What is the ecological niche of a species. Abstract ecological niches

Abstract on ecology

Any species is adapted to certain environmental conditions (factors). The output of the parameters of at least one of the many factors beyond the tolerance of the organism causes its oppression. The requirements of an organism for the composition and parameters of environmental factors inherited from ancestors determine the boundaries of the distribution of the species to which this organism belongs, i.e., the range, and within the range, specific habitats.

In other words, any kind of animal, plant, microorganism is able to normally live, feed, reproduce only in the place where it was "registered" by evolution over many millennia, starting with its ancestors. To designate this phenomenon, biologists borrowed the architectural term "niche". Thus, each type of living organism occupies its own unique ecological niche in nature.

ecological niche - this is the place of the organism in nature and the whole way of its life activity or, as they say, vital status, which includes attitudes to environmental factors, types of food, time and methods of feeding, places of reproduction, shelters, etc. This concept is much more voluminous and meaningful than the concept of "habitat".

habitat - this is a spatially limited set of conditions of the abiotic and biotic environment, providing the entire cycle of development of the organism.

The American ecologist Y. Odum figuratively called the habitat the "address" of the organism, and the ecological niche - its "profession". As a rule, a large number of organisms of different species live in one habitat. For example, a mixed forest is a habitat for hundreds of species of organisms, but each of them has its own ecological niche. Ecological niche - the functional role of the species in the place of its "registration". On the one hand, the organism is a participant in the general flow of life in the environment, and on the other hand, the creator of such a flow. And this, indeed, is very similar to the profession of a person.

First of all, an ecological niche cannot be occupied by two or more types, just as there are no two absolutely identical professions. A species occupies an ecological niche in order to perform a unique function only in its own way, thus mastering the habitat and at the same time shaping it. Nature is very economical - even just two species occupying the same ecological niche cannot coexist stably, because as a result of competition one of them will be replaced by the other. This pattern is not without exceptions, but it is so objective that it is formulated in the form of a provision called the “principle of competitive exclusion” (the principle of G.F. Gause): if two species with similar environmental requirements (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. 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.

An ecological niche, as a functional place of a species in the system of life, cannot be empty for a long time - this is evidenced by the rule of mandatory filling of ecological niches: an empty ecological niche is always naturally filled .

Of the other properties of ecological niches, we note that an organism (species) can change them throughout its life. life cycle. The most striking example in this respect is insects. Thus, the ecological niche of larvae Maybug associated with the soil, nutrition by the root systems of plants. At the same time, the ecological niche of beetles is associated with the terrestrial environment, feeding on the green parts of plants.

Communities of living organisms 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. At the same time, it should be borne in mind that the employment of ecological niches is, to a certain extent, a relative concept. All niches are usually mastered by those organisms that are characteristic of the given region. But if the organism comes from outside (for example, seeds are brought in) accidentally or intentionally, then it can find a free niche for itself due to the fact that there were no applicants for it from the set existing species. In this case, a rapid increase in the number (outbreak) of the alien species is usually inevitable, since it finds extremely favorable conditions (a free niche) and, in particular, has no enemies.

The ecological niche as a functional place of the species in the habitat allows a form capable of developing new adaptations to fill this niche, but sometimes this requires a significant amount of time. Often, empty ecological niches that seem to a specialist are just a hoax. Therefore, a person should be extremely careful with the conclusions about the possibility of filling these niches by acclimatization. Acclimatization is a set of measures to introduce a species into new habitats, carried out in order to enrich natural or artificial communities with organisms useful to humans. The heyday of acclimatization fell on the 20-40s of the twentieth century. However, as time passed, it became obvious that either the experiments were unsuccessful, or, worse, they brought very negative results - the species became pests, spread dangerous diseases etc. It could not have been otherwise: placed in an alien environment with an actually occupied ecological niche, new species displaced those who had already performed similar work. New species did not meet the needs of the ecosystem, sometimes they did not have enemies and therefore could multiply rapidly. But then limiting factors came into play. The number of the species fell sharply, or, on the contrary, it multiplied intensively, like a rabbit in Australia, and became a pest.

ecological niche - the place of the species in the biogeocenosis, determined by its biotic potential and a combination of factors external environment 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.

In structure ecological niche distinguish 3 components:

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 a given species decreases to a territory with optimal conditions and, at the same time, the specialization of the species increases.

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

general characteristics

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

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

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

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

Characteristics of ecological niches

The characteristics of ecological niches include three main components:

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

Principle of competitive exclusion

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

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

Law of constancy

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

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

Mandatory rule

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

Ways of coexistence of organisms

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

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

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

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

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

The evolution of human ecological niches

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

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

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

Human ecological niche

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

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

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

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

The concept of an ecological niche has proved to be very fruitful for understanding the laws of cohabitation of species. Many ecologists worked on its development: J. Grinnell, C. Elton, G. Hutchinson, Y. Odum and others.

The concept of "ecological niche" should be distinguished from the concept of "habitat". In the latter case, that part of the space is meant which is inhabited by the species and which has the necessary abiotic conditions for its existence. The ecological niche of a species depends not only on abiotic environmental conditions, but also, to no lesser extent, on its biocenotic environment. The nature of the ecological niche occupied is determined both by the ecological possibilities of the species and by the extent to which these possibilities can be realized in specific biocenoses. This is a characteristic of the lifestyle that a species can lead in a given community.

G. Hutchinson put forward the concepts of fundamental and realized ecological niche. Under fundamental refers to the entire set of conditions under which a species can successfully exist and reproduce. In natural biocenoses, however, species do not develop all the resources suitable for them due, first of all, to competitive relations. Realized ecological niche - this is the position of the species in a particular community, where it is limited by complex biocenotic relationships. In other words, the fundamental ecological niche characterizes the potential possibilities of the species, and the realized niche characterizes that part of them that can be realized under given conditions, given the availability of the resource. Thus, the realized niche is always smaller than the fundamental one.

In ecology, the question of how many ecological niches a biocenosis can accommodate and how many species of any particular group with similar environmental requirements can get along together is widely discussed.

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, while reverse processes are characterized as its expansion. Competitors greatly influence the expansion or narrowing of the ecological niche of a species in the community. competitive exclusion rule formulated by G.F. Gause for ecologically close species, can be expressed in such a way that two species do not coexist in the same ecological niche.

Experiments and observations in nature show that in all cases where species cannot avoid competition for basic resources, weaker competitors are gradually forced out of the community. However, in biocenoses, there are many opportunities for at least partial differentiation of ecological niches of ecologically close species.

The exit from competition is achieved due to the divergence of requirements for the environment, a change in lifestyle, which, in other words, is the delimitation of the ecological niches of species. In this case, they acquire the ability to coexist in one biocenosis. Each of the species living together in the absence of a competitor is capable of a more complete use of resources. This phenomenon is easy to observe in nature. So, herbaceous plants spruce forests are able to be content with a small amount of soil nitrogen, which remains from its interception by tree roots. However, if the roots of these spruces are cut off in a limited area, the conditions for the nitrogen nutrition of the grasses improve and they grow rapidly, taking on a dense green color. The improvement of living conditions and an increase in the number of a species as a result of the removal from the biocenosis of another, close in ecological requirements, is called competitive release.

The division of ecological niches by cohabiting species with their partial overlap is one of the mechanisms for the stability of natural biocenoses. If any of the species drastically reduces its numbers or falls out of the community, others take over its role. The more species in the composition of the biocenosis, the lower the number of each of them, the more pronounced their ecological specialization. In this case, one speaks of "a denser packing of ecological niches in the biocenosis".

In closely related species living together, very fine delineations of ecological niches are usually observed. So, ungulates grazing in the African savannas use pasture food in different ways: zebras mainly cut off the tops of grasses, wildebeest feed on what zebras leave them, choosing certain types of plants, gazelles pluck out the lowest grasses, and topi antelopes are content with high dry stems left over from other herbivores. The same "division of labor" in the southern European steppes was once carried out by wild horses, marmots and ground squirrels (Fig. 92).

Rice. 92. Different types of herbivores eat grass at different heights in the African savannas (upper rows) and in the steppes of Eurasia (lower rows) (according to F. R. Fuente, 1972; B. D. Abaturov, G. V. Kuznetsov, 1973)

In our winter forests, insectivorous tree-feeding birds also avoid competition with each other due to the different nature of the search. For example, nuthatches and pikas gather food on trunks. At the same time, nuthatches quickly examine the tree, quickly grabbing insects that catch their eye or seeds caught in large cracks in the bark, while small pikas carefully search the smallest cracks on the surface of the trunk, into which their thin awl-shaped beak penetrates. In winter, in mixed flocks, great tits conduct a wide search in trees, bushes, stumps, and often in the snow; tit tits examine mainly large branches; long-tailed tits seek food at the ends of branches; small kinglets carefully search the upper parts of coniferous crowns.

Ants exist in natural conditions in multi-species associations, the members of which differ in their way of life. In the forests of the Moscow region, such an association of species is most often found: the dominant species (Formica rufa, F. aquilonia or Lasius fuliginosus) occupies several layers, L. flavus is active in the soil, Myrmica rubra is active in the forest litter, L. niger and F. fusca, trees - Camponotus herculeanus. Specialization for life in different tiers is reflected in the life form of species. In addition to separation in space, ants also differ in the nature of obtaining food, in the time of daily activity.

In deserts, the complex of ants is most developed, collecting food on the surface of the soil. (herpetobionts). Representatives of three trophic groups stand out among them: 1) diurnal zoonecrophages - active in the hottest time, feed on insect corpses and small living insects active during the day; 2) nocturnal zoophages - prey on sedentary insects with soft covers that appear on the surface only at night, and on molting arthropods; 3) carpophages (day and night) - eat the seeds of plants.

Several species from the same trophic group can live together. The mechanisms for exiting competition and delimiting ecological niches are as follows.

1. Dimensional differentiation (Fig. 93). For example, the average weights of working individuals of the three most common diurnal zoonecrophages in the Kyzylkum sands are related as 1:8:120. Approximately the same ratio of weights in a medium-sized cat, lynx and tiger.

Rice. 93. Comparative sizes of four species of ants from the group of diurnal zoonecrophages in the sandy desert of the Central Karakum and the distribution of prey of three species by weight classes (according to G. M. Dlussky, 1981): 1 – medium and large worker Cataglyphis setipes; 2 - C. pallida; 3 – Acantholepis semenovi; 4 – Plagiolepis pallescens

2. Behavioral differences are in different strategies foraging. Ants that create roads and use the mobilization of carriers to carry food to the nest, feed mainly on the seeds of plants that form clumps. Ants, whose foragers work as solitary foragers, collect mainly the seeds of dispersed plants.

3. Spatial differentiation. Within the same layer, food gathering by different species can be confined to different areas, for example, in open areas or under sagebrush bushes, on sandy or clay sites, etc.

4. Differences in activity time relate mainly to the time of day, but in some species there are discrepancies in activity according to the seasons of the year (mainly spring or autumn activity).

Ecological niches of species are variable in space and time. They can be sharply demarcated in individual development depending on the stage of ontogenesis, as, for example, in caterpillars and adults of Lepidoptera, larvae and beetles of the May beetle, tadpoles and adult frogs. In this case, both the habitat and the entire biocenotic environment change. In other species, the ecological niches occupied by young and adult forms are closer, but nevertheless there are always differences between them. Thus, adult perches and their fry living in the same lake use different energy sources for their existence and enter different food chains. Fry live off small plankton, adults are typical predators.

The weakening of interspecific competition leads to the expansion of the ecological niche of the species. On oceanic islands with poor fauna, a number of birds, in comparison with their relatives on the mainland, inhabit more diverse habitats and expand the range of food, since they do not encounter competing species. In the island inhabitants, even an increased variability in the shape of the beak is noted as an indicator of the expansion of the nature of food relations.

If interspecific competition narrows the ecological niche of a species, preventing all its potentialities from manifesting, then intraspecific competition, on the contrary, contributes to the expansion of ecological niches. With an increased number of species, the use of additional feed, the development of new habitats, the emergence of new biocenotic relationships begins.

In water bodies, plants that are completely submerged in water (elodea, hornwort, urut) find themselves in different conditions of temperature, illumination, gas regime than those floating on the surface (telorez, water paint, duckweed) or rooting at the bottom and bringing leaves to the surface (water lily, jug, victoria). They also differ in their relationship with the environment. Epiphytes of tropical forests occupy similar, but still not identical niches, as they belong to different ecological groups in relation to light and water (heliophytes and sciophytes, hygrophytes, mesophytes and xerophytes). Different epiphytic orchids have highly specialized pollinators.

In a mature broad-leaved forest, the trees of the first tier - common oak, smooth elm, plane maple, heart-leaved linden, common ash - have similar life forms. The tree canopy formed by their crowns is in the same horizon, under similar environmental conditions. But careful analysis shows that they participate in community life in different ways and, therefore, occupy different ecological niches. These trees differ in the degree of photophilous and shade tolerance, the timing of flowering and fruiting, the methods of pollination and distribution of fruits, the composition of consorts, and so on. Oak, elm and ash are anemophilous plants, but the environment is saturated with their pollen in different dates. Maple and linden are entomophiles, good honey plants, but they bloom at different times. In oak - zoochory, in other broad-leaved trees - anemochory. The composition of consorts is different for everyone.

If in a broad-leaved forest the tree crowns are in the same horizon, then the active root endings are located at different depths. The roots of oak penetrate the deepest, the roots of maple are located higher, and even more superficially - ash. The litter of different types of trees is disposed of at different rates. Linden, maple, elm, ash leaves almost completely decompose by spring, and oak leaves still form loose forest litter in spring.

In accordance with the ideas of L. G. Ramensky about the ecological individuality of species and taking into account the fact that plant species in the community are involved in the development and transformation of the environment and energy transformation in different ways, we can assume that in the established phytocenoses each plant species has its own ecological niche .

In ontogenesis, plants, like many animals, change their ecological niche. As they age, they use and transform their environment more intensively. The transition of the plant to the generative period significantly expands the range of consorts, changes the size and intensity of the phytogenic field. The environment-forming role of aging, senile plants decreases. They lose many consorts, but the role of their associated destructors increases. Production processes are weakened.

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

Rice. 94. Correlation between diversity of deciduous layers and species diversity birds (Shannon indices according to MacArthur from E. Pianka, 1981)

Bibliography

Shilov I. A. Ecology. Moscow: Higher school, 1997.

Khristoforova N.K. Fundamentals of ecology. Vladivostok: Dalnauka, 1999.

Gilyarov A. M. Population ecology. M.: Publishing House of Moscow State University, 1990.

Any living organism is adapted (adapted) to certain environmental conditions. Changing its parameters, their going beyond certain boundaries suppresses the vital activity of organisms and can cause their death. The requirements of one or another organism to the environmental factors determine the range (distribution boundaries) of the species to which the organism belongs, and within the range - specific habitats.

habitat- a spatially limited set of environmental conditions (abiotic and biotic), providing the entire cycle of development and reproduction of individuals (or groups of individuals) of the same species. This, for example, hedge, pond, grove, rocky shore, etc. At the same time, within the habitat, places with special conditions can be distinguished (for example, under the bark of a rotting tree trunk in a grove), in some cases called microhabitats.

For the overall characterization of the physical space occupied by organisms of a species, their functional role in the biotic habitat, including the mode of nutrition (trophic status), lifestyle and relationships with other species, the American scientist J. Grinnell in 1928. the term "ecological niche" was introduced. His modern definition such.

An ecological niche is a set

· All the requirements of the organism to the conditions of the environment (composition and modes of environmental factors) and the place where these requirements are met;

・Total set biological characteristics and physical parameters of the environment that determine the conditions for the existence of a particular species, its transformation of energy, the exchange of information with the environment and their own kind.

Thus, the ecological niche characterizes the degree of biological specialization of a species. It can be argued that the habitat of an organism is its “address”, while the ecological niche is its “occupation”, or “lifestyle”, or “profession”. For example, the thrush's habitat includes forests, parks, meadows, orchards, kitchen gardens, and yards. Its ecological niche includes such factors as nesting and incubation of chicks on trees, feeding on insects, earthworms and fruits, transferring fruit and berry seeds with their excrement.

Ecological specificity of species is emphasized axiom of ecological adaptability: each species is adapted to a strictly defined, specific set of conditions of existence for it - an ecological niche.

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.

Organisms that lead a similar way of life, as a rule, do not live in the same places due to interspecific competition. According to the established in 1934. Soviet biologist G.F. Gause (1910-1986) principle of competitive mutual exclusion: two species do not occupy the same ecological niche.

It also works in nature rule of obligatory filling of ecological niches: The empty ecological niche will always and will definitely be filled.

Folk wisdom formulated these two postulates as follows: “Two bears cannot get along in one lair” and “Nature does not tolerate emptiness.”

These systematic observations are realized in the formation of biotic communities and biocenoses. Ecological niches are always filled, although this sometimes takes a considerable amount of time. The common expression “free ecological niche” means that in a certain place there is little competition for any type of food and there is an insufficiently used amount of other conditions for a certain species that is included in similar natural systems, but is absent in the one under consideration.

It is especially important to take into account natural patterns when trying to intervene in an existing (or prevailing in a certain place) situation in order to create more favorable conditions for a person. So, biologists have proved the following: in cities, with an increase in the contamination of the territory with food waste, the number of crows increases. When trying to improve the situation, for example, by physically destroying them, the population may face the fact that the ecological niche in the urban environment, vacated by ravens, will be quickly occupied by a species that has a close ecological niche, namely, rats. Such a result can hardly be considered a victory.

Each biological species plays a specific role in its ecosystem. Ecologists have proven that some species, called key species, drastically affect many other organisms in the ecosystem. The disappearance of a key species from an ecosystem can provoke a whole cascade of sharp drops in population size and even the extinction of those species that depended on it in one form or another.

An example of a key species is the earth turtle. The earth turtle lives on sandy uplands in Florida and other southern regions of the United States. This slow, dinner plate-sized animal digs a hole up to 9 meters deep. In the hot, inhospitable ecosystems of the US South, these burrows provide shelter from the heat for nearly 40 other animal species such as the gray fox, opossum, indigo snake and many insects. Where the earth tortoise has been extirpated or driven to the brink of extinction by numerous hunters for its exquisite meat, many species dependent on the tortoise have ceased to exist.

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.

The variety of species and forms of flora and fauna that exists in tropical rainforests is associated with the presence of a number of specialized ecological niches in each of the clearly defined tiers of forest vegetation. Therefore, the intensive deforestation of these forests has caused the extinction of millions of specialized plant and animal species.

General niches. 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.

As long as an ecosystem has enough common resources, different species consume them together. However, if two or more species in the same ecosystem begin to consume the same scarce resource, they will find themselves in a relationship interspecies competition.

A species gains an advantage in interspecific competition if it is characterized by

More intensive reproduction;

Adaptation to a wider range of temperature, light, water salinity or

concentrations of certain harmful substances;

Depriving a competitor of access to a resource.

Ways to reduce interspecific competition:

Relocation to another area;

Switching to more inaccessible or difficult to digest food;

Change in time and place of foraging.

The most characteristic form of species interaction in food chains and networks is predation, in which an individual of one species (predator) feeds on organisms (or parts of organisms) of another species (prey), and the predator lives separately from the prey. These two organisms are involved in a predator-prey relationship.

Prey species use a range of defense mechanisms to avoid becoming easy prey for predators:

The ability to run or fly fast;

Possession of thick skin or shell;

Possession of a protective coloration or a way to change color;

The ability to highlight chemical substances with a smell or taste that repels a predator or even poisons it.

Predators also have several ways to prey:

The ability to run fast (for example, a cheetah);

Hunting in packs (eg spotted hyenas, lions, wolves);

Capturing as victims predominantly sick, wounded and other inferior individuals;

The fourth way to provide yourself with animal food is the way that a reasonable person went, the way of inventing hunting tools and traps, as well as domesticating animals.

It often happens that two different kind organisms directly interact in such a way that they bring mutual benefit to each other. Such mutually beneficial interspecies interactions are called mutualism. For example, flowers and pollinating insects.

Commensalism is characterized by the fact that one of the two species benefits from interspecies interaction, while the other is practically not reflected in any way (neither positively nor negatively). For example, crustaceans in the jaws of a whale.

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.

In the course of the evolutionary process, the global ecological niche of the biosphere expanded. When a species exhausted the genetically determined potential of the development of the ecological niche where it was born, it either displaced other species, conquering their ecological niches, or mastered a previously lifeless niche, genetically reorganizing itself under it, possibly generating the new kind organisms.

At some stage in the development of the biosphere, a species of Homo sapiens arose, the representatives of which are all mankind, despite all the diversity of races, peoples, nationalities, tribes.

The potential for the development of adults of each biological species for all the qualities of an individual is genetically determined, although it may not be revealed, not filled with real content if the environmental conditions do not favor it. In relation to the population, genetic conditioning and the potential for its development are subject to probabilistic predeterminations, reflected in the statistical patterns of what happened. This fully applies to humans - a biological species that carries the largest absolute and relative volume (compared to other types of living organisms of the Earth's biosphere) of non-genetically determined behavioral information, providing the greatest flexibility of behavior in a rapidly changing environment.