Data from: Post-glacial colonization of northern coastal habitat by bottlenose dolphins: a marine leading-edge expansion?

Oscillations in the Earth’s temperature and the subsequent retreating and
advancing of ice-sheets around the polar regions are thought to have
played an important role in shaping the distribution and genetic
structuring of contemporary high-latitude populations. After the Last
Glacial Maximum (LGM), retreating of the ice-sheets would have enabled
early colonizers to rapidly occupy suitable niches to the exclusion of
other conspecifics, thereby reducing genetic diversity at the
leading-edge. Bottlenose dolphins (genus Tursiops) form distinct coastal
and pelagic ecotypes, with finer scale genetic structuring observed within
each ecotype. We reconstruct the post-glacial colonization of the
Northeast Atlantic (NEA) by bottlenose dolphins using habitat modelling
and phylogenetics. The AquaMaps model hindcasted suitable habitat for the
LGM in the Atlantic lower latitude waters and parts of the Mediterranean
Sea. The time-calibrated phylogeny, constructed with 86 complete
mitochondrial genomes including 30 generated for this study and created
using a multi-species coalescent model, suggests that the expansion to the
available coastal habitat in the NEA happened via founder events starting
~15,000 years ago (95% highest posterior density interval: 4,900–26,400).
The founders of the two distinct coastal NEA populations comprised as few
as two maternal lineages that originated from the pelagic population. The
low effective population size and genetic diversity estimated for the
shared ancestral coastal population subsequent to divergence from the
pelagic source population are consistent with leading-edge expansion.
These findings highlight the legacy of the Late Pleistocene glacial cycles
on the genetic structuring and diversity of contemporary populations.