Bottlenose Dolphins are Pretty New to the Mediterranean, Says DNA

Bottlenose dolphins are iconic sea creatures, with thousands of vacationers flocking to the Mediterranean's clear waters to watch playful pods in action each year. Now, however, it has been revealed that these dolphins would not be found there thousands of years ago, making them relatively new settlers to the biblical "Great" or "Middle Sea."

That's at least according to a study recently published in the journal Evolutionary Biology, which details how bottlenose dolphins only colonized the Mediterranean Sea after the last Ice Age.

How do we know? A team of researchers reportedly conducted analyses of tissue samples from 194 adult bottlenose dolphins (Tursiops truncatus) collected between 1992 and 2011 from the five main eastern Mediterranean basins.

The results helped the team piece together a timeline of genetic adaptation and distribution, as it occurred since Mediterranean colonization by the dolphins. This led them to conclude that the species didn't show up in the "Great Sea" until about 18,000 years ago. Prior to that, the region likely didn't see much cetacean activity despite being a biologically diverse hotspot.

Research lead Andre Moura, from the UK's University of Lincoln, explained in a recent statement that as a consequence of this late arrival, the genetic diversity among Mediterranean bottlenoses is not terribly complex.

"Similar to the North Atlantic, two ecological types are likely to exist, one occupying deep 'pelagic' - or away from the coast - waters, and another occupying 'coastal' shallow water areas," Moura said.

"By comparing our results with genetic data from previous studies on Atlantic bottlenose, we concluded that bottlenose dolphin in the North Atlantic, Mediterranean, and North Sea are likely to represent a single metapopulation - This is a particular type of population structure, when a single population is subdivided into regional subgroups that exchange individuals at varying rates," he added.

According to Moura and his colleagues, understanding this can help conservationists preserve the region's biodiversity, highlighting the need to ensure that various regional pods are not isolated from one another - as is seen with many roaming land-dwelling predators today.

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