The antibiosis is such a form of relationships in which both interacting species or one of them experience a harmful, overwhelming activity, influence from the other.

Neutralism is such a form of relationships, in which there are no direct interactions between the species and they do not have a noticeable influence on each other.

In nature, such relationships between organisms are defined rather difficult, since the complexity of biocenotic connections leads to the fact that most species indirectly affect each other.

For example, many forest animals (earthmock, small rodents, proteins, woodwoods) are not associated with a biocenosis direct relationships, but all depend on the stock of seeds of coniferous rocks and on this basis they indirectly affect each other.

The relationship of neutralism is characteristic of the rich species of communities.

Competition (- -).

Competition(from lat. Concurro - Face, knock) - this is a form of relationship, which is observed between organisms when we share the resources of the medium, the number of which is not enough for all consumers.

Competitive relationships will play an extremely important role in the formation of the species composition, the distribution of species in space and the regulation of the number of species in the community.

Distinguish intraspecific and interspecific competition.

Intraspecific competition - this is the struggle for the same medium resources that occur between individuals of the same species.

Intravidaya competition is the most important form of the struggle for the existence, which thoroughly increases the intensity of natural selection.

At the same time, interspecific competition manifests itself to the more severe, the more similar to the environmental needs of competitors.

Distinguish two forms of interspecific competitive relations: direct and indirect competition.

Direct (active) competition -suppression of one type of other.

With direct competition between species, directed antagonistic relations are developed, which are expressed in different forms of mutual oppression (fighting, overlapping access to the resource, chemical suppression of a competitor, etc.).

At the same time, many birds and animals aggression it is the main form of relationship, which determines the competitive displacement of one species to others in the process of struggle for shared resources.

for example:

- In forest biocenoses, competition between forest mice and red rowers leads to regular changes in habitats in these species. During the years with an increased number of forest mice, a variety of biotopes are populated, displacing red pools in less favorable places. And, on the contrary, the voles in numerical superiority are widely spread in places, of which were previously ousted by mice. It has been shown that the mechanism of competitive separation of habitats is based on aggressive interactions;


- Sea hedgehogs settled in coastal algae, physically eliminate other consumers from their pastures. Experiments with removal of marine hens have shown that the algae thickets are immediately populated by other animal species;

- In European settlements of a man, gray rat, like a larger and aggressive, completely displaced another species - a black rat, which now lives in steppe and desert areas.

Indirect (passive) competition -consumption of resources of the environment necessary by both types.

Indirect competition is expressed in the fact that one species worsens the conditions for the existence of another species with similar environmental requirements without providing direct forms of impact on a competitor.

With indirect competition, success in competitive struggle is determined by biological features of species: the intensity of reproduction, growth rate, population density, resource intensity, etc.

for example:

- In one reservoir, there can be jointly widespread and narrowly cancer. Usually the winner is narrowly cancer, as the most prolific and adapted to modern living conditions;

- In the settlements of a person, a small red-haired cockroach-Prussac pushed out a larger black cockroach only because it is more prolific and better adapted to the specific conditions of human dwelling.

Classic example of indirect interspear competitionare laboratory experiments conducted by Russian scientists G.F. Gause, according to the joint content of two types of infusories with a similar power character.

It turned out that with the joint growing of two types of infusories after a while in the nutrient medium there was only one of them. At the same time, the infusoria of one species did not attack individual species and did not allocate harmful substances to suppress a competitor. This was explained by the fact that these species differed in an unequal rate of growth and in competition for food fascinated the growing and multiplying appearance.

Model experiments conducted by G.F. Gause, led him to the wording widely known the principle of competitive exception (Theorem Gause):

Two ecological species of the species cannot jointly exist on the same territory, i.e. Cannot take a completely equal ecological niche. Such kinds must be separated in space or in time.

From this principle follows, what a joint habitat on one territory of nearby species is possible in cases where they differ in their environmental requirements, i.e. occupy various ecological niches.

for example:

- Insectivore birds avoid competition with each other at the expense of different food search sites: on tree trunks, in shrubs, on stumps, on large or small branches, etc.;

- Hawks and owls that feed about the same animals, avoid competition due to the fact that at different times of the day :: Hawks are hunting during the day, and Owls - at night.

Thus, interspecific competition arising between close species can have two consequences:

- displacement of one species to others;

- Different environmental specialization of species, allowing them to exist together.

An interspecific competition is called an active search in two or several types of the same foods of habitat. Competitive relations, as a rule, arise between species with similar environmental requirements. Competition between species is extremely widespread in nature and relates to almost all of them, since it is rarely as a species does not feel at least a small pressure on the part of individual species. With joint habitat, each of them is in a disadvantage due to the fact that the presence of another species reduces the possibilities in mastering food resources, asylum and other means of existence available in habitat. Ecology considers intersportal competition in a concrete, narrower sense - only as interconnected relations of species occupying a similar environmental niche.

Competitive relations can be very diverse: from direct physical struggle to almost peaceful joint existence. And at the same time, if two types with the same environmental needs turn out to be in one community, then it is necessarily one competitor displaces another. For example: in Europe in the settlements of a man, gray rat has completely displaced another type of the same kind - a black rat, which now lives in steppe and desert areas. Gray rat is larger, more aggressive, it is better floating, so managed to win. In Russia, on the contrary, a relatively small red-haired cockroach - Prussac was completely supplanted by a larger black cockroach only because it managed to better adapt to the specific conditions of human housing. In Australia, an ordinary bee, brought from Europe, pushed out a small native bee, not having a sting.

Intervidal competition can be demonstrated on simple laboratory experiments. Thus, in the studies of the Russian scientist G. F. Gauz culture of two types of infusories - shoes with a similar nutritional characteristics were placed separately and jointly in the vessels with the Senasta. Each species placed separately, successfully multiplied by achieving optimal numbers. However, when living together, the number of one of the species gradually decreased, and its individuals disappeared from infusion, while the second species infusories were preserved. It was concluded that a long joint existence of species with close environmental requirements is impossible. As it turned out, after a while alive there are individuals of only one species that survived in the struggle for food, since his population grew faster and multiplied. This conclusion was called the rule of competitive exception.

But the outcome of competition depends not only on the properties of interacting species, but also on the conditions in which there is a competitive struggle. Depending on the conditions that develop in particular habitat, the winner of the competitive struggle can be supposed to be either one or another species, which in this environmental situation has at least a small advantage over other, and therefore, and large fitness to the environmental conditions.

The researchers figured out the effect of temperature and humidity on the outcome of interspecific competition between the two types of flour beetles. The vessels with the flour contained with a certain combination of heat and moisture were placed several individuals of both species. Here, beetles and began to multiply, but after some time there were individuals of only one species. It is noteworthy that at high heat and moisture and moisture, the victory overlooked one species, and at the lowest one.

In some cases, this leads to the coexistence of competing species. After all, heat and humidity, as well as other environmental factors, are not even uniform distributed in nature. Even within a small area (forests, fields or other habitats), you can detect zones that differ in the microclimate. In this variety of conditions, each species is mastering the place where he was being survived.

Thus, in the community only those competing species that have adapted to at least break into environmental requirements. Thus, in African savannas, hoofs use pasture food in different ways: zebras tear the tops of herbs, the antiflages of the GNU eaten the plants of certain species, the gazelles are plucking only the lower herbs, and the antiflands of the fopies are rumbing up with high stems.

In our country, insectivore birds, rustling in trees, avoid competition with each other due to the different nature of the search for mining at different parts of the tree.

Competition is one of the reasons that two types, weakly differing specifics of nutrition, behavior, lifestyle, etc., rarely cohabit in one

community. Here competition is the character of direct hostility. The most cruel competition with unforeseen consequences arises, if a person enters the community species of animals without taking into account the already established relationships.

More often, competition is indirectly manifested, it is insignificant in nature, since various kinds of different types perceive the same environmental factors. The more diverse the possibilities of the organisms, the less tense there will be competition.

The value of competition as an environmental factor.

As already mentioned, competitive relations play an extremely important role in the formation of the species composition and regulation of the number of species in the community.

Ecologists know that organisms leading a similar lifestyle with a similar structure do not live in the same places. And if you live nearby, you use different resources and are active at different times. Their ecological niches are as if diverge in time and space.

The discrepancy between ecological niches with the joint habitat of related species is well illustrated by an example with two types of marine fishing birds - large and long-axis cormorants, which usually feed in the same waters and nest next door. Scientist managed to find out that the composition of the food of these birds differs significantly: the long-axis cormide catches the fish floating in the upper layers of water, while the Big Cormorant produces it mainly at the bottom, where Cambals are dominated, Cambals have a bottom invertebrates, such as shrimp.

Competition has a huge impact on the distribution of nearby species, although it is often about this only indirect data. Types with very similar needs are usually inherent in different geographic areas or different habitats in the same area or avoid competition in any other way, for example, due to differences in food or differences in daily, and even in seasonal activity.

The ecological action of natural selection, apparently, is aimed at excluding or preventing the continuous confrontation of species with a similar way of life. Environmental disagreement of closely related species is fixed during evolution. In Central Europe, for example, there are five close types of cells, the insulation of which is due to the differences in habitats, sometimes in the fields of feeding and size of production. Environmental differences are reflected in a number of small parts of the external structure, in particular in changes in the length and thickness of the beak. Changes in the structure of organisms, accompanying the processes of discrepancies of their environmental niches, suggest that interspecific competition is one of the most important factors for evolutionary transformations. If the interspecific competition is expressed weakly, then under the influence of intraspecific competition, the population of this species is expanding the boundaries of their habitat.

Thus, interspecific competition can play an important role in the formation of the appearance of the natural community. Giving and enshrining the variety of organisms, it helps to increase community sustainability, more efficient use of available resources.

Competitive relations.

If there are two or more types in the environmental system (population) with similar environmental requirements together, between them there are negative type relations, which are called competition (??). In the general sense, the word "competition" means configuration, rivalry, competition. In fact, when two populations use the same medium resources, then rivalry for mastering these resources inevitably arises between the species. At the same time, each population experiences oppression from another, which adversely affects their growth and survival and may even lead to the displacement and disappearance of one of them, less adapted.

Competition is extremely widespread in nature. For example, all plants compete (compete) per light, moisture, soil nutrients and for expanding the territory of their habitat. Animals fight for food resources and for shelters (if they are in short supply), that is, ultimately, also for the territory. However, if the population is not large and consists of a few, rarely encountered species, the environmental significance of competition will be insignificant: for example, in the Arctic or desert regions there is almost no competition of plants for the light.

Competition cannot be considered simply the use of the same natural resources by the organisms. You can only talk about negative interaction when this resource is missing and when the joint consumption is adversely affected by the population.

Types of competitive relationship

Competitive interaction can concern the territory, food, light, shelters and all other types of environmental resources. The outcome of competition is of great interest not only for environmentalists studying the processes of formation of natural communities, but also for evolutionists that study the mechanisms of natural selection.

Competition is divided into intraspecific and interspecific. Both intraspecific and interspecific competition can play a big role in the formation of a variety of species and the dynamics of the number of organisms.

Intraspecific competition. Territoriality

Intraspecific competition? This is the struggle for the same resources that occur between the individuals of the same species. This is an important factor in self-regulation of populations.

In some organisms, an interesting type of behavior has been formed under the influence of intraspecific competition for living space? territoriality. It is characteristic of many birds, some fish, other animals.

In birds, territoriality is manifested as follows. At the beginning of the breeding season, the male reveals the "its" territory (part of the habitat) and protects it from the invasion of males of the same species. Note that the loud voices of the males, which we hear in the spring, signals only about the "right of ownership" on the attractive area, and they do not put a task to entertain the female, as is usually considered.

The male, strictly guarding his site, has more chances to fly and build a nest, while the male, which is not able to secure its territory, will not participate in reproduction. Sometimes a female takes part in the protection of the territory. In the protected area, difficult concerns about the nest and juvenile will not be violated by the presence of other parent couples.

The protection of the territory is not necessarily accompanied by an active struggle. Loud singing and threatening positiveness is usually enough to drive a competitor. However, if one of the parent partners dies, it quickly replaces the bird from among those who have not yet had substantiated individuals. Thus, territorial behavior can be considered a regulator that does not allow both overpopulation and union.

A vivid example of intraspecific competition that everyone could see in the forest,? The so-called self-indispensation in plants. This process begins with the seizure of the territory: for example, somewhere in an open place, not far from the big spruce, which gives many seeds, there are several dozen shoots? Small Christmas trees. The first task is made? The population has grown and captured the territory needed to survive it. Thus, the territoriality of plants occurs differently than in animals: the site is not a separate individual, and their group (part of the population).

Young trees grow, in the passage of grassy plants under their crowns under their crowns (this is an example of interspecific competition (see here)). Over time, the inevitable growth difference appears between the trees: one thing is weaker, others are lagging behind, others? overtake. Since fir? A very light-loving plant (her crown absorbs almost all the incident light), then weaker young Christmas trees begin to make more and more shading from high trees and gradually dry out, die away.

In the end, after many years in the meadow, only two or three trees (the strongest individuals of all generation) remain on the meadow. But no herbs are no longer there, the roots of the trees spread over the entire territory of the Polyana, and nothing prevents the lush coniferous crown even higher to the sun.

In some species, intraspecific regulation begins long before serious competition is found. Thus, the high density of animals is a factor of oppression that reduces the reproduction rate of this population even with the abundance of food resources. (See Part II. Ecology of populations? Demixology.)

Internal competition is an important regulator controlling population growth. Thanks to this competition, a certain dependence occurs between the population density and the rate of dying processes (mortality) or reproduction (fertility) of individuals. This, in turn, leads to the emergence of a certain relationship between the number of parental couples and the number of offspring they produced. Such connections act as regulators of vibrations of population numbers ...

The world of wildlife is amazingly diverse. The same can be said about the relationship between all kinds inhabiting the planet. Like people, animals can exploit, interfere in the affairs of each other or at all in no way interact with each other. Examples of competition in nature are quite frequent and natural phenomenon. Which of them are the most stronnight and interesting?

Examples of competitive relations in nature

Intervida competition has always been difficult to demonstrate in the field, and therefore you can not observe many specific examples. If two types use the same resource, it does not mean that they compete. Animals just no need to join the struggle where everything you need for survival is available in unlimited quantities. Such examples can be found in natural systems.

To say that the types compete, they must occupy the same ecosystem and use the overall resource, and as a result, this should lead to a decrease in the number of one of the populations or even to its complete destruction or exile. As a rule, it is much easier to demonstrate interference competition. This is when one species directly prevents access to a different type to a limited resource, and this leads to a decrease in survival.

One example of competition of organisms in nature is the Argentine ant. His homeland is South America, and this is one of the worst species of invasive ants around the world. When a colony finds a food resource, they are physically and chemically protect it, not allowing indigenous ants to access the food resource. They often attack and displace other colonies of fellow in the area. This leads to a decrease in the number of populations of ants. Since they physically interact with other colonies of ants, this is a classic example of interspecific competition in nature.


Invisible competition

It is much more difficult to detect examples of competition in nature in animals that do not directly interact with each other. Turtles eat only shrubs that they can reach, pulling the neck. Goats also eat bushes, but their choice is sewn than in the turtles. As a result, the second gets less vegetation, which is needed for survival and prosperity. This example of interspecific competition in nature proves the fact that some animals can reduce the number of others even without direct physical interaction.

Operation and intervention (interference)

Interwide competition occurs when different types of species in the ecosystem compete for the same resources: food, shelter, light, water and other important needs. Such a struggle can reduce the number of concrete species, moreover, the increase in the population of competitors also tends to limit the growth of a particular type. Thus, competition can be carried out in two ways at the level of individual organisms, namely: operational competition and interference competition.

Examples of competition in the nature of the first type include often invisible struggle for limited resources. As a result of using their specific species, they become insufficient for others. Intervention or interference means direct interaction to obtain resources.

Examples of intraspecific competition in nature, as well as interspecific, may include the struggle between prey predators. Thus, a cruel confrontation may occur inside the type (between two tigers) and between several species (between the lion and hyenas).


Possible effects

  • As a result, there may be restrictions in the size of the population, as well as changes in communities and evolution of species.
  • According to the principle of competitive exception, none of two species using the same limited resources in the same way in the same space can not exist together.
  • Although local extinction is rarely found compared to the competitive exception and differentiation of niches, it also occurs.

Examples of competitive relationships

In a dense forest between tree plants, interspecific competition may occur. This is due to the fact that when there are mixed types of trees, access to resources for some of them can be easier than for others. For example, higher trees are able to absorb more sunlight, which makes it less affordable for lower trees.

Wild animals, such as lions and tigers, are also bright examples of competition in nature. They hunt for the same prey that can cause less availability of food resources for one of them. In addition, spotted hyenas compete with African lion for food. The same thing happens with brown bears and tigers. Zebra and Gazelles are fighting for the grass.

Competitive relations can be observed in the oceans, for example, it may be sponges and corals, rival for space. In the desert areas of Coyote and the rattle snake fiercely fighting for food and water. Intervida competition is also observed in small animals, such as proteins and chipmunks that tend to compete for nuts and other products.

Where both organism live in one niche and are in competition for resources or space, the negative result will inevitably be inevitably for each body, since the available resource will decrease for both sides.


Intraspecific struggle for existence

This competition is the most fierce and especially stubborn. This confrontation implies oppression and violent displacement, expulsion or destruction of less adapted individuals. Nature does not like weak in the struggle for resources and living space. One of the most bloodshed is the fights for female in the marriage.

Examples of competition in nature can be a variety of, including competition when choosing a sexual partner to continue the kind (deer), the struggle for living space and food (a stronger corona will be weak) and so on.

Interspear struggle for existence

If there is something directly or indirectly, individuals of various species are fighting, then here it is about interspecific competition. Especially persistent confrontation is observed between nearby creatures, for example:

  1. Gray rat huses black from its living space.
  2. Dremat's Drozd causes a decrease in the population of a singing thrush.
  3. The cockroach Prusak successfully surpasses and infringe on black relatives.

Competition and struggle for existence are important driving forces of evolution. An important role is played by natural selection and hereditary variability. It is difficult to imagine how diverse and complex are the relationship between living beings inhabiting our planet. Intravidaya and interspecific competition are huge, if not crucial in the formation of biological diversity and regulating the numerical composition of populations.

The interactions of species in the composition of biocenosis are characterized not only by bonds on the line of direct trophic relations, but also by numerous indirect bonds that unite species of both one and different trophic levels.

Competition - this is The form of relationship arising in cases where two types use the same resources (space, food, shelter, etc.).

Distinguish 2 forms of competition:

- direct competition, in which directional antagonistic relations, expressed in different forms of oppression: fights, chemical suppression of a competitor, and so para;

- indirect competition, which expresses in the fact that one species worsens the conditions for habitat for the existence of another species.

Competition can be both inside the species and between several species of one kind (or several childbirth):

Internal competition is manifested between individuals of the same species. This type of competition is radically different from interspecific and is expressed mainly in the territorial behavior of animals that protect the places of their nesting and the famous area in the district. These are many birds and fish. The relations of individuals in populations (inside the form) are diverse and contradictory. And if species devices are useful for the entire population, then for individual individuals, they can be harmful and cause their death. With an excessive increase in the number of individuals, the intraspecific struggle is exacerbated. That is, the intraspess struggle is accompanied by a decrease in the fecundity and the death of part of the species of the species. There are a number of devices that help individuals of one population avoid direct clashes among themselves - you can meet mutual assistance and cooperation (joint feeding, education and protection of offspring);

Interwide competition is any interaction between populations that harmful affects their growth and survival. The interspest struggle is observed between populations of various types. It proceeds very quickly if kinds need similar conditions and belong to one family. The interspecific struggle for existence includes one-sided use of one species to others, i.e. the relationship "Predator - Victim". The form of the struggle for the existence in a broad sense is and favored by one species to another without prejudice to itself (for example, birds and mammals spread fruits and seeds); Mutual favored one species to another without prejudice to itself (for example, flowers and their pollinators). The fight against unfavorable environmental conditions is observed in any part of the range, when the external environmental conditions deteriorate: for daily and seasonal fluctuations in temperature and humidity. Biotic interactions of populations of two species are classified on:

neutralism - when one population does not affect the other;

competition is the suppression of both species;

amenzalism - one population suppresses another, but at the same time does not have a negative impact;

predation - individuals of the predator larger than the individuals of the victim;

commminasalism - the population benefits from the association with another population, and the latter is indifferent;

protocooperation - interaction favorably for both species, but not necessarily;

mutualism - interaction must necessarily be favorable for both species.

An example of a model of interpopulation interactions can serve "the spread of individuals of the" marine acorns "- Balyanus, which set on the rocks above the tidal zone, since not to withstand drying. Smaller chthameclus, on the contrary, are only above this zone. Although their larvae is settled in the settlement zone, direct competition from Balyanus, who are able to disrupt competitors from the substrate, impede their appearance in this territory. In turn, Balyanas may be ousted by mussels. But nevertheless later, when mussels occupy all the space, Balyanus begin to settle on their sinks, again increasing their number. In competition for nesting shelters, the big tit dominates the smallest Lazorovka, capturing the doupels with the years of larger size. Outside the competition of Lazorovka prefer the pilot in 32 mm, and in the presence of a big tity, they will settle in the doupels with a 26 mm flyer, unsuitable for a competitor. In forest biocenoses, competition between forest mice and red pools leads to regular changes in the biotopic distribution of species. During the years with an increased number of forest mice, a variety of biotopes are populated, displacing red pools in less favorable places.

The main types of interpopulation relationships ("Predator - Victim", Mutualism, Symbiosis)

Competitive relations can be the most different - from direct physical struggle to a peaceful joint existence. And at the same time, if two types with the same environmental needs turn out to be in one community, then it is necessarily one competitor displaces another. This environmental rule was called "law competitive exception", Formulated P. Gause. According to the results of his experiments, it can be said that among the species with a similar characteristic of nutrition after a while, the individuals of only one species survived in the struggle for food, since his population grew faster and multiplied. The winner in the competitive struggle is the one. The view that in this ecological situation has at least small advantages over others, and consequently a large fitness to the environmental conditions.

Competition performs one of the reasons that two types, weakly differing nutrition, behavior, lifestyle, etc., rarely cohabit in one community. In this case, competition is character Direct hostility. The most cruel competition with unforeseen consequences occurs if a person introduces the types of animals in the community without taking into account the already established relationships. But often competition is manifested indirectly, it is insignificant, since various types of otherwise perceive the same environmental factors. The more diverse the possibilities of organisms, the less tense there will be competition.

Mutualism (Symbiosis) - one of the stages of development of the dependence of two populations from each other, When the union occurs between very different organisms and the most important moustunistic systems occur between autotrophs and heterotrophs.Classic examples of Mutualistic relations - Actinia and inhabitants of their fishes fishes in the wreath; Hermitage Cancers and Actius. Other examples of this type of relationship are also known. So, ASPIDOSIPHON worm at a young age hides his body into a small empty shell of bunthogged clams.

Mutualistic forms of relations are also known in the plant world: in the root system of higher plants there are connections with mikrizing mushrooms, nitrogen-forming bacteria. Symbiosis with mineral mushrooms provides plants with minerals, and mushrooms - sugars. Similarly, nitrogen-fixing bacteria, supplying a plant with nitrogen, is obtained from it carbohydrates (in the form of sugars). On the basis of such relations, a complex of adaptations is formed, ensuring the stability and functional efficacy of mutualistic interactions.

Closer and biologically significant forms of connections occur with the so-called endosimbiosis - Cohabitation, in which one of the species is settled inside the body of another. These are the relationship of higher animals with bacteria and the simplest intestinal tract.

Many animals contain photosynthetic organisms in their fabrics (mostly lower algae). It is known a settlement of green algae in the wool of slides, while the algae use wool as a substrate, and for sloths create a patronage color.

Unlikely symbiosis of many deep-sea fish with luminous bacteria. This form of mutualism provides a light painting so important in the dark by creating glowing organs - photophors. Fabrics of luminous organs are abundantly supplied with nutrient substances necessary for the life of bacteria.

Predation. Laws of the system "Predator - Victim"

Predator - This is free-lived organism, eating by other animal organisms or vegetable foods, i.e., the organisms of the same population serve as a different population for organisms. A predator, as a rule, first catches the victim, kills her, and then eats. It has special devices for this.

W. victims Also historically developed Protective properties In the form of anatomy-morphological, physiological, biochemical features, for example: body grows, spikes, spines, shells, protective painting, poisonous glands, the ability to break into the ground, quickly hide, build inaccessible asylum predators, resort to danger alarm.

As a result of such interdependent devices, certain Grouping organisms In the form of specialized predators and specialized victims. Extensive literature is devoted to the analysis and mathematical interpretation of these relationships, starting from the classical Volterra-Lotch model (A Lotka, 1925; V. Volterra, 1926, 1931) to numerous modifications.

Laws of the "predator - victim" system (V. Volterra):

- law periodic cycle - the process of destroying the victim by a predator often leads to periodic fluctuations in the population of both species depending only on the growth rate of the predator population and victims, and on the initial ratio of their number;

- law middle Savings - the average number of populations for each species is constant, regardless of the entry level, provided that the specific speed of increasing the population number, as well as the effectiveness of predatoryness is constant;

- law middle Violations - with a similar violation of the population of a predator and the victim (for example, fish in the course of the fishery is proportional to their number), the average population of the victim is growing, and the population of the predator - falls.

Volterry trays model. The predator-victim model is considered as a spatial structure. Structures can be formed both in time and in space. Such structures are called "Spatio-temporal".

An example of temporary structures can serve as the evolution of the number of blessing bias and a fish, which is characterized by oscillations in time. Ryys feed on the hares, and the hares eate the vegetable feed, which is available in unlimited quantities, therefore the number of Zaitsev (the growth of reserves of available food for a fish) is increasing. As a result, the number of predators is increasing to the time when they become a significant% amount, and then the destruction of the hare occurs very quickly. As a result, the number of victims decreases, food reserves are dried and, accordingly, their number decreases. Then again the number of hares increases, respectively, the lynys begin to strengthen themselves, and everything is repeated first.

This example is considered in the literature as a model of trays - Volterra, which describes not only the vibration of the population in ecology, it is also a model of non-unforgettable concentric oscillations in chemical systems.

Limit factors

The idea of \u200b\u200bthe limiting factors is based on two laws of ecology: the law of the minimum and the law of tolerance.

Minimum law. In the middle of a last century, German chemist Y. Libik (1840), studying the effect of nutrients on the growth of plants, found that the crop depends not on those elements of power, which are required in large quantities and are present in abundance (for example, C0 2 and H 2 0), and from those that, though And we need a plant in smaller quantities, but practically absent in the soil or unavailable (for example, phosphorus, zinc, boron). This pattern of libes formulated this: "The growth of the plant depends on the element of the power, which is present in the minimum number." Later, this conclusion was known as the law of a minimum of libege and was distributed to many other environmental factors.

Limit, or limit, the development of organisms can heat, light, water, oxygen, and other factors, if their value corresponds to an environmental minimum.

For example, Tropical Fish "Marine Angel" dies if the water temperature drops below 16 ° C. And the development of algae in deep-sea ecosystems is limited to the penetration of sunlight: in the bottom layers there is no algae.

The libiha minimum law in general can be formulated as follows: The growth and development of organisms depend primarily from those factors of the natural environment, the values \u200b\u200bof which are approaching an environmental minimum.

Studies have shown that the minimum law has 2 restrictions that should be taken into account in practice:

- the first limitation is that the Libiha law is strictly applicable only in conditions stationary system status.

For example, in some reservoir, the growth of algae is limited in vivo the lack of phosphates. In this case, nitrogen compounds are contained in water in excess. If there is a high content with high content in such an oil: mineral phosphorus, then the reservoir can "bloody". This process will be progress until one of the elements is spent to a restrictive minimum. Now it can be nitrogen if phosphorus continues to flow. In the transitional moment (when nitrogen is not enough, and the phosphorus is already enough) the effect of a minimum is not observed, i.e. neither, one of these elements does not affect the growth of algae;

- second limitassociated with interaction of several factors. Sometimes the body is able Replace the deficient element other, chemically close .

So, in places where there is a lot of strontium, in mollusc sinks, it can replace calcium with the latter shortage. Or, for example, the need for zinc in some plants is reduced if they grow in the shade. Consequently, the low concentration "zinc will less limit the growth of plants in the shade than i in bright light. In these cases, the limiting effect of even an insufficient number of one or another element may not appear.

The law of tolerance (from lat. Tolerantia. - patience) was opened by an English biologist V. Shefod (1913), which drew attention to the fact that limiting the development of living organisms can not only those environmental factors that are minimal, but also those that are characterized by Environmental maximum. Excess heat, light, water and even nutrients can have an equally destructive effect, as well as their disadvantage. The range of the ecological factor between the minimum and maximum V. Sheford called the "Tolerance limit".

Tolerance limit Describes the amplitude of the vibrations of the factors that ensures the most complete existence of the population.

Later, the tolerance limits relative to various environmental factors for many plants and animals were established. Laws of Yu. Libiha and V. Sheford helped to understand many phenomena and the distribution of organisms in nature. Organisms cannot be distributed everywhere because populations have a certain limit of tolerance with respect to fluctuations in environmental environmental factors.

The law of tolerance V. Sheford Formulated: The growth and development of organisms depend, first of all, from those environmental factors, the meanings of which are approaching an environmental minimum or an environmental maximum. The following was established:

Organisms with a wide range of tolerance to all factors are widespread in nature and are often cosmopolitans (for example, many pathogenic bacteria);

Organisms can have a wide range of tolerance in relation to one factor and a narrow range relative to the other (for example, people are more enduring to the absence of food than to the absence of water, i.e. the tolerance limit relative to the water is narrower, than relative to food);

If the conditions according to one of the environmental factors become non-optimal, then the limit of tolerance for other factors can be changed (for example, with a lack of nitrogen in the soil of cereals, much more water is required);

Observed real limits of tolerance less potential capacity capabilities to adapt to this factor. This is due to the fact that in nature, the limits of tolerance in relation to the physical environment can be dried by biological relations: competition, lack of pollinators, predators, etc. Anyone is better implementing its potential

opportunities in favorable conditions (for example, athlete fees for special training before responsible competitions). The potential ecological plasticity of the organism, defined in laboratory conditions, more realized opportunities in natural conditions. Accordingly, distinguish Potential and implemented Environmental niches;

- the limits of tolerance in breeding individuals andthe offspring is less than adult individuals, that is, females during the reproduction period and their offspring are less hardy than adult organisms.

Thus, the geographical distribution of fishing birds is more often determined by the influence of climate on eggs and chicks, and not on adult birds. Caring for offspring and careful attitude towards motherhood are dictated by the laws of nature. Unfortunately, sometimes social "achievements" contradict these laws;

Extreme (stressful) values \u200b\u200bof one of the factors lead to a decrease in tolerance limit to other factors.

If the raged water is reset into the river, the fish and other organisms spend almost all their energy to overcome stress. They lack energy to produce food, protection against predators, reproduction, which leads to gradual extinction. Psychological stress can also cause many somatic (from Greek. Soma. -To) the disease is not only in humans, but also in some animals (for example, in dogs). With stressful values \u200b\u200bof the factor, adaptation to it becomes more and more difficult.

Many organisms can change tolerance to individual factors if the conditions change gradually. You can, for example, to get used to the high temperature of the water in the bath, if climb hot water, and then gradually add hot. Such an adaptation to a slow change in factor is a useful protective property. But it may be dangerous. Unexpected, without warning signals, even a small change may be critical. Becoming threshold effect. For example, a thin twig can lead to a fracture already overloaded camel back.

If the value of at least one of the environmental factors approaches a minimum or maximum, the existence and development of the body, the population or community becomes dependent on this, limiting the vital activity, factor.

Limit factor called Any environmental factor approaching extreme values \u200b\u200bof the limits of tolerance or exceeding them.Such strongly deviating factors are primarily acquired in the lives of organisms and biological systems. They are they control the conditions of existence.

The importance of the concept of limiting factors is that it allows you to understand complex relationships in ecosystems. Note that not all possible environmental factors regulate the relationship between the environment, organisms and man. Various limiting factors are prioritized in one or another segment. They need to focus their attention when studying ecosystems and managing them. For example, the oxygen content in terrestrial habitats is large, and it is so available that it almost never serves as a limiting factor (with the exception of large heights, anthropogenic systems). Oxygen is little interested in ecologists engaged in ground ecosystems. And in the water he is often a factor limiting the development of living organisms ("Zamok" of fish, for example). therefore Hydrobiologist Measures the oxygen content in water, in contrast to a veterinarian or an ornithologist, although for ground organisms oxygen is no less important than for water.

Limit factors determine and geographic Area species.So, the promotion of organisms to the north is limited, as a rule, disadvantage Heat.

The distribution of certain organisms often limit and biotic Factors.

For example, the figs brought from the Mediterranean in California did not be fruiting there until they guessed to get there and a certain appearance of the osse - the only pollinator of this plant.

The identification of limiting factors is very important for many activities, especially agriculture. With a focused impact on limiting conditions, it is possible to quickly and efficiently increase the yield of plants and animal productivity.

Thus, when breeding wheat on acidic soils, no agronomic measures give effect if not to use lime, which reduces the limiting effect of acids. Or if they grow corn on soils with a very low phosphorus content, then even with sufficient water, nitrogen, potassium and other nutrients, it stops growing. Phosphorus in this case is a limiting factor. And only phosphoric fertilizers can save the crop. Plants may die from too much water or excess: fertilizers, which in this case are limiting factors.

Knowledge of limiting factors gives the key to the management of ecosystems. However, in different periods of the life of the body and in different situations, various factors protrude as limiting. Therefore, only the skillful regulation of the existence conditions can give effective management results.


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