title: Contemporary and historical separation of transequatorial migration between genetically distinct seabird populations.
abstract: Pelagic seabirds are highly mobile, reducing the likelihood of allopatric speciation where disruption of gene flow between populations is caused by physically insurmountable, extrinsic barriers. Spatial segregation during the non-breeding season appears to provide an intrinsic barrier to gene flow among seabird populations that otherwise occupy nearby or overlapping regions during breeding, but how this is achieved remains unclear. Here we show that the two genetically distinct populations of Cook's petrel (Pterodroma cookii) exhibit transequatorial separation of non-breeding ranges at contemporary (ca. 2-3 yrs) and historical (ca. 100 yrs) time scales. Segregation during the non-breeding season per se appears as an unlikely barrier to gene flow. Instead we provide evidence that habitat specialization during the non-breeding season is associated with breeding asynchrony which, in conjunction with philopatry, restricts gene flow. Habitat specialization during breeding and non-breeding likely promotes evolutionary divergence between these two populations via local adaptation.
authors.affiliation: National Institute of Water & Atmospheric Research Ltd, Private Bag 99940, Auckland, New Zealand. m.rayner@niwa.co.nz
authors.forename: Matt J
authors.initials: MJ
authors.lastname: Rayner
authors.forename: Mark E
authors.initials: ME
authors.lastname: Hauber
authors.forename: Tammy E
authors.initials: TE
authors.lastname: Steeves
authors.forename: Hayley A
authors.initials: HA
authors.lastname: Lawrence
authors.forename: David R
authors.initials: DR
authors.lastname: Thompson
authors.forename: Paul M
authors.initials: PM
authors.lastname: Sagar
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Bury
authors.forename: Todd J
authors.initials: TJ
authors.lastname: Landers
authors.forename: Richard A
authors.initials: RA
authors.lastname: Phillips
authors.forename: Louis
authors.initials: L
authors.lastname: Ranjard
authors.forename: Scott A
authors.initials: SA
authors.lastname: Shaffer
mesh_terms: D000222:Adaptation, Physiological; D025041:Animal Migration; D000818:Animals; D001717:Birds / Q000235:genetics* / Q000502:physiology; D001947:Breeding; D051456:Gene Flow; D014644:Genetic Variation; D008969:Molecular Sequence Data; D012621:Seasons; D012934:Social Isolation