Living Reference Work Entry

Encyclopedia of Evolutionary Psychological Science

pp 1-16

Date: Latest Version

Sperm Competition Theory

  • Clint D. KellyAffiliated withDépartement des sciences biologiques, Université du Québec à Montréal Email author 
  • , Michael D. JennionsAffiliated withResearch School of Biology, Australian National UniversityWissenschaftskolleg zu Berlin, Wallot strasse 19


Male-male competition; Postcopulatory sexual selection; Sperm allocation; Sperm expenditure; Strategic ejaculation


Sperm competition is an intrasexual process in which the sperm from two or more males compete to fertilize a female’s ova.


Darwin’s classic view of sexual selection holds that, controlling for differences in survivorship, variation in the reproductive success of the members of one sex can be attributed to two main processes. First, the members of one sex (usually females) preferentially choose to mate with certain members of the opposite sex (usually males), leading to the evolution of sexual “ornaments,” “seductive” traits, and sexual “advertisements.” Second, members of one sex (usually males) directly compete against each other for access to sexually receptive members of the opposite sex (usually females), leading to the evolution of weaponry. These processes are commonly referred to as female mate choice (or intersexual sexual selection) and ...

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