How guppy females avoid sexual harassment

What do you do if you’re being showered with attention by someone you’re not really that interested in, but who just will not give up?

Photo credit: judhi

Well, if you’re a guppy, the answer could be to seek the company of someone you think your pursuer might prefer.

Researchers from the universities of Exeter and Copenhagen have found that Trinidadian guppies actively avoid being harassed by lusty males by hanging out with more attractive females.

Male guppies have a bad reputation for being serial stalkers. They pursue, court and repeatedly attempt to mate with females, even if the latter show no interest whatsoever. It can get so bad for females that spending so much time avoiding males makes them miss their meals, and makes them vulnerable to predators.

Lots of female creatures have evolved ways to avoid this unwanted attention. But evidence is now emerging that some females use social strategies to protect themselves against being hounded by the opposite sex.

Other studies, in creatures like house finches and forked fungus beetles, have shown that males spend time with less attractive males to increase their chances of being rated highly by females. Dr. Safi Darden from the University of Exeter, who led the study, explained:

We thought that if that’s the case, it’s highly likely that females also construct social niches to their advantage.

But in the case of females, their aim would be to avoid sexual attention, not to attract it. Darden said:

It’s not that females never want to mate with males; they’re receptive when they’re virgins and for several days each month.

At these times, females emit a sexual pheromone that males can’t resist. But for the rest of the month, they’re not up for it all and find the males’ continual advances particularly stressful.

Darden and her colleagues wondered if unreceptive females would choose to spend time with females who are ready to mate as a way to avoid unwanted attention.

When they paired different females with each other and introduced males into the mix, they saw different responses from the females depending on where they were in their monthly cycle.

They found that sexually-unreceptive females are harassed by lusty males much less often if they pair up with their more attractive pals, compared with if they paired up with an equally disinterested female.

But they don’t pair up with attractive females just by chance. Instead, it seems they actively choose to hang out with more attractive females as a way to avoid being pestered by over-enthusiastic males.

But sexually-receptive females didn’t show any particular preference for spending time with more attractive or less attractive females.

It looks like they do this using chemical cues about the reproductive state of their neighbours to assess them before they make these decisions. The report authors wrote:

Our findings provide direct support for the hypothesis that females can reduce levels of sexual harassment by actively selecting partners that are relatively more attractive to males.

The study highlights the fact that the way females cope with sexual harassment has a huge effect on the social structure of the community.

January 10, 2012

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