OK, so since they cross-bred, technically they’re sub-species but it’s still pretty interesting and the picture really shows that this is no normal polar bear. I wonder if this has anything to do with the loss of ice flows that polar bears usually live on and the fact that they have had to live more on the “mainlands” where grizzlies are found?
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3 Responses to “Bears Getting Busy Cross Species”
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“technically they’re sub-species” is that true? I did not think that hybrids were considered sub-species. I thought a sub species were reproductively isolated groups of a species that had diverged genetcally from other of its’ species. And yet if brought together can reproduce fertile offspring.
Well a species, as I was taught, is defined as any two animals that can succesfully breed and produce viable, fertile offspring. Species that are capable of this but are isolated geographically (as you said) are then considered sub-species. Now I’m sure currently polar bears and grizzly bears are different species. But this discovery may change how scientists view and categorize these types of bears. The other big question here is whether polars and grizzlies can cross breed on a regular basis or if the succesful birth rate is very low. So, to answer your question, I guess it’s too early to call them a sub-species just yet but they may be moving in that direction. I may have jumped the gun a little bit in calling them sub-species right away.
Many similar species can breed successfully. Some produce viable offspring, some don’t. There are some birds that are recognized to have separate eastern and western species yet where the territory overlaps there are reproductively viable hybrid crosses between the two species.
This grizzly/polar bear cross may be a similar happenstance, though much rarer.