Tag Archives: DNA

NY Times pushes an implausible story of polar bear evolution and what makes a species

Carl Zimmer over at the New York Times penned a misleading story of speciation, using the polar bear as an example. It explains polar bear evolution based on a genetic interpretation that ignores the fossil record, bear behaviour, and geological history. [h/t Kip Hanson].

In my opinion, this kind of ‘science communication’ is more misleading than enlightening because it fails to alert readers to the fact that the topic is actually more complicated and gives the impression that the author considers readers too stupid to understand a more accurate explanation.

Polar Bear Evolution does a better job for those who are really interested in the process: it doesn’t hide the complicated nature of speciation or polar bear evolution. It doesn’t pretend to present “the truth” but explains how a good scientist gets to a plausible explanation that best fits the evidence.

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BREAKING: DNA results prove so-called polar bear hybrid was a blonde grizzly

All the hubris last month about polar bear x grizzly hybrids, based on an unusual-looking bear killed near Arviat, has turned out to be wishful thinking by those who’d like to blame everything to do with polar bears on climate change. An awful lot of “experts” now have egg on their faces. That “hybrid” was just a blonde grizzly, as I warned it might.

grizzly-polar-bear-hybrid_Arviat 2016 Didji Ishalook

According to one report, Nunavut wildlife manager Mathieu Dumond said:

“Some otherwise pretty renown bear biologists jumped on the hybrid bear story without even knowing what they were talking about,” Dumond said.

“I think it was something blown out of proportion, with the wrong information to start.”

Gee, ya think? CBC ran a story too. But the CBC don’t really admit (see below) that they were the first out of the gate on this story and started the media madness. It was the CBC that relied on the opinion of a black bear expert from Minnesota (who likely only saw a picture) – but since he was willing to say it was a hybrid and that its presence was a sign of climate change, they went with it.  See “Grolar or pizzly? Experts say rare grizzly-polar bear hybrid shot in Nunavut: Expert says interbreeding may be happening more frequently due to climate change” (CBC 18 May 2016).

For background, see these recent posts on this putative hybrid and the issues on hybridization it spawned:
Another alleged grizzly-polar bear hybrid shot but it’s not a sign of climate change

Polar bear hybrid update: samples sent for DNA testing to rule out blonde grizzly

Five facts that challenge polar bear hybridization nonsense

Most polar bear hybrids said to exist have not been confirmed by DNA testing

Blonde grizzlies, like the one pictured below (which I posted the day the story broke), are actually a proven sign of natural variation within species – a critical lesson in biology that should be the take-home message here. [ADDED: 2007 Alaska Fish & Wildlife Service Newsletter article on colour variation in black and brown/grizzly bears. h/t Wayne D]

“Paging Professor Derocher”: PBSG biologist and University of Alberta professor Andrew Derocher gave so many interviews to the media on this issue I lost count – he fed the media frenzy almost single-handedly. Well, except for granddaddy of polar bear experts Ian Stirling, who said (via the Toronto Star)[update: Toronto Star published correction]:

“I think it’s 99 per cent sure that it’s going to turn out to be a hybrid,” said Ian Stirling, an emeritus research scientist with Environment Canada and adjunct professor at the University of Alberta.”

 

Grizzly light_NPS photo

Quotes from today’s story below.
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Polar bear gene flow blamed on melting ice is another model result that doesn’t make sense

Polar bear researchers just published a study that suggests polar bears have moved around the Arctic in direct response to recent sea ice changes — a conclusion I suggest you take with a grain of salt and a raised eyebrow.

That’s because they have also proposed, among other things, that the Svalbard Archipelago was a sea ice refugium during warm interglacial periods, and could be again if the Arctic warms as predicted. That they would accept and promote such a model-based conclusion, which has no relationship with reality, calls their scientific judgment into question.

Svalbard as a potential warm refugium_Jan 8 2015_PolarBearScience

Based on genetic model results, the Svalbard Archipelago (circled) has been proposed as a sea ice refugium for polar bears during previous warm Interglacial periods and during predicted sea ice declines in the future. Yet most years since 1979 (2014 was one exception), this region has been ice free during the summer, making Svalbard a decidedly poor candidate for retaining sea ice when it’s much warmer than today.

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