Why do nearly half of North American wolves have black coats while European wolves are overwhelmingly gray or white? The surprising answer, according to teams of biologists and molecular geneticists from Stanford University, UCLA, Sweden, Canada and Italy, is that the black coats are the result of historical matings between black dogs and wild gray wolves.
The research, federally funded by the National Science Foundation, appears Feb. 5 in the online edition of the journal Science and will be published later in the journal's print edition.
The scientists used molecular genetic techniques to analyze DNA sequences from 150 wolves, about half of them black, in Yellowstone National Park, which covers parts of Wyoming, Montana and Idaho. They found that a novel mutated variant of a gene in dogs, known as the K locus, is responsible for black coat color and was transferred to wolves through mating.
The biologists are unsure of when the black coat color was transferred from dogs to wolves, but they believe it was not a recent occurrence; the black coat could not have spread as widely as it has throughout North America in just a few hundred years, they say. They suspect the transfer took place sometime before the arrival of Europeans to North America and involved dogs that were here with Native Americans.
"This is the first example where a gene mutation originated in a domesticated species, was transferred to and became very common in a closely related wild species," said Robert Wayne, a UCLA professor of ecology and evolutionary biology and co-author of the Science paper.