種内競争

WordNet

a business relation in which two parties compete to gain customers; "business competition can be fiendish at times"
the act of competing as for profit or a prize; "the teams were in fierce contention for first place" (同)contention, rivalry

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〈U〉〈C〉(…との…の)『競争』《+『with』+『名』+『for』+『名』》 / 〈C〉試合

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/12/11 11:39:22」(JST)

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A male Blackbird (Turdus merula) singing. Bird song often functions as a signal in territory defense.

Intraspecific competition is a particular form of competition in which members of the same species vie for the same resource in an ecosystem (e.g. food, light, nutrients, space). This can be contrasted with interspecific competition, in which different species compete.

For example, two trees of the same species growing close together will compete for light, water and nutrients in the soil. Getting less resources, they will perform more poorly than if they grew by themselves (for example lowered growth rates and fewer seed output). Trees have therefore adapted to grow taller or develop larger root systems through natural selection.

Grasshoppers provide an animal example. By eating grass, individual grasshoppers deprive their fellow conspecifics of food. This is an example of exploitation competition, which means that the grasshoppers do not interact directly with each other, but rather have a negative effect on others' growth and reproduction by their effect on a resource (in this case, grass). In other cases, intraspecific competition may be a case of interference competition, in which the animals interact directly. This is the case, most notably, in territorial animals: some individuals actively prevent others from exploiting a given resource, usually food or space.

Intraspecific competition is a major factor affecting the carrying capacity of a population (maximum population level supported by the environment). The levelling of population growth at high densities (known as density dependent inhibition) can be seen as an effect of intraspecific competition. Indeed, whereas at low densities organisms do not compete for resources, at higher densities resources become limiting, and the population size can no longer increase. In terms of population growth rate, this produces a sigmoidal curve, which is a familiar sight for ecologists.

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English Journal

Is the body condition of the invasive zebra mussel (Dreissena polymorpha) enhanced through attachment to native freshwater mussels (Bivalvia, Unionidae)?

Pilotto F1, Sousa R2, Aldridge DC3.
The Science of the total environment.Sci Total Environ.2016 May 15;553:243-9. doi: 10.1016/j.scitotenv.2016.02.119. Epub 2016 Feb 27.
The invasion of zebra mussels, Dreissena polymorpha, into Western Europe and North America has driven widespread ecological change. Attachment of zebra mussels to the shell of native unionoid mussels has resulted in reductions in unionoid abundance and, in extreme cases, their localised extirpations
PMID 26925735

Linking intra- and interspecific assortative mating: consequences for asymmetric sexual isolation.

Svensson EI1, Nordén A2, Waller JT2, Runemark A3.
Evolution; international journal of organic evolution.Evolution.2016 May 6. doi: 10.1111/evo.12939. [Epub ahead of print]
Assortative mating is of interest because of its role in speciation and the maintenance of species boundaries. However, we know little about how within-species assortment is related to interspecific sexual isolation. Most previous studies of assortative mating have focused on a single trait in males
PMID 27151764

Daphnia magna's sense of competition: intra-specific interactions (ISI) alter life history strategies and increase metals toxicity.

Gust KA1, Kennedy AJ2, Melby NL2, Wilbanks MS2, Laird J2, Meeks B3, Muller EB4, Nisbet RM5, Perkins EJ2.
Ecotoxicology (London, England).Ecotoxicology.2016 May 5. [Epub ahead of print]
This work investigates whether the scale-up to multi-animal exposures that is commonly applied in genomics studies provides equivalent toxicity outcomes to single-animal experiments of standard Daphnia magna toxicity assays. Specifically, we tested the null hypothesis that intraspecific interactions
PMID 27151402