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Function of copulatory plugs in house mice: mating behavior and paternity outcomes of rival males


Sutter, Andreas; Simmons, Leigh W; Lindholm, Anna K; Firman, Renée C (2016). Function of copulatory plugs in house mice: mating behavior and paternity outcomes of rival males. Behavioral Ecology, 27(1):185-195.

Abstract

Polyandry is widespread across animal taxa, and subjects males to intense post-copulatory sexual selection which favors adaptations that enhance a male’s paternity success, either by decreasing the risk of sperm competition and/or by increasing the competitiveness of the ejaculate. Copulatory plugs deposited by males are thought to have evolved in the context of sperm competition. However, experimental studies that assess the function of copulatory plugs remain scarce. Moreover, most studies have used unnatural manipulations, such as ablating plug-producing male glands or interrupting copulations. Here, we investigated whether repeated ejaculation affects plug size in a mammalian model species, the house mouse. When males experience short periods of sexual rest we found that plug size decreased over repeated ejaculations so that time since last ejaculation can be applied as an approximation for plug size. We induced natural variation in plug size arising from variation in male sexual restedness, and investigated the behavior and paternity success of rival males. Male behavior in the offensive mating role (second) was influenced, albeit not significantly, by the sexual restedness of the first male-to-mate, and therefore the size of his plug. However, second males sired a significantly greater proportion of embryos when competing against a male that had recently mated compared to a male that had not. This supports a potential role of the plug in promoting a male's competitive fertilization success when remating occurs, which could be mediated both by delaying female remating and by ensuring efficient sperm transport through the female reproductive tract.

Abstract

Polyandry is widespread across animal taxa, and subjects males to intense post-copulatory sexual selection which favors adaptations that enhance a male’s paternity success, either by decreasing the risk of sperm competition and/or by increasing the competitiveness of the ejaculate. Copulatory plugs deposited by males are thought to have evolved in the context of sperm competition. However, experimental studies that assess the function of copulatory plugs remain scarce. Moreover, most studies have used unnatural manipulations, such as ablating plug-producing male glands or interrupting copulations. Here, we investigated whether repeated ejaculation affects plug size in a mammalian model species, the house mouse. When males experience short periods of sexual rest we found that plug size decreased over repeated ejaculations so that time since last ejaculation can be applied as an approximation for plug size. We induced natural variation in plug size arising from variation in male sexual restedness, and investigated the behavior and paternity success of rival males. Male behavior in the offensive mating role (second) was influenced, albeit not significantly, by the sexual restedness of the first male-to-mate, and therefore the size of his plug. However, second males sired a significantly greater proportion of embryos when competing against a male that had recently mated compared to a male that had not. This supports a potential role of the plug in promoting a male's competitive fertilization success when remating occurs, which could be mediated both by delaying female remating and by ensuring efficient sperm transport through the female reproductive tract.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Language:English
Date:2016
Deposited On:14 Oct 2015 13:25
Last Modified:08 Dec 2017 14:18
Publisher:Oxford University Press
ISSN:1045-2249
Funders:Swiss National Science Foundation, Claraz Foundation, Australian Research Council
Additional Information:This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Behavioral Ecology following peer review. The definitive publisher-authenticated version [Sutter et al: Function of copulatory plugs in house mice: mating behavior and paternity outcomes of rival males, Behavioral Ecology (2015) doi: 10.1093/beheco/arv138] is available online at: http://beheco.oxfordjournals.org/content/early/2015/08/21/beheco.arv138.
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.1093/beheco/arv138

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