Mice with many sexual partners produce more fertile sons than do monogamous mice, according to a study by scientists at the Centre for Evolutionary Biology, University of Western Australia.
The team discovered that sperm from polygamous mice are better competitors in the race for fertilisation.
Dr Renee Firman and her team attempted to show that sperm 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.
The study found that while 53 percent of the litters had mixed paternity, 33 percent of litters were fathered by the polygamous males compared to 14 percent by monogamous males.
And whether they were mated first or second, polygamous males retained this advantage, showing that the increased fitness applies to both offensive and defensive competition.
The study seems to debunk previously held theories about the merits of monogamy versus polygamy.
The study appears in the journal BMC Evolutionary Biology.