杏吧原创

BY EVOLVING a 鈥渟hield鈥� for their genitals, female red-backed water striders from east Asia can call the shots in the mating game.

So say and of Seoul National University, South Korea, after detailed experiments and anatomical analyses of the water strider Gerris gracilicornis (PLoS ONE, ).

Suitors have to 鈥渟ing鈥� for the female 鈥� tapping out rippling rhythms on the surface of the water with the tips of their long mid-legs, the pair discovered. If the 15-minute performance passes muster, then and only then will the female lift her genital shield and consent to sex.

鈥淭his is exactly the kind of thing you might expect to evolve in a system where females are vulnerable to forced matings,鈥� comments of the University of Sheffield, UK, who has studied how female mallard ducks have evolved intricate vaginas to isolate unwanted sperm and thwart forced matings.

In all other pond skater or water strider species, males run the show, taking females almost at will, generally with no courtship.