mortality is low, the survival curve is characterized by a slight decrease up to a certain age, after which there is a sharp drop as a result of natural (physiological) mortality.

Type II in the picture. The nature of the survival curve close to this type is characteristic of humans (although the human survival curve is somewhat flatter and, thus, is something between types I and II). This type is called the Drosophila type: it is what fruit flies exhibit in laboratory conditions (not eaten by predators). Many species are characterized by high mortality in the early stages of ontogenesis. In such species, the survival curve is characterized by a sharp drop in the younger ages. Individuals that survive the “critical” age exhibit low mortality and live to older ages. The type is called the oyster type. Type III in the picture. The study of survival curves is of great interest to the ecologist. It allows us to judge at what age a particular species is most vulnerable. If the effects of causes that can change fertility or mortality occur at the most vulnerable stage, then their influence on the subsequent development of the population will be greatest. This pattern must be taken into account when organizing hunting or pest control.

Age and sex structures of populations.

Any population is characterized by a certain organization. The distribution of individuals over the territory, the ratio of groups of individuals by sex, age, morphological, physiological, behavioral and genetic characteristics reflect the corresponding population structure : spatial, gender, age, etc. The structure is formed on the one hand on the basis of general biological properties species, and on the other hand, under the influence of abiotic environmental factors and populations of other species.

The population structure is thus adaptive in nature. Different populations of the same species have both similar and distinctive features that characterize the specific environmental conditions in their habitats.

In general, in addition to the adaptive capabilities of individual individuals, in certain territories adaptive features of group adaptation of the population as a supra-individual system are formed, which suggests that adaptive features populations are much higher than those of the individuals composing them.

Age composition- is important for the existence of a population. The average lifespan of organisms and the ratio of numbers (or biomass) of individuals of different ages are characterized by the age structure of the population. The formation of the age structure occurs as a result of the combined action of the processes of reproduction and mortality.

In any population, 3 age ecological groups are conventionally distinguished:

Pre-reproductive;

Reproductive;

Post-reproductive.

The pre-reproductive group includes individuals that are not yet capable of reproduction. Reproductive - individuals capable of reproduction. Post-reproductive - individuals who have lost the ability to reproduce. The duration of these periods varies greatly depending on the type of organism.

At favorable conditions the population contains all age groups and maintains a more or less stable age composition. In rapidly growing populations, young individuals predominate, while in declining populations, older individuals are no longer able to reproduce intensively. Such populations are unproductive and not stable enough.

There are types with simple age structure populations that consist of individuals of almost the same age.

For example, all annual plants of one population are in the seedling stage in the spring, then bloom almost simultaneously, and produce seeds in the fall.

In species with complex age structure populations have several generations living at the same time.

For example, the life history of elephants includes young, mature and aging animals.

Populations that include many generations (of different age groups) are more stable and less susceptible to the influence of factors affecting reproduction or mortality in a particular year. Extreme conditions can lead to the death of the most vulnerable age groups, but the most resilient survive and give birth to new generations.

For example, a person is seen as biological species, which has a complex age structure. The stability of the species' populations was demonstrated, for example, during the Second World War.

To study the age structures of populations, graphic techniques are used, for example, age population pyramids, widely used in demographic studies (Fig. 3.9).

Fig.3.9. Population age pyramids.

A - mass reproduction, B - stable population, C - declining population

The stability of species populations largely depends on sexual structure , i.e. ratios of individuals of different sexes. Sexual groups within populations are formed on the basis of differences in morphology (shape and structure of the body) and ecology of the different sexes.

For example, in some insects, males have wings, but females do not, males of some mammals have horns, but females do not, male birds have bright plumage, while females have camouflage.

Ecological differences are reflected in food preferences (females of many mosquitoes suck blood, while males feed on nectar).

The genetic mechanism ensures an approximately equal ratio of individuals of both sexes at birth. However, the initial ratio is soon disrupted as a result of physiological, behavioral and environmental differences between males and females, causing uneven mortality.

Analysis of the age and sex structure of populations makes it possible to predict its numbers for a number of coming generations and years. This is important when assessing the possibilities of fishing, shooting animals, saving crops from locust attacks, and in other cases.

Today, October 6, is World Animal Habitat Day. In honor of this holiday, we offer you a selection of 5 animals that have chosen as their home places with the most extreme conditions.

Living organisms are distributed throughout our planet, and many of them live in places with extreme conditions. Such organisms are called extremophiles. These include bacteria, archaea and only a few animals. We talk about the latter in this article. 1. Pompeii worms. These deep-sea polychaete worms, no more than 13 cm in length, are among the most resistant to high temperatures animals. Therefore, it is not surprising that they can be found exclusively at hydrothermal vents at the bottom of the oceans (), from which highly mineralized hot water. Thus, for the first time a colony of Pompeii worms was discovered in the early 1980s at hydrothermal vents in Pacific Ocean near the Galapagos Islands, and later, in 1997, near Costa Rica and again at hydrothermal vents.

Typically, the Pompeian worm places its body in the tube-like structures of black smokers, where the temperature reaches 80°C, and it sticks its head with feather-like structures outward, where the temperature is lower (about 22°C). Scientists have long sought to understand how the Pompeii worm manages to withstand such extreme temperatures. Research has shown that special bacteria help him in this, forming a layer up to 1 cm thick on the back of the worm, reminiscent of a woolen blanket. In a symbiotic relationship, the worms secrete mucus from tiny glands on their backs that feed the bacteria, which in turn insulate the animal's body from high temperatures. It is believed that these bacteria have special proteins that make it possible to protect the worms and the bacteria themselves from high temperatures. 2. Gynaephora caterpillar. Greenland and Canada are home to the moth Gynaephora groenlandica, known for its ability to withstand extremely low temperatures. Thus, living in cold climates, the caterpillars of G. groenlandica, while hibernating, can tolerate temperatures down to -70° C! This becomes possible thanks to compounds (glycerol and betaine) that the caterpillars begin to synthesize at the end of summer, when the temperature drops. These substances prevent the formation of ice crystals in the animal's cells and thereby prevent it from freezing to death.

However, this is not the only feature of the species. While most other moth species take about a month to develop from egg to adult, G. groenlandica can take anywhere from 7 to 14 years to develop! Such a slow growth of Gynaephora groenlandica is explained by the extreme environmental conditions in which the insect has to develop. Interestingly, the caterpillars of Gynaephora groenlandica spend most of their lives in hibernation, and the rest of the time (about 5% of their lives) they devote to eating vegetation, for example, the buds of the Arctic willow. 3. Oil flies. They are the only insects known to science that can live in and feed on crude oil. This species was first discovered at the La Brea Ranch in California, where several tar lakes are located.

Authors: Michael S. Caterino & Cristina Sandoval. As is known, oil is a very toxic substance for most animals. However, as larvae, oil flies swim near the oil surface and breathe through special spiracles that protrude above the oil film. Flies eat large amounts of oil, but mainly insects that fall into it. Sometimes the intestines of flies are completely filled with oil. Until now, scientists have not described the mating behavior of these flies, nor where they lay their eggs. However, it is assumed that this does not occur within the oil basin.

Bitumen Lake at La Brea Ranch in California. Interestingly, the temperature of the oil in the pool can reach 38°C, but the larvae easily tolerate these changes. 4. Artemia. Located in the northwestern part American state Utah The Great Salt Lake has a salinity reaching 270 ppm (for comparison, the saltiest sea in the world's oceans - the Red Sea - has a salinity of only 41 ppm). The extremely high salinity of the reservoir makes it unsuitable for life of all living creatures in it, except for the larvae of shore flies, some algae and brine shrimp - tiny crustaceans.

The latter, by the way, live not only in this lake, but also in other bodies of water, the salinity of which is not lower than 60 ppm. This feature allows Artemia to avoid cohabitation with most species of predators, such as fish. These crustaceans have a segmented body with a broad leaf-like appendage at the end, and usually do not exceed 12 millimeters in length. They are widely used as feed for aquarium fish, and are also bred in aquariums. 5. Tardigrades. These tiny creatures, no more than 1 millimeter in length, are the most heat-resistant animals. They live in different places on the planet. For example, they were found in hot springs, where temperatures reached 100°C, and on the top of the Himalayas, under a layer of thick ice, where temperatures were much below zero. And soon it was discovered that these animals are able not only to withstand extreme temperatures, but also to survive without food and water for more than 10 years!

Scientists have found that the ability to suspend their metabolism helps them in this, entering a state of cryptobiosis, when chemical processes in the animal’s body approach zero levels. In this state, the water content in the tardigrade's body can drop to 1%! And besides, the ability to do without water largely depends on high level a special substance in the body of this animal is the non-reducing sugar trehalose, which protects membranes from destruction. Interestingly, although tardigrades are capable of living in places with extreme conditions, many species can be found in milder environments, such as lakes, ponds or meadows. Tardigrades are most common in humid environment, in mosses and lichens.