Love Changes All

Flowers and chocolate won’t get you far in the animal world, where courting is considerably tougher than it is for humans. Studying a group of insects called water striders, professors Locke Rowe of U of T’s zoology department and Göran Arnqvist of Uppsala University in Sweden have unveiled a sexual “arms race” and offered a new look at the fundamental conflicts of interest between males and females. What is best for one sex is rarely best for the other in terms of reproduction, says Rowe. “Males of most animal species benefit from mating often with as many partners as possible, while females lose from mating too much.” In the case of water striders, the male has developed elaborate grasping structures aimed at immobilizing the female as he attempts to mate with her. The female, in turn, has developed a spine that holds the male away and foils his mating attempts. The result is a battle of the sexes whereby male persistence is matched by female resistance. The research not only confirms that sexual conflict can shape males and females but also indicates that such conflicts can lead to new species.