Bisexual fish boost mating chances

December 12, 2012

In an unusual mating strategy, hard-up males of a tiny, promiscuous fish species engage in homosexual acts in a bid to entice females to copulate with them, a study said Wednesday.

And it works.

Researchers said small, non-dominant Atlantic molly males, often overlooked for larger, flashier rivals as mating partners, rose vastly in the esteem of females that observed them copulating—regardless of the partner's sex.

Some female animals are known to show a preference for mating with males they had observed coupling with other females in a phenomenon known as "mate choice copying".

This allows them to evaluate the quality of a potential mate from a distance.

For this study, the researchers set out to show that homosexual behaviour in the tropical Poecilia mexicana would similarly boost a drabber male's chances of heterosexual coupling.

"P. mexicana females increase their preference for initially non-preferred males not only after observing those males interacting sexually with females, but also when having observed them initiating homosexual behaviour," the team wrote of their findings in the journal Royal Society Biology Letters.

Normally, females of the species, a popular tropical aquarium fish and close relative of the better-known , show a preference for large, colourful and .

"As homosexual behaviour is regularly seen in small P.mexicana males, we speculate that it might represent an alternative mating tactic used by subordinate, and thus, less attractive males, the University of Frankfurt researchers wrote.

And they cited a quote attributed to US filmmaker Woody Allen that "bisexuality immediately doubles your chances for a date on Saturday night".

"Direct benefits for males of exhibiting homosexual behaviour may help explain its occurrence and persistence in species in which females rely on copying as one component of mate ," said the study.

While exclusive male homosexuality has been shown only in humans, sheep and some birds, bisexual behaviour is quite common in the animal kingdom.

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