Is this likely response to global warming beneficial or detrimental?
In 2006, Jim Martell from Idaho, was hunting in the high arctic and shot the first confirmed grizzly bear – polar bear hybrid. There had been unconfirmed reports of rare hybrids in the past, but this was the first confirmed instance. That the two species of bear could successfully mate was proven in captivity in 2004 when two hybrid cubs were born in a zoo.
Since 2006 reports and photographs of confirmed hybrids are on the increase. In addition the barren ground grizzly bear population is clearly moving northward into the high arctic as the climate warms. Climate warming has been especially prominent at the poles. There is also some indication the polar bears are moving southward in search of food on land off of the diminishing sea ice. These movements will, of course, put the two bears in proximity and allow for some mating.
Recent genetic research shows that polar bears are a relatively new species on the geological time scale, and that they emerged from brown bears (grizzly bears) a couple million years ago. Now they might be turning back into grizzlies and creating a new species that might be more suitable to make a living and reproduce in the rapidly changing Arctic.
Observations of hybrids so far show that their size and other physical characteristics are intermediate between polar bears and grizzlies. In terms of their behavior, the “compromise” falls to acting more like polar bears than grizzlies.
An overview of the march of grizzlies north and the increasing number of hybrids is now making it into the media. This article gives an overview. Unusual Number of Grizzly and Hybrid Bears Spotted in High Arctic. By Ed Struzik. Yale Environment 360.
As hybrid bears appear, the question is raised whether this is a beneficial change for bears in general in the High Arctic? Hybrid animals, as opposed to plants that often show “hybrid vigor,” are often less able the either of their parent species. However, as with coywolves they might be more adaptive in a new environment where they appear — the changed Arctic. Polar bears are much more carnivorous than grizzly bears, and the fish and seals of the High Arctic are loaded with many human released pollutants which are carried north and fall out in what we used to think was a near pristine environment. If hybrid bears, eat lower on the food change as grizzlies do, their health and reproduction might benefit, further increasing their numbers. First generation hybrid animals often show hybrid vigor too, but sometimes subsequent generations show genetic depression, especially with grizzlies, hybrids, and polar bears giving each generation of hybrids different amounts of polar bear, hybrid, or grizzly bear genes.
Because climate change does not stop unless humans stabilize their effect on the climate, it might be that no kind of bear (and most other animals and plants too) will be well adapted.
Comments
Grizzly bears have also been observed far to the southeast of the high arctic in eastern Manitoba in polar bear habitat near Churchill MB, only a couple of hundred miles from northwestern Ontario.
Manitoba still lists grizzlies as extirpated in the province.
http://www.eurekalert.org/pub_releases/2010-02/amon-gbm022310.php
My wife was co-author on that paper and actually took that grizzly photo from a helicopter. She was flying to a location to collect polar bear scat and hair (with our super scat-detecting dog).
here’s a link to the full article
http://research.amnh.org/~rfr/rockwelletal09.pdf
Wow!
A small world, huh?
I should add–I was in Newfoundland in May and while it is not out of the question for a stray polar bear to be found there in the spring, this spring had seen far more sightings than what is considered normal.
Apparently this was caused by the very early breakup of the sea ice further north, leaving more bears stranded on ice floes and floating south on the Labrador current.
An interesting adaptation.
Does Climate Change Mean More Polar-Grizzly Bear Hybrids?
http://www.motherjones.com/blue-marble/2012/07/study-climate-change-polar-bear-grizzly-hybrid
Also, notice the additional articles suggested at the bottom of the page that this article appears on.
Ed Struzik’s article quoting Andy Derocher (polar bear biologist) is absolutely incorrect and misleading. Polar bears do NOT almost exclusively hunt and eat seals, they are opportunistic hunters who will eat whatever is available to them. Obviously, they prefer seals because they supply everything they need (are are so tasty), but their diet is changing as a result of climate change. Here’s an article my wife and co-worker published which shows how the changing ice dates for bears and geese breeding dates are starting to overlap, providing more food (flightless birds and nests of eggs). http://research.amnh.org/~rfr/rockwell&gormezano09.pdf
As an aside, Struzik is a bit of a hack – he accused my wife and her partner of being climate change deniers because they theorized that polar bears will not go extinct as rapidly (or at all)as predicted by the “polar bear club” (Ian Stirling, Derocher, et al). It just shows you he has difficulty comprehending technical science articles.
Interesting article, MAD. Thanks for sharing. Clearly animals can exhibit behavioral flexibility especially in regards to prey. Fishers now live throughout the northeast when most thought they needed old growth forested areas. Nobody told them that suburban backyards and their abundant squirrel populations aren’t good habitat!
Yes, and who would’ve thought that the nation’s most densely populated state, New Jersey, would be so thick with black bears.
They seem to have an amazing ability to adapt to a human-centered habitat.
MAD,
Thanks for the clarification (and citation). It’s good when a primary source can be obtained and findings put in proper context. And thanks to your spouse for her work! And whatever role you played in all of that. Super scat-detecting dog, I like that.
The new genetics article cited in the motherjones link is also very interesting:
http://www.pnas.org/content/early/2012/07/20/1210506109.full.pdf+html
Not long ago, the story based on genetics was that polar bears had diverged from brown bears something like 130 or 150 thousand years ago. Then within the past year, another estimate came out at 600 thousand years, and now even further back. I usually have trouble completely understanding, let alone critiquing genetics papers, but it is interesting that this one gives effective population estimates back millions of years into the Pliocene for black, brown and ABC (Admiralty-Baranof-Chichagof) brown bears, and polar bears back 1 million years in figure 6. It indicates that polar bears decreased greatly in abundance about 500,000 years ago. In figure 3, they put the split between black and brown bears at 4 to 5 million years ago with gene flow between the two up until 100-200 thousand years ago (cave bears split off from brown bears after the black-brown split and are now extinct). They show a much later split between brown and polar bears with gene flow similarly occurring between polar bears and ABC brown bears until very recently, with the ancient polar bear lineage (based on one fossil sample from Svalbard) going extinct and being re-established from the ABC bears about 160 thousand years ago. While the ABC bears play a key role in this newest version of the story, they obviously occupied different and probably much more extensive habitat until recently, as Admiralty, Baranof and Chichagof Islands near here were under hundreds of feet of ice a few thousand years ago — so I gather that they are an isolated remnant with genetic similarity to polar bears, and were at some point restricted and then replaced over much of their range by the regular brown bear lineage. Of course, now they really have no noticeable physical differences from other brown bears nearby on the mainland that have a substantially different genetic legacy.
Most of this is based around mitochondrial genomes of only 40 individuals distributed across black, cave, brown, ABC brown, ancient polar and modern polar bears (shown in appendix figure S5).
I have noticed on the grizzly bear listserv, this issue stirs a big pot of controversy.
I find the whole idea of the intermixing of genetic “material” in regard to different species fascinating. For example, the western coyote migrating to the Eastern seaboard and mating with the smaller Eastern Timberwolf to create an animal that is vastly different than it’s western cousins. Of course, Jon Way can explain better than I, but the Eastern Coyote is larger and has even been observed hunting in packs similar to wolves. Good stuff…
I’d like to throw out a shameless plug for my wife & doggie, here’s a link to a NY Times article Andy Revkin did on them & her research project
http://www.nytimes.com/2007/06/05/science/05prof.html
Wow, and shameless it should be. Something to be proud of and also a set of studies that are of great import. Thanks to them for their insight and work and to you for sharing!
Salle, thanks for the thumbs up. My wife has experienced ALOT of blowback from the “polar bear club” because her research doesn’t fall in line with their “theories” – fuck them, old bastards that they are, they’re more interested in protecting their reputation & getting research dollars than doing good science. I spent 4 years on the ground as a tech for my wife’s polar bears project; which was more time on the ground with bears than the polar bear club did in 20 yrs.
3 cheers for those that do research instead of rehashing nonsense.
SEAK,
Thanks for that food for thought.
Studies that you and MAD have presented are fascinating, to me at least. Makes me think that I should have chosen a different route in academics. I went for social sciences, nobody seems to want to think much about that train of thought these days… I’m getting a little burned out on it myself as trends indicate that everybody “knows” all they want to know about people and their behaviors.