Competition (biology)

Competition is an interaction between organisms or species in which both require one or more resources that are in limited supply (such as food, water, or territory).

[2] In the study of community ecology, competition within and between members of a species is an important biological interaction.

More recently, however, researchers have suggested that evolutionary biodiversity for vertebrates has been driven not by competition between organisms, but by these animals adapting to colonize empty livable space; this is termed the 'Room to Roam' hypothesis.

[6] In animals, interference competition is a strategy mainly adopted by larger and stronger organisms within a habitat.

[7] Plants, on the other hand, primarily engage in interference competition with their neighbors through allelopathy, or the production of biochemicals.

[8] Interference competition can be seen as a strategy that has a clear cost (injury or death) and benefit (obtaining resources that would have gone to other organisms).

However, does and fawns have dealt with this through temporal resource partitioning — foraging for food only when adult males are not present.

[7] Since smaller organisms have an advantage when exploitative competition is important in an ecosystem, this mechanism of competition might lead to a juvenile-driven generation cycle: individual juveniles succeed and grow fast, but once they mature they are outcompeted by smaller organisms.

Apparent competition occurs when two otherwise unrelated prey species indirectly compete for survival through a shared predator.

[13][14] Holt found that field ecologists at the time were erroneously attributing negative interactions among prey species to niche partitioning and competitive exclusion, ignoring the role of food-limited predators.

The effect on realized niches could be incredibly strong, especially when there is an absence of more traditional interference or exploitative competition.

[13] Support for the impact of competition on the breadth of the realized niche with respect to diet is becoming more common in a variety of systems based upon isotopic and spatial data, including both carnivores[15] and small mammals.

The most extreme scenario of asymmetric apparent competition is when one species is not affected at all by the increase in the predator, which can be seen as a form of amensalism (0, -).

An example of fully asymmetric apparent competition which often occurs near urban centers is subsidies in the form of human garbage or waste.

An empirical example is provided by two small fish species in postglacial lakes in Western Canada, where resource competition between prickly sculpin and threespine stickleback fish leads to a spatial niche shift mainly in threespine stickleback.

Among plants, size asymmetry is context-dependent and competition can be both asymmetric and symmetric depending on the most limiting resource.

[23] Whether above-ground or below-ground resources are more limiting can have major effects on the structure and diversity of ecological communities; in mixed beech stands, for example, size-asymmetric competition for light is a stronger predictor of growth compared with competition for soil resources.

[citation needed] Intraspecific competition occurs when members of the same species compete for the same resources in an ecosystem.

Interspecific competition may occur when individuals of two separate species share a limiting resource in the same area.

Interspecific competition has the potential to alter populations, communities, and the evolution of interacting species.

An example among animals could be the case of cheetahs and lions; since both species feed on similar prey, they are negatively impacted by the presence of the other because they will have less food, however, they still persist together, despite the prediction that under competition one will displace the other.

For example, in southern California coyotes often kill and eat gray foxes and bobcats, all three carnivores sharing the same stable prey (small mammals).

Russian ecologist, Georgy Gause, studied the competition between the two species of Paramecium that occurred as a result of their coexistence.

For example, mammals lived beside reptiles for many millions of years of time but were unable to gain a competitive edge until dinosaurs were devastated by the Cretaceous–Paleogene extinction event.

Typically, r-selected species exploit empty niches, and produce many offspring, each of whom has a relatively low probability of surviving to adulthood.

In contrast, K-selected species are strong competitors in crowded niches, and invest more heavily in much fewer offspring, each with a relatively high probability of surviving to adulthood.