Hey good looking ... spending too much time chasing good looking females may be good for males, but is bad for the species.
Credit: Wikimedia
SYDNEY: Aggressively courting the most attractive females could be bad for the species as a whole, according to a new study on sexual selection in fruit flies.
The paper, published in the journal PLoS Biology, found that when males evolve a preference for the most 'attractive' females, the adaptive rate of evolution decreases.
This is partly a result of constant harassment by affectionate males restricting the females’ ability to forage, and partly because the seminal fluid of the fruit fly, Drosophila melanogaster, is mildly toxic to females, reducing their lifetime reproductive success.
"We tend to think of sexual selection as being good for a species," said Bill Rice, co-author of the study and evolutionary geneticist from the University of California at Santa Barbara.
In the case of fruit flies, however, "the aggressive courtship of attractive females is good for males, but harmful for the species."
There is a conflict of interest when it comes to sex between fruit flies, the researchers noted. Competitive males select a mate based on short-term fertility, thus preventing the chances of other males reproducing with the same female.
Females, on the other hand, benefit by maximising their long-term reproductive potential. According to Rice, females allowed only minimal exposure to males increase their lifetime reproductive success by more than 20%.
He gives the example of a hypothetical genetic mutation resulting in an increased efficiency in digestion as well as increased body size in females.
As these larger females attract more attention, their reproductive success decreases, reducing the ability of the entire species to benefit from the mutation through natural selection.
"The findings are important," said Anneli Hoikkala, an evolutionary geneticist from the University of Jyvaskyla in Finland. "The most intriguing finding is that male mate choice for high-fecundity females may lead to a diminished rate of adaptive evolution."
According to Anneli, who was involved in a similar study earlier in 2009, this paper is particularly interesting because it focuses on sexual selection on the part of males, rather than on female choice and preferred traits in males "which has been the main trend during the last decades."
