The dogs we have today were probably selectively bred from different species of wild dogs and wolves that are mostly now extinct. For example, the wolves here in Alaska before the glaciers melted were of a different species (sub species? I can't remember) of wolf than what lives here today. The huskies and malamutes may have been bred from those wolves instead of the ones here now, depending how far back you want to go. An example of trait selection is breeding for the upraised tail in huskies; some people think this is so the Natives could distinguish them from wolves at a distance. No one really knows 100% where all the variations of dogs originated from. Some scientists say "wolves"... but there are multiple species of wolves, and like you mentioned, dogs like the African wild dog (plus whatever-else-I'm-forgetting). It's a really fascinating topic to me and a person could theorize endlessly about it and never get bored.