Ecology: biology of interaction. 4.13. Competition and ecological niches
As we have established, competition is defined as a relationship between two populations in which the increase of each causes a decrease in the size of the other. However, this definition applies only to interspecific competition, and besides it there is also intraspecific competition, which unfolds...
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April 12. Parasitism
D. Shabanov, M. Kravchenko. Ecology: Interaction Biology Section 4. Population Ecology
4.13. Competition and Ecological Niches As we have established, competition is defined as a relationship between two populations where an increase in the population size of one leads to a decrease in the population size of the other. Competition arises from the limited availability of resources necessary for both species. Competition can be direct or indirect. Direct competition is the struggle for resources within an individual's territory. Indirect competition is the struggle for shared resources where organisms do not come into direct contact with each other. An ecological niche is the role an organism plays in its habitat. It is a combination of all its characteristics: territory, geographic location, activity time, diet, and other variables. Two populations cannot occupy the same ecological niche if they compete with each other. This is the basis for the coexistence of closely related species in the same location – it can be achieved by partitioning the ecological niche. Depending on the type of limiting factor, competition arises for space (territorial competition), for food (resource competition), or for reproductive partners (sexual competition). Studies of competition in natural and experimental populations have shown that one species often has an advantage over another. Often, the winner in competition is the species best adapted to the given environmental conditions. As a result of competitive exclusion, the weaker species is displaced from the population by the less adapted species, and survival depends on the stronger species. The process of one species displacing another in natural populations can take years, decades, or even centuries, depending on the species' reproductive cycle length, population density, and environmental conditions. Numerous examples from various large-scale systems demonstrate that the more competitive species often displaces the less competitive species over a longer period.