More Evidence Nice Guys Don’t Always Finish Last

WaterStriderMating-Eldakar-4web.lg_horizA team of researchers led by Omar Tonsi Eldakar, a postdoctoral fellow at the Center for Insect Science at the University of Arizona, studied a group of water striders and found that when females are given a choice, they’ll move away from “jerks” (the more persistent and sexually aggressive males) and group themselves around “nice guys.”
In past experiments, the water striders’ ability to move has been limited, and researchers found that more aggressive males monopolized the females and did better than less aggressive males when they competed for a mate one on one. But something didn’t make sense, as John Pepper, a University of Arizona professor of ecology and evolutionary biology, explains:

If the early laboratory studies were a realistic representation of nature, nature should be overrun by hyperaggressive males—and it’s not. So something was wrong with that idea, and now we know what.

This time, the researchers used a wading pool with special doors that let the insects move freely between groups of “gentlemen” and “psychopaths,” as evolutionary biologist David Sloan Wilson calls them:

The presence of psychopaths dramatically reduced the productivity of the population. When all the males were gentlemen, the females laid about three times more eggs than they did when all the males were psychopaths. And yet within each group the psychopaths were doing better than the gentlemen. How do the gentlemen persist if they’re disadvantaged within the group?

When they opened the doors, the females would leave whenever a psychopath came around. The whole thing resulted in a heterogeneity in which the females were clustered with the gentlemen. It’s the movement of individuals that creates these differences between groups that favor nonaggressive males.

Category: Animal Studies

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