Sexual dimorphism

Article By:

Dunn, Alison M. School of Biology, University of Leeds, Leeds, United Kingdom.

Wedell, Nina School of Biology, University of Leeds, Leeds, United Kingdom.

Last reviewed:June 2020

DOI:https://doi.org/10.1036/1097-8542.617800

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• Sexual dimorphism, published June 2014:Download PDF Get Adobe Acrobat Reader

Any difference, morphological or behavioral, between males and females of the same species. Sexual dimorphism is a condition in which there are differences in size, appearance, and behavior between males and females of the same species. This dimorphism is seen throughout the animal and plant kingdoms, with males and females differing in traits ranging from gamete size to ornaments, weapons, and behavior. In animals that exhibit sexual dimorphism, the sex of an individual can be determined at a glance. For example, roosters have bright plumage, a large comb, and an elaborate tail, all of which are lacking in hens. Sexual dimorphism arises as a result of the different reproductive functions of the two sexes and is a consequence of both natural selection and sexual selection. Primary differences, such as the structure of the reproductive organs, are driven by natural selection and are key to the individual's function as a mother or father. Other differences, such as the enormous tail of the peacock (Pavo cristatus) [Fig. 1], are driven by sexual selection and increase the individual's success in acquiring mates. See also: Behavioral ecology; Evolution; Reproductive behavior; Reproductive system

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