No island hopping for Hawaiian petrels

Understanding the mechanisms of population differentiation is critical to studying evolutionary ecology, speciation and population connectivity. Gene flow via dispersal ultimately determines the levels and patterns of population differentiation for any species. Seabirds present an enigma with respect to dispersal potential and realized gene flow. They are capable of traveling tens of thousands of kilometers either on single foraging trips or during the non-breeding season, yet they are highly philopatric often returning not only to their natal island, but to their natal colony to breed. Their longevity (some live >50 years) and delayed sexual reproduction make using traditional mark-recapture methods to study dispersal more challenging. Molecular markers allow researchers to study multigenerational movements by measuring gene flow. Most of the population genetic studies on seabirds have found evidence of gene flow among breeding sites at small geographic scales (Friesen et al., 2007a). In order for populations to become, and remain, genetically homogenous, only a few individuals per generation need to be exchanged between breeding sites. Some seabirds do show evidence of restricted gene flow, however, these are often geographically clustered (for example, New Zealand seabirds), species with restricted dispersal (for example, flightless cormorant) or species with temporally segregated breeding (for example, band-rumped storm petrel) (Friesen et al., 2007a and references therein; Duffie et al., 2009; Friesen et al., 2007b).