Tag Archives: Lindqvist

Low genetic diversity will not make polar bears more vulnerable to extinction

You’ve probably heard the argument: animal populations that have been through a major decline in numbers often have such low genetic diversity that they are extremely vulnerable to subsequent extinction.

Photo credit USGS

Photo credit USGS

In an interview in late March regarding a new genetic paper on polar bear evolution (by Matt Cronin and colleagues), polar bear biologist and Polar Bears International spokesperson Steve Amstrup made a ridiculous statement: that polar bears have never experienced a rate of warming like they’ve seen over the last 30 years. I countered that easily here.

In that same interview about the Cronin et al. paper, fellow geneticist Charlotte Lindqvist offered an outdated argument against future polar bear survival that is as easy to refute as Amstrup’s “unprecedented rate of warming” nonsense.

I didn’t have time to deal with it back in April [where has the time gone?] but want to get back to it now because it’s important: there is lots of evidence to support my contention that polar bears are not more vulnerable to extinction just because they have low genetic diversity.
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Amstrup grasps at straws to defend his polar-bears-are-doomed computer model

Polar bear activist Steven Amstrup made an astonishing statement in an interview earlier this week — he insisted that the current rate of warming in the Arctic is greater than anything polar bears have lived through before. He also said that optimistic comments on the future of polar bears made by geneticist Matt Cronin a few weeks ago were “incautious” and “misleading.”

Polar bear cubs in den wikipedia

Previously, I described how a new paper by Cronin and colleagues confirmed that genetic evidence indicates polar bears have been around long enough to have survived several past Interglacial periods that were warmer than today (and therefore, would have had virtually no summer ice). Cronin, not unreasonably, had some critical things to say about computer modeled predictions that polar bears could not survive in an Arctic without summer sea ice.

On Monday, the Anchorage Daily News gave Amstrup a forum to rebuke Cronin for his comments. A similar story was also carried by the Washington Post. [In the same ADN article, geneticist Charlotte Lindqvist, offered an outdated argument against future polar bear survival that I’ll deal with later]

Today, I’ll address Amstrup’s ridiculous assertion that the current rate of warming, attributed by him primarily to human activities rather than natural variation, is something polar bears have never experienced in their evolutionary history (a period of more than 400,000 years!).

Let’s start with the offending portion of the news item (published March 31, 2014):

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