There is a new polar bear genetics paper out in the Journal of Heredity, by University of Alaska Fairbanks genetics professor Matt Cronin and colleagues. Matt Cronin, in case you didn’t know, was the first to pick up the close genetic relationship between polar bears and grizzlies, as a result of research he and colleagues did back in the early 1990s (Cronin et al. 1991).
Figure 1 from Cronin et al. 2014 (in press) showing the locations of bear samples used in their genetic study. MT, Montana; AK, Alaska; Polar bear samples were taken from the Chukchi, Beaufort and Barents Sea populations.
While no earth-shattering new information was revealed in this new study, reported over the weekend by the Alaska paper SitNews (March 15), it used a more detailed method to confirm the results of previous work – that polar bears have been around long enough to have survived several past Interglacial periods that were warmer than today (with less ice in the Arctic) and are genetically distinct from grizzlies.
A feature that really set this work apart was how it was promoted.
Posted in Evolution, Hybridization, Sea ice habitat
Tagged Beth Shapiro, Cahill, Ed Green, genetics, geological time, global warming, Matthew Cronin, polar bear, polar bear evolution, survival, University of Alaska Fairbanks, warm interglacials
The authors of a new paper out in PLoS Genetics (Cahill et al. 2013, entitled “Genomic Evidence for Island Population Conversion Resolves Conflicting Theories of Polar Bear Evolution”) propose to explain how and why the brown bears (aka grizzlies) of the ABC islands of southeast Alaska (Admiralty, Baranof, and Chicagof – see previous post here), got to be so genetically distinct from brown bears on the Alaska mainland and so surprisingly similar (genetically) to polar bears. The authors determined (using a model) that this genetic pattern could be explained by an ancient hybridization event resulting from female polar bears cavorting with male brown bears in SE Alaska.
I had some issues with the way the paper was promoted by some of the co-authors, which I dealt with separately here. More importantly, I found the scenario these geneticists offered to explain how hybridization might have occurred to be patently implausible. Geological and fossil evidence from SE Alaska largely refutes their scenario, although another explanation may be more tenable. It is not impossible, in my opinion, that hybridization occurred in SE Alaska during the last Ice Age, but if it did, it almost certainly did not happen the way Cahill and colleagues suggest.
Posted in Evolution, Hybridization
Tagged ABC bears, black bears, brown bears, Cahill, genetics, Haida Gwaii, hybridization, Jim Baichtal, last glacial maximum, polar bear evolution, Prince of Wales Island, ringed seals, SE Alaska, sea ice extent, Tim Heaton
A new paper out in the journal PLoS Genetics proposes that a hybridization event between female polar bears and male brown bears (aka grizzlies) occurred in Southeast Alaska at the end of the last ice age. I’ll get to a discussion of the paper itself (coming in a day or two) but first I have a few things to say about the global warming hyperbole generated by the people promoting the paper. I found it simply mind-boggling.
While the paper itself (Cahill et al. 2013: “Genomic Evidence for Island Population Conversion Resolves Conflicting Theories of Polar Bear Evolution”) contains only one short phrase that could possibly be interpreted as linking the results to future scenarios of catastrophic global warming, some of the co-authors have made statements (for the press release and in media interviews) that spin the global warming mantra right over the top. Continue reading
Posted in Advocacy, Evolution, Sea ice habitat
Tagged ABC bears, Beth Shapiro, brown bears, Cahill, climate, Ed Green, global warming hype, hybridization, ice age, polar bear evolution, polar bear spin, sea ice extent, sea ice models