In Yellowstone National Park, several wolf packs reside, competing for territory and pack leadership. A successful wolf pack survives by keeping order, respecting hierarchy and obeying the leaders. But a dark wolf is about to challenge the definition of this "normal" behaviour. In 2008, Dr. Gregory S. Barsh, a professor of genetics and pediatrics at the Stanford University School of Medicine used molecular genetic techniques to analyze DNA sequences from 150 wolves, half of them black, in Yellowstone National Park, which covers parts of Wyoming, Montana and Idaho. It was discovered that a gene mutation responsible for the protein beta-defensin 3, known as the K locus, is responsible for the black coat color in dogs. After finding that the same mutation was responsible for black wolves in North America and the Italian Apennines, he set out to discover the origin of the mutation. 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 after comparing large sections of wolf, dog and coyote genomes. At the University of California, Los Angeles, Robert K. Wayne, a canine evolutionary biologist, stated that he believed that dogs were the first to have the mutation. He further stated that even if it originally arose in Eurasian wolves, it was passed on to dogs who, soon after their arrival, brought it to the New World and then passed it to wolves and coyotes. Black wolves with recent dog ancestry tend to retain black pigment longer as they age. A black wolf is a melanistic colour variant of the grey wolf (Canis lupus). Black specimens are recorded among red wolves (Canis lupus rufus), but these colour variants are probably extinct. Genetic research from the Stanford University School of Medicine and the University of California, Los Angeles revealed that wolves with black pelts owe their distinctive coloration to a mutation which occurred in domestic dogs, and was carried to wolves through wolf-dog hybridisation. Although the black wolves of America were originally given the same bionomial name as those in Europe, Anselme Gaëtan Desmarest believed that they were a different species. Historically, the natives of the banks of the Mackenzie River, Saskatchewan River and southern Canada apparently never viewed black wolves as a distinct species. In his 1791 book Travels, William Bartram mentioned seeing black wolves among the few red wolf populations he saw in Florida. He stated that they were "perfectly black", except the females which were described as having a white spot on the breast. Bartram also described a "black wolf-dog of the Florida Indians" which was identical to the local wolves, save for the fact that it could bark, and could be trusted around horses. The fur of a black wolf was once considered by the natives of New England to be worth over 40 American beaver skins. A chieftain accepting a gift of black wolf fur was seen as an act of reconciliation. The black wolves of the Southern United States were considered a separate species to the northern kind due to differences in colour and morphology, and were named clouded or dusky wolves (Canis nubilus). The dusky wolves occurred in Missouri Territory, and were intermediate in size between common wolves and coyotes. They apparently produced a foul odour. On January 15, 2009, a black male wolf from "Mollie's Pack" in the Yellowstone National Park's Pelican Valley was weighed in at 143 lbs, making it the largest Yellowstone wolf on record.

• published: 13 Dec 2013
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