Genetic Stock Structure of Green Turtle (Chelonia mydas) Nesting Populations Across the Pacific Islands
Peter H. Dutton, Michael P. Jensen, Karen Frutchey, Amy Frey, Erin LaCasella, George H. Balazs, Jennifer Cruce, Alden Tagarino, Richard Farman, and Miri Tatarata, 451

Abstract: More than two decades have passed since the first studies documenting genetic population structure of green turtles (Chelonia mydas) were published. Since then many more have followed and characterization of the genetic structure of green turtle rookeries now covers most of the global distribution of the species, benefitting conservation of this threatened species worldwide. However, important data gaps still exist across a large part of the western and central Pacific Ocean (WCPO). This large area is made up of hundreds of scattered islands and atolls of Micronesia, Melanesia, and Polynesia, most of which are remote and difficult to access. In this study, we assessed stock structure of green turtles throughout the WCPO using mitochondrial (mt) DNA from 805 turtles sampled across 25 nesting locations. We examined whether sequencing longer fragments (770 bp) of the control region increases resolution of stock structure and used genetic analysis to evaluate level of demographic connectivity among island nesting populations in the WCPO. We identified a total of 25 haplotypes characterized by polymorphism within the 770 bp sequences, including five new variants of haplotypes that were indistinguishable with shorter 384 bp reads from previous studies. Stock structure analysis indicated that rookeries separated by more than 1,000 km were significantly differentiated from each other, but neighboring rookeries within 500 km showed no genetic differentiation. Results presented in this paper establish that sequencing of longer fragments (770 bp) of the control region does in some cases increase resolution and that there are at least seven independent stocks in the region.
Continue reading “Pacific Science, vol. 68, no. 4 (2014)”

Predominance of Unbalanced Gene Flow from Western to Central North Pacific Colonies of the Black-Footed Albatross (Phoebastria nigripes)
Haruko Ando, Lindsay Young, Maura Naughton, Hajime Suzuki, Tomohiro Deguchi and Yuji Isagi, 309

Abstract: The Black-Footed Albatross (Phoebastria nigripes) breeds in two remote regions, approximately 4,000 km apart, in the North Pacific. The population in the central North Pacific region (Northwestern Hawaiian Islands), which contains >95% of the total population, is currently stable, although concerns exist about future declines. In contrast, the population in the western North Pacific (Izu and Ogasawara Islands in Japan) is rapidly increasing, and the breeding areas are expanding. To estimate possible gene flow caused by dispersal between populations, we performed genetic analysis on six colonies of Black-Footed Albatross using 10 microsatellite markers. The central and western North Pacific populations were genetically differentiated. However, an estimation of migrants per generation indicated directional dispersal from the western to the central North Pacific. In particular, the population on Kure Atoll, the westernmost atoll in the Hawaiian Islands in the central North Pacific, exhibited weak genetic differentiation from the western North Pacific populations, suggesting frequent immigration from the western North Pacific. The recent expansion of the western North Pacific population may be due to an increase in returning individuals, which may be caused by increased breeding success rates and/or survival rates. Range-wide and long-term monitoring of the Black-Footed Albatross population using genetic markers may help to uncover dispersal dynamics of this highly mobile but philopatric albatross species and to make appropriate conservation decisions in light of environmental changes.

Continue reading “Pacific Science, vol. 68, no. 3 (2014)”