Posts Tagged ‘wolves’
Wolves in black: Domestic dogs give gift of dark coat
North American wolves likely have domestic dogs to thank for their dark locks, according to a study appearing online Thursday (2.5.09) in Science.
Though scientists believe that dogs were domesticated between 15,000 and 40,000 years ago in East Asia, the report suggests interbreeding between the playful Native American pups and North American wolves more than 10,000 years ago led to the emergence of wolves with black coats.
“We usually think that dogs developed from wolves,” Stanford geneticist and study co-author Greg Barsh during a Science podcast. “Here’s an example of dogs giving something back to wolves.”
Two genes are credited with the diverse skin, feather and hair shades in nature — agouti controls yellow and red pigments and Melanocortin 1 receptor (Mc1r) controls brown and black. In 2007, Barsh’s lab discovered domestic dogs with black fur such as great Danes, and German shepherds shared a gene called K that, when missing a few pieces of genetic code, works to suppress Mc1r activity, leading to black coats.
Researchers studied the molecular variation at K in hundreds of white, gray and black Yellowstone and Canadian wolves. Of the 113 black wolves surveyed, only two did not have K mutation; none of the 142 white and gray wolves had the mutation.
Though a comparative analysis of the DNA surrounding the black-coat gene in dogs and wolves led researchers to conclude that domesticated dogs were responsible for the emergence of trait in North American wolf population.
“Although genes that evolve under domestication may be transferred to wild species, they generally do not proliferate in the wild because the natural context is so different from that under domestication,” said UCLA evolutionary biologist and study co-author Robert Wayne in a press release. “No one would have guessed that the common black coat color in North American wolves came from dogs — there is no precedent for it. Moreover, for whatever reason, the transfer of the black coat-color gene from dogs to wolves and its success in the wild occurred uniquely in North America.”
Black wolves are relatively rare outside of North America, except for in Italy where there has been a rise in interbreeding between dogs and wolves, according to Barsh. At first glance, the fact that most black wolves inhabit forested regions while steering clear of the open tundra regions seems may seem to suggest coat color selection may act to camouflage wolves from their predators or prey. One problem: wolves don’t have many predators besides humans, of course and even black wolves gray as the age.
The study authors speculate the selective advantage of the black-coat gene likely plays a role in a yet-to-be identified biological process that spans beyond its effect on pigmentation.
“This work shows how domestication can preserve and ultimately enrich the genetic legacy of the original natural populations,” Barsh said in a press release. “Our work is on wolves, but there are many other examples of domestic plants — wheat, rice, maize, soybean — and animals — bison, cattle, cats — where gene flow from domesticated to natural populations has been documented.”
