Black wolves, found nearly exclusively in North America, likely inherited their coats from breeding with domestic dogs, a study published on Thursday showed.
The dogs of the earliest Native Americans or of European immigrants probably contributed to the genetic variability of their wild counterparts, researchers from Stanford University and the University of Calgary found in a study published in the journal Science.
Most canine geneticists believe that North American dogs today are all descended from European dogs, the study said.
“Although it happened by accident, black wolves are the first example of wolves being genetically engineered by people,” said study co-author Marco Musiani, a University of Calgary professor and wolf expert.
“Domestication of dogs has led to dark-colored coats in wolves, which has proven to be a valuable trait for wolf populations as their arctic habitat shrinks,” Musiani said.
A darker coat helps wolves hide when chasing their prey in forested areas, where the black wolves make up about 62 percent of the wolf population. Wolves gray with age, and coats vary from white to gray to black.
Lighter-colored wolves are more prevalent in the icy tundra, where only about 7 percent of dark wolves are found.
“I have spent a lot of time in tree-line areas at the southern edge of the tundra and it has always surprised me that there are white wolves and black wolves but no gray wolves in these areas,” Musiani said. “This work may provide an explanation: Wolf populations are quickly adapting to conditions with less snow by taking advantage of the human-created shortcut of black coloration.”
The researchers said the wolves acquired their dark coats at some point over the past 10,000 to 15,000 years, after the first humans migrated to North America across the Bering Strait with their dogs.
The study compared DNA from 41 black, gray and white wolves in the Canadian Arctic and 224 black and gray wolves in Yellowstone National Park with the DNA of domestic dogs and gray and black coyotes.
The researchers set out to explain how pigmentation in dogs differs from most other mammals, but instead discovered the genetic mutation that accounts for wolves’ pigmentation.
“Wildlife biologists don’t really think that wolves rely much on camouflage to protect themselves or to increase their hunting success,” genetics professor Greg Barsh said.