The definition of a species: individuals can reproduce and their young are fertile. Thus horses and donkeys are separate species because mules are infertile. Wolves and dogs cross readily and produce young who themselves can also produce young. Jackals can hybridize with dogs but fertility in the young is limited (but not entirely sterile) due to differing lengths of chromosomes, though the chromosome number is the same.
A further definition of a species: populations may have natural barriers against breeding with another population. Barriers can be geologic (the squirrels on opposite sides of the Grand Canyon are an excellent example), behavioral, or genetic. Dogs and coyotes can also produce fertile young, but this is uncommon because the reproductive cycle of the two species are not synchronized. Most reported "coydogs" have turned out to be unusually colored full coyotes or full dogs that look coyote-ish, but there is no doubt that some exist.
Some zoologists think dogs should be a separate species from wolves based on behavior (as a barrier) alone. Others think dogs should be classified as Canus lupus familiaris - a subspecies of wolves.
Either way, the genetic evidence is overwhelmingly in favor of wolves either as the ancestor of the dog, or both come from a common wolf-like ancestor. There is no way dogs could have come from foxes because they are not even in the same genus and have a different chromosome count.
I do love the idea of domestic foxes as pets, though! I was amazed at how few generations it took.
One of my degrees was in zoology and I just love this sort of discussion!
A further definition of a species: populations may have natural barriers against breeding with another population. Barriers can be geologic (the squirrels on opposite sides of the Grand Canyon are an excellent example), behavioral, or genetic. Dogs and coyotes can also produce fertile young, but this is uncommon because the reproductive cycle of the two species are not synchronized. Most reported "coydogs" have turned out to be unusually colored full coyotes or full dogs that look coyote-ish, but there is no doubt that some exist.
Some zoologists think dogs should be a separate species from wolves based on behavior (as a barrier) alone. Others think dogs should be classified as Canus lupus familiaris - a subspecies of wolves.
Either way, the genetic evidence is overwhelmingly in favor of wolves either as the ancestor of the dog, or both come from a common wolf-like ancestor. There is no way dogs could have come from foxes because they are not even in the same genus and have a different chromosome count.
I do love the idea of domestic foxes as pets, though! I was amazed at how few generations it took.
One of my degrees was in zoology and I just love this sort of discussion!
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