Adaptive introgression of coat color in wolves

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Mark Derr of the NY Times reports on a new study showing that black North American wolves got their melanism from 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 Thursdays Science Express, the online edition of the journal Science. Since black wolves are more common in forested areas than on the tundra, the researchers concluded that melanism the pigmentation that came from the mutation must give those animals an adaptive advantage.

There are so many examples of this phenomenon in mammals now! This one is interesting because it would have been carried in by early dogs brought in via Beringia – so it’s another case where an intercontinental migration has brought a new adaptive allele that introgressed into a natural population.

There is also a date:

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. Since 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.

This could have been selected in the very earliest domesticated dogs, based on that date. It would be useful to have a number of genomes from ancient wolves to screen against variation present in the wild population around the time of domestication.

The really cool thing is that we will probably have samples like that within the next several years…