Researchers from three universities in California wonder why evolution has not created super-aggressive males if it is the warriors that get the girls. Results from their investigation, which suggests that there is more to mating than destroying the competition, are published in the open-access journal PLoS ONE.
The biologists, hailing from the University of Southern California (USC); Cal State University, Sacramento; and the University of California, Davis, studied mating behavior among fruit flies. They find that although females choose males who win fights, they also select ones who do not fight and select others for no clear reason. Their findings contribute to understanding the large variations in aggressive behavior in humans and most other species.
Research leader Brad Foley (post-doctoral fellow at USC) explains that, “If aggression makes you more likely to father children, all males should be selected to be very aggressive. Male fruit flies (like humans and other animals) show a lot of genetic variation in aggression, and we wanted to find out why.”
According to this analysis and previous research conducted on lizards, the authors suggest that a possible reason for this variation is due to the fact that there is no optimal fighting strategy in mating that works every time – much like the game of rock-paper-scissors.
“We showed in fruit flies that even the most genetically aggressive flies can have an Achilles heel, and lose against males who are (for the most part) wimps,” noted Foley.
Foley adds that, “There’s no single way to win a fight, or win mates. Females didn’t necessarily prefer aggressive males – some males mated less when they lost fights, but some males mated more if they didn’t fight. Moreover, different females preferred different males.”
“Unexpected interactions between individuals can define winners and losers (so-called ‘chemistry’),” the author concluded. “In order to understand why flies, and humans, and other animals, are so genetically different from each other, we need to stop imagining there’s a ‘best’ kind of strategy.”
Does Sex Trade with Violence among Genotypes in Drosophila melanogaster?
Cabral LG, Foley BR, and Nuzhdin SV.
PLoS ONE (2008). 3(4): e1986.
doi:10.1371/journal.pone.0001986
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About PLoS ONE
PLoS ONE is the first journal of primary research from all areas of science to employ both pre- and post-publication peer review to maximize the impact of every report it publishes. PLoS ONE is published by the Public Library of Science (PLoS), the Open-access publisher whose goal is to make the world’s scientific and medical literature a public resource.
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Written by: Peter M Crosta