Saturday, May 13, 2006

Bear Hybrids


Many have already commented on the discovery and the sad end of the Pizzly, the hybrid between a polar bear and a grizzly:
Polar bears and grizzlies require an extended mating ritual to reproduce, Stirling said. Both live by themselves in large, open habitats. To prevent wasting their eggs, females ovulate only after spending several days with a male, Stirling explained. "Then they mate several times over several days." In other words, the mating between the polar bear and grizzly was more than a chance encounter.
Archy makes a very important point:
Polar bears and grizzlies are essentially different breeds of the same species, so a hybrid isn't a genetic problem. What mainly separates them is that they have completely different ranges and slightly different breeding seasons. David Paetkau, a geneticist quoted in the article, suggests the hybrid might be a sign that the bears are moving to new, overlapping ranges in response to global warming climate change.
So, this is another example of the break-down and remodelling of entire ecosystems in response to global warming, with different species migrating at different rates to different places, as well as changing the timing of reproduction.

In the case of bears, what is going to happen long term? Is hybridization going to become common and the two sub-species eventually completely fuse into one species? Is that good or bad? Only time will tell, but what do you think?


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