Dolphins aren't the homebodies they were once thought to be, according to a new genetic study. Luciana Moeller and Luciano Beheregaray of Macquarie University in Sydney, Australia, took tissue samples from two populations of southern bottlenose dolphins (Tursiops truncatus aduncus) near Sydney. Paternity tests on each sample determined the family relationships within each pod.
Previous behavioral studies of American and other Australian dolphins suggested that both sexes remained near their region of birth. But the new DNA data found otherwise. The researchers report in the journal Molecular Ecology that the males in each group were less likely to be related to other dolphins in the group than females. Males were also more likely to have come from a completely different dolphin pod.
The finding helps explain why males dally and visit other dolphin groups more often than females. The biologists believe males leave to avoid inbreeding. It may also be more important for females to stay by known food sources to support their young.