Problem:
I've done some research and it appears that dogs are the most diverse looking single species of mammals.
Required:
Question: Are dogs special in respect to genes/gene activation mechanisms related to appearance?
Question: Does dramatic difference in appearance have something to do with respect to how dog anatomy and how they give birth?
Question: If dogs are not special, this makes me interested if other species of mammals can also be bred selectively (or genetically engineered) to produce such dramatic variation?
Please describe all the answers briefly.