Genetic studies of Grizzlies have indicated that the bears down here in the Greater Yellowstone have less genetic variability or genetic diversity. This is usually measured by expected heterozygosity. So the bears in Yellowstone have less heterozygosity than most of their neighboring populations and almost all other populations except these bears on Kodiak Island. This loss of heterozygosity may be related to some degree of isolation. The bears in Kodiak have probably been isolated for over 10,000 years and it's dropped their heterozygosity levels down to a third of most other bear populations.
However, this doesn't seem to have an effect on the viability of that population yet. It's a very large population; about 3,000 bears. It's a fairly stable environment, but the thing about reduced genetic variation is that it reduces your genetic options in case there's a change in the environment. So that if the environment changes - something such as global climate change - bears on Kodiak will have fewer options to respond to that genetically and may be in big trouble.
Actually, this little number up here in extreme Northwest Alaska was one of the major results of my Ph.D. thesis. I studied a population up in the Western Brooks range with Harry Reynolds of the Alaska Department of Fish and Game. These data are from microsatellite DNA analysis. Other researchers have looked at bears all across the Arctic and some of these populations down here in Canada and the Lower-48 States.
|
Narrative Index
BioForum Index
