12 May 2006

Species: Polar and Grizzly bears

Traditionally, the definition of species has been that if two animals could produce viable, fertile, offspring, they were the same species.

TORONTO, Ontario (AP) -- A DNA test has confirmed what zoologists, big-game hunters and aboriginal trackers in the far northern reaches of Canada have imagined for years: the first documented case of a hybrid grizzly-polar bear in the wild.
"It's something we've all known was theoretically possible because their habitats overlap a little bit and their breeding seasons overlap a little bit," said Ian Stirling, a polar bear biologist with the Canadian Wildlife Service in Edmonton. "It's the first time it's known to have happened in the wild."
Stirling said polar bears and grizzlies have been successfully paired in zoos and that their offspring are fertile, but there has been no documented case in the wild.


Well, by that definition, polar bears and grizzly bears are the same species! Now, DNA evidence did conclude that this hybrid had a polar father and grizzly mother, so there are significant enough DNA differences between the two species. Evolutionary biologists have definitely been moving towards a more genetic-based definition of species, and this seems like further evidence that we should do so.

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