New World Wolves and Coyotes Owe Debt to Dogs
In a bit of genetic sleuthing, a team of researchers has determined that black wolves and coyotes in North America got their distinctive color from dogs that carried a gene mutation to the New World.
The finding presents a rare instance in which a genetic mutation from a domesticated animal has benefited wild animals by enriching their "genetic legacy," the scientists write in Thursday's Science Express, the online edition of the journal Science. Because black wolves are more common in forested areas than on the tundra, the researchers concluded that melanism -- the pigmentation that resulted from the mutation -- must give those animals an adaptive advantage.
Although common in many species, melanism in dogs follows a unique genetic pathway, said Dr. Gregory S. Barsh, a professor of genetics and pediatrics at the Stanford University School of Medicine and the senior author of the paper.
Last year, Dr. Barsh and his laboratory identified a gene mutation responsible for the protein beta-defensin 3, which regulates melanism in dogs. After finding that the same mutation was responsible for black wolves and black coyotes in North America, and for black wolves from the Italian Apennines where wolves have recently hybridized with free-ranging dogs, the researchers set out to discover where and when the mutation evolved.
Comparing large sections of wolf, dog and coyote genomes, Dr. Barsh and his colleagues concluded that the mutation arose in dogs 12,779 to 121,182 years ago, with a preferred date of 46,886 years ago. Because the first domesticated dogs are estimated to date back just 15,000 to 40,000 years ago in East Asia, the researchers said that they could not determine with certainty whether the mutation arose first in wolves that predate that time, or in dogs at an early date in their domestication.