Introduction

In this work, I want to introduce you to such concepts as an ecological niche, limiting factors, and tell you more about the law of tolerance.

An ecological niche is a place occupied by a species in a biocenosis, including a complex of its biocenotic relationships and requirements for environmental factors.

The concept of an ecological niche was introduced to denote the role that a particular species plays in a community. An econiche should be understood as a way of life and, above all, a way of nourishing the body.

ecological niche- an abstract concept, it is a set of all environmental factors within which the existence of a species in nature is possible. This term was introduced in 1927 by Charles Elton. It includes the chemical, physical, and biotic factors that an organism needs for life and is determined by its morphological fitness, physiological responses, and behavior. V different parts In the world and in different territories there are species that are systematically different, but similar in ecology - they are called ecologically equivalent.

An ecological niche is a place occupied by a species (more precisely, by its population) in a community (biocenosis). The interaction of a given species (population) with partners in the community to which it belongs as a member determines its place in the cycle of substances due to food and competitive ties in the biocenosis. The term "Ecological niche" was proposed by the American scientist J. Grinell (1917). The interpretation of an ecological niche as the position of a species in the food chains of one or more biocenoses was given by the English ecologist C. Elton (1927). Such an interpretation of the concept of ecological niche makes it possible to give a quantitative description of the ecological niche for each species or for its individual populations.

The limiting factor is an environmental factor that goes beyond the endurance of the organism. The limiting factor limits any manifestation of the organism's vital activity. With the help of limiting factors, the state of organisms and ecosystems is regulated.

Shelford's law of tolerance - in ecology - the law according to which the existence of a species is determined by limiting factors that are not only at a minimum, but also at a maximum. The law of tolerance extends Liebig's law of the minimum.

J. Liebig's Law of the Minimum - in ecology - a concept according to which the existence and endurance of an organism is determined by the weakest link in the chain of its environmental needs.

According to the law of the minimum, the vital possibilities of organisms are limited by those environmental factors, the quantity and quality of which are close to the minimum required by the organism or ecosystem.

ecological niche

Any kind of organisms is adapted for certain conditions of existence and cannot arbitrarily change the habitat, diet, feeding time, breeding place, shelter, etc. The whole complex of relations to such factors determines the place that nature has allocated to a given organism, and the role that it must play in the general life process. All this is combined in the concept ecological niche.

An ecological niche is understood as the place of an organism in nature and the whole way of its life activity, its vital status anchored in its organization and adaptations.

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

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

Using the concept of an ecological niche, Gause's rule of competitive exclusion can be rephrased as follows: two different species cannot occupy the same ecological niche for a long time and even enter 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 different stages life cycle many organisms occupy different ecological niches. For example, a tadpole is a herbivore, while adult frogs that live in the same pond are predators. Another example: insects in the larval and adult stages.

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

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

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

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

3. ECOLOGICAL NICHE

An ecological niche is a place occupied by a species in a biocenosis, including a complex of its biocenotic relationships and requirements for environmental factors. The term was introduced in 1914 by J. Grinnell and 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. According to Hutchinson, an ecological niche can be:

● fundamental - determined by a combination of conditions and resources that allows the species to maintain a viable population;

● realized - the properties of which are determined by competing species.

This difference emphasizes that interspecific competition leads to a decrease in fertility and viability and that there may be a part of a fundamental ecological niche that a species, as a result of interspecific competition, can no longer live and reproduce successfully.

Principle of competitive exclusion

The essence of the principle of competitive exclusion, also known as the Gause principle, is that each species has its own ecological niche. No two different species can occupy the same ecological niche. Modern approach to the problem of sharing an ecological niche by several species indicates that in some cases two species can share the same ecological niche, and in some cases such a combination leads one of the species to extinction.

If two species coexist, then there must be some ecological difference between them, which means that each of them occupies its own special niche.

Competing with a stronger species, a weak competitor loses its realized niche. Thus, the exit from competition is achieved by a divergence of requirements for the environment, a change in lifestyle, or, in other words, is the delimitation of the ecological niches of species. In this case, they acquire the ability to coexist in one biocenosis.

The law of constancy of V. I. Vernadsky

The amount of living matter in nature (for a given geological period) is a constant.

According to this hypothesis, any change in the amount of living matter in one of the regions of the biosphere must be compensated in some other region. True, in accordance with the postulates of species depletion, highly developed species and ecosystems will most often be replaced by evolutionary objects of more low level. In addition, the process of ruderalization of the species composition of ecosystems will take place, and species “useful” for humans will be replaced by less useful, neutral or even harmful ones.

The consequence of this law is the rule of obligatory filling of ecological niches. (Rosenberg et al., 1999)

The rule of obligatory filling of the ecological niche

An ecological niche cannot be empty. If a niche is empty as a result of the extinction of a species, then it is immediately filled with another species. The habitat usually consists of separate areas (“spots”) with favorable and adverse conditions; these spots are often only temporarily available, and they occur unpredictably both in time and space.

Habitat gaps or gaps occur unpredictably in many habitats. Fires or landslides can lead to the formation of wastelands in forests; the storm can bare open area sea ​​coast, and voracious predators anywhere can exterminate potential victims. These vacant plots are invariably repopulated. However, the very first settlers will not necessarily be those species that for a long time are able to successfully compete with other species and displace them. Therefore, the coexistence of transient and competitive species is possible as long as uninhabited areas appear with suitable frequency. A transient species usually first populates a free area, develops it and reproduces. A more competitive species populates these areas slowly, but if the colonization has begun, then over time it defeats the transient species and multiplies. (Bigon et al., 1989).

Human ecological niche

Man, as a biological species, occupies his own ecological niche. A person can live in the tropics and subtropics, at altitudes up to 3-3.5 km above sea level. In reality, at present, a person lives in much larger spaces. Man has expanded a free ecological niche through the use of various devices: housing, clothing, fire, etc.

BIBLIOGRAPHY

1. Bigon M., Harper J., Townsend K. Ecology. Individuals, populations and communities. Volume 1. - M.: Mir, 1989. - 667s.

2. Bigon M., Harper J., Townsend K. Ecology. Individuals, populations and communities vol. 2. - Moscow: Mir, 1989. - 477p.

3. Brodsky A. K. A short course in general ecology, Tutorial for universities. - St. Petersburg: "Dean", 2000. - 224 p.

4. Vernadsky V.I. Biosphere and noosphere. - M .: Iris-press, 2003. - 576 p.

5. Gilyarov A. M. Population ecology: Textbook. - M.: Publishing House of Moscow State University, 1990 - 191s.

6. Giller P. Community structure and ecological niche. - M.: Mir, 1988. - 184p.

7. Odum Yu. Fundamentals of ecology. - M.: Mir, 1975 - 741s.

8. Odum Yu. Ecology vol. 1. - M.: Mir, 1986 - 328s.

9. Rozenberg G. S., Mozgovoy D. P., Gelashvili D. B. Ecology. Elements of theoretical constructions of modern ecology. - Samara: SamNTs RAS, 1999. - 397p.

With an average daily minimum temperature below 0 ° C, p - months it with an absolute minimum temperature below 0 ° C, c - frost-free [period. The abscissa shows the months. 2. Ecological systems, biocenosis, biocycles. 2.1. SYNECOLOGY Synecology is the branch of ecology that studies ecological systems. The generally accepted concept of the system still does not exist. The system is usually understood as a holistic ...

Nature. "Reverence for life" (Schweitzer) as a possible ethical basis for human interaction with the biosphere. “Nonlinear” and “noospheric” thinking, the ideology of biocentrism as a new scientific paradigm and the path to “sustainable development of mankind. The transition from anthropocentrism to biocentrism. 2. Greenhouse effect The greenhouse effect is a rise in temperature on the surface of the planet as a result of ...

ecological niche call the position of the species, ĸᴏᴛᴏᴩᴏᴇ oi ranks in common system biocenosis, a complex of its biocenotic relationships and requirements for abiotic environmental factors. The ecological niche reflects the participation of the species in the biocenosis. This does not mean its territorial location, but the functional manifestation of the organism in the community. In the words of C. Elton (1934), an ecological niche is ʼʼ this is a place in a living environment, the relation of a species to food and to enemiesʼʼ. The concept of an ecological niche has proven to be very fruitful for understanding the laws living together types. 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 the belonging of organisms 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 cover organisms that feed on root tissues or leaf tissues, flowers, fruits, root secretions, etc. (Fig. 11.11).

Rice. 11.11. Placement of ecological niches dedicated to the plant:

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

(according to I. N. Ponomareva, 1975)

Each of these niches includes groups of organisms that are heterogeneous in species composition. So, the ecological group of root beetles includes both nematodes and the larvae of some beetles (click beetle, May beetle), and bugs and aphids are in the niche of plants sucking juices. The ecological niches of ʼʼstalk beetlesʼʼ or ʼʼstem beetlesʼʼ cover a large group of animals, among which insects are especially numerous (wood borers, woodworms, bark beetles, barbels, etc.).

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

Exists different types division of resources.

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 the inhabitants of different microhabitats. Each of these types or their combination leads to the division of organisms into groups that are less competitive with each other, since each of them occupies its own niche. For example, there is a division of birds into ecological groups based on the place of their feeding: air, foliage, trunk, soil. A 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 food: air, foliage, trunk, earth

(according to N. Green et al., 1993)

The specialization of a species in terms of nutrition, use of space, time of activity, and other conditions is characterized as a narrowing of its ecological niche, and reverse processes as its expansion.

The narrowing or expansion of the ecological niche of a species in the community is greatly influenced by competitors. The rule of competitive exclusion formulated by G. F. Gause for ecologically close species should be expressed in such a way that two species do not coexist in the same ecological niche. The exit from competition is achieved by a divergence of requirements for the environment, a change in lifestyle, or, in other words, is the delimitation of the ecological niches of species. In this case, they acquire the ability to coexist in one biocenosis. Thus, a variety of herons live in the mangroves of the coast of South Florida, and often up to nine different species feed on fish on the same shoal. 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 fish, adaptations have been developed that allow them to occupy various niches within the same shallow. The green night heron passively waits for fish, sitting on the roots of mangrove trees protruding from the water. The Louisiana heron makes sudden movements, churning the water and scaring away the hidden fish. The snowy heron 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 spreads its wings wide, creating a shadow. At the same time, firstly, she herself sees well everything that happens in the water, and, secondly, the frightened fish take the shadow for shelter, rush to it, falling directly into the beak of the enemy. The size of the great blue heron allows it to hunt in places inaccessible to its smaller and short-legged relatives. Insectivorous birds in the winter forests of Russia, feeding on trees, at the expense of different nature foraging also avoid competition with each other. Nuthatches and pikas gather food on trunks. The nuthatches quickly examine the trees, quickly grabbing insects, seeds found in large cracks in the bark, and small pikas carefully rummage through the smallest cracks on the surface of the trunk, into which their thin awl-shaped beak penetrates. In the European part of Russia, there are close species of tits, the isolation of which from each other is due to differences in habitats, feeding places and prey sizes. Ecological differences are 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. Tit-tits examine mostly large branches. Long-tailed tits search for food at the ends of branches, and small kinglets 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 (ground squirrels, marmots, mouse-like). All of them make up one large functional group of biocenosis (ecosystem) - herbivores. At the same time, studies show that the role of these animals in the consumption of plant mass is not the same, since they use different components of the grass cover in their diet.

Rice. 11.13. Food lands various kinds tits

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

So, 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 high, most nutritious grasses, biting them off at a considerable height (4-7 cm) from the soil surface. Marmots living here choose food among the grassland, thinned and changed by ungulates, eating it, which was inaccessible to them. Marmots settle and feed only where there is no tall grass. Smaller animals - ground squirrels - prefer to forage where the herbage is even more disturbed. Here they collect what is left from feeding ungulates and marmots. Between these three groups of herbivores that form a zoocenosis, there is a division of functions in the use of grass cover biomass. The relations that have developed between these groups of animals are not of a competitive nature. All these animal species use different components of the vegetation cover, ʼʼeatingʼʼ what is not available to other herbivores. Different-quality participation in eating grass or placing organisms in different ecological niches provides a more complex structure of the biocenosis in a given area, ensuring a more complete use of living conditions in natural ecosystems and the maximum consumption of its products. The joint existence of these animals is characterized not only by the absence of competitive ties, but, on the contrary, ensures their high abundance. So, the increase in ground squirrels noted in recent decades and their resettlement is the result of increased grazing of domestic animals in the steppe regions due to an increase in livestock. In places deprived of grazing (for example, protected lands), there is a decrease in the number of marmots and ground squirrels. In areas with rapid growth of grasses (especially in tall grass areas), marmots leave completely, and ground squirrels remain in small numbers.

In plants living in the same layer, ecological niches are similar, which contributes to the weakening of competition between plants of different layers and determines the development of different ecological niches by them. In the biocenosis different types plants occupy different ecological niches, which weakens the interspecific competitive tension. The same plant species in different natural areas can occupy different ecological niches. So, pine and blueberries in the blueberry forest, aquatic plants (weeds, egg-pods, water-color, duckweeds) settle together, but are distributed in different niches. In temperate forests, blueberries and blueberries are typical shady forms, while 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.

In the presence of competition with closely related or ecologically similar species, the habitat area 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 полном объёме, то внутривидовая конкуренция, напротив, способствует расширению экологических ниш. При возросшей численностщ вида начинается использование дополнительных кормов, освоение новых местообитаний, появление новых биоценотических связей.

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.

ecological niche - the place of the species in the biogeocenosis, determined by its biotic potential and the totality of environmental factors to which it is adapted. This is not only the physical space occupied by the organism, but also its functional role in the community (position in the food chain), and its place relative to external factors.

There are 3 components in the structure of the ecological niche:

1. Spatial niche (habitat) - "address" of the organism;
2. Trophic niche - the characteristic features of nutrition and the role of the species in the community - "profession";
3. A multidimensional (hyperspace) ecological niche is the range of all conditions under which an individual or population lives and reproduces itself.

Distinguish fundamental (potential) niche, which the organism or species could occupy in the absence of competition, predators, in which abiotic conditions are optimal; and realized niche- the actual range of conditions for the existence of an organism, which is less than or equal to the fundamental niche.

The rule of obligation to fill the ecological niche.
An empty ecological niche is always and necessarily naturally filled. In saturated biogeocenoses, life resources are used most fully - in them all ecological niches are occupied. In unsaturated biogeocenoses, vital resources are partially utilized; they are characterized by the presence of free ecological niches.

Environmental duplication- occupation of the vacated ecological niche by another species capable of performing the same functions in the community as the extinct species. It follows from this that knowing the distribution of species over the ecological niche in the community and the parameters of each ecological niche, it is possible to describe in advance the species that can occupy one or another niche if it is released.

Ecological diversification- the phenomenon of division of the ecological niche as a result of interspecific competition. It is carried out according to three parameters:
- by spatial arrangement
- by diet
- according to the distribution of activity over time.
As a result of diversification, a shift in characters occurs - individuals of two closely related species are more similar to each other in those parts of the ranges where they occur separately than in areas of joint residence.

Characteristics of an ecological niche:
1. Width
2. Overlapping this niche with neighboring

Ecological niche width- a relative parameter, which is estimated by comparison with the width of the ecological niche of other species. Eurybionts generally have wider ecological niches than stenobionts. However, the same ecological niche can have a different width in different directions: for example, in terms of spatial distribution, food connections, etc.

Covering the ecological niche occurs when different species cohabitate using the same resources. The overlap can be total or partial, according to one or more parameters of the ecological niche.

If the ecological niches of organisms of two species are very different from each other, then these species that have the same habitat do not compete with each other (Fig. 3).

If ecological niches partially overlap (Fig. 2), then their coexistence will be possible due to the presence of specific adaptations for each species.

If the ecological niche of one species includes the ecological niche of another (Fig. 1), then intense competition arises, the dominant competitor will push its rival to the periphery of the fitness zone.

Competition has important environmental consequences. In nature, individuals of each species are simultaneously subjected to interspecific and intraspecific competition. Interspecific in its consequences is opposite to intraspecific, since it narrows the area of ​​habitats and the quantity and quality of the necessary environmental resources.

Intraspecific competition promotes the territorial distribution of species, that is, the expansion of the spatial ecological niche. The end result is the ratio of interspecific and intraspecific competition. If interspecific competition is greater, then the range of this species decreases to a territory with optimal conditions and at the same time the specialization of the species increases.

An ecological niche is a place of a species in nature, mainly in a biocenosis, including both its position in space and its functional role in a community, and its relation to abiotic conditions of existence (Khrustalev and Matishov, 1996). It is important to emphasize that this niche is not just the physical space occupied by the organism, but also its place in society, determined by its ecological functions. Y. Odum (1975) figuratively presented an ecological niche as an occupation, a “profession” of an organism in the system of species to which it belongs, and its habitat is the “address” of the species.

Knowledge of the ecological niche allows one to answer the questions of how, where and what a species feeds on, whose prey it is, how and where it rests and breeds (Dajo, 1975).

The ecological niche model proposed by G. E. Hutchinson is quite simple: it is enough to plot the intensity values ​​on orthogonal projections various factors, and restore perpendiculars from the points of tolerance limits, then the space limited by them will correspond to the ecological niche of this species. An ecological niche is an area of ​​combinations of such values ​​of environmental factors within which a given species can exist indefinitely.

For example, a certain combination of temperature and humidity is sufficient for the existence of a terrestrial plant, in which case one can speak of a two-dimensional niche. For a marine animal, in addition to temperature, at least two more factors are needed - salinity and oxygen concentration - then we should already talk about a three-dimensional niche, etc. In fact, there are many of these factors and the niche is multidimensional.

The ecological niche, determined only by the physiological characteristics of organisms, is called fundamental, and the one within which the species actually occurs in nature is called realized.

A realized niche is that part of the fundamental niche that a given species, population is able to “defend” in competition. Competition, according to Y. Odum (1975, 1986), is a negative interaction between two organisms striving for the same thing (Table 4.1). Interspecific competition is any interaction between populations that adversely affects their growth and survival. Competition manifests itself in the form of the struggle of species for ecological niches.

The classification of biotic interactions between populations of the two species is given in Table 1. 4.1.

In Table 4.1, "O" means that the population is not affected by the species interaction; "+" - that she benefits from the interaction of species; "-" - that she experiences the negative impact of such interaction.

No two different species occupy the same ecological niches, but there are closely related species, often so similar that they require essentially the same niche. In this case, when the niches partially overlap, there is especially fierce competition, but in the end the niche is occupied by one species. The phenomenon of ecological separation of closely related (or otherwise similar) species was called the principle of competitive exclusion, or the Gause principle, in honor of the scientist who proved its existence experimentally in 1934.

Neutralism is a form of biotic relationship when the cohabitation of two species in the same territory does not entail either positive or negative consequences for them. In this case, the species are not directly related to each other and do not even contact each other. For example, squirrels and elks, monkeys and elephants, etc. Neutralism relationships are characteristic of species-rich communities.

Amensalism is a biotic relationship in which the growth of one species (amensal) is inhibited by the excretory products of another. Such relationships are usually referred to as direct competition and are called antibiosis. They are best studied in plants that use various poisonous substances in the fight against competitors for resources, and this phenomenon is called allelopathy.

Amensalism is very common in aquatic environment. For example, blue-green algae, causing water blooms, thereby poison the aquatic fauna, and sometimes even livestock that comes to drink. Other algae show similar "abilities". They secrete peptides, quinone, antibiotics and other substances that are poisonous even in small doses. These poisons are called ectocrine substances.

Predators are called animals that feed on other animals, which they catch and kill. Predators are characterized by hunting behavior. The abundance of insects, their small size and easy availability turn the activity of carnivorous predators, usually birds, into a simple "gathering"

prey, just as they collect seeds, “grains of a bird that feed on them. Insectivorous predators, in a way that has mastered food, approach the grazing of herbivores. Some birds can eat both insects and seeds.

So, the toughest competition appears when the contact between populations is established recently, for example, due to changes that have occurred in the ecosystem under the influence of human activity. That is why ill-conceived human intervention in the structure of the biocenosis often leads to epidemic outbreaks.