Battle of the Sexes

Scientists discover an arms race between male and female water-strider insects

• Mark Cheater
• Jun 01, 2002

THERE'S GOOD NEWS about the timeless strife between males and females--it helps creatures evolve. Throughout the animal kingdom, males prefer to mate often, and females are choosier about their partners. Each gender tries to gain the upper hand, scientists believe, by evolving new structures to grab or fend off the other. A recent study of water-striding insects provides the first hard evidence for this sexual arms race. Scientists looked at the grasping genitalia males use to mate, and the abdominal spines females wield to rebuff suitors. In some water strider species, males have the advantage and are able to mate often. In others, female spines rule and males are often frustrated. These slight disparities among similar species prove that an arms race is occurring and contributing to evolutionary change, the scientists say. Vive la difference!