# Climate change making sterile grizzly x polar bear hybrids more common



## GeoTerraTestudo (Oct 4, 2012)

I saw this article today in Spiegel Online International, and thought it was not only interesting and significant, but also relevant to our debates about hybridization here on TFO. It seems that hybrids between the closely related grizzly and polar bear species are becoming more common, now that climate change is changing their northern habitats. The hybrids are sterile, however, and not as well adapted to the land or sea as either of their parent species.

10/03/2012
In the Land of the Pizzly
As Arctic Melts, Polar and Grizzly Bears Mate

By Laura HÃ¶flinger

*The melting Arctic ice has brought polar bears and grizzly bears together and their hybrid offspring, known as "pizzlies," have been detected on Canadian islands. It is a trend that is happening with other species as well, and scientists are worried because it poses a risk to biodiversity.*

The two students from the University of Alberta, flying across the Arctic ice in a helicopter, were startled by what they saw below: a white dot and a brown dot on the ice. The biologists soon realized it was a grizzly bear next to a polar bear. The sighting was on Victoria Island, 500 kilometers (313 miles) from the grizzlies' normal habitat on the Canadian mainland.

The polar bear also struck them as a little strange. It had a dark stripe on its back, its snout looked dirty, its head was noticeably larger than normal, and there was a hump behind its shoulders, which is normally found only on brown bears. The paws looked as if the animal were wearing socks. The students had discovered a strange hybrid that goes by various names: grolar bear, pizzly or Nanulak, a combination of the two Inuit words for the animals' parents: polar bear (Nanuk) and grizzly (Aklak).

Two days later, on April 25, they spotted another strange-looking animal, probably also a hybrid. They also saw two other grizzlies. One was so fat that they believed it was feeding on seals, as polar bears do. Brown bears occasionally stray far north. But it's unusual for them to stay there, and it's even more unusual to find them mating with polar bears.

There have been hybrids in zoos, but their existence in the wild had for a long time only been speculated about. It isn't as if polar bears and brown bears never came into contact with one another, but their encounters were usually of the aggressive kind. In 2006, an American hunter shot an unusual-looking polar bear on Nelson Head, a cape in Canada's Northwest Territories.

DNA analysis established that the animal was the first recorded pizzly found in the wild. Another bear was shot on Victoria Island in 2010. This time it was an even greater sensation, because the animal was the offspring of a hybrid bear, which meant that it was already a second-generation pizzly.

*Very Distant Relations*
The polar bear and the brown bear are considered to be two different species and, therefore, should not be capable of producing viable offspring. But the polar bear emerged as an offshoot from the bloodline of the brown bear only 600,000 years ago. Thus, in a sense the polar bear is basically a white brown bear. Five hybrids have been reported to date, all living on the archipelago surrounding Victoria Island. A small group of grizzlies have settled there, says Andrew Derocher, the two students' professor. The bears probably got there while pursuing reindeer in the winter, when the ice was frozen. When the ice melted in the summer, they stayed on the islands. They can find everything they need there, and the summers are also getting longer.

Scientists expect that climate change and environmental degradation will result in more hybrids in the future. The melting of polar ice is increasingly forcing polar bears onto dry land, while road construction and mining in southern Canada are pushing grizzlies north. This summer marked the most drastic melting of Arctic sea ice to date. Biologists fear that this will promote the development of hybrids. A 2010 essay in the journal Nature counted 34 species that could be affected. Populations whose habitats have been separated by masses of ice could interbreed: belugas with narwhals, largha seals with common seals, Greenland whales with North Pacific right whales.

*Threat to Wildlife*
"Hybridization will endanger polar biodiversity," the authors wrote. But why should it be unnatural for polar and brown bears to mate, merely because one species is white and the other brown? Hybrids are not unknown in nature. For instance, a finback and blue whale hybrid was caught that had been impregnated by a blue whale.

But scientists argue that the frequency of such hybridization is disconcerting. It's as if two groups had long been living separately, but in adjacent rooms, and suddenly man came along and pushed open the door between them. In the end, it's conceivable that only hybrids will survive. This is currently happening with coyotes and wolves in North America, as well as between two types of flying squirrel.

Another problem is that the offspring are infertile, the animals are expending unnecessary energy in raising their young without passing on their genes. For example, in the case of North Pacific right whales, whose numbers have dwindled to only 200, it would spell the extinction of the species. It is true that in evolution, not every mistake is necessarily a flaw. But hybrids are usually inferior to their parents, because they are not as well adapted to their environments.

A case in point is that of two hybrids born in a zoo in the northern German city of OsnabrÃ¼ck in 2004. Their coats were caramel-colored, and in many respects they were a combination of their father and mother. They move like polar bears when they catch seals, and yet the hybrids, with their shortened necks, aren't as proficient swimmers, and their long claws are poorly suited to ice. Canadian scientist Derocher doesn't believe that the pizzlies pose a threat to polar bears, because they are still too rare. Besides, he says, they are exposed to a unique kind of threat: Hybrids are not a protected species, because they are not considered polar bears. For hunters, on the other hand, their rarity makes them an especially coveted trophy.

Translated from the German by Christopher Sultan

http://www.spiegel.de/international...ybrid-offspring-as-arctic-melts-a-859218.html


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## Liam Owen (Oct 4, 2012)

Ideas just reading about the the other day, very interesting!


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## Brewster320 (Oct 5, 2012)

I have two issues with this article. If they found a F2 hybrid then clearly these hybrid are not sterile and could increase in number as a group. And also they are acting as if the hybrids are incapable of surviving. There is a theory that another form of evolution could hybridizing. Yes they may not be adapted for the ice as much as polar bears or the land as much as a grizzly but seeing that the world is changing they could have the best of both parents that will allow them to live in a habitat in between. These hybrids still follow the rules of evolution for survival of the fittest, so the flaws that the scientist point out will be altered and the qualities that allow them to survive will be enhanced and eventually they could become their own species. Remember the goal in evolution is not to continue your species but to pass on your genes.


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## CDNPyxis (Oct 5, 2012)

I agree with Brewster, they are obviously not sterile, and they may exploit a new nitche, the climate is changing and most predict that the polar bear is going to face extinction do to the changing climate. The new polar bear will be a shore dwelling animal and slecetion pressure will determine the best coat colour and nail length. 

It also doesn't really decrease biodiversity, it increases it, the new genes from the other species have been added to the mix and they will be assorted to best exploit the environment. Yes, it changes the genes present in the species, but if the new genes don't serve as a benifit, they will be eliminated over time. 

Yes, in the case of a species that has very few numbers, it could be the end of the "pure" bloodline but it will live on in the hybrid. In the case of many of these sepecies they will go extinct with or without hybridization. It is sad, but the climate is changing and regardless of where you stand on why it is, the change is an inevidable fact. 

Craig


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## shellysmom (Oct 5, 2012)

Brewster320 said:


> I have two issues with this article. If they found a F2 hybrid then clearly these hybrid are not sterile and could increase in number as a group. And also they are acting as if the hybrids are incapable of surviving. There is a theory that another form of evolution could hybridizing. Yes they may not be adapted for the ice as much as polar bears or the land as much as a grizzly but seeing that the world is changing they could have the best of both parents that will allow them to live in a habitat in between. These hybrids still follow the rules of evolution for survival of the fittest, so the flaws that the scientist point out will be altered and the qualities that allow them to survive will be enhanced and eventually they could become their own species. Remember the goal in evolution is not to continue your species but to pass on your genes.



YES!! ^^^^ You're smart.


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## acrantophis (Oct 5, 2012)

Fascinating! Thanks for posting!


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## Yvonne G (Oct 5, 2012)

*WHAT????* Hybridization without interference from man?


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## EricIvins (Oct 6, 2012)

emysemys said:


> *WHAT????* Hybridization without interference from man?



Actually it would be, seeing that we are altering the Polar Ice caps with Greenhouse emmisions.......

I do have to say this though - Why is research being based on two STUDENTS FLYING OVER TWO BEARS? Alot of speculation here, and I wouldn't find this to be research, more like a half hearted observation if you could even call it that......


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## CDNPyxis (Oct 6, 2012)

EricIvins said:


> I do have to say this though - Why is research being based on two STUDENTS FLYING OVER TWO BEARS? Alot of speculation here, and I wouldn't find this to be research, more like a half hearted observation if you could even call it that......



I don't think that is what the article is saying, that is how some of the bears have been found, but they say that they have genotyped them so there is a lot more going on in this research than flying over and seeing a couple from the plane.

It does not look like he has published any of this yet, so they have quite a bit more to do. 

Craig


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## GeoTerraTestudo (Oct 6, 2012)

Brewster320 said:


> I have two issues with this article. If they found a F2 hybrid then clearly these hybrid are not sterile and could increase in number as a group. And also they are acting as if the hybrids are incapable of surviving. There is a theory that another form of evolution could hybridizing. Yes they may not be adapted for the ice as much as polar bears or the land as much as a grizzly but seeing that the world is changing they could have the best of both parents that will allow them to live in a habitat in between. These hybrids still follow the rules of evolution for survival of the fittest, so the flaws that the scientist point out will be altered and the qualities that allow them to survive will be enhanced and eventually they could become their own species. Remember the goal in evolution is not to continue your species but to pass on your genes.



Good points, Brewster. The article appears to contradict itself, saying early on that the hybrids can reproduce, and later on that they can't. At first I chalked this up to Haldane's Rule, the phenomenon I often cite here on TFO, in which heterogametic hybrids (males in mammals) are sterile, while homogametic hybrids (females in mammals) are not. However, it seems this article has a few inaccuracies in it.

Brown and polar bears did not diverge 600,000 years ago, but rather only 200,000 years ago. That's about how long anatomically modern humans have been around. Going by genetics (as opposed to morphology) they may even be considered the same species. I don't think anyone knows yet for sure whether brown x polar bear hybrids are usually sterile or usually fertile, but they might end up proliferating after all. This would be a bit like the red wolf, which it turns out is really a population of wolf x coyote hybrids, with no new mutations of their own.

So, depending on how the habitat is changing, these hybrids might even be at an advantage compared to their parent species (or subspecies, from a phylogenetic point of view). In that case, I would want their hunting to be regulated. Again, a lot remains unknown. I think we need a lot more information before making up our minds about how to regard these animals.

http://www.slate.com/articles/news_and_politics/explainer/2010/05/pizzly_bears.html
http://whyevolutionistrue.wordpress.com/2010/03/17/do-polar-bears-exist/


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## GeoTerraTestudo (Oct 7, 2012)

A nice BBC article from 2009, detailing the characteristics of these brown x polar hybrid bears. It's a little vague, but I think it suggests that some are sterile while others are fertile, possibly falling along gender lines, with the males apparently being the sterile ones and the females being fertile:
http://news.bbc.co.uk/earth/hi/earth_news/newsid_8321000/8321102.stm


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