Data from: Global population structure and demographic history of the grey seal

Although the grey seal Halichoerus grypus is one of the most familiar and
intensively studied of all pinniped species, its global population
structure remains to be elucidated. Little is also known about how the
species as a whole may have historically responded to climate-driven
changes in habitat availability and anthropogenic exploitation. We
therefore analysed samples from over 1500 individuals collected from 22
colonies spanning the Western and Eastern Atlantic and the Baltic Sea
regions, represented by 350bp of the mitochondrial hypervariable region
and up to nine microsatellites. Strong population structure was observed
at both types of marker, and highly asymmetrical patterns of gene flow
were also inferred, with the Orkney islands being identified as a source
of emigrants to other areas in the Eastern Atlantic. The Baltic and
Eastern Atlantic regions were estimated to have diverged a little over
10,000 years ago, consistent with the last proposed isolation of the
Baltic Sea. Approximate Bayesian computation also identified genetic
signals consistent with postglacial population expansion across much of
the species range, suggesting that grey seals are highly responsive to
changes in habitat availability.