Population genetics of polar bear populations

From Paetkau et al. 1999, Molecular Ecology 8: 1571-1584
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This study investigates genetic differences between polar bears from most of the 19 subpopulations identified at the time of the study, except Southern Hudson Bay, Queen Charlotte Island and Laptev Sea. There were no samples from these 3 subpopulations. Queen Charlotte was removed as a separate subpopulation at the PBSG meeting in Seattle in 2005, and the Arctic Basin is treated as a subpopulation, although there are no movement data from this area.

Polar bear immobilised in Storfjorden, Svalbard Image: Andrew Derocher

Genetic samples from a total of 473 individual polar bears from 16 subpopulations were analysed using 16 genetic microsatellite markers. Among the main findings of this study was:

1. Polar bears from all the subpopulations are genetically similar. The similarity is such that one can exclude the eventuality that any of the groups have been evolutionary separated for significant periods of time.
2. The variation in the genetic material generally supports the existing management units except in two cases: The similarity between bears from Kane Basin and Baffin Bay don't support the existing differentiation between management units, and the same is the case for bears from Svalbard and Frans Josef Land (which now are pooled into the Barents Sea subpopulation).
3. There are 4 genetic clusters of polar bear populations in the Canadian Arctic.
4. It is suggested that the observed dissimilarities in the genetic material has developed in reponse to differences in the seasonal distribution and pattern of sea ice habitat and the effects of these differences on the distribution and abundance of seals.