By Tom Spears, Canwest News ServiceFebruary 6, 2009 10:10 AM
Source: Dogs important to wolf evolution: study (external - login to view)
Canada's grey wolves have black relatives among them because they interbred with dogs hundreds or thousands of years ago, a new Canada-U.S. study says.
This looks like an extremely rare case where genes from a domestic animal -- the dog -- can actually help a wild animal survive in the wild.
Grey wolves are the main wolf species in North America. Any wolf found in Canada is a grey -- even if it's black, or a white Arctic wolf. (The Arctic wolf and its southern relatives are simply close relatives adapted to different ecosystems, the study notes.)
But while there are wolves scattered across Europe and northern Asia, none is black.
Now Marco Musiani from the University of Calgary has traced the black gene back to its source, in dogs.
His team's study analyzed DNA from dozens of Canadian Arctic wolves, and more than 200 wolves in Yellowstone Park in the Northern U.S. that are descended from an Alberta group sent there for repopulation.
"We usually think that dogs developed from wolves, and here's an example where dogs gave something back to wolves," says Dr. Greg Barsh of Stanford University Medical Center, which joined in the genetic analysis. The study was published today in the journal Science.
Dogs split from wolves 15,000 to 30,000 years ago, through domestication and breeding by humans.
But the "black-coat gene" came back to wolves in the past 10,000 years, and it's the same gene found in black poodles and Labradors.
Is there an evolutionary advantage to the wolf? Black wolves don't seem to have any special hunting ability, says Barsh.
Yet black wolves live mainly in forested areas. Wolf packs in open country have fewer black members.
"It does seem pretty clear that there is an advantage" to the forest-dwelling black wolves, he concludes -- likely because black fur provides camouflage in dark forests, and helps them sneak up on prey.
The dark fur developed by human dog-breeding may actually help wolves adapt to climate change, which is also caused by humans, Musiani said. He's a professor in the faculty of environmental design.
Normally, the environment changes slowly, and animals adapt at the same pace, he said. But the climate is now changing too fast for animals that adapt slowly
"The wolves have found a shortcut," he said. Dark wolves, even in the Arctic, can help a pack hunt as winters become shorter. There are now more months with bare, dark ground where prey can see a white wolf from far off.
"People are influencing the environment so much," Musiani said. "Sometimes, if we want to give (an) organism a chance to survive and to evolve, we shouldn't underestimate the role of exchanging DNA and getting back mutations (i.e., genetic traits) from domesticated animals."
While this seems unnatural, he said, "we have already reached a point where the environment is human-determined."