Formulate a definition of the concept of an ecological niche. What is an ecological niche: an example

The concept of an 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, under which the normal functioning of the organism is maintained, i.e. his viability. The greater the range of changes in the parameters of the environment allows (normally withstands) a particular organism, the higher the resistance of this organism to changes in the factors of the state of the environment. The requirements of a particular species to various environmental factors determine the range of the species and its place in the ecosystem, i.e. their ecological niche.

ecological niche- a set of living conditions in an ecosystem, presented by a species to a variety of environmental environmental factors from the point of view of its normal functioning in the ecosystem. Therefore, the concept of an ecological niche primarily includes the role or function that a given species performs in a community. Each species occupies its own, unique place in the ecosystem, which is due to its need for food and is associated with the reproduction function of the species.

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

Conditions for the normal functioning of the species. The most important biotic factor for every living organism is food. It is known that the composition of food is determined primarily by a set of proteins, carbohydrates, 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 a harmful effect 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 the normal functioning of the organism is possible. If the value of the environmental factor becomes below its lower limit or above the upper limit for a given species, and if this species cannot quickly adapt to changing environmental conditions, then it is doomed to extinction and its place in the ecosystem (ecological niche) will be occupied by another species.

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Any kind of living organism occupies its own unique ecological niche in nature. The ecological niche of an organism is the combination of all its requirements for environmental conditions (to the composition and regimes of environmental factors) and the place where these requirements are met; or the whole conscience of a multitude of biological characteristics and physical parameters of the environment that determine the conditions for the existence of one or another

type; transformation of energy by him, exchange of information with the environment and his own kind.

A habitat is a spatially limited set of conditions of the abiotic and biotic environment, providing the entire development cycle of individuals or groups of individuals of the same species.

ecological niche of an organism

The ecological niche of an organism is the place occupied by an organism, more precisely, its population in a biocenosis community, a complex of its biocenotic relationships and requirements for abiotic environmental factors. This term was introduced in 1927 by Charles Elton.

The ecological niche is the sum of factors for the existence of a given species, the main of which is its place in the food chain - the ecological niche of a person.

The ecological niche of man.

Man is a biological species of the class of mammals. Despite the fact that many specific properties are inherent in him (mind, mental d-th, articulate speech, labor d-th), he has not lost his biological essence and all the laws of ecology are valid for him to the same extent as for others live orgs. Therefore, people have a kind of ecological niche and the space in which it is implemented is very limited: the land limits are the equatorial poles (tropics, subtropics), vertically the niche extends 3-3.5 km above sea level. Thanks to his specific saints, man expanded the boundaries of his initial range, settled in high, middle and low latitudes, mastered the depths of the ocean and outer 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 adaptation, but with the help of specially created protective devices and adaptations that imitate its niche, similar to how it is done for exotic animals in zoos, oceanariums, botanical gardens. Environmental protection consists in a system of measures to preserve the ecological niches of living organisms, including humans.

The concept of the so-called saturated and unsaturated biocenoses is closely related to the concept of an ecological niche. The former are ecosystems in which life resources at each stage of biomass and energy conversion are used to the fullest extent. When vital resources are partially utilized, biocenoses can be called unsaturated. They are characterized by the presence of free ecological niches. However, this is highly arbitrary, since ecological niches cannot exist on their own, regardless of the species occupying them.

Unused reserves, unrealized opportunities for intensifying the flow of substances and energy are available in almost any biogeocenosis (otherwise their constant development in time and space could not be carried out!), All biocenoses can conditionally be considered unsaturated. The lower the saturation of the biocenosis, the easier it is to introduce new species into its composition and more successfully acclimatize.

A very important property of biogeocenoses, as biological systems, is their self-regulation - the ability to withstand high loads of adverse external influences, the ability to return to a conditionally initial state after significant violations of their structure (Le Chatelier's principle). But above a certain threshold of influence, the self-healing mechanisms do not work, and the biogeocenosis is irreversibly destroyed.

When studying the behavior of animals in natural settings, it is important to understand the impact of the consequences of behavior on the ability of an animal to survive. The consequences of a particular type of activity depend mainly on the immediate living conditions of animals. In conditions to which the animal is well adapted, the consequences of this or that type of activity can be beneficial. The same activity carried out in other conditions can be harmful. To understand how animal behavior has evolved, we need to understand how animals adapt to their environment.

Ecology - This is a branch of natural science that studies the relationship of animals and plants with their natural environment. It is relevant to all aspects of these relationships, including the flow of energy through ecosystems, the physiology of animals and plants, the structure of animal populations and their behavior, and so on. In addition to obtaining precise knowledge about specific animals, the ecologist seeks to understand the general principles of ecological organization, and here we will consider some of them.

In the process of evolution, animals adapt to specific environmental conditions, or habitats. Habitats are usually characterized by describing their physical and chemical features. The type of plant communities depends on the physical properties of the environment, such as soil and climate. Plant communities provide a variety of possible habitats that are used by animals. The association of plants and animals, together with the specific conditions of the natural habitat, forms an ecosystem. On the globe, there are 10 main types of ecosystems called biomes. On fig. 5.8 shows the distribution of the main terrestrial biomes of the world. There are also marine and freshwater biomes. For example, a biome such as savannahs covers large areas of Africa, South America and Australia and is grassy plains with sparse trees growing on them in tropical and subtropical regions of the globe. Savannahs typically have a rainy season. At the upper end of the rainfall distribution range, the savanna gradually gives way to tropical forests, and at the lower end to deserts. Acacias predominate in the African savannah, palm trees in the South American savannah, and eucalyptus trees in the Australian savannah. A characteristic feature of the African savannah is a wide variety of herbivorous ungulates, which provide the existence of a variety of predators. In South America and Australia, the same niches are occupied by other species.

The collection of animals and plants that inhabit a particular habitat is called a community. The species that form a community are divided into producers, consumers and decomposers. Producers are green plants that capture solar energy and turn it into chemical energy. Consumers are animals that eat plants or herbivores and thus indirectly depend on plants for energy. Decomposers are usually fungi and bacteria that decompose the dead remains of animals and plants into substances that can again be used by plants.

Niche - it is the role of the animal in the community, determined by its relationships both with other organisms and with the physical environment. So, herbivores usually eat plants, and herbivores, in turn, are eaten by predators. The species occupying this niche are different in different parts of the globe. For example, the niche of small herbivores in temperate zones in the Northern Hemisphere is occupied by rabbits and hares, in South America by agoutis and viscaches, in Africa by hyraxes and white-footed hamsters, and in Australia by wallabies.

Rice. 5.8. Distribution of major terrestrial biomes of the world.

In 1917, the American ecologist Grinnell first put forward the theory of niches, based on the study of the California mockingbird. (Toxostoma redivivum) - a bird that nests in dense foliage one to two meters above the ground. The location of the nest is one of the characteristics by which an animal's niche can be described. In mountainous areas, the vegetation necessary for nesting is found only in an ecological community called chaparral. The habitat of the mockingbird, described by the physical characteristics of the environment, is determined in part by the reaction of the mockingbird population to the situation in the niche. Thus, if the height of the nest above the ground is a decisive factor in escaping from predators, then there will be strong competition in the population for nest sites at the optimal height. If this factor were not so decisive, then more individuals would be able to build nests in other places. The habitat conditions in a given niche are also affected by competition from other species for nesting sites, food, etc. The habitat of the California mockingbird is determined in part by the situation with niches, the distribution of other shrub species characteristic of the chaparral, and the population density of the mockingbird itself. It is clear that if its density is low, birds nest only in the best places, and this affects the habitat of the species. Thus, the overall relationship of the mockingbird to habitat conditions, which is often referred to by the term ecotope, are the result of complex interactions of niche, habitat, and population characteristics.

If animals of different species use the same resources, are characterized by some common preferences or limits of stability, then we are talking about overlapping niches (Fig. 5.9). Niche overlap leads to competition, especially when resources are scarce. Principle of competitive exclusion states that two species with identical niches cannot exist in the same place at the same time with limited resources. It follows from this that if two species coexist, then there must be ecological differences between them.

Rice. 5.9. Niche overlap. The fitness of an animal can often be represented as a bell-shaped curve along some environmental gradient, such as temperature. Niche overlap (shaded area) occurs in the portion of the gradient occupied by representatives of different species.

As an example, consider the relationship of niches in a group of "leaf-picking" bird species that feed on the oaks of the mountainous coast in central California (Root, 1967). This group, called guild, are species that use the same natural resources in the same way. The niches of these species overlap to a large extent and therefore they compete with each other. The advantage of the guild concept is that in this case all competing species of a given site are analyzed, regardless of their taxonomic position. If we consider the diet of this guild of birds as an element of their habitat, then it must be said that most of this diet should consist of arthropods collected from the leaves. This is an arbitrary classification, as any species can be a member of more than one guild. For example, the plains tit (Parus inornatus) refers to a guild of leaf picking birds based on its foraging behavior; in addition, she is also a member of the guild of birds nesting in hollows due to nesting requirements.

Rice. 5.11. The three types of foraging behavior in leaf-picking birds are represented as the three sides of a triangle. The length of the line perpendicular to the side of the triangle is proportional to the amount of time spent on this behavior. The sum of all three lines for each view is 100%. (After Root, 1967.)

Although in this case, five species of birds feed on insects, each species takes insects that differ in size and taxonomic position. The taxonomic categories of insects eaten by these five species overlap, but each species specializes in a particular taxon. Prey sizes overlap completely, but their means and variances are different, at least in some cases. Root (1967) also found that birds of these species are characterized by three types of foraging behavior:

1) picking up insects from the surface of the leaves, when the bird moves on a solid substrate;

2) picking up insects from the surface of leaves by a soaring bird;

3) catching flying insects.

The proportion of time that each species spends on one or another way of obtaining food is shown in Fig. 5.11. This example clearly demonstrates the process of ecological specialization in behavior. The behavior of each species influences the behavior of other species in such a way that the members of that guild develop all possible types of foraging behavior and use all kinds of prey.

Competition often results in the dominance of one species; this is reflected in the fact that dominant species have an advantage in the use of resources such as food, space and shelter (Miller, 1967; Morse, 1971). Based on the theory, one would expect that a species that becomes subordinate to another species would have to change its resource use in such a way as to reduce overlap with the dominant species. Usually in this case, the subordinate species reduces the use of some resources, thus reducing the width of the niche. In some cases, a subordinate species may expand a niche to include previously unused resources, either by subordinating other species in adjacent niches or by making fuller use of the fundamental niche.

If a subordinate species survives in competition with a dominant species, then its main niche is wider than that of the dominant species. Such cases have been noted in bees and New World blackbirds (Orians and Willson, 1964). Since priority in resource use belongs to dominant species, subordinate species can be excluded from niche space when resources are limited, their number is unpredictable, and foraging requires significant effort; and all this significantly reduces the fitness of the subordinate species in the area of ​​overlap. In such cases, subordinate species can be expected to be subject to significant selection pressure and change their fundamental niches, either through specialization or by developing resistance to a wider range of physical habitat conditions.

Adaptability of animal behavior

Naturalists and ethologists have discovered numerous examples of the amazing ways in which animals are perfectly adapted to the conditions of their environment. The difficulty in explaining this kind of animal behavior is that it only seems convincing because the various details and observations fit together too well; in other words, a good story can seem compelling simply because it is a good story. This does not mean that a good story cannot be true. In any correct explanation of behavioral adaptation, the various details and observations must indeed be fitted together. The problem is that biologists, as scientists, have to evaluate data, and a good description is not always good data. As in a court of law, the data must be more than thorough and must carry some elements of independent verification.

One way to get data indicative of behavioral adaptability is to compare related species that occupy different habitats. A classic example of this approach is the work of Ester Cullen (1957) comparing the nesting habits of a rock-nesting kittiwake (Rissa tridactyla) and ground-nesting gulls such as the common (Lams ridibundus) and silver (Lams argentatus). Kittiwakes nest on rocky ledges inaccessible to predators and apparently evolved from ground-nesting gulls as a result of predation pressure. Kittiwakes have inherited some traits of ground-nesting gulls, such as the partially camouflaged coloration of their eggs. Eggs of ground-nesting birds are usually well camouflaged to protect against predators, but in kittiwakes, the color of the eggs cannot serve this function, as each nest is marked with conspicuous white droppings. Ground-nesting adults and juveniles are tidy and avoid defecation near the nest so as not to reveal its location. Thus, it seems most likely that the camouflage coloration of kittiwake eggs is evidence that their ancestors nested on the ground.

Cullen (1957) studied a breeding colony of kittiwakes in the Farne Islands off the east coast of the United Kingdom, where they nest on very narrow rock ledges. She established that neither land animals such as rats nor birds such as herring gulls, which often prey on the eggs of birds nesting on the ground, prey on their eggs. Kittiwakes feed mainly on fish and do not devour eggs and chicks from neighboring nests, as gulls nesting on the ground often do. Kittiwakes appear to have lost most of the adaptations that protect other gulls from predators. For example, not only do they not mask the nest, they also rarely emit alarm cries and do not attack predators en masse.

Rice. 5.12. Red-legged talkers (Rissa brevirostris), nesting on rocky ledges of the Pribylov Islands in the Bering Sea

Kittiwakes have many special adaptations for rock nesting. They have a light body and strong fingers and claws that allow them to cling to ledges that are too small for other gulls. Compared to ground-nesting gulls, adult kittiwakes have a number of behavioral adaptations to rocky habitats. Their behavior during fights is limited by strict stereotypes in comparison with relatives nesting on the ground (Fig. 5.12). They build rather elaborate cup-shaped nests using twigs and mud, while ground-nesting gulls build rudimentary nests from grass or seaweed without using mud as cement. Kittiwake chicks differ from chicks of other gulls in many ways. For example, they stay in the nest for a longer period and spend most of their time with their heads turned towards the rock. They snatch regurgitated food directly from the throats of their parents, while most gulls pick it up from the ground, where it is thrown by adults. Nestling gulls nesting on the ground run away and hide when frightened, while young kittiwakes remain in the nest. Chicks of gulls are characterized by cryptic coloration and behavior, while kittiwake chicks do not.

Comparison of species can shed light on the functional significance of a particular type of behavior in the following ways: When a type of behavior occurs in one species but not in another, it may be due to differences in the way natural selection acts on the two species. For example, herring gulls remove eggshells near the nest in order to maintain nest camouflage because the inner white surface of the eggshell is highly visible. Evidence supporting this hypothesis comes from observations of kittiwakes that do not remove their shells. As we have already seen, kittiwake nests are not attacked by predators and their nests and eggs are not camouflaged. If eggshell removal serves primarily to maintain nest camouflage, then we are unlikely to find this in kittiwakes. However, if it serves other purposes, such as disease prevention, then this behavior would be expected to occur in kittiwakes. Kittiwakes usually keep the nest very clean and discard any foreign objects from it. Herring Gulls do not usually do this.

The above data will be further strengthened if we can show that other related species under the same selection pressure develop similar adaptations. One such example is given by Hailman (1965), who studied the Fork-tailed Gull nesting on rocks. (Lams furcatus) in the Galapagos Islands. Heilman studied various behaviors that are determined by the ability to prevent the danger of falling from rocks. Fork-tailed gulls nest not on such steep rocks as kittiwakes, and not so high above the ground. Thus, one would expect that the respective adaptations of fork-tailed gulls would be intermediate between those of kittiwakes and typical ground-nesting gulls. Fork-tailed gulls are subject to more predation than kittiwakes, and Heilman found some behaviors that appear to be driven by this difference. For example, as mentioned above, kittiwake chicks defecate on the edge of the nest, thus making it very conspicuous. Forked-tailed gull chicks defecate behind the edge of this edge. He found that fork-tailed gulls occupy an intermediate position between kittiwakes and other gulls in a number of characters, also associated with the intensity of predation. In this way, Heilman assessed those behavioral traits of forked-tailed gulls that are adaptations to the availability of available nesting space and the availability of nest sites and nesting material. He then decided to evaluate the data on which Cullen (1957) had based his hypothesis that the characteristic traits of kittiwakes are the result of selective pressures that accompany rock nesting. He selected 30 features of the fork-tailed gull and divided them into three groups depending on the degree of similarity with the behavior of kittiwakes. Taken as a whole, this comparison supports Cullen's hypothesis that the particular traits of kittiwakes are the result of an act of selection that accompanies rock nesting.

The work of Crook (Crook, 1964) on almost 90 species of weavers (Ploceinae) is another example of this comparative approach. These small birds are distributed throughout Asia and Africa. Despite their superficial similarity, the different types of weavers differ markedly in social organization. Some of them defend a large territory in which they build camouflaged nests, while others nest in colonies in which the nests are clearly visible. Crook found that the species living in the forests lead a solitary lifestyle, feed on insects, nests are masked in a large protected area. They are monogamous, sexual dimorphism is weakly expressed. Species living in the savannah are usually seed-eating, live in groups, nest colonially. They are polygamous, with males brightly colored and females dull.

Crook believed that since food was hard to come by in the forest, it was necessary for both parents to feed the chicks, and for that, the parents had to stay together during the breeding season. The density of insects that forest birds feed on is low, so a pair of birds must defend a large area to ensure adequate food supply for the chicks. Nests are well camouflaged and adult birds are dull-colored to prevent predators from revealing the location when they visit the nest.

In the savannah, seeds can be abundant in some places and few in others, an example of patchy food distribution. Foraging under such conditions is more efficient if the birds form groups to search a wide area. Nesting sites protected from predators are rare in the savanna, so many birds nest in the same tree. The nests are voluminous to provide protection from the heat of the sun, so the colonies are highly visible. For protection from predators, nests are usually built high up on thorny acacias or other similar trees (Figure 5.13). The female herself is able to feed the offspring, since there is a relatively large amount of food. The male almost does not participate in this and cares for other females. Males compete for nesting sites within the colony, and those who succeed may each attract several females while the other males remain single. In the colonial settlement of weavers (Textor cucullatus), for example, males steal nesting material from each other. Therefore, they are forced to constantly be near the nest in order to protect it. To attract females, the male arranges a complex "performance" by hanging from the nest. If the male is successful in courtship, the female enters the nest. This attraction to the nest is typical of colonial weavers. The courtship ritual is quite different for bird species living in the forest, in which the male chooses a female, courts her at a noticeable distance from the nest, and then leads her to the nest.

Rice. 5.13. Weaver colony Ploceus cucullatus. Note that a large number of nests are relatively inaccessible to predators. (Photo by Nicholas Collias.)

The comparative approach has proved to be a fruitful method in studying the relationship between behavior and ecology. Birds (Lack, 1968), ungulates (Jarman, 1974), and primates (Crook and Gartlan, 1966; Glutton-Brock and Harvey, 1977) have been studied using this method. Some authors (Clutton-Brock, Harvey, 1977; Krebs, Davies, 1981) criticize the comparative approach, however, it provides satisfactory data regarding the evolutionary aspects of behavior, provided that appropriate measures are taken to avoid the substitution of concepts and overlapping evidence. Heilman (Hailman, 1965) considers the comparative method to be appropriate only in those cases where the comparison of two populations of animals allows conclusions to be drawn regarding a third population that has not yet been studied by the time these conclusions are formulated. In this case, the hypothesis formulated as a result of a comparative study can be tested independently without using the data obtained as a result of this study. It is not difficult to see that if there are interrelated differences in behavior and ecology between two populations, then this is not enough to say that these traits reflect the selection pressure that arises as a result of differences in the living conditions of these two populations. Differences arising from confounding variables or from comparing inappropriate taxonomic levels can be avoided by careful statistical analysis (Clutton-Brock and Harvey, 1979; Krebs and Davies, 1981).



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 range 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 reservoir occupied by a population of one species or part of it and having all the necessary conditions for its existence (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 eats 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 specific 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, norms of behavior, etc. But the individual niches of different people can overlap in certain ecological 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 standard measurements are usually used - 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 implemented 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 a given 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 at different times (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.

The ecological niche is usually understood as the place of the organism in nature and the whole way of its life activity, or, as they say, the life status, including the attitude to environmental factors, types of food, time and methods of nutrition, places of reproduction, shelters, etc. This concept is much more voluminous and more meaningful than the concept of "habitat". The American ecologist Odum figuratively called the habitat the "address" of the organism (species), and the ecological niche - its "profession".

Thus, the ecological niche characterizes the degree of biological specialization of a species. The ecological specificity of species is emphasized by the axiom of ecological adaptability: "Each species is adapted to a strictly defined, specific set of conditions of existence for it - an ecological niche."

G. Hutchinson put forward the concept of a fundamental and realized ecological niche.

Fundamental is understood as the whole set of conditions under which a species can successfully exist and reproduce. In nature, however, species do not develop all the resources suitable for them due, first of all, to competitive relationships.

A realized ecological niche is the position of a species in a particular community, where it is limited by complex biocenotic relationships. Those. the fundamental niche is the potential of the species, and the realized niche is the part that can be realized under given conditions. Thus, the realized niche is always smaller than the fundamental one.

Three important rules follow from the figure.

• 1. The wider the requirements (tolerance limits) of a species to any or many environmental factors, the greater the space that it can occupy in nature, and hence the wider its distribution.
• 2. The combination of the organism's requirements for various factors is not arbitrary: all organisms are adapted to the modes of "linked" among themselves, interconnected and interdependent factors.
• 3. If the regime of any, at least one ecological factor in the habitat of individuals of a given species has changed in such a way that its values ​​go beyond the niche as hyperspace, then this means the destruction of the niche, i.e., the restriction or impossibility of preserving the species in this habitat .

Since the species of organisms are ecologically individual, they also have specific ecological niches. Thus, there are as many species of living organisms on Earth as there are ecological niches.

In nature, there is also a rule of obligatory filling of ecological niches: "An empty ecological niche will always and certainly be filled." Folk wisdom formulated these two postulates as follows: “Two bears cannot get along in one lair” and “Nature does not tolerate emptiness.”

If organisms occupy different ecological niches, they usually do not enter into competitive relations, 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 for possession of a niche. Evolutionary relationships have developed in such a way that species with similar requirements for the environment 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 that has been called the "rule of competitive exclusion." The author of this rule is the ecologist G.F. Gause. It sounds like this: “if two species with similar requirements for the environment (nutrition, behavior, breeding sites, etc.) enter into competitive relations, then one of them must die or change its lifestyle and occupy a new ecological niche.” Sometimes, for example, in order to remove 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 arises on the basis of food relations), or to find a new habitat (if competition takes place on the basis of this factor) and etc.

Of the other properties of ecological niches, we note that an organism (species) can change them throughout its life cycle.

Communities (biocenoses, ecosystems) are formed according to the principle of filling ecological niches. In a naturally formed community, usually all niches are occupied. It is in such communities, for example, in long-existing (primary) forests, that the probability of introduction of new species is very low.

Ecological niches of all living organisms are divided into specialized and general. This division depends on the main food sources of the respective species, the size of the habitat, and sensitivity to abiotic environmental factors.

Specialized niches. Most species of plants and animals are adapted to exist only in a narrow range of climatic conditions and other environmental characteristics, they feed on a limited set of plants or animals. Such species have a specialized niche that determines their habitat in the natural environment. So, the giant panda has a highly specialized niche, because it feeds on 99% of leaves and bamboo shoots. The mass destruction of certain types of bamboo in areas of China where the panda lived led this animal to extinction.

Species with common niches are characterized by easy adaptability to changes in environmental environmental factors. They can successfully exist in a variety of places, eat a variety of foods and withstand sharp fluctuations in natural conditions. Flies, cockroaches, mice, rats, humans, etc. have common ecological niches.

For species that have common ecological niches, there is a significantly lower threat of extinction than for those with specialized niches.

Human ecological niche

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 (mind, 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 living organisms. .

A person also has his own, unique to him, ecological niche, that is, 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 only live 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.

Thanks to the specific (primarily social) properties mentioned above, man expanded the boundaries of his initial range (habitat), settled in high, middle and low latitudes, mastered the depths of the ocean and outer 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 adaptation, 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 a space flight it is impossible to reproduce such an important factor as gravity, and after returning to Earth from a long space expedition, astronauts need time to readjust.

In the conditions of industrial enterprises, many factors (noise, vibration, temperature, electromagnetic fields, impurities of a number of substances in the air, etc.) are periodically or constantly 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 the safety of labor activity by reducing the level of exposure to the body of dangerous and harmful environmental production factors.

It is far from always possible to ensure optimal conditions for such factors, and therefore for a number of industries the total work experience of employees is limited, the working day is reduced (for example, when working with toxic substances - up to four hours). Special design devices are created to reduce vibration and noise in the cabins of transport and traction vehicles.

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 the niche.

From the foregoing, the second basic rule of nature protection follows from an ecological standpoint: “Nature (and the environment) protection 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 the present and future generations, or the human being as a biological species is doomed to extinction.