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There are 34 species in the dog family, Canidae, ranging from the squat dachshund-like bushdogs to the long-legged maned wolf, a species sometimes called a fox-on-stilts. And they live in almost all possible environments from forests to tundra to deserts. In the past, the evolutionary relationship of these species was based upon factors in their appearances.
Now it is possible to use genetic tools for examining DNA, the molecular codes carried in all cells. This technique produces a more exact answer as to the evolutionary relationships between the 34 canids.
Based on molecular analysis, four divisions exist among the canidae:
1. The wolf-like canids, which include the domestic dog, gray wolves, coyotes, and jackals
2. The South American canids
3. The red-fox-like canids of the Old and New World, including red foxes and kit foxes.
4. Monotypic species--unique, undivided species such as the bat-eared fox and raccoon dog.
The fossil record and genetic differences indicate that these divisions among the canids began about 7-10 million years ago. Of particular interest are the wolf-like canids. They all have 78 chromosomes and share much of their genetic code in common. Yet they range from the Subsahara Africa to the Arctic North.
Within this wolf-like group, however, there are still substantial genetic differences. A very close relationship exists between gray (timber) wolves, dogs, coyotes, and Simien jackals. The gray wolf and coyote may have had a common North American ancestor about two million years ago, whereas the Simien jackal, found in only a small area of the Ethiopian highlands, is possibly an evolutionary relic of a past African invasion of gray wolf-like ancestors. The Simien jackal is the most endangered canid, and should be called a wolf rather than a jackal to reflect its evolutionary heritage.
The earliest remains of the domestic dog date from 10 to 15 thousand years ago. Since these remains are quite diverse, it would seem that domestication took place in numerous locations and at different times. And probably for a variety of reasons.
Dogs may well be derived from several different ancestral gray wolf populations. It will take many more studies of dogs and wolves--world-wide--to determine the specific genetic sources of the domestic dog gene pool. But an examination of seven dog breeds and 26 gray wolf populations show that the domestic dog is an extremely close relative of the gray wolf.
In comparison, the coyote differs from the gray wolf by about 4% (mitochondrial DNA sequence), whereas the dog and gray wolf have a difference of only two-tenths of one percent (.2%). Nor does the genetic evidence support the view that dogs descended from jackal ancestors.
Our dogs are gray wolves, despite their diversity in size and proportion.
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