The reproductive success of male dolphins is not determined by strength or age, but by social bonds with other males. The better integrated males are in their social network, researchers found, the more offspring they produce. Biologists studied bottlenose dolphins (Tursiops aduncus) in western Australia’s Shark Bay, where the males live form long-lasting bonds that become stable alliances. Within these alliances, males former smaller groups of two or three to mate with females and defend against attacks.
After analyzing 30 years of behavioral and genetic data, researchers found males with strong social bonds to many alliance partners produce the most offspring. Findings like these had only been found previously among chimpanzees (Pan troglodytes) and other primates, researchers said.