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Intraspecific competition, its role and density factors

The concept of competition is increasingly being covered in the sphere of economics, but its origins nevertheless come from biology. What does this concept mean? What is the role of competition in wildlife? On the types and mechanisms of competition, read further in the article.

Different effects on organisms

No living organism exists isolated. It is surrounded by many factors of animate and inanimate nature. Therefore, in one way or another, he constantly interacts with the environment, other organisms. First of all, the biosphere influences the living creature, its components include the lithosphere, the hydrosphere, and also the atmosphere. The vital activity of plants and animals is directly related to the amount of sunlight, access to water resources, and so on.

Significant influence of organisms and experiencing interaction with each other. Such influence is called biotic factors, which manifest themselves as the impact of living organisms on plants, which, in turn, affects the habitat. In biology, they are divided into trophic (according to food relations among organisms), topical (with respect to environmental change), factory (depending on the place of residence), foreclosure (the possibility or impossibility of transporting the other by one organism of another) factors.

Interaction of living organisms

Carrying out their livelihoods, living organisms certainly affect the "personal space" of other organisms. This can occur both between representatives of one species, and different. Depending on whether the interaction affects organisms or not, the neutral, positive and negative types of relationships are distinguished.

Relations in which both organisms do not receive anything are called neutralism. Positive interaction is considered mutualism - mutually beneficial cohabitation of individuals. A completely negative relationship can be called allelopathy, when cohabitation harms both participants. Intraspecific and interspecific competition also applies here .

Some relationships have different effects on organisms. For example, with parasitism and predation, one organism survives at the expense of another or feeds on it. With commensalism, only one participant in the relationship benefits, for the other they are neutral. In the case of amensalism, one organism harms another, but does not receive any harm or benefit.


Important factors for the normal life of animals, plants, microorganisms is the resource of the environment and space. When there is a shortage between living organisms, competition appears. This is a kind of antibiosis - antagonistic relations, where different individuals are forced to fight for their existence.

Rivalry in wildlife often occurs when individuals have similar needs. If the struggle occurs among individuals of the same species, it is intraspecific competition, if to different - interspecific.

To compete with living organisms can openly, directly interfering with the life of the opponent. For example, when the roots of some plants are oppressed by others, or some animals drive others away from the grassy place. Also, competition can be indirect. It manifests itself when the opponent more actively destroys the necessary resource.

Intraspecific competition

Examples of intraspecific fighting can be found quite often. This type of competition is observed between individuals of one or more populations. The main reason for this is the same structure of organisms, and hence, the same needs for environmental factors and food.

Intraspecific competition is more rigid than interspecific competition. The manifestation of such a struggle can be observed in the delineation of the territory between individuals. Thus, bears leave traces of claws on tree trunks, warning of their presence. To separate the space often use a smell, a loud signal shout. Sometimes individuals simply attack each other.

If rivalry is for resources, then sometimes it is asymmetric. In this case, one side suffers more than the other. As a result of intraspecific competition, eventually one of the populations may disappear or change.

Why is there competition?

One of the most important tasks of living organisms is to survive, while transferring the best genetic material to the offspring. Under ideal conditions, an ecological vacuum, there are no obstacles for this, and therefore there is no rivalry.

Intraspecific competition occurs under adverse environmental conditions, when organisms are forced to fight for light, water or food. Harsh conditions can lead to a change in the life cycle of the species, to accelerate its development. However, this is not necessary. Sometimes rivalry occurs when individuals argue for the right to dominate the herd, flock or pride. This behavior is observed in animals with a developed social hierarchy.

The density of the population plays an important role. Excessive growth of a population of one species over time leads to a shortage of resources, which can lead to extinction of the species. To avoid this, some species, such as rodents, even have a shock disease. The ability of animals to multiply sharply decreases, but the susceptibility to various diseases increases.

The role and mechanisms of competition

Competition is the most important tool of nature. First of all, it is designed to regulate the number of individuals. Each species has its own allowable density, and when there are too many individuals within one population, control mechanisms are included. To realize this role, nature uses different methods: increasing mortality, dividing the territory.

In conditions of high numbers and limited space, some individuals can leave habitual habitat and master another. So from one population two different are allocated. This ensures a wide spread of the species and a high survival rate. In certain species this process is temporary, for example in migratory birds.

As a result of intraspecific competition, the more enduring and viable individuals end up surviving. Their physiological qualities are transmitted genetically, and therefore contribute to the improvement of the species.

Examples of intraspecific and interspecific competition

It is not always easy to distinguish two main types of competition. Understand this better visually. An example of interspecies competition is the "victory" of a gray rat over a black one. They belong to the same genus, but they are different species. The gray rat is more aggressive and predominant in size, so it could easily drive out black from human houses. But black was frequent guests on ships of seafarers.

As a model of intraspecific competition can be mentioned cannibalism, which is noted in about 1,300 species of animals. Female mantis eat males immediately after mating. The same behavior is observed in packs-Karakurts. Scorpions and salamanders eat some of their offspring. In many beetles, the larvae eat up their brethren.

The kind of internal competition is territoriality. It is observed in fish, penguins and most other birds. During the breeding season, they do not allow representatives of their species to visit their own territory, which is carefully guarded.

Competition with plants

Plants, although they can not openly attack an opponent and scare him off, also have their own methods of rivalry. They struggle mainly for light, water and free space. In severe conditions of existence, the intraspecies competition of plants manifests itself in the form of self-thinning.

This process begins with the spread of seeds and the capture of the plant territory. Sprouted sprouts can not develop the same way, some grow more actively, others grow slower. High trees with a spreading crown obscure other trees, taking away all the solar energy themselves, and their powerful roots block the way to nutrients. So small and weak plants wither and die.

Competition is reflected in the appearance of plants. Representatives of one species can vary significantly, depending on the degree of their isolation from other individuals. Observe this phenomenon can be oak. Separately growing, it has a wide, spreading crown. The lower branches are strong and well developed, no different from the upper ones. In the forest, among other trees, the lower branches can not receive enough light and die. The oak acquires a narrow, elongated shape of the crown instead of a spherical shape.


Competition is a type of relationship. It occurs between all living organisms without exception. The main objective of competition is to regulate the density of individuals, as well as increase their ability to survive. Often competition is due to the struggle for food, water, light or territory. It can arise as a result of a sharp shortage of one of these resources.

Rivalry, as a rule, occurs between species that have similar needs. The more similarities in living organisms, the stronger and more aggressive the struggle. Compete for the resource can be individuals of one and the same species. Intraspecific competition often occurs to establish a dominant individual, and also to ensure that the population does not grow excessively.

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