DNA Analysis Fills in Piece of Dolphins' History

Bottlenose dolphins may be an iconic draw to the Mediterranean, but they're not exactly indigenous. So say researches out of the University of Lincoln in the UK, who report in the journal Evolutionary Biology that the water-dwelling mammals didn't arrive until the end of the last Ice Age some 18,000 years ago. They reached this conclusion based on an analysis of DNA samples collected from 194 adult bottlenose dolphins between 1992 and 2011, from which they were able to form a recent evolutionary genetic timeline.

In fact, they say the area likely wasn't home to many cetaceans (dolphins, whales, porpoises) at all until this point, likely because the water was too salty. As glaciers melted and diluted the salt concentration, other fish began to move into the area, thus giving hungry dolphins a reason to follow suit, reports LiveScience. But because the move was so recent, the population of dolphins isn't genetically complex, reports Nature World News, with just one "metapopulation" divided into subgroups by region. (Dolphins use signature whistles as a sort of naming system.)