Gray Wolf

Hybridisation
• Wolf-dogs
Although dogs and wolves are genetically very close, and have shared vast portions of their ranges for millennia, the two generally do not voluntarily interbreed in the wild. They can produce viable offspring, with all subsequent generations being fertile, as opposed to coydogs and jackal-dog hybrids. The captive breeding of wolf-dog hybrids has proliferated in the United States, with 300,000 such animals being present there. The most commonly used dog breeds for this purpose are of the spitz group. Although wolves normally kill dogs, lone wolves may fraternise with guard or herding dogs as surrogate pack members. Most wolf-dog matings in the wild involve female wolves soliciting male dogs. Wolf-hybrids may be bolder than pure wolves, and thus more dangerous to livestock and human life. In the wild, hybrids may preferentially associate and mate with dogs and other hybrids and live on the periphery of human settlements more readily. Although wolf-dog hybridisation in Europe has raised concern among conservation groups fearing for the wolf's purity, an analysis on the mtDNA sequences show that introgression of dog genes into European wolf populations does not pose a significant threat. Also, as wolf and dog mating seasons do not fully coincide, the likelihood of wild wolves and dogs mating and producing surviving offspring is small. Like pure wolves, hybrids breed annually, though their mating season occurs 3 months earlier, with pups mostly being born in the winter period, thus lessening their chances of survival. Although it is popularly believed that some Inuit tribes mate their sled dogs to wolves in order to improve their stamina, this is likely untrue, as wolf hybrids are generally unable to cooperate effectively in pulling harnesses, and their stamina is much less than that of sled dogs. At least two wolf-dog breeds have been created in Europe, the Saarlooswolfhond and the Czechoslovakian Wolfdog, both by crossing wolves with German shepherds.