Recessive black is most commonly found in German and Belgian shepherds. It can also be found in pulik, Samoyeds, schipperkes. Shetland sheepdogs, and the so-called “American Eskimo dog,” which is actually an American variant of the German spitz.
It’s one of two ways that a dog can be solid black, but it’s far less common than dominant black.
The mutation that causes dominant black originated either in dogs or the wolf population that became dogs, because the mutation is older in domestic dog populations than in wolves. This black coloration wasthen transmitted to Italian and New World wolves through cross-breeding with domestic dogs. All wolves that have been examined in North America thus far have turned out to be dominant blacks, as have those in Italy.
However, there was at least one case of a wolf carrying recessive black in the literature.
The Soviet zoologist and dog expert N.A. Iljin carried out several experiments crossing various dogs with wolves. In 1941, he reported on the progeny of a male wolf that was bred to a female mongrel sheepdog. In the first litter, there were black and “zonar gray” (wild wolf gray puppies). If the dog in question were a dominant black, then the entire litter would have been black, but getting gray puppies suggested a very different conclusion.
After breeding from the offspring for several generations, Iljin discovered that the black was being inherited as a recessive allele, which means the dog in question was a recessive black– and the wolf was a carrier!
Now, results of Iljin’s study have been used to show that wolves carried recessive black from the beginning.
However, since the time of Iljin’s work, no one has found a recessive black wolf. The team of geneticists at UCLA have found only dominant black in wolves.
So it’s possible that this wolf was not actually “pure,” and at some point, one of its ancestors was a recessive black dog. I would not be surprised if someone had crossed a recessive black German shepherd into captive Russian wolves at some point. Iljin himself was very much into breeding German shepherds to wolves, and his studies on wolf and German shepherd morphology are pretty much classic literature for those interested in wolves and dogs.
So maybe recessive black did exist in certain Old World wolves from the beginning, but it’s just not been confirmed in the genetic literature in the same way that dominant black has.
I don’t know of another species besides Canis lupus that has two separate genetic variants for melanism. Coyotes have inherited dominant black from breeding with either dogs or wolves, and golden jackals and Ethiopian wolves could also inherit both types of melanism through similar hybridization.
So it’s very interesting that we have this one case of a wolf carrying recessive black, but we need more information to see where this color came from.