Evolution is not just for the long-term – natural selection also goes on over short time periods. In the case of polar bears, this adaptation is almost certainly critical for its long-term survival.
Hudson Bay female with cub Wapusk National Park, Thorsten Milse, Government of Canada
Not all polar bears are identical — that is the reality that allows natural selection to operate.
I will argue that early breakup years in Western Hudson Bay weed out individual polar bears that do not have the physiological or behavioral characteristics necessary to be useful members of the population – and that this is a good thing for the entire population.
Posted in Evolution, Population, Sea ice habitat
Tagged adaptation, declining sea ice, early breakup, evolution, historical sea ice record, indivdual variation, late freeze-up, natural selection, NSIDC, polar bear, resilience, sea ice minimum, sea ice variability, Stirling, Stroeve, survival, western hudson bay
What with polar bear populations higher than they were 50 years ago and with many bears onshore during the ice-free season, a few polar bear attacks are to be expected – but how does the behaviour that drives those attacks compare with their closest evolutionary cousin, the grizzly?
I’ve done some summer reading on this topic, which I’ve summarized below. The results may surprise you.
While I was in London, ahead of my House of Lords lecture on June 11, 2014 (“Healthy Polar Bears, Less Than Healthy Science“)*, I had a chat with Benny Peiser of the Global Warming Policy Foundation.
Have a listen here: “An Interview with Dr Susan Crockford on polar bears, evolution and Arctic controversies.”
I’ve been traveling for a month but I am finally home — tired and jet-lagged after a journey that took me two-thirds of the way around the world and back. More on my experiences as my energy for blogging returns.
*I shouldn’t have to point this out but I will: I was not paid for this lecture, nor for the airfare to London (I was passing through town anyway). As the timing of the lecture required an overnight stay, GWPF did pick up the tab for a hotel room and dinner, as hosting organizations for such events do as a matter of course.
Posted in Conservation Status, Summary
Tagged Benny Peiser, Dr Susan Crockford, evolution, Global Warming Policy Foundation, GWPF, healthy polar bears, House of Lords, interview, lecture, less than healthy science, London, polar bears
The latest addition to the never-ending story of when-and-why polar bear evolution took place according to geneticists (Liu et al. 2014 — the 8th such paper in less than 4 years, if you can believe it) is getting way, way more media attention than it deserves.
Liu et al. 2014 figure provided in the abstract.
This multi-member research team used a new data set (mostly Scandinavian brown bears and Greenland polar bears, for a change) to add not much of anything new on the evolutionary insight front except yet another estimate of when polar bears came to be.1
However, the real focus of the paper is the description of their finding of a few genetic differences between brown bears and polar bears that they identified. They found a few genes in polar bears were different than brown bears and made a boat load of assumptions about what these might mean.
Their discovery was not accompanied by any attempt to demonstrate that the changes in gene architecture they found also involved a change in the function of the genes or were associated with different effects on bear physiology. If a changed gene cannot be shown to act differently or to have a demonstrated new physiological effect on the animal in question, the changes themselves mean next to nothing – especially for evolution!
That’s my take – see what you think. It looks long but a lot of it is quotes.
Posted in Evolution
Tagged adaptation, age of polar bears, APOB gene, blubber, brown bear, evolution, fat genes, genetic divergence, genetics, high-fat diet, Liu, polar bear, speciation, UC Berkeley, when polar bears arose
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