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.

Year-round distribution and habitat preferences of the Bugio petrel

“…In contrast, the northern population was more spread from the eastern to northern Pacific (i.e. north of Hawaii) but still tightly concentrated within the distinct North Pacific convergence habitat (Rayner et al 2011). Environmental regimes explaining the non-breeding distribution of Bugio petrels in coastal areas were similar to those of the southern population of Cook's petrel, which utilised habitats with low depth, low SST and high chl a concentration (Rayner et al 2011).…”

“…Values represent the mean (± SD) inside individual 50% kernels during the non-breeding phase and excluding periods of migration the Barau's petrel Pterodroma baraui from Réunion Island, which migrate east to a specific area of the central and eastern Indian Ocean (Pinet et al 2011b). Similarly, the southern population of Cook's petrel P. cookii, tracked in New Zealand, migrated to a well-defined region and habitat type on the coastal upwelling regimes off Peru and California (Rayner et al 2011). In contrast, the northern population was more spread from the eastern to northern Pacific (i.e.…”

“…Nevertheless, these data allowed the designation of a Marine Important Bird Area (PTM16-Desertas) in 2008, which was presumed to cover some of the key areas used by breeding birds (Ramírez et al 2008). Previous studies of the movements of Pterodroma species clearly indicate that they disperse over large ocean areas, even during the breeding season (MacLeod et al 2008, Rayner et al 2008, Pinet et al 2012 and are highly migratory (Pinet et al 2011b, Rayner et al 2011. Given the lack of information on the location of core habitat for the Bugio petrels beyond the boundary of the ship surveys, including areas used during the nonbreeding period, the purpose of the present study was to analyse the at-sea distribution, movements and activity patterns of Bugio petrels tracked year-round.…”

Escaping the oligotrophic gyre? The year-round movements, foraging behaviour and habitat preferences of Murphy’s petrels

“…Individuals conducted long looping trips southeast of the colony, and may benefit from following trade winds (Weimerskirch et al 2005b). Birds avoided the most productive areas in the South Pacific, including the eastern tropical region, probably to reduce competition with other seabirds (Ballance et al 1997, Rayner et al 2016, and they overlapped little with other gadfly species that spend the austral winter in the southeast Pacific (Rayner et al 2011(Rayner et al , 2012.…”

Wanderer of the deepest seas: migratory behaviour and distribution of the highly pelagic Bulwer’s petrel

“…The huge bias in the knowledge gathered so far for these species, compared with what little is known for small-sized Procellariiformes, is mainly due the technological limitations involved in manufacturing small and light tracking devices (Burger and Shaffer 2008). This constraint has been gradually alleviated (Pollet et al 2014a, b) but still to date very few small-sized seabird species (200 g or less) have been studied in relation to their migratory and at-sea distribution patterns (but see, e.g., Rayner et al 2011Rayner et al , 2012Quillfeldt et al 2012;Zino and Biscoito 2013;Navarro et al 2013;Pollet et al 2014a, b). This is despite the fact small Procellariiformes represent about 40 % of all species in their order (Harrison 1983).…”