How much sex is enough?

Jan 20, 2011

Society has long debated the contrasting advantages of monogamy and promiscuity and, in western society at least, the long term benefits of monogamy have in general won out. However new research published in BioMed Central's open access journal BMC Evolutionary Biology shows that sperm from polygamous mice are better competitors in the race for fertilisation.

Dr Renée Firman at the Centre for Evolutionary Biology, University of Western Australia, has used house mice to show that from rival males compete to fertilise females and that, over several generations, polygamy can select for mice who produce more sperm, with stronger motility, than monogamous males.

After 12 generations of competitive selection (polygamous) or relaxed selection (monogamous) female mice were mated twice, in succession, with males from both groups. While 53% of the litters had mixed paternity, 33% of litters were fathered by the polygamous males compared to 14% by monogamous males. Polygamous males retained this advantage regardless of whether they were mated first or second, demonstrating that the increased fitness applies to both offensive and defensive competition. The selection procedure had no obvious effect on male size or behaviour, nor did it affect female fertility.

So in the age old debate about the merits of versus polygamy is seems that, for male mice at least, the more partners you have the more fertile your offspring will be.

Explore further: Evolution of competitiveness

More information: Experimental evolution of sperm competitiveness in a Mammal, Renée C. Firman and Leigh W. Simmons, BMC Evolutionary Biology (in press).

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User comments : 1

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dogbert
4.3 / 5 (6) Jan 20, 2011
Another piece of useless research.

When you select for certain traits, you are likely to obtain the traits you select for. This has been known for thousands of years.

The headline, by the way, has nothing at all to do with the research. The research was about monogamy vs polygamy -- not frequency of sex.

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