Concept ecological niche. In an ecosystem, any living organism is evolutionarily adapted (adapted) to certain environmental conditions, i.e. to changing abiotic and biotic factors. Changes in the values ​​of these factors for each organism are permissible only within certain limits, within which the normal functioning of the organism is maintained, i.e. its viability. The greater the range of changes in environmental parameters a particular organism allows (normally withstands), the higher the resistance of this organism to changes in environmental factors. The requirements of a certain species to various environmental factors determine the species’ range and its place in the ecosystem, i.e. the ecological niche it occupies.

Ecological niche– a set of living conditions in an ecosystem, imposed by a species on many environmental factors environment from the point of view of its normal functioning in the ecosystem. Consequently, the concept of an ecological niche primarily includes the role or function performed by this type in the community. Each species occupies its own, unique place in the ecosystem, which is determined by its need for food and is associated with the function of reproduction of the species.

The relationship between the concepts of niche and habitat. As shown in the previous section, a population first needs a suitable habitat, which in its abiotic (temperature, soil type, etc.) and biotic (food resources, vegetation type, etc.) factors would correspond to its needs. But the habitat of a species should not be confused with an ecological niche, i.e. the functional role of the species in a given ecosystem.

Conditions for the normal functioning of the species. Essential for every living organism biotic factor is food. It is known that the composition of food is determined primarily by the set of proteins, hydrocarbons, fats, as well as the presence of vitamins and microelements. The properties of food are determined by the content (concentration) of individual ingredients. Of course, the required properties of food differ for different types of organisms. The lack of any ingredients, as well as their excess, have harmful effects on the viability of the organism.

The situation is similar with other biotic and abiotic factors. Therefore, we can talk about the lower and upper limits of each environmental factor, within which normal functioning of the body is possible. If the value of the environmental factor becomes lower than it lower limit or above the upper limit for a given species, and if this species cannot quickly adapt to changed environmental conditions, then it is doomed to extinction and its place in the ecosystem (ecological niche) will be occupied by another species.

Previous materials:

Ecological niche– the totality of all environmental factors within which the existence of a species in nature is possible. Concept ecological niche usually used when studying the relationships of ecologically similar species belonging to the same trophic level. The term “ecological niche” was proposed by J. Greenell (1917) to characterize the spatial distribution of species (i.e., the ecological niche was defined as a concept close to habitat).

Later, C. Elton (1927) defined an ecological niche as the position of a species in a community, emphasizing the special importance of trophic relationships. Back in the late 19th and early 20th centuries, many researchers noticed that two species, ecologically close and occupying a similar position in the community, could not coexist stably in the same territory. This empirical generalization has been confirmed in mathematical model competition of two species for one food (V. Volterra) and experimental work G.F. Gause ( Gause's principle).

Modern concept ecological niche formed on the basis of the ecological niche model proposed by J. Hutchinson (1957, 1965). According to this model, an ecological niche can be represented as part of an imaginary multidimensional space (hypervolume), the individual dimensions of which correspond to the factors necessary for the normal existence of a species.

The divergence of ecological niches of different species through divergence occurs for the most part due to being confined to different habitats, different foods and different times of use of the same habitat. Methods have been developed for assessing the width of an ecological niche and the degree of overlap of ecological niches various types. Liter: Giller P. Community structure and ecological niche. – M.: 1988 (according to BES, 1995).

In environmental modeling the concept ecological niche characterizes a certain part of the space (abstract) of environmental factors, a hypervolume in which none of the environmental factors goes beyond the tolerance limits of a given species (population). The set of such combinations of values ​​of environmental factors at which the existence of a species (population) is theoretically possible is called fundamental ecological niche.

Realized ecological niche They call part of the fundamental niche, only those combinations of factor values ​​at which the stable or prosperous existence of a species (population) is possible. Concepts sustainable or prosperous existence require the introduction of additional formal restrictions when modeling (for example, mortality should not exceed birth rate).

If, with a given combination of environmental factors, a plant can survive, but is not able to reproduce, then we can hardly talk about well-being or sustainability. Therefore, this combination of environmental factors refers to the fundamental ecological niche, but not to the realized ecological niche.

Outside the framework of mathematical modeling, of course, there is no such rigor and clarity in the definition of concepts. In modern environmental literature, four main aspects can be distinguished in the concept of an ecological niche:

1) spatial niche, including a complex of favorable environmental conditions. For example, insectivorous birds of spruce-blueberry live, feed and nest in different layers of the forest, which largely allows them to avoid competition;

2) trophic niche. It stands out especially because of the enormous importance of food as an environmental factor. The separation of food niches among organisms of the same trophic level living together allows not only to avoid competition, but also contributes to a more complete use of food resources and, therefore, increases the intensity of biological cycle substances.

For example, the noisy population of bird markets creates the impression complete absence any order. In fact, each bird species occupies a strictly defined position. biological features trophic niche: some feed near the shore, others at a considerable distance, some fish near the surface, others at depth, etc.

The trophic and spatial niches of different species may partially overlap (remember: the principle of ecological duplication). Niches can be wide (non-specialized) or narrow (specialized).

3) multidimensional niche, or a niche as a hypervolume. The idea of ​​a multidimensional ecological niche is associated with mathematical modeling. The entire set of combinations of environmental factor values ​​is considered as a multidimensional space. In that a huge variety we are only interested in such combinations of values ​​of environmental factors under which the existence of an organism is possible - this hypervolume corresponds to the concept of a multidimensional ecological niche.

4) functional idea of ​​an ecological niche. This idea complements the previous ones and is based on the functional similarity of a wide variety of ecological systems. For example, they talk about the ecological niche of herbivores, or small predators, or animals that feed on plankton, or burrowing animals, etc. Functional view emphasizes the ecological niche role organisms in an ecosystem and corresponds to the usual concept of “profession” or even “position in society.” It is in functional terms that we speak of environmental equivalents– species occupying functionally similar niches in different geographical regions.

“An organism's habitat is where it lives, or where it can usually be found. Ecological niche– a more capacious concept that includes not only the physical space occupied by a species (population), but also the functional role of this species in the community (for example, its trophic position) and its position relative to gradients external factors– temperature, humidity, pH, soil and other living conditions. These three aspects of the ecological niche are conveniently referred to as the spatial niche, the trophic niche, and the multidimensional niche, or niche as hypervolume. Therefore, the ecological niche of an organism depends not only on where it lives, but also includes total amount its environmental requirements.

Species that occupy the same niches in different geographical areas, are called environmental equivalents"(Y. Odum, 1986).

V.D. Fedorov and T.G. Gilmanov (1980, pp. 118 – 127) note:

“The study of realized niches by describing the behavior of the well-being function at the cross section of them with straight lines and planes corresponding to some selected environmental factors is widely used in ecology (Fig. 5.1). Moreover, depending on the nature of the factors to which the considered private function well-being, one can distinguish between “climatic”, “trophic”, “edaphic”, “hydrochemical” and other niches, the so-called private niches.

A positive conclusion from the analysis of private niches can be a conclusion from the opposite: if the projections of private niches onto some (especially some) of the axes do not intersect, then the niches themselves do not intersect in a space of higher dimension. ...

Logically there are three options relative position niches of two types in the space of environmental factors: 1) separation (complete mismatch); 2) partial intersection (overlapping); 3) complete inclusion of one niche into another. ...

Niche separation is a fairly trivial case, reflecting the fact of the existence of species adapted to different environmental conditions. Cases of partial overlap of niches are of much greater interest. As mentioned above, overlapping projections even along several coordinates at once, strictly speaking, does not guarantee the actual overlapping of the multidimensional niches themselves. Nevertheless, in practical work, the presence of such intersections and data on the occurrence of species in similar conditions is often considered sufficient evidence in favor of overlapping niches of species.

For quantitative measurement the degree of overlap between the niches of two species, it is natural to use the ratio of the volume of intersection of sets... to the volume of their union. ... In some special cases, it is of interest to calculate the measure of intersection of niche projections.”

TRAINING TESTS FOR TOPIC 5

Define an ecological niche. How do you understand the term “human ecological niche”?

environmental adaptive recycling pollutant

An ecological niche is the position of a species that it occupies in common system biocenosis, the complex of its biocenotic connections and requirements for abiotic factors environment. An ecological niche reflects the participation of a species in a biocenosis. In this case, what is meant is not its territorial location, but the functional manifestation of the organism in the community. According to Ch. Elton (1934), an ecological niche is “a place in a living environment, the relationship of a species to food and to enemies.” The concept of ecological niche has proven to be very fruitful for understanding the laws life together species. In addition to C. Elton, many ecologists worked on its development, among them D. Grinnell, G. Hutchinson, Y. Odum and others.

Each species or its parts (populations, groups of various ranks) occupy a certain place in their environment. For example, certain type an animal cannot arbitrarily change its food ration or feeding time, place of reproduction, shelter, etc. For plants, such conditioning of conditions is expressed, for example, through love of light or shade, place in the vertical division of the community (confined to a certain tier), time of the most active growing season . For example, under the forest canopy, some plants manage to complete the main life cycle, ending with the ripening of seeds, before the leaves of the tree canopy (spring ephemerals) bloom. In more late time their place is taken by other, more shade-tolerant plants. A special group of plants is capable of quickly capturing free space (pioneer plants), but is characterized by low competitive ability and therefore quickly gives way to other (more competitive) species.

Figure 1 Ecological niches of organisms feeding on roots (1), root secretions (2), leaves (3), stem and trunk tissues (4), fruits and seeds (5, 6), flowers and pollen (7, 8), juices (9) and kidneys (10) (according to I. N. Ponomareva, 1975)

The given examples illustrate an ecological niche or its individual elements. An ecological niche is usually understood as the place of an organism in nature and the entire pattern of its life activity, or, as they say, vital status, including attitude to environmental factors, types of food, time and methods of feeding, breeding places, shelters, etc. This concept is much broader and more meaningful than the concept of “habitat”. The American ecologist Odum figuratively called the habitat the “address” of an organism (species), and the ecological niche its “profession.” As a rule, they live in one habitat a large number of organisms of different species. For example, a mixed forest is a habitat for hundreds of species of plants and animals, but each of them has its own and only one “profession” - an ecological niche. Thus, a similar habitat, as noted above, in the forest is occupied by elk and squirrel. But their niches are completely different: the squirrel lives mainly in the crowns of trees, feeds on seeds and fruits, reproduces there, etc. The entire life cycle of an elk is associated with the subcanopy space: feeding on green plants or their parts, reproduction and shelter in thickets, etc. etc. If organisms occupy different ecological niches, they usually do not enter into competitive relationships; their spheres of activity and influence are separated. In this case, the relationship is considered neutral. At the same time, in each ecosystem there are species that claim the same niche or its elements (food, shelter, etc.). In this case, competition is inevitable, the struggle to own a niche. Evolutionary relationships have developed in such a way that species with similar environmental requirements cannot exist together for a long time. This pattern is not without exceptions, but it is so objective that it is formulated in the form of a provision called the “rule of competitive exclusion.” The author of this rule is ecologist G. F. Gause. It sounds like this: if two species with similar requirements for the environment (nutrition, behavior, breeding sites, etc.) enter into a competitive relationship, then one of them must die or change its lifestyle and occupy a new ecological niche. Sometimes, for example, in order to relieve acute competitive relations, it is enough for one organism (animal) to change the time of feeding without changing the type of food itself (if competition occurs at the bud of food relations), or to find a new habitat (if competition takes place on the basis of this factor) and etc.

Among other properties of ecological niches, we note that an organism (species) can change them throughout its life cycle. Most shining example in this regard - insects. Thus, the ecological niche of the cockchafer larvae is associated with the soil and feeding on the root systems of plants. At the same time, the ecological niche of beetles is associated with terrestrial environment, feeding on green parts of plants.

The life forms of organisms are largely associated with ecological niches. The latter include groups of species that are often systematically far apart, but have developed the same morphological adaptations as a result of existing in similar conditions. For example, the similarity of life forms is characterized by dolphins (mammals) and intensively moving in aquatic environment predatory fish. In steppe conditions similar life forms jerboas and kangaroos (jumpers) are represented. IN flora individual life forms are represented by numerous species of trees that occupy the upper tier as a thread, shrubs existing under the forest canopy, and grasses in the ground cover.

An unlimited ecological niche allowed it to become a unique species, capable of subordinating other species to its interests and destroying them. Such phenomena are alien to species existing within the boundaries of ecosystems and occupying certain places in food chains, since the destruction of other species is tantamount to self-destruction. This is one of the paradoxes of human development as biosocial being. Man ensured his transformation into a hypereurybiont not through biochogic mechanisms, but through technical means, and therefore it has largely lost the potential for biological adaptation. This is the reason that a person is among the first candidates for leaving the arena of life as a result of environmental changes caused by him.

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, its population) in a community (biocenosis). The interaction of a given species (population) with partners in the community of which it is a member determines its place in the cycle of substances determined by food and competitive relationships 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 several biocenoses was given by the English ecologist C. Elton (1927). Such an interpretation of the concept Ecological Niche allows us to give quantitative characteristics 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 identify the optimum zone and the limits of deviations tolerated by the type - the maximum and minimum of each factor or set of factors. As a rule, each species occupies a certain ecological niche, to the existence in which it is adapted in its entirety. evolutionary development. The place occupied by a species (its population) in space (spatial ecological niche) is more often called habitat.

Ecological niche - the spatiotemporal position of an organism within the ecosystem (where, when and what it eats, where it makes a nest, 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 using sparrow grain. And flycatchers and the bats catch midges, but in different time- day and night. The giraffe eats leaves from the treetops 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 action of the law of the limiting factor. Trying to use resources outside of its niche, the animal faces stress, i.e. with increasing resistance of the medium. In other words, in its own niche its competitiveness is great, but outside it it weakens significantly or disappears altogether.

The adaptation of animals to certain niches took millions of years and occurred differently in each ecosystem. Species introduced from other ecosystems can cause the extinction of local ones precisely as a result of successful competition for their niches.

1. Starlings, brought to North America from Europe, due to their aggressive territorial behavior, displaced the local “blue” birds.

2. Feral donkeys have poisoned desert ecosystems, displacing bighorn sheep.

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 not previously been found in the Nile Valley. A short plant with large leaves and powerful roots has been attacking 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”. It was probably brought by Russian specialists who were building a metallurgical plant.

The concept of ecological niche also applies to plants. Like animals, their competitiveness is high only in certain conditions.

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

Human ecological niche - composition of air, water, food, climatic conditions, level of electromagnetic, ultraviolet, radioactive radiation etc.

2. Ecological niche and ecosystems

At various times, the concept of an ecological niche was attributed different meaning. 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 ecological niche is interpreted mainly as a habitat, or 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: type of food, time and place of feeding, who is the predator for of a given organism etc. This is now called the 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 (hyperdimensional niche).

That is, in modern understanding An ecological niche can be distinguished into at least three aspects: the physical space occupied by an organism in nature (habitat), its relationship to environmental factors and to neighboring living organisms (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 a rather narrow framework assigned to it from birth. However, its descendants can claim other ecological niches if appropriate genetic changes have occurred in them.

Using the concept of ecological niche, Gause's rule of competitive exclusion can be rephrased in the following way: two different species cannot long time occupy the same ecological niche and even be part of the same 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 at different stages of the life cycle many organisms occupy different ecological niches. For example, a tadpole is a herbivore, and adult frogs living 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 relationships and, in a certain sense, become neutral to each other. However, often the ecological niches of different species may overlap in at least one aspect, for example, habitat or diet. This leads to interspecies competition, which is usually not rigid in nature and promotes clear delineation of ecological niches.

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

Does a similar differentiation occur over more low levels system hierarchy, for example, at the level multicellular organism? Here we can also distinguish different “types” of cells and smaller “bodies”, the structure of which determines their functional purpose within 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” do: they 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 structured in such a way that, while “living for itself,” it simultaneously works for the benefit of the entire organism. Such work does not tire us at all, just as we are not tired by the process of eating, or doing what we love (if, of course, all this is in moderation). The cells are designed in such a way that they simply cannot live 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, all of nature “from bottom to top” seems to be permeated with the idea of ​​differentiation, which in ecology has taken shape in the concept of an ecological niche, which in a certain sense is analogous 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.

It is known that in similar conditions ecosystems similar to each other are formed, having 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, for a long time developed separately from the rest of the land world. In Australian ecosystems, functional niches can be identified that are equivalent to the corresponding niches of ecosystems on other continents. These niches turn out to be 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 a given ecological niche. Such types of organisms are called ecologically equivalent. For example, Australia's large kangaroos are equivalent to bison and antelopes North America(on both continents these animals are now replaced mainly by cows and sheep).

Such phenomena in the theory of evolution are called parallelism. Very often parallelism is accompanied by convergence (convergence) of many morphological (from Greek word morphe - form) of characteristics. 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 several species of animals brought much later than the living world of Australia finally took shape. However, there are also marsupial moles, marsupial squirrels, marsupial wolves, etc. 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 indicates the presence of a certain “program” for the formation of ecosystems in these specific conditions. All matter can act as “genes” that store this program, each particle of which holographically stores information about the entire Universe. This information is implemented in the actual world in the form of laws of nature, which contribute to the fact that various natural elements can form into ordered structures not at all in an arbitrary manner, 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 form, regardless of whether the reaction occurred here or in Australia, although according to Isaac Asimov's calculations, only one chance in 60 million is realized. Probably something similar happens in the case of the formation of ecosystems.

Thus, in any ecosystem there is specific set Potentially possible (virtual) ecological niches strictly linked to each other, designed to ensure the integrity and sustainability of the ecosystem. This virtual structure and is a kind of “biofield” of a given ecosystem, containing a “standard” of its actual (material) structure. And 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 mandatory filling of ecological niches. Its mechanism is based on the property of life to densely fill all the space available to it (under the space in in this case refers to 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 are subordinated to the single goal of functioning of the ecosystem as a single whole, which has mechanisms of homeostasis (stability), binding and release of energy and 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, an ecosystem cannot be sustainable if all its ecological niches are not filled. Therefore, the generally accepted definition of an ecological niche given above is apparently not entirely correct. It comes from the vital status of a particular organism (reductionist approach), while the needs of the ecosystem in realizing its vital important functions(holistic approach). Specific types 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 structural unit ecosystem characterized specific function, necessary to ensure the viability of the ecosystem, and which for this purpose 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(Scots pine in pine forest) before complete dependence and subordination (light-loving herbs under the forest canopy). At the same time, on the one hand, it strives to carry out its life processes as fully as possible in its own interests, and on the other hand, it automatically ensures the life 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 representative of the species in the ecosystem, has its place in it. American ecologist R. McIntosh called it an ecological niche.

Main components of ecological niches:

1. 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 the sphere of life activity of a species in an ecosystem. Since a species is represented in an ecosystem by one population, it is obvious that it is the population that occupies a particular ecological niche in it. The species, by and large, occupies its ecological niche in the global ecosystem - the biosphere. A more complex question is whether an individual has its own ecological niche. A niche not only as a section of ecotope territory, but also as a kind of its own and unique role, determined by its ability to struggle for existence. In a number of cases, such a role cannot be identified either practically or theoretically. For example, a mosquito in a cloud of mosquitoes or a wheat plant of any variety in an agrocenosis do 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. Obviously, the more differentiated or social the community (population), the more clearly the signs of the ecological niches of each individual appear. They are most clearly differentiated and outlined in human communities: the president of a state, the head of a company, a pop star, etc. and so on.

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

Literature

1. Radkevich V.A. Ecology. - Mn.: Vysh.shk., 1997, pp. 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.

Ecological niche called the position of the view, ĸᴏᴛᴏᴩᴏᴇ oi occupies in the general system of biocenosis, a complex of its biocenotic connections and requirements for abiotic environmental factors. An ecological niche reflects the participation of a species in a biocenosis. In this case, what is meant is not its territorial location, but the functional manifestation of the organism in the community. According to Ch. Elton (1934), an ecological niche is “a place in a living environment, the relationship of a species to food and to enemies.” The concept of an ecological niche has proven to be very fruitful for understanding the laws of joint life of species. In addition to C. Elton, many ecologists worked on its development, among them D. Grinnell, G. Hutchinson, Y. Odum and others.

The existence of a species in a community is determined by the combination and action of many factors, but in determining whether organisms belong to any niche, they proceed from the nature of the nutrition of these organisms, from their ability to obtain or supply food. Thus, a green plant, taking part in the formation of a biocenosis, ensures the existence of a number of ecological niches. These are niches that include organisms that feed on root tissue or leaf tissue, flowers, fruits, root secretions, etc. (Fig. 11.11).

Rice. 11.11. Placement of ecological niches associated with the plant:

1 - root beetles; 2 - eating root secretions; 3 - leaf beetles; 4 - stem eaters, 5 - fruit eaters; 6 - seed eaters; 7 - flower beetles; 8 - pollen eaters; 9 - juice eaters; 10 - bud eaters

(according to I. N. Ponomareva, 1975)

Each of these niches includes heterogeneous species composition groups of organisms. Thus, the ecological group of root beetles includes nematodes and the larvae of some beetles (nutcrackers, May beetles), and the niche of plants sucking plant juices includes bugs and aphids. The ecological niches of “stem beetles” or “stem beetles” cover large group animals, among which insects are especially numerous (carpenter beetles, woodworms, bark beetles, longhorn beetles, etc.).

It should be noted that among them there are also those that feed only on the wood of living plants or only on the bark - both belong to different ecological niches. Specialization of species in relation to food resources reduces competition and increases the stability of community structure.

There are different types of resource sharing.

1. Specialization of morphology and behavior in accordance with the type of food: for example, the beak of birds must be adapted for catching insects, chiseling holes, cracking nuts, tearing meat, etc.

2. Vertical separation, for example, between the inhabitants of the canopy and the forest floor.

3. Horizontal separation, for example, between inhabitants of different microhabitats. Each of these types or their combination leads to the division of organisms into groups that compete less with each other, since each of them occupies its own niche. For example, there is a division of birds into environmental groups, based on the place of their feeding: air, foliage, trunk, soil. Further subdivision of these groups based on the main type of food is shown in Fig. 11.12.

Rice. 11.12. The division of birds into ecological groups based on

at the place of their feeding: air, foliage, trunk, earth

(after N. Green et al., 1993)

Specialization of a species in nutrition, use of space, time of activity and other conditions is characterized as a narrowing of its ecological niche, and reverse processes- as its extension.

The narrowing or expansion of the ecological niche of a species in a community is greatly influenced by competitors. The rule of competitive exclusion for ecologically similar species formulated by G.F. Gause should be expressed in such a way that two species do not coexist in the same ecological niche. Exit from competition is achieved by diverging requirements for the environment, changing lifestyles, or, in other words, is the delimitation of ecological niches of species. In this case, they acquire the ability to coexist in the same biocenosis. Thus, in the mangroves of the coast of South Florida, a wide variety of herons live and often feed on up to nine different species of fish on the same shallows. At the same time, they practically do not interfere with each other, since in their behavior - in what hunting areas they prefer and how they catch fish - adaptations have been developed that allow them to occupy different niches within the same shallows. A green night heron passively waits for fish, sitting on the roots of mangrove trees protruding from the water. The Louisiana heron makes sudden movements, stirring up the water and scaring away hidden fish. The snowy egret moves slowly from place to place in search of prey.

The most sophisticated method of fishing is used by the red heron, which first stirs up the water and then opens its wings wide to create shade. At the same time, firstly, she herself clearly sees everything that is happening in the water, and, secondly, the frightened fish take the shadow for cover, rush towards it, falling straight into the enemy’s beak. The size of the great blue heron allows it to hunt in places inaccessible to its smaller and shorter-legged relatives. Insectivorous birds in winter forests Russia, feeding on trees, at the expense of of different nature searching for food also avoid competition with each other. Nuthatches and pikas collect food on tree trunks. Nuthatches quickly explore the trees, quickly grabbing insects and seeds caught in large cracks in the bark, and small pikas carefully search the surface of the trunk for the slightest cracks into which their thin awl-shaped beak penetrates. In the European part of Russia there are closely related species of tits, the isolation of which from each other is due to differences in habitats, feeding areas and prey sizes. Environmental differences are also reflected in a number of small details. external structure, incl. in changes in the length and thickness of the beak (Fig. 11.13).

In winter, in mixed flocks, great tits conduct a wide search for food in trees, bushes, stumps, and often in the snow. Chickadees mostly inspect large branches. Long-tailed tits search for food at the ends of branches, and small tits carefully examine the upper parts of coniferous crowns.

Numerous orders of grass-eating animals include steppe biocenoses. Among them are many large and small mammals, such as ungulates (horses, sheep, goats, saigas) and rodents (gophers, marmots, mice). They all make up one big functional group biocenosis (ecosystem) - herbivores. At the same time, research shows that the role of these animals in consuming plant matter is not the same, since they use different components of the grass cover in their diet.

Rice. 11.13. Food grounds for different tit species

(according to E. A. Kriksunov et al., 1995)

Thus, large ungulates (currently these are domestic animals and saigas, and before human development of the steppes - only wild species) only partially, selectively eat food, mainly tall, most nutritious grasses, biting them at a considerable height (4-7 cm) from the soil surface. Marmots living here choose food among the grass, thinned out and modified by ungulates, eating it, which was inaccessible to them. Marmots settle and feed only where there is no tall grass. Smaller animals - gophers - prefer to collect food where the grass stand is even more disturbed. Here they collect what is left from feeding ungulates and marmots. Between these three groups of herbivores that form the zoocenosis, there is a division of functions in the use of herbaceous biomass. The relationships that have developed between these groups of animals are not competitive in nature. All these animal species use different components of the vegetation cover, “eating” what is not available to other herbivores. Different quality participation in eating grass or placement of organisms in different ecological niches provides more complex structure biocenosis in a given territory, providing more full use living conditions in natural ecosystems and maximum consumption of its products. The coexistence of these animals is characterized not only by the absence of competitive relationships, but, on the contrary, ensures their high numbers. Thus, the increase in gophers and their distribution observed in recent decades is the result of increased grazing of domestic animals in the steppe regions due to an increase in the number of livestock. In places deprived of grazing (for example, reserved lands), there is a decrease in the number of marmots and gophers. In areas with rapid grass growth (especially in tall grass areas), marmots leave completely, and ground squirrels remain in small numbers.

Plants living in the same layer have similar ecological niches, which helps to weaken competition between plants of different layers and causes them to develop different ecological niches. In the biocenosis different types plants occupy different ecological niches, which weakens interspecific competitive tension. The same plant species in different natural zones can occupy different ecological niches. So, pine and blueberries in the blueberry forest, aquatic plants(pondweed, egg capsule, water kras, duckweed) settle together, but are distributed into different niches. Sedmichnik and blueberry in temperate forests are typical shady forms, and in the forest-tundra and tundra they grow on open spaces and become luminous. The ecological niche of a species is influenced by interspecific and intraspecific competition.

If there is competition with closely related or ecologically similar species, the habitat zone is reduced to otsch small boundaries (Fig. 11.14), i.e. the species is distributed in the most< благоприятных для него зонах, где он обладает преимуществом пс сравнению со своими конкурентами. В случае если межвидовая конкуренция сужает экологическую нишу вида, не давая проявиться в in full, then intraspecific competition, on the contrary, contributes to the expansion of ecological niches. With an increased number of species, the use of additional food begins, the development of new habitats, and the emergence of new biocenotic connections.

Rice. 11.14. Habitat division due to competition

(according to E. A. Kriksunov, 1995)

Ecological niches - concept and types. Classification and features of the category "Ecological niches" 2017, 2018.