When bears came across from Asia, it appears that there were probably four major waves of migration. These resulted in four distinct lineages or clades of mitochondrial DNA. One group is here in the ABC Islands of Southeast Alaska, which was probably the first group of bears to immigrate. They've got the oldest lineage. Another distinct lineage is this group down here in the Rocky Mountains. So, this is a somewhat genetically unique group. The question is, how can we try to preserve that uniqueness in that population?.

This diagram shows one of the models for reserve design. I'm not sure exactly when this was first proposed, but the original one was called the Biosphere Reserve Design. There was a core area surrounded by buffer zones. The core area had a minimum amount of human disturbance and buffer zones had increasing amounts as you go farther out. This was first proposed on a global scale by the UN and I think by UNESCO. A lot of sites around the world are now designated as Global Biosphere Reserves. Yellowstone is one of them.

Subsequent modifications of this conceptual model were done by Reed Noss and other people where they enlarged the idea to include a couple of core areas with a connecting corridor, so that if you don't have a large enough area to completely maintain a population you try to allow for movement between those areas. There's been some discussion in scientific literature of whether corridors are effective or not. Paul Beier and Reed Noss published a paper in the last Journal of Conservation Biology that reviewed the literature and they came to the conclusion and it's fairly well documented. In any event, connecting populations is a much better idea than increasing fragmentation, which is the only alternative.

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