Genetic Evidence for Philopatry in a Colonially Nesting Seabird, the Fairy Prion (Pachyptila turtur)

Abstract

Philopatry is the selective return of individual birds to breed close to the site of their own hatching. This phenomenon can greatly influence the operation of evolutionary forces within and among populations of a species. Detection of philopatry normally involves long-term mark, release, and recapture studies. As an alternative, we have applied restriction enzyme analysis of mitochondrial DNA to a colonially nesting seabird species, the Fairy Prion (Pachyptila turtur), as a test of philopatry. As the mitochondrial genome is strictly maternally inherited, each colony in a philopatric species should have a unique combination of mitochondrial haplotypes. Twenty-one prions taken from one colony all had identical mitochondrial genomes, and we argue that juveniles as well as experienced adults return to the colony to breed. Philopatry within this colony does not explain the lack of mtDNA sequence variation. The most likely explanation is the recent occurrence of either a bottleneck or founder event within the colony probably involving a maximum of four females and an unspecified number of male prions. Two additional colonies of prions were not genetically homogeneous and did not have significantly different combinations of mitochondrial DNA lineages. It was not possible to confirm the existence of philopatry in these colonies.