title: Detecting genetic structure in migrating bowhead whales off the coast of Barrow, Alaska.
abstract: We develop a general framework for analysing and testing genetic structure within a migratory assemblage that is based on measures of genetic differences between individuals. We demonstrate this method using microsatellite DNA data from the Bering-Chukchi-Beaufort stock of bowhead whales (Balaena mysticetus), sampled via Inuit hunting during the spring and autumn migration off Barrow, Alaska. This study includes a number of covariates such as whale ages and the time separation between captures. Applying the method to a sample of 117 bowhead whales, we use permutation methods to test for temporal trends in genetic differences that can be ascribed to age-related effects or to timing of catches during the seasons. The results reveal a pattern with elevated genetic differences among whales caught about a week apart, and are statistically significant for the autumn migration. In contrast, we find no effects of time of birth or age-difference on genetic differences. We discuss possible explanations for the results, including population substructuring, demographic consequences of historical overexploitation, and social structuring during migration.
authors.affiliation: Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, PO Box 1066 Blindern, N-0316 Oslo, Norway. p.e.jorde@bio.uio.no
authors.forename: P E
authors.initials: PE
authors.lastname: Jorde
authors.forename: T
authors.initials: T
authors.lastname: Schweder
authors.forename: J W
authors.initials: JW
authors.lastname: Bickham
authors.forename: G H
authors.initials: GH
authors.lastname: Givens
authors.forename: R
authors.initials: R
authors.lastname: Suydam
authors.forename: D
authors.initials: D
authors.lastname: Hunter
authors.forename: N C
authors.initials: NC
authors.lastname: Stenseth
mesh_terms: D000367:Age Factors; D000413:Alaska; D025041:Animal Migration; D000818:Animals; D050642:Bowhead Whale / Q000235:genetics*; D016000:Cluster Analysis; D014644:Genetic Variation; D005828:Genetics, Population; D018895:Microsatellite Repeats / Q000235:genetics; D008957:Models, Genetic; D009792:Oceans and Seas; D012621:Seasons