Reconstructing the Genetic Legacy of Cook’s Petrels (Pterodroma cookii)
Cook’s petrel (Pterodroma cookii) is a threatened, migratory seabird endemic to New Zealand. Cook’s petrel previously bred throughout mainland New Zealand, but today it breeds exclusively at the northern and southern extremes of its historic distribution (Little Barrier Island and Codfish Island, respectively). Comparative studies have shown significant behavioural, morphological, and ecological differences between the two extant populations. Mitochondrial DNA (mtDNA) data suggests that they are genetically distinct. However, because mtDNA is maternally inherited, it solely reflects the evolutionary patterns of females. In addition, the genetic composition of extinct populations and the taxonomic status of the two extant populations remain unknown. Here, I provide an additional measure of genetic differentiation between the two extant Cook’s petrel populations using biparentally inherited nuclear intron sequence data. I also investigated the genetic structure among extant and extinct populations of Cook’s petrel by including mitochondrial and nuclear sequence data obtained from historic and ancient samples. The combined mitochondrial and nuclear data indicates significant genetic structure between the two extant populations. The genetic data from this study, combined with previous comparative studies, suggest that birds on Little Barrier Island and Codfish Island should be considered distinct sub-species: P. cookii cookii and P. cookii orientalis, respectively.