There are several species with the name dog in them. Example, the African wild dog. The ancestor of the domestic dog (including breeds such as the poodle, bulldog, German shepherd, Great Dane, Chihuahua, and golden retriever, among others) is the grey wolf. The domestic dog has been considered a valid species, but some people want to lump it with the grey wolf. BTW, the dingo of Australia is also the same species as the domestic dog and it probably descended from some domestic dogs that arrived in Australia on boats carrying human migrants from Asia a few thousand years ago.