Contest competition

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In ecology, contest competition refers to a situation where available resources, such as food and mates, are utilized only by one or a few individuals, thus preventing development or reproduction of other individuals. It refers to a hypothetical situation in which several individuals stage a contest for which one eventually emerges victorious. Contest competition is the opposite of scramble competition, a situation in which available resources are shared equally among individuals.

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As contest competition allows the monopolization of resources, offspring will typically always be produced and survive until adulthood independent of the population size, resulting in stable population dynamics. This is in stark contrast to scramble competition which can result in periodic or chaotic population dynamics. The Beverton–Holt model is often used to represent population dynamics arising from contest competition. This model, and a few other well-known population models, can be explicitly derived from individual-level processes assuming contest competition and a random distribution of individuals among resources. [1]

Contest competition has been observed in a variety of species. In white-faced monkeys, Cebus capucinus , regardless of aggression, avoidance, or sex, higher ranking monkeys had higher energy intake within their group. [2] For female Microcebus murinus groups, if the resource (fruit) could be monopolized, they would compete within their group for it. [3] In a controlled lab experiment with three parasitic wasp species ( Dinarmus basalis , Anisopteromalus calandrae , and Heterospilus prosopidis ) they found that between the first larvae in the host and the second, the larvae that would win depended on the time between them. [4] There was also a Nicholson–Bailey model made to partially explain the relationship between Heterospilus prosopidis and its host Callosobruchus maculatus . [5]

Fitness gains for the winner of the contest is not always known. For example, in mountain gorillas, Gorilla beringei , higher ranking females had higher average food-site resident times and higher aggression and avoidance while eating than lower ranking females. [6] Higher ranking females have higher reproductive success, but both energy intake and the energy needed for travel to the food site do not differ among ranks. [6]

Other research in contest competition focus on what aspects are relevant for contest resolution. In a study looking at aerial wars of attrition in territorial insects, they found that the energy Cuterebra austeni got from their resources before adulthood played a role in who won. [7] Some species have obvious gains when they win, but no morphological and/or physiological tell to determine who would win. This is the case with several species of butterflies where males hold a contest over territory. [8] However, a study in 2010 that staged contests between male Pararge aegeria found motivation to be a factor. [9] The more time a male spent with a female, the more persistent they were, which increased the likelihood of the male to win the contest over the previous male holding dominance over the territory.

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<i>Jalmenus evagoras</i> Species of butterfly

Jalmenus evagoras, the imperial hairstreak, imperial blue, or common imperial blue, is a small, metallic blue butterfly of the family Lycaenidae. It is commonly found in eastern coastal regions of Australia. This species is notable for its unique mutualism with ants of the genus Iridomyrmex. The ants provide protection for juveniles and cues for adult mating behavior. They are compensated with food secreted from J. evagoras larvae. The ants greatly enhance the survival and reproductive success of the butterflies. J. evagoras lives and feeds on Acacia plants, so butterfly populations are localized to areas with preferred species of both host plants and ants.

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<span class="mw-page-title-main">Scramble competition</span>

In ecology, scramble competition refers to a situation in which a resource is accessible to all competitors. However, since the particular resource is usually finite, scramble competition may lead to decreased survival rates for all competitors if the resource is used to its carrying capacity. Scramble competition is also defined as "[a] finite resource [that] is shared equally amongst the competitors so that the quantity of food per individual declines with increasing population density". A further description of scramble competition is "competition for a resource that is inadequate for the needs of all, but which is partitioned equally among contestants, so that no competitor obtains the amount it needs and all would die in extreme cases."

Filial cannibalism occurs when an adult individual of a species consumes all or part of the young of its own species or immediate offspring. Filial cannibalism occurs in many species ranging from mammals to insects, and is especially prevalent in various types of fish species with males that engage in egg guardianship. The exact evolutionary purpose of the practice in those species is unclear and debated among zoologists, though there is consensus that it may have, or may have had at some point in species' evolutionary history, certain evolutionary and ecological implications.

References

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