Global phylogeography and genetic diversity of the long-finned pilot whale Globicephala melas, with new data from the southeastern Pacific

Abstract

The matrilineal long-finned pilot whale presents an antitropical distribution and is divided into two subspecies, one in the temperate seas of the Southern Hemisphere and the other restricted to the North Atlantic and Mediterranean. Until now, population genetic and phylogeographic studies have included localities of most of its Northern Hemisphere distribution, while only the southwestern Pacific has been sampled in the Southern Hemisphere. We add new genetic data from the southeastern Pacific to the published sequences. Low mitochondrial and nuclear diversity was encountered in this new area, as previously reported for other localities. Four haplotypes were found with only one new for the species. Fifteen haplotypes were detected in the global dataset, underlining the species' low diversity. As previously reported, the subspecies shared two haplotypes and presented a strong phylogeographic structure. The extant distribution of this species has been related to dispersal events during the Last Glacial Maximum. Using the genetic data and Approximate Bayesian Calculations, this study supports this historical biogeographic scenario. From a taxonomic perspective, even if genetic analyses do not support the subspecies category, this study endorses the incipient divergence process between hemispheres, thus maintaining their status and addressing them as Demographically Independent Populations is recommended.