MULTIPLE AND ANCIENT ORIGINS OF THE DOMESTIC DOG

Mitochondrial DNA control region sequences were analyzed from 162 wolv es at 27 localities worldwide and from 140 domestic dogs representing 67 breeds. Sequences from both dogs and wolves showed considerable div ersity and supported the hypothesis that wolves were the ancestors of dogs. Most dog sequences belonged to a divergent monophyletic clade sh aring no sequences with wolves. The sequence divergence within this cl ade suggested that dogs originated more than 100,000 years before the present. Associations of dog haplotypes with other wolf lineages indic ated episodes of admixture between wolves and dogs. Repeated genetic e xchange between dog and wolf populations may have been an important so urce of variation for artificial selection.