The wolf-dog connection
Scientists discover genetic link between black wolves, first domesticated dogs
By BRETT FRENCH
Of The Gazette Staff
The black wolf trotting across Yellowstone National Park's Lamar Valley can trace its heritage back to the first domesticated dogs that crossed with humans from Asia 10,000 to 15,000 years ago.
Researchers collaborating in a study of the genetic mutation for dark coat color made the link, according to a report published Thursday in the journal Science.
"It's also fascinating to think that a portion of the first Native American dogs, which are now extinct, may live on in wolves," said Greg Barsh, a Stanford University genetics professor.
Barsh and graduate student Tovi Anderson collaborated with scientists at the University of California-Los Angeles, the University of Calgary, the National Park Service at Yellowstone National Park and the National Human Genome Research Institute. Scientists from Sweden and Italy also participated. The study was based largely on genetic data gathered by Yellowstone National Park wolf biologist Doug Smith and his crew as part of their research to find out whether there was genetic exchange among wolves reintroduced in the park, those planted in Idaho and those that live in northwestern Montana.
"This is really a spin-off of the more intensive research we're doing," Smith said.
Since wolves were reintroduced to Yellowstone from Canada 13 years ago, about half have been black and half gray.
Because the black coat tends to be found more predominantly among forested wolves in the Canadian Arctic - 62 percent, compared with 7 percent of the wolves on the tundra - researchers speculated that a darker coat may have some advantage for woodland wolves.
To find out, the scientists compared DNA samples from 224 black and gray wolves in Yellowstone and 41 black, white and gray wolves in the Canadian Arctic with domestic dogs and gray and black coyotes.
Using a variety of genetic tests, the researchers found that the black-coat mutation was probably introduced into wolves by dogs sometime in the past 10,000 to 15,000 years, about the same time the first Americans were migrating across the Bering land bridge. These humans were probably accompanied by dogs, some of which carried the black-coat mutation estimated to have arisen about 50,000 years ago.
"I was very surprised," Smith said. "This just attests to how readily these different species of canids interbreed. It doesn't take much to get a gene transfer between species to take off and do pretty well."
Smith said it's extremely rare for Western wolves, which have a larger body, to interbreed with dogs, and they usually kill any coyotes they see. Interbreeding with coyotes and dogs may be more common for Eastern and Midwestern wolves, which have smaller bodies, he said.
The multitude of blood samples that Smith and his colleagues have collected from Yellowstone's wolves show that there has been genetic exchange between the park's wolves and the surrounding populations, Smith said.
"That's why we think delisting should move forward," he said. "There are several wolves that have moved between Yellowstone and Idaho, and there is connectivity."
In a seesaw battle, wolves in Montana and Idaho and the Great Lakes region were to be delisted in February, but the Obama administration has put the move on hold. Wyoming was left out of the delisting because its management rules consider the animal a predator, which can be shot on sight, across most of the state.
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