In leafcutter ants and honeybees, it's survival of the fittest sperm. Biologist Boris Baer, for a study out this week in Science, investigated these two species because of their peculiar sexual practices: In one day, the queen acquires all the sperm she'll need to fertilize her eggs over the course of her lifetime. But in the race to be the top genetics-spreader, the males have evolved a dirty trick. Their seminal fluids actually do battle within the female's reproductive tract. To test out the idea, Baer and colleagues exposed the sperm of the bee and ant males to their own seminal fluid, and also to that of other males of the same species.
The seminal fluid killed more than 50 per cent of the rival sperm within 15 minutes. "The males seemed to use the seminal fluid to harm the sperm," says Baer [New Scientist]
. When the team studied ...
