Social Behavior can Shape Genetic Makeup in Dolphins, Researchers Find

A new study on bottlenose dolphins has found that social behavior can change the genetic make-up of animal populations in the wild. 

Bottlenose dolphins in Shark Bay in Western Australia use sponges as hunting aids. Dolphins use sponges to cover their rostrum while hunting, most probably to protect their beaks from the  rocks on the seafloor. Previous research has shown that this behavior might have originated some 120 to 180 years back.

The behavior isn't known to be etched in the genes of the mammals, but was thought to be learnt by calves by observing their mothers.

Researchers at University of New South Wales while studying this unique behavior in dolphins have found that social behavior can alter genetic makeup of animals. According to the researchers, this is one of the few studies looking at cultural hitchhiking in animals other than humans.

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

For the study, Kopps and colleagues studied behavior of dolphins living some 850 kilometres north of Perth. The team also collected DNA samples of the mammals. They specifically looked for mitochondrial DNA type and assigned dolphins based on genetic groups.

Researchers found that dolphins living in sponge-free, shallow waters belonged to genetic group Haplotype H.

Haplotype is a set of DNA variations that are inherited together.

Dolphins hunting in deep waters with abundant sponges were in group Haplotype E or Haplotype F. Also, DNA from 22 dolphins that hunted in both shallow and deep waters fell into Haplotype E, suggesting that behavior of a certain population of dolphins has shaped their DNA.  

"This striking geographic distribution of a genetic sequence cannot be explained by chance," said Dr Kopps, who is now at the University of Groningen.

"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 behaviour like tool use can also lead to different genetic characteristics within a single animal population, depending on which habitat they live in" she added.

The study is published in the journal Proceedings of the Royal Society B.