Female guppy fish are able to avoid unwanted male attention by associating with more attractive females, say scientists. Here two male guppy fish are approaching a female.
Credit: Safi Darden
ABERYSTWYTH: To avoid unwanted male harassment, female guppy fish have developed a unique strategy - associating themselves with more attractive females.
In research published today in Proceedings of the Royal Society, scientists from the University of Exeter in Cornwall have found that female Trinidadian guppy (Poecilia reticulate) use a strategy that involves choosing social partners based on their sexual attractiveness. By swimming alongside females that were considered to be more attractive, they were able to manipulate the behaviour of the males, deflecting away their sexual attention.
"This is an important finding because it represents the first evidence that females will actively tailor their social environment based on sexual attractiveness, to meet the need to reduce sexual advances from males," said lead author Safi Darden. "It also opens a whole new avenue of research into the possible trade-offs that females face in choosing their social partners."
Deflecting sexual attraction
It's well known that animals choose particular social companions because of the benefits they gain from these relationships. Males of some species associate with males that are less attractive to increase their chances of being chosen as a mate. Until now only indirect evidence had supported the idea that the opposite behaviour occurred in females.
For Trinidadian guppies, harassment from males can have a significant negative effect on females' relationships and social structure. Through a series of experiments, Darden and her colleagues were able to discover the strategy used by female fish to reduce unwanted advances.
The team revealed that non-receptive females received less male attention when paired with a receptive female. They also discovered that when given a choice, females preferred to swim alongside a more sexually active member of the group. In a final experiment, the females were given the same choice, but by only providing them with the pheromones produced by females that are used to attract nearby males.
"We gave females the same choice, receptive versus non-receptive female social partner, but instead we only provided them with odour cues from the females. Again we found that the non-receptive females preferred the more sexually attractive partner," said Darden.
A wide spread strategy
This finding builds on research in other species that demonstrates the impact manipulating social structure can have on enhancing or diminishing sexual attractiveness. However, until now, most of this research was limited to how animals are able to improve their chances of mating.
"Most research on sexual attractiveness is limited to behaviours that enhance male attractiveness or female receptiveness in the context of sexual selection," commented Peter Reinthal from the Department of Ecology and Evolutionary Biology at the University of Arizona in the U.S. "However this paper demonstrates how social partner choice is much more complex, and how behavioral mediation of social structure can alleviate sexual conflict - an extremely important topic in evolutionary behavioral ecology."
The success of this strategy means that it is likely to be widespread throughout nature, according to Darden. "We cannot translate directly to humans, particularly given the differences in biology and the strong cultural effects present in human societies, however, it certainly would make an interesting avenue of research given the ubiquity of sexually coercive behaviour by men," she said.
