Life in boiling water. Extremophiles - organisms living in extreme habitats Seven general species criteria are most commonly used

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, depending mainly on temperature. Range, i.e. the range of temperatures in which life can exist ranges from about -200 ° C to + 100 ° C, sometimes the existence of bacteria in hot springs at a temperature of 250 ° C is found. In fact, most organisms can survive in an even narrower temperature range.

Certain types of microorganisms, mainly bacteria and algae, can live and multiply in hot springs at temperatures close to the boiling point. The upper temperature limit for hot spring bacteria is around 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. Outside of these critical extreme temperatures, cold or heat, death of the organism occurs. Somewhere in between is optimum temperature, in which the vital activity of all organisms, living matter as a whole is active.

According to the tolerance of organisms to the temperature regime, they are divided into eurythermal and stenothermal, i.e. able to withstand temperature fluctuations within wide or narrow ranges. For example, lichens and many bacteria can live at different temperatures, or orchids and other thermophilic plants in tropical zones are stenothermal.

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

Allen's rule- the ecogeographic 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 parts of the body: ears, legs, tails, etc.

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

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

Also, this rule is fulfilled in relation to human populations: the shortest (relative to body size) nose, arms and legs are typical for the Esskimo-Aleutian peoples (Eskimos, Inuit), and long arms and legs for trucks and Tutsis.

Bergman's rule- an ecogeographic rule formulated in 1847 by the German biologist Karl Bergman. The rule states that among the 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), which do not differ significantly in the nature of their diet and lifestyle, then larger species are also found in more severe (colder) 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. With an increase in the size of organisms, the volume of the body grows faster than its surface. Experimentally, this rule was first tested on dogs of different sizes. It turned out that heat production in small dogs is higher per unit mass, but regardless of size, it remains practically constant per unit surface area.

Bergman's rule is indeed often fulfilled both within the same species and among closely related species. For example, the Amur tiger form with Of the Far East larger than Sumatran from Indonesia. The northern subspecies of the wolf are on average larger than the southern ones. Among closely related species of the genus, the bear is the largest inhabiting the northern latitudes ( polar bear, brown bears with about. Kodiak), and the smallest species (for example, spectacled bear) - in areas with a warm climate.

At the same time, this rule has often been criticized; it was noted that it cannot be of a general nature, since many factors other than temperature affect the size of mammals and birds. In addition, adaptation to a harsh climate at the population and species level often occurs not due to changes in body size, but due to changes in size internal organs(an increase in the size of the heart and lungs) or due to biochemical adaptations. Taking into account this criticism, it should be emphasized 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. Thus, the smallest race of the woolly mammoth is known from the polar Wrangel Island; many forest wolf subspecies are larger than tundra ones (for example, the extinct subspecies from the Kenai Peninsula; it is assumed that the large size could give these wolves an advantage when hunting large elk inhabiting the peninsula). The Far Eastern subspecies of the leopard that lives on the Amur is significantly smaller than the African one. In the given examples, the compared forms differ in their way of life (island and continental populations; tundra subspecies, feeding on smaller prey and forest subspecies, feeding on larger prey).

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

Gloger's Rule consists in the fact that among related forms (different races or subspecies of the same species, related species) of homeothermal (warm-blooded) animals, those that live in a warm and humid climate are colored brighter than those that live in a cold and dry climate. Installed in 1833 by Constantine C. W. L .; 1803-1863, Polish and German ornithologist.

For example, most desert bird species are dimmer than their subtropical and rainforest... Gloger's rule can be explained both by considerations of masking and by the influence of climatic conditions on the synthesis of pigments. To a certain extent, Gloger's rule also applies to drinking kilothermal (cold-blooded) animals, in particular insects.

Humidity as an environmental factor

Originally, all organisms were aquatic. Having conquered the land, they have not lost their dependence on water. An integral part of of all living organisms is water. Humidity is the amount of water vapor in the air. There is no life without moisture or water.

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

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

Drying air is an important environmental factor. Especially for terrestrial organisms, it has great value drying up the action of the air. Animals adapt, moving to protected places and leading an active lifestyle at night.

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

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

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

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

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

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

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

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

1. Hydatophytes are aquatic plants.

2. Hydrophytes are terrestrial aquatic plants.

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

4. Mesophytes are plants that grow with medium moisture

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

While being inferior in value to temperature, humidity is, nevertheless, one of the main environmental factors. Throughout most of the history of living nature, the organic world was represented exclusively by the water norms of organisms. Water is an integral part of the vast majority of living things, and almost all of them need an aquatic environment to reproduce or merge gametes. Land animals are forced to create an artificial aquatic environment for fertilization, and this leads to the fact that the latter becomes internal.

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

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 pass 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 Earth's surface are exposed to the flow of energy, mainly solar energy, as well as long-wave thermal radiation from space bodies.

Both of these factors determine climatic conditions environment (temperature, rate of evaporation of water, movement of air and water). Sunlight with an energy of 2 cal falls on the biosphere from space. 1cm 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 significantly changes in different parts of the spectrum.

The attenuation of sunlight and cosmic radiation depends on the wavelength (frequency) of the light. Ultraviolet radiation with a wavelength of less than 0.3 microns hardly passes 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 substances 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 - with the help of radiant energy in the process of assimilation). All organisms depend on terrestrial photosynthesizing for nutrition 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 longer than these magnitudes.

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

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 shortwave radiation, which humans cannot perceive. Moths are very sensitive to ultraviolet rays. Bees and birds accurately locate and orientate themselves on the terrain even at night.

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

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

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

With a decrease in light intensity, photosynthesis also slows down. All living organisms have threshold sensitivity to light intensity, as well as to other environmental factors. The threshold sensitivity to environmental factors is not the same for different organisms. For example, intense light inhibits the development of Drosophila flies, even causes 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.

Ecological valence

the degree of adaptability of a living organism to changes in environmental conditions. E. In. is a specific property. Quantitatively, it is expressed by the range of changes in the environment, within which a given species maintains normal vital activity. E. In. 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 endure 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 effect of temperature, euryhaline - to salinity, eurybate - to depth, etc.); species adapted only to small changes in this factor are designated by a similar term with the prefix "steno" (stenothermic, stenohaline, etc.). Species with a wide E. century. in relation to a complex of factors, they are called eurybionts (see Eurybionts), in contrast to stenobionts (see Stenobionts), which have little adaptability. Since eurybionticity makes it possible to settle in various habitats, and stenobionticity sharply narrows the range of stations suitable for the species, these two groups are often called eury- or stenotopic, respectively.

Eurybionts, animals and plant organisms that can exist under significant changes in environmental conditions. So, for example, the inhabitants of the sea littoral endure regular drainage at low tide, in summer - strong warming, and in winter - cooling, and sometimes freezing (eurythermal animals); the inhabitants of the estuaries of the rivers endure means. fluctuations in water salinity (euryhaline animals); a number of animals exist in a wide range of hydrostatic pressures (eurybatic animals). Many terrestrial inhabitants of temperate latitudes are able to withstand large seasonal temperature fluctuations.

The eurybionism of the species is increased by the ability to tolerate unfavorable conditions in a state of suspended animation (many bacteria, spores and seeds of many plants, adult perennials of cold and temperate latitudes, wintering buds of freshwater sponges and bryozoans, eggs of crustaceans, adult tardigrades and some rotifers, etc.) or hibernation (some mammals).

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

View- is a historically formed set of populations of individuals, similar in morpho-physiological properties, capable of freely interbreeding with each other and giving fertile offspring, occupying a certain area. Each type of living organism can be described by the totality characteristic features, properties, which are called species characteristics. The 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: a set of characteristic features that make it possible to distinguish individuals of a given species from individuals of another.

2. Geographic certainty: the existence of individuals of a species in a specific place on the globe; habitat - the area of ​​habitation of individuals of this species.

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

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

5. Discreteness: individuals of a given species are separated from individuals by a gap - hiatus. The hiatus is determined by the action of isolating mechanisms, such as mismatch of breeding dates, 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 population: the number undergoes periodic (waves of life) and non-periodic changes.

Individuals of any kind are distributed in space extremely unevenly. 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 outskirts of swamps, in mixed forests and thickets of shrubs. Colonies of the European mole, clearly visible on the mounds of land, are found on forest edges, meadows and fields. Suitable for life
habitats, although they are often found within the range, do not cover the entire range, and therefore individuals of this species are not found in other parts of it. It makes no sense to look for nettles in a pine forest or a mole in a swamp.

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

Within the population, free crossing is practically carried out (panmixia). In other words, a population is a group of individuals freely bonding among themselves, living for a long time in a certain territory, and relatively isolated from other similar groups. Thus, a species is an aggregate of populations, and a population is a structural unit of a species.

Difference between population and species:

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

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

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

Speciation process. Let us assume that this species occupies a certain area, determined by the nature of its feeding. As a result of divergence between individuals, the range increases. The new habitat will contain areas with different fodder plants, physicochemical properties, etc. Individuals in different parts of the range will form populations. In the future, as a result of the ever increasing difference between individuals of populations, it will become more and more obvious that individuals of one population differ in some way from individuals of another population. There is a process of population divergence. Mutations accumulate in each of them.

Representatives of any species in a local part of the range form a local population. The totality of local populations associated with areas of the habitat homogeneous in terms of living conditions is ecological population... So, if a species lives in a meadow and in a forest, then they talk about its gum and meadow populations. Populations within the range of a species 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 gigantic populations arise.

A collection of geographic populations with stable traits, the ability to interbreed and produce fertile offspring is called a subspecies. Darwin said that the formation of new species goes through varieties (subspecies).

It should, however, be remembered that in nature, some element is often absent.
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 through the population, since individuals of the subspecies, as we know, are not reproductively isolated. If a mutation is useful, it increases the heterozygosity of the population; if it is harmful, it will simply be discarded by selection.

As a result of the constantly occurring mutational process and free crossing, mutations accumulate in populations. According to the theory of I.I.Shmalgauzen, a reserve of hereditary variability is being created, that is, the overwhelming majority of emerging mutations are recessive and do not manifest themselves phenotypically. Upon reaching a high concentration of mutations in a heterozygous state, it becomes possible to cross breeding individuals carrying recessive genes. In this case, homozygous individuals appear, in which mutations are already manifesting phenotypically. In these cases, the mutations already come under the control of natural selection.
But this is not yet decisive for the process of speciation, because natural populations are open and alien genes from neighboring populations are constantly being introduced into them.

There is a gene flow that is sufficient to maintain a large 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 of 200 individuals, each of which has 100,000 loci, is 100 times more 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 a change in its genetic composition under the influence of selection is called genetic homeostasis.

As a result of genetic homeostasis in the population, the formation of a new species is very difficult. One more condition must be realized! 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 geographic barriers such as deserts, forests, rivers, dunes, floodplains. Most often, spatial isolation occurs due to a sharp reduction in a continuous area and its disintegration into separate pockets or niches.

The population is often isolated as a result of migration. In this case, an isolate population appears. However, since the number of individuals in the isolate population is usually high, there is a danger of inbreeding - degeneration associated with closely related crossing. Speciation based on spatial isolation is called geographic.

The temporary form of isolation includes a change in the timing of reproduction and shifts in the entire life cycle. Speciation based on temporary isolation is called ecological.
The decisive factor 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. The population is an elementary evolutionary unit!

Statistical and dynamic characteristics of populations.

Species of organisms are included in the biocenosis not as separate individuals, but as populations or their parts. 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 down into populations. If we consider the impact of environmental factors on a single 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 one. Therefore, one can give another definition of the population: all living organisms, in order to survive and give offspring, must under dynamic ecological regimes. factors exist in the form of groups, or populations, i.e. a set of co-living individuals with a similar heredity. The most important feature of a population is the common territory it occupies. But within the population there can be more or less isolated different reasons groupings.

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 the population, therefore, is the form of existence of the species, its smallest evolving unit. For populations different types there are permissible limits for the decrease in the number of individuals, beyond which the existence of the population becomes impossible. There are no exact data on the critical values ​​of the population size in the literature. The given values ​​are contradictory. It remains, however, an undoubted fact that the smaller the individuals, the higher the critical values ​​of their numbers. For microorganisms, these are millions of individuals, for insects - tens and hundreds of thousands, and for large mammals- A few dozens.

The number should not decrease below the limits beyond which the likelihood of meeting sexual partners is sharply reduced. The critical number also depends on other factors. For example, for some organisms, a group lifestyle is specific (colonies, flocks, herds). Groups within a population are relatively isolated. There may be cases when the population as a whole is still quite large, and the number of individual groups has decreased below critical limits.

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

The following age groups are distinguished in animals:

Juvenile group (children's) senile group (senile, not participating in reproduction)

Adult group (individuals carrying out reproduction).

Usually, normal populations are most viable, in which all ages are represented relatively evenly. In the regressive (dying out) 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. Introduced (invasive) populations are represented mainly by young individuals. Their vitality usually does not cause concern, but the likelihood of outbreaks of an excessively high number of individuals is high, 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 in the area. In this case, populations usually find and occupy a free ecological niche and realize their reproductive potential, intensively increasing the number. If the population is in normal or close to normal condition, a person can withdraw from it the number of individuals (in animals) or biomass (in plants), which increases over the time interval between withdrawals. First of all, individuals of the postproductive age (those who have finished breeding) should be removed. If the goal is to obtain a certain product, then the age, sex and other characteristics of the populations are adjusted taking into account the task.

The exploitation of populations of plant communities (for example, for obtaining timber) is usually timed to coincide with the period of age-related slowdown in growth (accumulation of production). This period usually coincides with the maximum accumulation of wood pulp per unit area. The population is also characterized by a certain sex ratio, and the ratio of males to 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 have a complex spatial structure (subdivided into more or less large hierarchical groups - from geographical to elementary (micropopulations).

So, 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 in this type occurs evenly, the mortality rate remains constant throughout life. Such a survival curve is characteristic of species, the development of which occurs without metamorphosis with sufficient stability of the nascent offspring. This type is usually called the type of hydra - it is characterized by a survival curve approaching a straight line. In species for which the role of external factors in mortality is small, the survival curve is characterized by a slight decrease until a certain age, after which a sharp drop occurs as a result of natural (physiological) mortality.

Type II in the figure. A survival curve similar to this type is inherent in humans (although the human survival curve is somewhat flatter and, thus, is something in between types I and II). This type is called the type of Drosophila: it is what Drosophila displays in laboratory conditions (not eaten by predators). Very 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 area of ​​younger ages. Individuals that have survived the "critical" age demonstrate low mortality and live to a great age. The type is called the type of oyster. Type III in the figure. The study of survival curves is of great interest to the ecologist. It allows you to judge at what age a particular species is most vulnerable. If the effect of the causes that can change the birth rate or death rate falls on 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 in pest control.

Age and sex structure of populations.

A certain organization is inherent in any population. 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 the general biological properties of species, and on the other, under the influence of abiotic factors of the environment and populations of other species.

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

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

Age composition- is essential for the existence of the population. The average life span of organisms and the ratio of the number (or biomass) of individuals of different ages is characterized by the age structure of the population. The formation of the age structure occurs as a result of the joint action of the processes of reproduction and mortality.

In any population, 3 age ecological groups are conditionally 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 that have lost the ability to reproduce. The duration of these periods varies greatly depending on the type of organism.

Under favorable conditions, the population contains all age groups and a more or less stable age composition is maintained. In rapidly growing populations, young individuals predominate, and in decreasing populations, old ones, no longer able to reproduce intensively, prevail. Such populations are unproductive and not stable enough.

There are views 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 spring, then bloom almost simultaneously, and give seeds in autumn.

In species with complex age structure populations live simultaneously for several generations.

For example, there are young, mature and aging animals in the elephants' experience.

Populations that include many generations (different age groups) are more stable, 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 resistant ones survive and give new generations.

For example, a person is considered as a biological species with a complex age structure... The stability of the species' populations manifested itself, for example, during the Second World War.

To study the age structure of populations, graphical methods are used, for example, the age pyramids of a population, which are widely used in demographic studies (Fig. 3.9).

Figure 3.9. Age pyramids of the population.

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

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

For example, in some insects, males have wings, but females do not, males of some mammals have horns, but they are absent from females, male birds have bright plumage, and females have masking ones.

Ecological differences are expressed in food preferences (females of many mosquitoes suck blood and males feed on nectar).

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

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

Hot springs, usually found in volcanic areas, have a fairly rich living population.

Long ago, when there was a very superficial idea about bacteria and other lower creatures, the existence of a peculiar flora and fauna in the baths was established. For example, in 1774, Sonnerat reported the presence of fish in the hot springs of Iceland, with a temperature of 69 °. This conclusion was not later confirmed by other researchers in relation to the Icelandic baths, but similar observations were made elsewhere. On the island of Ischia, in springs with temperatures above 55 °, Ehrenberg (1858) noted the finding of fish. Hoppe-Seiler (1875) also saw fish in water with a temperature of about 55 ° too. Even if we assume that in all the cases noted, the thermometry was inaccurately performed, it is nevertheless clear to draw a conclusion about the ability of some fish to live at a rather elevated temperature. Along with fish, the presence of frogs, worms and molluscs was sometimes noted in the thermal baths. At a later time, the simplest animals were also found here.

In 1908, the work of Issel was published, who established in more detail the temperature limits for the animal world living in hot springs.

Along with the animal world, it is extremely easy to establish the presence of algae in the thermal baths, sometimes forming powerful fouling. According to Rodina (1945), the thickness of algae accumulated in hot springs often reaches several meters.

We talked enough about the associations of thermophilic algae and the factors determining their composition in the section “Algae living at high temperatures”. Here we just recall that the most thermally stable of them are blue-green algae, which can develop up to a temperature of 80-85 °. Green algae tolerate temperatures slightly above 60 °, and diatoms end up developing around 50 °.

As already noted, algae that develop in the thermal baths play an essential role in the formation of various types of scale, which include mineral compounds.

Thermophilic algae have big influence on the development of the bacterial population in the thermal baths. During their lifetime, by exosmosis, they release a certain amount of organic compounds into the water, and when they die off, they even create a rather favorable substrate for bacteria. It is not surprising, therefore, that the bacterial population of thermal waters is most abundantly represented in places where algae accumulate.

Moving on to thermophilic bacteria of hot springs, we must point out that in our country they have been studied by very many microbiologists. Here the names of Tsiklinskaya (1899), Gubin (1924-1929), Afanasyeva-Kester (1929), Egorova (1936-1940), Volkova (1939), Rodina (1945) and Isachenko (1948) should be noted.

Most of the researchers who have dealt with hot springs have limited themselves to the fact of establishing the bacterial flora in them. Only comparatively few microbiologists dwelled on the fundamental aspects of the life of bacteria in thermal baths.

In our review, we will focus only on the studies of the latter group.

Thermophilic bacteria have been found in hot springs in a number of countries - Soviet Union, France, Italy, Germany, Slovakia, Japan, etc. Since the waters of hot springs are often poor in organic matter, it is not surprising that they sometimes contain very little a large number of saprophytic bacteria.

The reproduction of autotrophically feeding bacteria, among which iron and sulfur bacteria are quite widespread in the thermal baths, is determined mainly by the chemical composition of the water, as well as by its temperature.

Some thermophilic bacteria isolated from hot waters have been described as new species. These forms include: Bac. thermophilus filiformis. studied by Tsiklinskaya (1899), two spore-bearing rods - Bac. ludwigi and Bac. ilidzensis capsulatus, isolated by Karlinsky (1895), Spirochaeta daxensis, isolated by Cantacuzen (1910), and Thiospirillum pistiense, isolated by Churda (1935).

The water temperature of hot springs strongly affects the species composition of the bacterial population. In waters with a lower temperature, cocci and spirochete-like bacteria were found (works by Rodina, Cantacuzen). However, here, too, spore-bearing rods are the predominant form.

Recently, the influence of temperature on the species composition of the bacterial population of the thermal baths was very vividly shown in the work of Rodina (1945), who studied the hot springs of Khoja-Obi-Garm in Tajikistan. The temperature of individual sources of this system ranges from 50-86 °. Combining, these baths give a stream, at the bottom of which, in places with temperatures not exceeding 68 °, a rapid growth of blue-green algae was observed. In places, the algae formed thick layers different color... At the water's edge, on the side walls of the niches, there were deposits of sulfur.

V different sources, in the runoff, as well as in the thickness of blue-green algae, fouling glasses were placed for three days. In addition, the collected material was sown on nutrient media. It was found that the water with the highest temperature contains mainly rod-shaped bacteria. Wedge-shaped forms, in particular resembling azotobacter, are found at temperatures not exceeding 60 °. Judging by all the data, it can be said that Azotobacter itself does not grow above 52 °, and the large round cells found in fouling belong to other types of microbes.

The most heat-resistant are some forms of bacteria growing on meat-peptone agar, thio-bacteria such as Tkiobacillus thioparus and desulphurizers. Incidentally, it is worth mentioning that Egorova and Sokolova (1940) found Microspira in water with a temperature of 50-60 °.

In Rodina's work, nitrogen-fixing bacteria were not detected in water at 50 °. However, in the study of soils, anaerobic nitrogen fixers were found even at 77 °, and azotobacter - at 52 °. This suggests that water is generally an unsuitable substrate for nitrogen fixers.

A study of bacteria in the soils of hot springs revealed the same temperature dependence of the group composition as in water. However, the micropopulation of soils was much richer in numbers. Sandy soils, poor in organic compounds, had a rather scarce micropopulation, while those containing dark-colored organic matter were abundantly inhabited by bacteria. Thus, the connection between the composition of the substrate and the nature of the microscopic creatures contained in it was revealed here extremely clearly.

It is noteworthy that neither in the water nor in the silt was the Homeland able to detect thermophilic bacteria that decompose fiber. We are inclined to explain this moment by methodological difficulties, since thermophilic cellulose-decomposing bacteria are quite demanding on nutrient media. As Imshenetsky showed, their isolation requires rather specific nutrient substrates.

In hot springs, in addition to saprophytes, there are autotrophs - sulfur and iron bacteria.

The oldest observations on the possibility of the growth of sulfur bacteria in the thermal baths were apparently made by Meyer and Ahrens, and also by Mioshi. Mioshi observed the development of filamentous sulfur bacteria in springs, the water temperature of which reached 70 °. Egorova (1936), who studied the Bragun sulfur springs, noted the presence of sulfur bacteria even at a water temperature of 80 °.

In the chapter “ general characteristics morphological and physiological characteristics of thermophilic bacteria ”, we described in sufficient detail the properties of thermophilic iron and sulfur bacteria. It is not advisable to reiterate this information, and we will limit ourselves here only to a reminder that individual genera and even species of autotrophic bacteria finish development at different temperatures.

Thus, the maximum temperature for sulfur bacteria is recorded at about 80 °. For iron bacteria such as Streptothrix ochraceae and Spirillum ferrugineum, Mioshi set the maximum at 41-45 °.

Dufrenois (Dufrencfy, 1921) found iron bacteria very similar to Siderocapsa on sediments in hot waters with a temperature of 50-63 °. According to his observations, the growth of filamentous iron bacteria occurred only in cold waters.

Volkova (1945) observed the development of bacteria from the genus Gallionella in the mineral springs of the Pyatigorsk group when the water temperature did not exceed 27-32 °. In thermae with a higher temperature, iron bacteria were completely absent.

Comparing the materials we have noted, we involuntarily have to conclude that in some cases not the temperature of the water, but its chemical composition determines the development of certain microorganisms.

Bacteria, along with algae, take an active part in the formation of some bioliths and caustobioliths. The role of bacteria in calcium precipitation has been studied in more detail. This issue is covered in detail in the section on physiological processes caused by thermophilic bacteria.

The conclusion made by Volkova is noteworthy. She notes that the "barrezhina", which is deposited with a powerful cover in the streams of the sources of the sulfur springs of Pyatigorsk, contains a lot of elemental sulfur and is basically mycelium mold fungus from the genus Penicillium. The mycelium makes up the stroma, which includes rod-shaped bacteria, apparently related to sulfur bacteria.

Brusoff believes that thermal bacteria are also involved in the formation of silicic acid deposits.

Bacteria that reduce sulfates have been found in the thermal baths. According to Afanasyeva-Kester's instructions, they resemble Microspira aestuarii van Delden and Vibrio thermodesulfuricans Elion. A number of considerations about the possible role of these bacteria in the formation of hydrogen sulfide in the thermal baths were expressed by Gubin (1924-1929).

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Some organisms have a special advantage that allows them to withstand the most extreme conditions, where others simply cannot. Among such abilities are resistance to immense 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 hardy organism.

10. Himalayan jumping spider

The Asian wild goose is famous for flying at an altitude of over 6.5 kilometers, while the tallest human settlement is at 5100 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 6700 meters, this spider feeds mainly on small insects brought there by gusts of wind. Key feature this insect is able to survive in an almost complete absence of oxygen.

9. Giant kangaroo jumper


Usually, when we think about animals that can live 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 when you learn that there is an animal in the world that can live its entire life without drinking a drop of water. The giant kangaroo jumper is a close relative of beavers. Their average life expectancy is usually 3 to 5 years. They usually get moisture from food by eating various seeds. In addition, these rodents do not sweat, thereby avoiding additional water losses. Usually these animals live in Death Valley, and in this moment are endangered.

8. "Heat-resistant" 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, it is mainly bacteria that thrive in hot underwater springs, which cannot be said about multicellular life forms. However, there is a special kind of worm called paralvinella sulfincola that happily settle in places where the water reaches 45-55 degrees. Scientists conducted an experiment where one of the walls of the aquarium was heated, as a result of which it turned out that the worms preferred to stay in this particular place, ignoring the cooler places. It is believed that such a feature developed in worms so that they could feast on bacteria that are abundant in hot springs. Since they had no natural enemies before, bacteria were relatively easy prey.

7. Greenland Arctic Shark


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

6. Devil worm


For many decades, scientists believed that only single-celled organisms were able to survive at great depths. In their opinion, high 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 found in water samples 2.2 kilometers below the surface of the earth, lying in one of the caves in South Africa... They managed to survive extreme environmental conditions, which made it possible to assume that life on Mars and other planets in our galaxy is possible.

5. Frogs

Some species of frogs are widely known for their ability to literally freeze for the entire winter and come to life with the arrival of spring. V 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 good at burrowing, 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 bloodstream from the frog's liver. What's even more surprising is the fact that frogs are able to demonstrate their ability to freeze not only in the natural environment, but also in the laboratory, 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 by 1100 times. Several years ago, scientists managed to find giant amoebas there, which they managed to photograph with a high-resolution camera 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 mined, which proved that the depression is literally teeming with microbes. This fact amazed scientists, because the extreme conditions prevailing there, as well as the enormous pressure, are far from being a paradise.

3. Bdelloidea


Bdelloidea rotifers are incredibly tiny female invertebrates, usually found in fresh water. Since their discovery, not a single male of this species has been found, and the 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, moreover, 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 the need to survive in an extremely arid environment.

2. Cockroach


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

1. Tardigrades


Tiny aquatic organisms called tardigrades have proven to be the most resilient organisms on our planet. These, at first glance, 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 they are placed in a pond.

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

Living organisms are found 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. Pompeian worms... These deep-sea polychaete worms, not exceeding 13 cm in length, are among the most resistant to high temperatures. Therefore, it is not surprising that they can be found exclusively on hydrothermal springs at the bottom of the oceans (), from which highly mineralized hot water comes. So, for the first time a colony of Pompeian worms was discovered in the early 1980s at hydrothermal springs in Pacific near the Galapagos Islands, and later, in 1997, near Costa Rica and again at hydrothermal vents.

Usually, the Pompeian worm places its body in the pipe-like structures of black smokers, where the temperature reaches 80 ° C, and it sticks out its feathery head, where the temperature is lower (about 22 ° C). Scientists have long sought to understand how the Pompeian worm can withstand such extreme temperatures. Studies have shown that this is helped by special bacteria that form a layer up to 1 cm thick on the back of the worm, resembling a woolen blanket. In a symbiotic relationship, the worms secrete mucus from tiny glands on their back, which bacteria feed on, 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. Caterpillar Gynaephora... Greenland and Canada are home to the moth Gynaephora groenlandica, known for its ability to withstand extremely low temperatures. So, living in cold climates, the caterpillars of G. groenlandica, while hibernating, can tolerate temperatures down to -70 ° C! This is made possible by compounds (glycerin and betaine) that caterpillars begin to synthesize in late summer when temperatures drop. These substances prevent the formation of ice crystals in the cells of the animal and thereby prevent it from freezing to death.

However, this is not the only feature of the species. While it takes about a month for most other species to transform from eggs to adult, G. groenlandica can take 7 to 14 years to develop! This slow growth of Gynaephora groenlandica is due to the extreme environmental conditions in which the insect has to develop. It is interesting that the caterpillars of Gynaephora groenlandica spend most of their life in hibernation, and the rest of the time (about 5% of their life) 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 and feed on crude oil. This species was first discovered at La Brea Ranch in California, where there are several bituminous lakes.

Authors: Michael S. Caterino & Cristina Sandoval. As you know, 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 slick. Flies eat large amounts of oil, but mainly insects that enter it. Sometimes the intestines of flies are completely filled with oil. Until now, scientists have not described the mating behavior of these flies, as well as where they lay their eggs. However, it is assumed that this is not happening inside the oil basin.

A bituminous lake at La Brea Ranch in California. Interestingly, the temperature of the oil in the basin can reach 38 ° C, but the larvae can easily tolerate these changes. 4. Artemia... Located in the northwestern part of the American state of Utah, the Great Salt Lake has a salinity of up to 270 ppm (for comparison: the saltiest sea in the World Ocean - the Red Sea - has a salinity of only 41 ppm). The extremely high salinity of the reservoir makes it unsuitable for the life of all living things in it, except for the larvae of coastal flies, some algae and Artemia - 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 at least 60 ppm. This feature allows brine shrimp to avoid cohabitation with most predator species, such as fish. These crustaceans have a segmented body with a wide leaf-like appendage at the end, and usually do not exceed 12 millimeters in length. They are widely used as food for aquarium fish and are also bred in aquariums. 5. Tardigrades... These tiny creatures, no more than 1 millimeter in length, are the most resistant animals to high temperatures. They live in different parts of 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 freezing. And soon it was found out that these animals are able not only to endure extreme temperatures, but also to do without food and water for more than 10 years!

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

.(Source: "Biological Encyclopedic Dictionary." - M .: Sov.Encyclopedia, 1986.)

See what "THERMOPHILIC ORGANISMS" are in other dictionaries:

- (thermo ... gr. phileo I love) thermophilic organisms (mostly microscopic) that can live at relatively high temperatures(up to 70); their natural habitat are various hot springs and thermal waters Wed cryophilic ... ... Dictionary of foreign words of the Russian language

- (from thermo (See thermo ...) ... and Greek philéo I love) thermophiles, organisms that live at temperatures exceeding 45 ° C (fatal for most living things). These are some fish, representatives of various invertebrates (worms, ... ... Great Soviet Encyclopedia

- ... Wikipedia

Organisms Scientific classification Classification: Organisms of the Super Kingdom Nuclear Non-nuclear Organism (late lat. Organismus from late Latin organizo ... Wikipedia

Lower organisms, like all living things in general, can live only under precisely defined external conditions their existence, that is, the conditions of the environment in which they live, and for each external factor, for temperature, pressure, humidity, etc.

This is the name of bacteria that have the ability to develop at temperatures above 55-60 ° C. Miquel was the first to find and isolated from the water of the Seine an immobile bacillus capable of living and multiplying at a temperature of 70 ° C. Van Tieghem ... Encyclopedic Dictionary of F.A. Brockhaus and I.A. Efron

Organisms Scientific classification Classification: Organisms of the Superkingdom Nuclear Non-nuclear Organism (late lat. Organismus from late Latin organizo ... Wikipedia - See also: Largest organisms Smallest organisms are all representatives of bacteria, animals, plants and other organisms found on Earth, which have minimal values ​​in their classes (units) by parameters such as ... Wikipedia