Homosexual Behavior in Poecilia mexicana Helps Attract Female Mates

Female Atlantic mollies get attracted to males who exploit homosexual behavior to attract them.

A new study published in Biology Letters says that same sex activity of male Atlantic mollies attracts female mollies that would otherwise choose a different and flashier mate. In a practice known as mate choice copying, (female mating with same male as observed female did before) the female Poecilia mexicana uses social information to choose a mate, often going with the more colorful, larger and dominant males as mates rather than other less flashier males. However, when the females see these less flashier males engaging in same sex interactions, they tend to get attracted to those engaging in that activity.

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 behavior,” the researchers reported in their paper, “Homosexual behaviour increases male attractiveness to females.”

The researchers used captive bred female P. mexicana and exposed them to computer generated (CG) male P. mexicana with specific color intensities in the animated males in 10 minute increments. As the researchers predicted, most of the female fish preferred to associate with the colorful male. The more colorful male was chosen 92 times out of 116 trials. They then randomly assigned females to observe a CG drab male swimming with a slightly larger and more colorful CG male, performing heterosexual activity with a CG female, and the drab male performing homosexual behavior with the more colorful male.

The results showed that the female P.mexicana increased their preference for the drab males after observing them interacting sexually with females as well as males. The results also showed that the females were also able to distinguish between the female and male heterosexual and homosexual video animations.

The researchers believe that male mollies exhibiting this homosexual behavior could help explain why this activity occurs and persists in certain species where females rely on mate choice copying when choosing a potential partner. The researchers speculate that the homosexual behavior of the less flashy males is an alternative breeding tactic that is used to overcome what they call reproductive constraints due to the female’s preference for flashier males.

The full paper and supporting documentation can be found on the Royal Society Publishing website.

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