Learning to Use Sea Sponges as a Foraging Aid Changes Dolphin Genetics

Dolphins that have learned from their social groups to use sea sponges as a protective buffer for their beaks have a genetic makeup that's different from other dolphins of the same species, according to new research.

University of New South Wales researchers report bottlenose dolphins that use sea sponges to protect their sensitive beaks as they forage on the sea floor do so as function of social learning, a non-genetic skill that is apparently inherited form the mother.

This social behavior goes on to shape the genetic makeup of the dolphins that use the foraging skill, the researchers report in the Proceedings of the Royal Society B.

"Our research shows that social learning should be considered as a possible factor that shapes the genetic structure of a wild animal population," said lead study author Anna Kopps. "Our research shows that social learning should be considered as a possible factor that shapes the genetic structure of a wild animal population."

Working in waters off the coast of western Australia, Kopps and her colleagues identified individual dolphins via boat, where they observed the animals foraging for food, traveling, resting and playing with other dolphins.

The researchers also collected genetic samples from the dolphins, including samples of mitochondrial DNA, which is only inherited from the mother.

They learned that dolphins found in shallow waters, where sea sponges do not occur, predominantly belonged to a genetic group called Haplotype H.

Dolphins living in deeper waters, where sea sponges do grow, were mainly Haplotype E or Haplotype F.

"This striking geographic distribution of a genetic sequence cannot be explained by chance," said Kopps, who carried out the research while at UNSW and is now at the University of Groningen.

Additionally, each of the 22 dolphins in deep water that were observed using sponges to forage were all Haplotype E.

"For humans we have known for a long time that culture is an important factor in shaping our genetics. Now we have shown for the first time that a socially transmitted behavior like tool use can also lead to different genetic characteristics within a single animal population, depending on which habitat they live in," Kopps said.