ecological niches. The concept of an ecological niche

Abstract on ecology

Man is one of the representatives of the animal kingdom, a biological species of the class of mammals. Despite the fact that it has many specific properties (reason, articulate speech, labor activity, biosociality, etc.), it has not lost its biological essence and all the laws of ecology are valid for it to the same extent as for other organisms.

A person has his own, unique to him, ecological niche, i.e. a set of requirements for a variety of environmental factors, developed in the process of evolution. The space in which the human niche is localized (ie, the place where the regimes of factors do not go beyond the limits of tolerance inherited from the ancestors) is very limited. As a biological species, a person can live only within the land of the equatorial belt (tropics, subtropics), where the hominid family arose. Vertically, the niche extends approximately 3.0-3.5 km above sea level.

Due to its specific (primarily social) properties, man has expanded the boundaries of his initial range, settled in high, middle and low latitudes, mastering the depths of the ocean and space. However, its fundamental ecological niche remained practically unchanged, and outside its original range it can survive, overcoming the resistance of limiting factors not through adaptations, but with the help of specially created protective devices and devices (heated dwellings, warm clothes, oxygen devices, etc.). .), which imitate its niche in the same way as it is done for exotic animals and plants in zoos, oceanariums, botanical gardens. Nevertheless, it is not always possible to fully reproduce all the factors necessary for a person from the point of view of the law of tolerance. For example, in space flight it is impossible to reproduce such the most important factor, like gravity, and after returning to Earth from a long space expedition, astronauts need time to readapt.

In industrial environments, many factors (noise, vibration, temperature, electromagnetic fields, impurities of a number of substances in the air, etc.) are periodically or permanently beyond the tolerance of the human body. This negatively affects him: so-called occupational diseases, periodic stresses may occur. Therefore, there is a special system of technical and organizational measures aimed at ensuring safety labor activity by reducing the level of impact on the body of hazardous and harmful production factors.

It is far from always possible to ensure optimal conditions for such factors, and therefore, for a number of industries, the total length of service of employees is limited, the length of the working day is reduced (for example, when working with harmful substances up to four hours).

Human production and economic activities, the use (processing) of natural resources inevitably lead to the formation of by-products (“waste”) dispersed in the environment. Chemical compounds entering the water, soil, atmosphere, and food are environmental factors and, consequently, elements of the ecological niche. In relation to them (especially to the upper limits), the resistance of the human body is small, and such substances turn out to be limiting factors that destroy its niche.

From the foregoing, one of the basic rules of nature protection from an ecological point of view follows: protection of nature (environment) consists in a system of measures to preserve the ecological niches of living organisms, including humans. Thus, either the human niche will be preserved for present and future generations, or the human being as a biological species is doomed to extinction.

1. General Provisions. Living beings, both plants and animals, are many and varied. There is no doubt that this diversity and abundance of organisms is determined by environmental factors. Thus, each species occupies a strictly assigned place in the geographic space with a specific set of physical and chemical parameters. However, the position of a species depends not only on abiotic environmental factors, but also on the relationships of a given organism with other organisms, both within its own species and with representatives of other species. The wolf will not live in those geographic areas, even if the set of abiotic factors is quite acceptable for him, if there is no food resource for him here. Therefore, the place that a species occupies in a particular habitat must be determined not only by the territory, but also be associated with the need for food and the function of reproduction. Each of the species, as well as a specific organism, in a community (biocenosis) has its own time of stay and its place, which distinguish it from other species.

Thus, we meet with different concepts. First, this area species - the distribution of the species in geographic space (the geographical aspect of the species), secondly, species habitat(habitat or biotope) is the type of geographic space in terms of a set of physical and chemical parameters and (or) biotic characteristics where the species lives and, thirdly, ecological niche, implying something more than just the place where this species lives. A species can occupy a number of different habitats in different parts of its range.

The best and most accurate comparative definition of the ecological niche and environment was given by the French ecologists R. Wiebert and C. Lagler: Wednesday is the address where the given organism resides, while niche additionally indicates the type of his occupation in this place, his profession.

Some ecologists are more willing to use the term "habitat," which is almost synonymous with "habitat," and the two terms often overlap, but remember that "habitat" refers only to the space in which a species occurs. In this sense, this term is very close to the concept of the range of a species.

2. Habitat. This is a piece of land or a body of water occupied by a population of one species or part of it and possessing for its existence all necessary conditions(climate, topography, soil, nutrients). The habitat of a species is a set of sites that meet its ecological requirements within the species range. Thus, a habitat is nothing but a component of an ecological niche. According to the breadth of the use of habitats, they distinguish stenotopic and eurytopic organisms, i.e. organisms that occupy specific spaces with a specific set of environmental factors, and organisms that exist in a wide range of environmental factors (cosmopolitans). If we are talking about the habitat of a community of organisms or the place of a biocenosis, then the term "biotope" is more often used. Location has another synonym ecotope– geographical space characterized by a specific set of environmental parameters. In this case, the population of any species living in a given space is called ecotype.

The term "habitat" can be applied both to specific organisms and to communities as a whole. We can point to a meadow as a single habitat for various herbs and animals, although both herbs and animals occupy different ecological niches. But this term should never replace the concept of "ecological niche".

Habitat can refer to a complex of interconnected some living and non-living characteristics of a geographic space. For example, the habitat of aquatic insects of the smooth bug and the float is shallow areas of lakes covered with vegetation. These insects occupy the same habitat, but have different trophic chains (smooth is an active predator, while float feeds on decaying vegetation), which distinguishes the ecological niches of these two species.

Habitat can also refer only to the biotic environment. This is how bacilli and bacteria live inside other organisms. Lice live in the hairline of the host. Some mushrooms are associated with a particular type of forest (boletus). But the habitat can also be represented by a purely physical-geographical environment. You can point to the tidal coast of the sea, where such a variety of organisms live. It can be a desert, and a separate mountain, dunes, a stream and a river, a lake, etc.

3. ecological niche concept, according to Y. Oduma, more capacious. Ecological niche, as shown by an English scientist C. Elton(1927), includes not only the physical space occupied by the organism, but also the functional role of the organism in the community. Elton distinguished niches as the position of a species in relation to other species in a community. Ch. Elton's idea that a niche is not a synonym for a habitat has received wide recognition and distribution. The trophic position, way of life, connections with other organisms, etc. are very important for the organism. and its position relative to the gradients of external factors as conditions of existence (temperature, humidity, pH, soil composition and type, etc.).

These three aspects of the ecological niche (space, the functional role of the organism, external factors) can be conveniently referred to as spatial niche(niche place) trophic niche(functional niche), in the understanding of Ch. Elton, and multidimensional niche(the whole volume and set of biotic and abiotic characteristics are taken into account, hypervolume). The ecological niche of an organism depends not only on where it lives, but also includes the total amount of its environmental requirements. The body not only experiences the action of environmental factors, but also makes its own demands on them.

4. The modern concept of ecological niche formed on the basis of the model proposed J. Hutchinson(1957). According to this model, an ecological niche is a part of an imaginary multidimensional space (hypervolume), individual dimensions of which correspond to the factors necessary for the normal existence and reproduction of an organism. Hutchinson's niche, which we will call multidimensional (hyperspace), can be described using quantitative characteristics and operated with it using mathematical calculations and models. R. Whittaker(1980) defines an ecological niche as the position of a species in a community, implying that the community is already associated with a particular biotope, i.e. with a certain set of physical and chemical parameters. Therefore, an ecological niche is a term used to denote the specialization of a population of a species within a community. Groups of species in a biocenosis with similar functions and niches of the same size are called guilds. Species that occupy the same niche in different geographical areas are called environmental equivalents.

5. Individuality and originality of ecological niches. No matter how close in habitat organisms (or species in general) are, no matter how close their functional characteristics in biocenoses are, they will never occupy the same ecological niche. Thus, the number of ecological niches on our planet is uncountable. Figuratively, one can imagine a human population, all individuals of which have only their own unique niche. It is impossible to imagine two absolutely identical people with absolutely identical morphophysiological and functional characteristics, including such as mental, attitude towards their own kind, an absolute need for the type and quality of food, sexual relations, norm of behavior, etc. But individual niches different people may overlap on individual environmental parameters. For example, students can be linked by one university, specific teachers, and at the same time, they can differ in their behavior in society, in the choice of food, biological activity, etc.

6. Measuring ecological niches. To characterize a niche, two are usually used. standard measurements – niche width and niche overlap with neighboring niches.

Niche width refers to gradients or the range of some environmental factor, but only within a given hyperspace. The width of a niche can be determined by the intensity of illumination, by the length of the trophic chain, by the intensity of the action of some abiotic factor. The overlapping of ecological niches means overlapping along the width of niches and overlapping of hypervolumes.

7. Types of ecological niches. There are two main types of ecological niches. First, this fundamental(formal) niche - the largest "abstract inhabited hypervolume”, where the action of environmental factors without the influence of competition ensures the maximum abundance and functioning of the species. However, the species experiences constant changes in environmental factors within its range. In addition, as we already know, an increase in the action of one factor can change the relation of a species to another factor (a consequence of Liebig's law), and its range can change. The action of two factors at the same time can change the attitude of the species to each of them specifically. There are always biotic restrictions (predation, competition) within ecological niches. All these actions lead to the fact that in reality the species occupies an ecological space that is much smaller than the hyperspace of the fundamental niche. In this case, we are talking about realized niche, i.e. real niche.

8 . Principle VanderMeer and Gause. J.H. Vandermeer (1972) greatly expanded the concept of Hutchinson's realized niche. He came to the conclusion that if N interacting species coexist in this particular habitat, then they will occupy completely different realized ecological niches, the number of which will be equal to N. This observation is called the Vandermeer principle.

Competitive interaction can concern both space, nutrients, the use of light (trees in the forest), and the process of fighting for a female, for food, as well as dependence on a predator, susceptibility to disease, etc. Usually, the toughest competition is observed at the interspecific level. It can lead to the replacement of a population of one species by a population of another species, but it can also lead to an equilibrium between two species (usually this the balance of nature is established in the predator-prey system). Extreme cases are the displacement of one species by another outside the given habitat. There are cases when one species displaces another in the trophic chain and forces it to switch to the use of other food. Observation of the behavior of closely related organisms with a similar way of life and similar morphology shows that such organisms try never to live in the same place. This observation was made Joseph Grinell in 1917-1928, who studied the life of California mockingbirds. Grinell actually introduced the concept "niche", but did not introduce into this concept the distinction between niche and habitat.

If closely related organisms live in the same water and in the same place, then they will either use different food resources or lead an active lifestyle in different time(night Day). This ecological separation of closely related species is called principle of competitive exclusion or Gause principle named after the Russian biologist who experimentally demonstrated the operation of this principle in 1932. In his conclusions, Gause used Elton's concept of the position of a species in a community depending on other species.

9. niche space. The ecological niches of species are more than the relation of a species to a single environmental gradient. Many signs or axes of multidimensional space (hypervolume) are very difficult to measure or cannot be expressed by linear vectors (for example, behavior, addiction, etc.). Therefore, it is necessary, as rightly noted by R. Whittaker (1980), to move from the concept of the niche axis (remember the width of the niche in terms of one or more parameters) to the concept of its multidimensional definition, which will reveal the nature of species relationships with their full range of adaptive relationships .

If a niche is a "place" or "position" of a species in a community according to Elton's concept, then it is right to give it some measurements. According to Hutchinson, a niche can be defined by a number of environmental variables within a community to which a species must be adapted. These variables include both biological indicators (for example, food size) and non-biological ones (climatic, orographic, hydrographic, etc.). These variables can serve as axes along which a multidimensional space is recreated, which is called ecological space or niche space. Each of the species can adapt or be resistant to some range of values ​​of each variable. The upper and lower limits of all these variables delineate the ecological space that a species can occupy. This is the fundamental niche in Hutchinson's understanding. In a simplified form, this can be imagined as an "n-sided box" with sides corresponding to the stability limits of the view on the axes of the niche.

By applying a multidimensional approach to the space of a community niche, we can find out the position of species in space, the nature of the response of a species to exposure to more than one variable, the relative sizes of niches.

Every organism during its existence is influenced by different conditions environment. These can be factors of animate or inanimate nature. Under their influence, through adaptation, each species takes its place - its ecological niche.

general characteristics

The general characteristic of a cell occupied by an animal or plant consists of the definition and description of its model.

An ecological niche is a place that a species or an individual organism occupies in a biocenosis. It is determined taking into account the complex of biocenotic relationships, abiotic and biotic factors of the environment. There are many interpretations of this term. According to the definitions of various scientists, the ecological niche was also called spatial or trophic. This is because, settling in his cell, the individual occupies the territory he needs and creates his own food chains.

J. E. Hudchence's model of hypervolume dominates today. It is a cube, on its axes there are environmental factors that have their own range (valency). The scientist divided niches into 2 groups:

• Fundamental ones are those that create optimal conditions and are equipped with the necessary resources to maintain the life of the population.
• Implemented. They have a number of properties that are due to competing species.

Characteristics of ecological niches

The characteristics of ecological niches include three main components:

• Behavioral characteristic is a way of responding of a species to stimuli. And also how he gets food, the features of his shelter from enemies, adaptability to abiotic factors (for example, the ability to withstand cold or heat).
• Spatial characteristic. These are the location coordinates of the population. For example, penguins live in Antarctica, New Zealand, South America.
• Temporary. It describes the activity of species in a certain period of time: day, year, season.

Principle of competitive exclusion

The principle of competitive exclusion states that there are as many ecological niches as there are species of different organisms. Its author is the famous scientist Gause. He discovered patterns while working with ciliates different types. The scientist grew organisms first in a monoculture, studying their density and mode of nutrition, and later combined the species for breeding in one container. It was noticed that each species significantly reduced the number, and as a result of the struggle for food, each organism occupied its own ecological niche.

It cannot be that two different species occupy the same cell in the biocenosis. To become a winner in this competitive struggle, one of the species must have some advantage over the other, be more adapted to environmental factors, since even very similar species always have some differences.

Law of constancy

The law of constancy is based on the theory that the biomass of all organisms on the planet must remain unchanged. This statement was confirmed by V. I. Vernadsky. He - the founder of the doctrine of the biosphere and noosphere - was able to prove that with an increase or decrease in the number of organisms in one niche, it is necessarily compensated in another.

This means that an extinct species is replaced by any other that can easily and quickly adapt to environmental conditions and increase its population. Or, conversely, with a significant increase in the number of some organisms, the number of others decreases.

Mandatory rule

The mandatory filling rule states that an ecological niche never remains empty. When a species goes extinct for any reason, its place is immediately taken by another. The organism that occupies the cell enters into a competitive struggle. If he turns out to be weaker, he is forced out of the territory and forced to look for another place to settle.

Ways of coexistence of organisms

Ways of coexistence of organisms can be conditionally divided into positive - those that benefit all organisms, and negative, which are beneficial only to one species. The first was called "symbiosis", the second - "mutualism".

Commensalism is a relationship in which organisms do not harm each other, but do not help either. It can be intraspecific and interspecific.

Amensalism is an interspecies mode of coexistence in which one species is oppressed by another. At the same time, one of them does not receive nutrients in the required amount, which slows down its growth and development.

Predation - Predatory species with this method of coexistence feed on the body of the victims.

Competition can be within the same species or between different ones. It appears under the condition that organisms need the same food or territory with optimal climatic conditions for them.

The evolution of human ecological niches

The evolution of human ecological niches began with the existence of archanthropes. They led a collective way of life, used only those abundances of nature that were the most accessible to them. The consumption of animal food in this period of existence was reduced to a minimum. To search for food, the archanthropes had to master a large number of forage area.

After man mastered the tool of labor, people began to hunt, thereby having a considerable impact on environment. As soon as a person got fire, he made the transition to the next stage of development. After the increase in population, agriculture arose - as one of the ways to adapt to the lack of food in those places where intensive hunting and gathering Natural resources were almost exhausted. In the same period, livestock raising began. This led to a settled way of life.

Then there was nomadic pastoralism. As a result of human nomadic activity, a huge amount of pastures is depleted, this forces nomads to move and develop more and more new lands.

Human ecological niche

The ecological niche of a person is changing along with changes in the way people live. Homo sapiens differs from other living organisms in the ability to articulate speech, abstract thinking, high level development of material and non-material culture.

Man as a biological species was distributed in the tropics and subtropics, in places where the height above sea level was up to 3-3.5 km. Due to certain features that a person is endowed with, his habitat has greatly increased in size. But as far as the fundamental ecological niche is concerned, it has remained virtually unchanged. The existence of a person becomes more complicated outside the original space, he has to confront various unfavorable factors. This is possible not only through the adaptation process, but also through the invention of various defense mechanisms and devices. So, for example, man invented different types heating systems to combat such abiotic factors as cold.

Thus, we can conclude that the ecological niche is occupied by each organism after competition and adheres to certain rules. It should have an optimal area of ​​​​the territory, suitable climatic conditions and be provided by living organisms that are part of the food chain of the dominant species. All living beings that are within the niche necessarily interact.

One of the main concepts in modern ecology is the concept of an ecological niche. For the first time, zoologists started talking about an ecological niche. In 1914, the American naturalist zoologist J. Grinnell and in 1927 the English ecologist C. Elton used the term "niche" to define the smallest unit of distribution of a species, as well as the place of a given organism in the biotic environment, its position in food chains.

The generalized definition of an ecological niche is the following: this is the place of a species in nature, due to a cumulative set of environmental factors. The ecological niche includes not only the position of the species in space, but also its functional role in the community.

- this is a set of environmental factors within which a particular type of organism lives, its place in nature, within which this species can exist indefinitely.

Since when determining the ecological niche, one should take into account big number factors, then the place of the species in nature, described by these factors, is a multidimensional space. This approach allowed the American ecologist G. Hutchinson to give the following definition of an ecological niche: it is a part of an imaginary multidimensional space, the individual dimensions of which (vectors) correspond to the factors necessary for the normal existence of a species. At the same time, Hutchinson singled out a niche fundamental, which can be occupied by the population in the absence of competition (it is determined physiological characteristics organisms), and a niche implemented, those. part of the fundamental niche within which a species actually occurs in nature and which it occupies in the presence of competition with other species. It is clear that the realized niche, as a rule, is always less than the fundamental one.

Some ecologists stress that, within their ecological niche, organisms must not only occur, but also be able to reproduce. Since there is species specificity for any environmental factor, insofar as the ecological niches of species are specific. Each species has its own ecological niche.

Most species of plants and animals can only exist in special niches that support certain physico-chemical factors, temperature, and food sources. After the destruction of bamboo began in China, for example, the panda, whose diet for 99% consists of this plant, was on the verge of extinction.

Species with common niches can easily adapt to changing habitat conditions, so the danger of their extinction is low. Typical representatives of species with common niches are mice, cockroaches, flies, rats and humans.

G. Gause's law of competitive exclusion for ecologically close species in the light of the doctrine of the ecological niche can be formulated as follows: two species cannot occupy the same ecological niche. An exit from competition is achieved by a divergence of requirements for the environment, or, in other words, by delineation of the ecological niches of species.

Competing species that live together often "share" available resources to reduce competition. A typical example is the division into animals that are active during the day and those that are active at night. Bats (every fourth mammal in the world belongs to this suborder of bats) share the airspace with other insect hunters - birds, using the change of day and night. True, bats have a few relatively weak competitors, such as owls and nightjars, which are also active at night.

A similar division of ecological niches into day and night "shifts" is observed in plants. Some plants bloom during the day (most wild-growing species), others - at night (two-leafed love, fragrant tobacco). At the same time, nocturnal species also emit an odor that attracts pollinators.

Ecological amplitudes of some species are very small. So, in tropical Africa, one of the species of worms lives under the eyelids of a hippopotamus and feeds exclusively on the tears of this animal. A narrower ecological niche is hard to imagine.

The concept of the ecological niche of a species

The position of the species that it occupies in the general system of biocenosis, including the complex of its biocenotic relationships and requirements for abiotic environmental factors, is called ecological niche of the species.

The concept of an ecological niche has proved to be very fruitful for understanding the laws of cohabitation of species. The concept of "ecological niche" should be distinguished from the concept of "habitat". In the latter case, that part of the space is meant which is inhabited by the species and which has the necessary abiotic conditions for its existence.

The ecological niche of a species depends not only on abiotic environmental conditions, but also, to no lesser extent, on its biocenotic environment. This is a characteristic of the lifestyle that a species can lead in a given community. How many species of living organisms there are on Earth - the same number of ecological niches.

Competitive exclusion rule can be expressed in such a way that two species do not get along in the same ecological niche. The way out of competition is achieved due to the divergence of requirements for the environment, a change in lifestyle, which is the delimitation of the ecological niches of species. In this case, they acquire the ability to coexist in one biocenosis.

Separation of ecological niches by cohabiting species with partial overlap one of the mechanisms of sustainability of natural biocenoses. If any of the species drastically reduces its numbers or falls out of the community, others take over its role.

The ecological niches of plants, at first glance, are less diverse than those of animals. They are clearly delineated in species that differ in nutrition. In ontogenesis, plants, like many animals, change their ecological niche. As they age, they use and transform their environment more intensively.

Plants have overlapping ecological niches. It intensifies in certain periods when environmental resources are limited, but since species use resources individually, selectively and with different intensity, competition in stable phytocenoses is weakened.

The richness of ecological niches in the biocenosis is influenced by two groups of reasons. The first is the environmental conditions provided by the biotope. The more mosaic and diverse the biotope, the more species can demarcate their ecological niches in it.

ecological niche

1. The concept of "ecological niche"

2. Ecological niche and ecosystems

Conclusion

Literature

1. The concept of "ecological niche"

ecological niche , the place occupied by a species (more precisely, by its population) in a community (biocenosis). The interaction of a given species (population) with partners in the community to which it belongs as a member determines its place in the cycle of substances due to food and competitive ties in the biocenosis. The term "Ecological niche" was proposed by the American scientist J. Grinell (1917). The interpretation of an ecological niche as the position of a species in the food chains of one or more biocenoses was given by the English ecologist C. Elton (1927). Such an interpretation of the concept of ecological niche makes it possible to quantify the ecological niche for each species or for its individual populations. To do this, the abundance of the species (number of individuals or biomass) is compared in the coordinate system with indicators of temperature, humidity, or any other environmental factor. In this way, it is possible to single out the optimum zone and the limits of the deviations tolerated by the species—the maximum and minimum of each factor or set of factors. As a rule, each species occupies a definite ecological niche, to which it is adapted throughout the course of evolutionary development. The place occupied by a species (its population) in space (spatial ecological niche) is more often called a habitat.

Ecological niche - the spatio-temporal position of an organism within an ecosystem (where, when and what it eats, where it nests, etc.)

At first glance, it seems that animals must compete with each other for food and shelter. However, this rarely happens, because. they occupy different ecological niches. Example: woodpeckers extract larvae from under the bark, sparrow-grain. Both flycatchers and bats catch midges, but at different times - day and night. The giraffe eats leaves from the tops of trees and does not compete with other herbivores.

Each animal species has its own niche, which minimizes competition with other species. Therefore, in a balanced ecosystem, the presence of one species usually does not threaten another.

Adaptation to different niches is associated with the law of the limiting factor. Trying to use resources outside of its niche, the animal faces stress, i.e. with an increase in the resistance of the medium. In other words, in its own niche its competitiveness is great, and outside it it significantly weakens or disappears altogether.

Adaptation of animals to certain niches took millions of years and proceeded in each ecosystem in its own way. Species imported from other ecosystems can cause local extinction precisely as a result of successful competition for their niches.

1. Starlings, brought to North America from Europe, due to their aggressive territorial behavior, forced out the local "blue" birds.

2. Feral donkeys poisoned desert ecosystems, displacing bighorn sheep from there.

3. In 1859, rabbits were brought to Australia from England for sport hunting. Natural conditions turned out to be favorable for them, and local predators were not dangerous. As a result

4. Farmers are looking for methods to combat a weed that has never been seen before in the Nile Valley. A low plant with large leaves and a powerful root has been advancing on the cultivated lands of Egypt for several years. Local agronomists consider it an extremely active pest. It turns out that this plant is known in Europe under the name "country horseradish". Probably it was brought by Russian specialists who built the metallurgical plant.

The concept of ecological niche applies to plants as well. Like animals, their competitiveness is high only under certain conditions.

Example: Plane trees grow along the banks of rivers and in floodplains, oaks on the slopes. The plane tree is adapted to waterlogged soil. Sycamore seeds spread upslope and this species can grow there in the absence of oaks. Similarly, acorns, falling into the floodplain, die due to excess moisture and are not able to compete with plane trees.

The ecological niche of a person - the composition of air, water, food, climatic conditions, the level of electromagnetic, ultraviolet, radioactive radiation etc.

2. Ecological niche and ecosystems

At different times, different meanings were attributed to the concept of an ecological niche. At first, the word "niche" denoted the basic unit of distribution of a species within the space of an ecosystem, dictated by the structural and instinctive limitations of a given species. For example, squirrels live in trees, moose live on the ground, some bird species nest on branches, others in hollows, etc. Here the concept of an ecological niche is interpreted mainly as a habitat, or a spatial niche. Later, the term "niche" was given the meaning of "the functional status of an organism in a community." This mainly concerned the place of a given species in the trophic structure of the ecosystem: the type of food, the time and place of feeding, who is the predator for this organism, etc. This is now called a trophic niche. Then it was shown that a niche can be considered as a kind of hypervolume in a multidimensional space built on the basis of environmental factors. This hypervolume limited the range of factors in which a given species could exist (the hyperspace niche).

That is, in the modern understanding of the ecological niche, at least three aspects can be distinguished: the physical space occupied by an organism in nature (habitat), its relationship to environmental factors and living organisms adjacent to it (connections), as well as its functional role in the ecosystem. All these aspects are manifested through the structure of the organism, its adaptations, instincts, life cycles, life “interests”, etc. The right of an organism to choose its ecological niche is limited by rather narrow limits assigned to it from birth. However, its descendants can claim other ecological niches if they have undergone appropriate genetic changes.

Using the concept of an ecological niche, Gause's rule of competitive exclusion can be rephrased as follows: two different species cannot long time occupy one ecological niche and even enter one ecosystem; one of them must either die or change and occupy a new ecological niche. By the way, intraspecific competition is often greatly reduced precisely because different stages life cycle, many organisms occupy different ecological niches. For example, a tadpole is a herbivore, while adult frogs that live in the same pond are predators. Another example: insects in the larval and adult stages.

A large number of organisms of different species can live in one area in an ecosystem. These may be closely related species, but each of them must occupy its own unique ecological niche. In this case, these species do not enter into competitive relations and, in a certain sense, become neutral to each other. However, often the ecological niches of different species may overlap in at least one of the aspects, such as habitat or diet. This leads to interspecific competition, which is usually not tough and contributes to the clear delineation of ecological niches.

Thus, ecosystems implement a law similar to the Pauli exclusion principle in quantum physics: in a given quantum system, more than one fermion (particles with half-integer spin, such as electrons, protons, neutrons, etc.) cannot be in the same quantum state. ). In ecosystems, the quantization of ecological niches also takes place, which tend to be clearly localized in relation to other ecological niches. Within a given ecological niche, that is, within a population that occupies this niche, differentiation continues into more private niches occupied by each individual, which determines the status of this individual in the life of this population.

Does such a differentiation occur for more low levels system hierarchy, for example, at the level of a multicellular organism? Here you can also distinguish various “types” of cells and smaller “bodies”, the structure of which determines them. functional purpose inside the body. Some of them are immobile, their colonies form organs, the purpose of which makes sense only in relation to the organism as a whole. There are also mobile simple organisms that seem to live their own "personal" life, which nevertheless fully satisfies the needs of the entire multicellular organism. For example, red blood cells do only what they “can”: bind oxygen in one place, and release it in another place. This is their “ecological niche”. The vital activity of each cell of the body is built in such a way that, “living for itself”, it simultaneously works for the benefit of the whole organism. Such work does not tire us at all, just as the process of eating food, or doing what we love does not tire us (unless, of course, all this is in moderation). Cells are arranged in such a way that they simply cannot live in any other way, just as a bee cannot live without collecting nectar and pollen from flowers (probably, this brings her some kind of pleasure).

Thus, the whole nature “from top to bottom” seems to be permeated with the idea of ​​differentiation, which in ecology took shape in the concept of an ecological niche, which in a certain sense is similar to an organ or subsystem of a living organism. These “organs” themselves are formed under the influence of the external environment, that is, their formation is subject to the requirements of the supersystem, in our case, the biosphere.

So it is known that under similar conditions similar ecosystems are formed with the same set of ecological niches, even if these ecosystems are located in different geographical areas separated by insurmountable obstacles. The most striking example in this regard is the living world of Australia, which for a long time developed separately from the rest of the land world. In the ecosystems of Australia, functional niches can be identified that are equivalent to the corresponding niches of ecosystems on other continents. These niches are occupied by those biological groups that are present in the fauna and flora of a given area, but are similarly specialized for the same functions in the ecosystem that are characteristic of this ecological niche. Such types of organisms are called ecologically equivalent. For example, the large kangaroos of Australia are equivalent to the bison and antelopes of North America (on both continents, these animals are now replaced mainly by cows and sheep).

Similar phenomena in the theory of evolution are called parallelism. Very often, parallelism is accompanied by convergence (convergence) of many morphological (from the Greek word morphe - form) features. So, despite the fact that the whole world was conquered by plantar animals, in Australia, for some reason, almost all mammals are marsupials, with the exception of a few species of animals brought much later than the living world of Australia finally took shape. However, marsupial mole, and marsupial squirrel, and marsupial wolf, etc. are also found here. All these animals are not only functionally, but also morphologically similar to the corresponding animals of our ecosystems, although there is no relationship between them.

All this testifies in favor of the presence of a certain “program” for the formation of ecosystems in these specific conditions. All matter, each particle of which hologram stores information about the entire Universe, can act as “genes” that store this program. This information is realized in the actual world in the form of laws of nature, which contribute to the fact that various natural elements can be added to ordered structures not at all in an arbitrary way, but in the only possible way, or at least in several possible ways. So, for example, a water molecule, obtained from one oxygen atom and two hydrogen atoms, has the same spatial shape, regardless of whether the reaction took place in our country or in Australia, although according to Isaac Asimov's calculations, only one chance is realized. out of 60 million. Probably, something similar happens in the case of the formation of ecosystems.

Thus, in any ecosystem there is a certain set of potentially possible (virtual) ecological niches strictly linked to each other, designed to ensure the integrity and stability of the ecosystem. This virtual structure is a kind of "biofield" of this ecosystem, containing the "standard" of its actual (real) structure. And by by and large, it doesn't even matter what the nature of this biofield is: electromagnetic, informational, ideal or some other. The very fact of its existence is important.

In any naturally formed ecosystem that has not experienced human impact, all ecological niches are filled. This is called the rule of obligation to fill ecological niches. Its mechanism is based on the property of life to densely fill all the space available to it (by space, in this case, we mean the hypervolume of environmental factors). One of the main conditions ensuring the implementation of this rule is the presence of sufficient species diversity.

The number of ecological niches and their interconnection is subordinated to the single goal of the functioning of the ecosystem as a single whole, which has the mechanisms of homeostasis (stability), binding and releasing energy and the circulation of substances. In fact, the subsystems of any living organism are focused on the same goals, which once again indicates the need to revise the traditional understanding of the term “living being”. Just as a living organism cannot exist normally without one or another organ, so an ecosystem cannot be stable if all its ecological niches are not filled. Therefore, the generally accepted definition of an ecological niche given above, apparently, is not entirely correct. It comes from the vital status of a particular organism (reductionist approach), while the first place should be given to the needs of the ecosystem in the implementation of its vital functions (holistic approach). Specific species of organisms can only fill a given ecological niche if it corresponds to their life status. In other words, life status is only a “request” for an ecological niche, but not yet the niche itself. Thus, an ecological niche should, apparently, be understood as a structural unit of an ecosystem characterized by a certain function necessary to ensure the viability of the ecosystem, and which for this must necessarily be filled with organisms with the appropriate morphological specialization.

Conclusion

The position of the population in the ecosystem can be different: from complete dominance (Scotch pine in a pine forest) to complete dependence and subordination (light-loving grasses under the forest canopy). At the same time, on the one hand, it seeks to carry out its life processes as fully as possible in its own interests, and on the other hand, it automatically ensures the vital activity of other populations of the same biocenosis, being a component of the food chain, as well as through topical, adaptive and other connections.

Those. each population, as a full-fledged representative of the species in the ecosystem, has its place in it. The American ecologist R. McIntosh called it an ecological niche.

The main components of ecological niches:

1. A specific habitat (physico-chemical properties of the ecotope and climatic conditions);

2. Biocenotic role (producer, consumer or destroyer of organic matter);

3. Position within one's own trophic level (dominance, co-dominance, subordination, etc.);

4. Place in the food chain;

5. Position in the system of biotic relations.

In other words, an ecological niche is a sphere of vital activity of a species in an ecosystem. Since the species is represented in the ecosystem by one population, it is obvious that it is the population that occupies one or another ecological niche in it. The species, by and large, occupies its ecological niche in the global ecosystem - the biosphere. More difficult is the question of whether an individual has its own ecological niche. A niche not only as a part of the territory of an ecotope, but also as a kind of own and unique role, determined by its ability to struggle for existence. In a number of cases, neither practically nor theoretically, such a role can be singled out. For example, a mosquito in a cloud of mosquitoes or a wheat plant of any variety in an agrocenosis does not differ from each other in any significant parameters. In other cases, the presence of its own ecological niche is obvious: a leader in a pack of wolves, a queen bee in a hive of bees, etc. It is obvious that the more differentiated or socially the community (population), the more clearly the signs of the ecological niches of each individual are manifested. They are most clearly differentiated and outlined in human communities: the president of the state, the head of a firm, a pop star, and so on. etc.

So in general ecology Ecological niches are considered as a reality for such taxa as a species (subspecies, variety) and population, and for separate heterogeneous communities - for an individual. In homogeneous communities, considering the place and role of individuals, it is quite possible to use the term microniche.

Literature

1. Radkevich V.A. Ecology.- Mn.: Vysh.shk., 1997, p.107-108.
2. Solbrig O., Solbrig D. Population biology and evolution. - M.: Mir, 1982.
3. Mirkin B.M. What are plant communities. - M.: Nauka, 1986, pp. 38-53.
4. Mamedov N.M., Surovegina I.T. Ecology. - M.: School-Press, 1996, pp. 106-111.
5. Shilov I.A. Ecology. - M.: Higher school, 2000, pp. 389-393.