Data from: Population divergence and gene flow in an endangered and highly mobile seabird

Seabirds are highly vagile and can disperse up to thousands of kilometers, therefore it can be difficult to identify the factors that promote isolation between populations. The endemic Hawaiian petrel (Pterodroma sandwichensis) is one such species. Today it is endangered, and known to breed only on the islands of Hawaii, Maui, Lanai, and Kauai. Historical records indicate that a large population formerly bred on Molokai as well, but this population has recently been extirpated. Given the great dispersal potential of these petrels it remains unclear if populations are genetically distinct and which factors may contribute to isolation between them. We sampled petrels from across their range, including individuals from the extirpated Molokai population. We sequenced 524 bp of mitochondrial DNA, 741 bp from three nuclear introns, and genotyped 18 microsatellite loci in order to examine patterns of divergence in this species and to investigate the potential underlying mechanisms. Mitochondrial and nuclear data sets indicated significant genetic differentiation among all modern populations, but no differentiation was found between historic samples from Molokai and modern birds from Lanai. Population-specific non-breeding distribution or perhaps strong natal philopatry may reduce gene flow between populations. However, the lack of population structure between extirpated Molokai birds and modern birds on Lanai suggests that petrels may be able to overcome these barriers and disperse prior to complete extirpation. Hawaiian petrel populations should be managed as distinct units, except potentially for the dwindling population on Hawaii, which may require translocation to prevent extirpation in the near future.