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The Influence of Operational Sex Ratio on the Intensity of Competition for Mates


The Influence of Operational Sex Ratio on the Intensity of Competition for Mates

Weir, Laura K. and Grant, James W.A. and Hutchings, Jeffrey A. (2011) The Influence of Operational Sex Ratio on the Intensity of Competition for Mates. The American Naturalist, 177 (2). pp. 167-176. ISSN 00030147

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Official URL: http://dx.doi.org/10.1086/657918


The evolution and maintenance of secondary sexual characteristics and behavior are heavily influenced by the variance in mating success among individuals in a population. The operational sex ratio (OSR) is often used as a predictor of the intensity of competition for mates, as it describes the relative number of males and females who are ready to mate. We investigate changes in aggression, courtship, mate guarding, and sperm release as a function of changes in the OSR using meta-analytic techniques. As the OSR becomes increasingly biased, aggression increases as competitors attempt to defend mates, but this aggression begins to decrease at an OSR of 1.99, presumably due to the increased costs of competition as rivals become more numerous. Sperm release follows a similar but not significant trend. By contrast, courtship rate decreases as the OSR becomes increasingly biased, whereas mate guarding and copulation duration increase. Overall, predictable behavioral changes occur in response to OSR, although the nature of the change is dependent on the type of mating behavior. These results suggest considerable flexibility of mating system structure within species, which can be predicted by OSR and likely results in variation in the strength of sexual selection.

Divisions:Concordia University > Faculty of Arts and Science > Biology
Item Type:Article
Authors:Weir, Laura K. and Grant, James W.A. and Hutchings, Jeffrey A.
Journal or Publication:The American Naturalist
Date:February 2011
Keywords:mating system , operational sex ratio , contest competition , sperm competition , courtship , mate guarding
ID Code:7113
Deposited On:02 Mar 2011 17:19
Last Modified:01 Feb 2012 06:38
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