POPULATION-STRUCTURE AND GENE FLOW OF THE ATLANTIC WALRUS (ODOBENUS-ROSMARUS-ROSMARUS) IN THE EASTERN ATLANTIC ARCTIC BASED ON MITOCHONDRIAL-DNA AND MICROSATELLITE VARIATION

The population structure of the Atlantic walrus, Odobenus rosmarus ros marus, was studied using 11 polymorphic microsatellites and restrictio n fragment length polymorphism detected in the NADH-dehydrogenase ND1, ND2 and ND3/4 segments in mtDNA. A total of 105 walrus samples were a nalysed from northwest (NW) Greenland, east (E) Greenland, Svalbard an d Franz Joseph Land. Two of the 10 haplotypes detected in the four sam ples were diagnostic for the NW Greenland sample, which implied that t he group of walruses in this area is evolutionary distinct from walrus es in the other three areas. One individual sampled in E Greenland exh ibited a Pacific haplotype, which proved a connection between the Paci fic walrus and walruses in eastern Greenland. The Franz Joseph Land, S valbard and E Greenland samples shared the most common haplotype, indi cating very little differentiation at the mtDNA level. Gene flow (Nm) estimates among the four areas indicated a very restricted exchange of female genes between NW Greenland and the more eastern Atlantic Arcti c samples, and a closer relationship between the three samples composi ng the eastern Atlantic Arctic. The genetic variation at 11 polymorphi c microsatellite loci grouped individuals into three populations, NW G reenland, E Greenland and a common Franz Joseph Land-Svalbard populati on, which were connected by moderate gene flow.