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Chickens eject sperm from males they don't fancy

Date:
August 28, 2011
Source:
University of Chicago Press Journals
Summary:
New research finds that even though hens aren't terribly picky about their mates, they are picky about whose sperm makes it to the egg. Female domestic chickens generally mate with multiple males and are known to sometimes eject sperm following mating encounters. It was unclear, however, whether the sperm ejection was a consequence of receiving a large amount of ejaculate, or because hens are actively trying to rid themselves of undesirable sperm.
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While sexual coercion is common in fowl, females are able to exert a strong influence on fertilization by differentially dumping sperm of individual males.
Credit: © Tommaso Pizzari

New research finds that even though hens aren't terribly picky about their mates, they are picky about whose sperm makes it to the egg. Female domestic chickens generally mate with multiple males and are known to sometimes eject sperm following mating encounters. It was unclear, however, whether the sperm ejection was a consequence of receiving a large amount of ejaculate, or because hens are actively trying to rid themselves of undesirable sperm.

A team led by Oxford researcher Rebecca Dean investigated the phenomenon in a group of feral chickens kept at Stockholm University in Sweden. After controlling for ejaculate size and other factors, Dean and her colleagues found that hens ejected a larger proportion of inseminations by socially subordinate males.

"These results show that promiscuous females can actively bias sperm utilization to exert a strong and predictable influence on the struggle for fertilization," Dean said. By doing so, females "retain control of paternity even in species such as fowl where males can force mating."

The research appears in the September 2011 issue of the The American Naturalist, published by The University of Chicago Press for The American Society of Naturalists.


Story Source:

The above post is reprinted from materials provided by University of Chicago Press Journals. Note: Materials may be edited for content and length.


Journal Reference:

  1. Rebecca Dean, Shinichi Nakagawa, Tommaso Pizzari. The Risk and Intensity of Sperm Ejection in Female Birds. The American Naturalist, 2011; 178 (3): 343 DOI: 10.1086/661244

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University of Chicago Press Journals. "Chickens eject sperm from males they don't fancy." ScienceDaily. ScienceDaily, 28 August 2011. <www.sciencedaily.com/releases/2011/08/110828210552.htm>.
University of Chicago Press Journals. (2011, August 28). Chickens eject sperm from males they don't fancy. ScienceDaily. Retrieved September 4, 2015 from www.sciencedaily.com/releases/2011/08/110828210552.htm
University of Chicago Press Journals. "Chickens eject sperm from males they don't fancy." ScienceDaily. www.sciencedaily.com/releases/2011/08/110828210552.htm (accessed September 4, 2015).

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