The more stable social contacts a male bottlenose dolphin maintained with same-sex conspecifics, the more offspring it produced. This was observed by a research group led by biologist Livia Gerber from the University of Zurich. The team published their results in the journal Current Biology. Marine mammals live in a complex social network. From a relatively stable, larger group of 4 to 14 animals ("alliance of the second order"), smaller groups ("alliance of the first order") form again and again, which together go in search of fertile females. From ten second-order alliances, a total of 85 male dolphins, the behavioral scientists evaluated data from 30 years. They determined reproductive success through genetic paternity analyses.
Bottlenose dolphins, which entered into especially many constant relationships within the large group, produced the most offspring. The dolphins with frequently changing friendships, on the other hand, had fewer children. "Our study was able to show for the first time that friendships among dolphin males have a direct influence on their reproductive success and thus their evolutionary fitness," says Gerber. "This was previously known only from a few terrestrial mammals." Well-integrated males could probably make better use of the advantages of cooperation and thus have better chances with dolphin females. In addition, they are more resistant to partner losses. The anthropologist says: "So it is not always the strongest and most dominant males that achieve the greatest reproductive success, but the most social animals.«
