Raph's Girl
05-11-2006, 01:01 PM
David Paetkau would like to call the odd-looking bear discovered in the N.W.T. in the spring of 2006 a "pizzly," but the geneticist who confirmed the creature was a hybrid grizzly/polar bear, lost out in the office pool to "grizzlar."
"I think people thought it was more dramatic," he says, sounding disappointed.
Paetkau says the creature was likely the offspring of a grizzly who "lowered his standards" and such cross-species creatures may be more common than most of us think.
Jim Martell, a sport hunter from the United States, was on a guided hunt when he shot the animal on April 16, 2006, near Nelson Head on southern Banks Island, 2,000 kilometres north of Edmonton.
Martell thought he'd shot a polar bear, but on closer inspection he and his Inuit guide, Roger Kuptana, discovered the creature had unusual features. Its white fur was mottled with brown patches, and thin circles of black skin rimmed its eyes. It also sported the grizzly's distinctive long claws and humped back.
"Hybridization does happen," says Paetkau, of Nelson, B.C.-based Wildlife Genetics International. "In the case of grizzly bears and polar bears, they're two of the most closely-related species you can imagine."
The bears likely separated into two distinct species sometime between one million and 100,000 years ago, a mere blip on the evolutionary time scale.
And because their territories abut one another, it's entirely possible there are other hybrids out there, even though this bear was the first of its kind ever discovered in the wild. (Zoos in Russia and the United States have successfully bred the two species.)
"It may not be a first and it may not be unusual. When you have a sample size of one, it's hard to tell," says Paetkau.
He suspects the hybrid bear was the offspring of a desperate grizzly male driven by biological urges to mate with a polar bear because he could find no females of his own kind in the high Arctic.
"Once you can’t find anyone of your own species to mate with, you perhaps lower your standards," says Paetkau.
But the geneticist worries about the implications for biological diversity.
If global warming is driving grizzlies farther north into polar bear territory, as some locals and scientists believe, there's a possibility that polar bear genes may disappear as the two species interbreed.
"Polar bears could lose their distinction," he says.
"The trickle of grizzlies going north is turning into a stream. The hybrid event might be more common than we know."
But cross-species romance isn't confined to polar and grizzly bears.
In Ontario, trysts between coyotes and wolves have led to hybrid offspring. While it's certainly the exception, it happens most often in places where their territories overlap, says Paetkau.
And red wolves, considered a distinct species, may in fact be descendants of coyote/wolf hybrids.
The same thing happens among wild cats.
"Where lynx are at a lower density, they'll interbreed with bobcats. This happens in the lower 48 states [of the U.S.]," says Paetkau.
Black bears and grizzlies have also been known to produce cubs, but their genes are different enough that offspring are infertile, like mules, which are a cross between a horse and donkey.
But scientists say because grizzlies and polar bears are so genetically close, their offspring are almost certainly fertile.
Meanwhile, Ian Sterling, Canada's leading polar bear expert, says if the bear in the North West Territories was the result of lowered standards, it was "not like bumping into each other in a singles bar."
Mom and dad still managed to spend anywhere from a week to 10 days together, mating over and over again.
"It takes several days before the female will allow him near enough to mate. And when they do get together, they will mate over a number of days," says Stirling.
http://www.cbc.ca/news/background/wildlife/
"I think people thought it was more dramatic," he says, sounding disappointed.
Paetkau says the creature was likely the offspring of a grizzly who "lowered his standards" and such cross-species creatures may be more common than most of us think.
Jim Martell, a sport hunter from the United States, was on a guided hunt when he shot the animal on April 16, 2006, near Nelson Head on southern Banks Island, 2,000 kilometres north of Edmonton.
Martell thought he'd shot a polar bear, but on closer inspection he and his Inuit guide, Roger Kuptana, discovered the creature had unusual features. Its white fur was mottled with brown patches, and thin circles of black skin rimmed its eyes. It also sported the grizzly's distinctive long claws and humped back.
"Hybridization does happen," says Paetkau, of Nelson, B.C.-based Wildlife Genetics International. "In the case of grizzly bears and polar bears, they're two of the most closely-related species you can imagine."
The bears likely separated into two distinct species sometime between one million and 100,000 years ago, a mere blip on the evolutionary time scale.
And because their territories abut one another, it's entirely possible there are other hybrids out there, even though this bear was the first of its kind ever discovered in the wild. (Zoos in Russia and the United States have successfully bred the two species.)
"It may not be a first and it may not be unusual. When you have a sample size of one, it's hard to tell," says Paetkau.
He suspects the hybrid bear was the offspring of a desperate grizzly male driven by biological urges to mate with a polar bear because he could find no females of his own kind in the high Arctic.
"Once you can’t find anyone of your own species to mate with, you perhaps lower your standards," says Paetkau.
But the geneticist worries about the implications for biological diversity.
If global warming is driving grizzlies farther north into polar bear territory, as some locals and scientists believe, there's a possibility that polar bear genes may disappear as the two species interbreed.
"Polar bears could lose their distinction," he says.
"The trickle of grizzlies going north is turning into a stream. The hybrid event might be more common than we know."
But cross-species romance isn't confined to polar and grizzly bears.
In Ontario, trysts between coyotes and wolves have led to hybrid offspring. While it's certainly the exception, it happens most often in places where their territories overlap, says Paetkau.
And red wolves, considered a distinct species, may in fact be descendants of coyote/wolf hybrids.
The same thing happens among wild cats.
"Where lynx are at a lower density, they'll interbreed with bobcats. This happens in the lower 48 states [of the U.S.]," says Paetkau.
Black bears and grizzlies have also been known to produce cubs, but their genes are different enough that offspring are infertile, like mules, which are a cross between a horse and donkey.
But scientists say because grizzlies and polar bears are so genetically close, their offspring are almost certainly fertile.
Meanwhile, Ian Sterling, Canada's leading polar bear expert, says if the bear in the North West Territories was the result of lowered standards, it was "not like bumping into each other in a singles bar."
Mom and dad still managed to spend anywhere from a week to 10 days together, mating over and over again.
"It takes several days before the female will allow him near enough to mate. And when they do get together, they will mate over a number of days," says Stirling.
http://www.cbc.ca/news/background/wildlife/