Colors of the Wolf

A wolf at Prague Zoo.

In most parts of the world, wolves have the color and pattern seen in the picture above, but for some reason in North America, wolves have a larger spectrum of colors, from almost white to pitch black. Researchers have recently found that the reason for this is that the North American population of wolves has been mixed with domesticated dogs. The gene for black fur in wolves is the same one found in dogs, and since black wolves are found all over North America, the mixing must have happened a long time ago. It must therefore be mixing with the dogs of the native Americans, rather than the dogs of the Europeans, that is the reason for this variation in color in the North American wolf.
According to some sources, the mixing of dogs with wolves was encouraged by some native American people who believed that they would get stronger dogs from it. But since all (examined) dog breeds of today are more closely related to the middle eastern wolves than to, in this case, the American population of wolves, it seems that the puppies born in wolf-dog mix litters were unfit to live with people, and only the ones born to a wild mother and incorporated in the society of the wolves lived on to get offspring. This is quite expected as the same text that gave me this information (see the sources below) also stated that the dogs of the native Americans were easily trained and good with children and people. Something that wolf-dog-hybrids aren't exactly known for.

A "wolf-colored" dog, Siberian husky, that in spite of it's appearance isn't more closely related to wolves than any other spitz-type dog. See the blogpost about the origin of dog breeds for more info on that [link].

Sources:

http://newsroom.ucla.edu/portal/ucla/biologists-solve-mystery-about-80301.aspx

http://doglawreporter.blogspot.com/2012/01/dogs-of-great-plains-nations.html