Dolphin Species Created by Natural Hybridization: New Insight into Evolution

It turns out that a small, sleek marine mammal may be the result of two closely-related dolphin species. Scientists have discovered that natural hybridization is to blame for the clymene dolphin, a species that makes its home in the Atlantic Ocean.

"Our study represents the first such documented instance of a marine mammal species originating through the hybridization of two other species," said Ana R. Amaral, one of the researchers, in a news release. "This also provides us with an excellent opportunity to better understand the mechanisms of evolution."

Classifying the clymene dolphin has been a longstanding challenge for taxonomists. In the past, it was considered to be a subspecies of the spinner dolphin. Then in 1981, researchers classified it as a distinct species after thorough morphological analyses. Now this more recent research shows how it's related to two species.

In order to better understand the clymene dolphin the researchers performed a genetic analysis. This allowed them to clarify outstanding questions about the dolphin's origins. More specifically, the level of discordance among the nuclear and mitochondrial markers from the three species--clymene, spinner and striped--is best explained as an instance of natural hybridization. In fact, while the mitochondrial genome of the clymene mostly resembled the striped dolphin, the nuclear genome revealed a closer relation to the spinner dolphin.

"With its similar physical appearance to the most closely related species, our genetic results now provide the key insights into this species origin," said Howard Rosenbaum, one of the researchers, in a news release. "Very little is known about the clymene dolphin, whose scientific name translated from Greek is oceanid, but ironically can mean fame or notoriety. Hopefully, our work will help draw greater attention to these dolphins in large parts of their range."

The findings reveal a bit more about this species. More specifically, it shows how natural hybridization can create an entirely new species over the course of evolution.

The findings are published in the journal PLOS One.