Quote Originally Posted by saibot
Mutations that create an entirely new animal has never been observed.
Because they do not exist. It's a statistical process.

Horse does not turn into zebra overnight. In a result of a mutation a gene of white stripe appears in a horses population. And those stripes apparently not that bright, and appear not on the whole body of the horse, just, let’s say, on legs or shoulders. If this horses population happens to live in Africa savannah where stripe give some advantage, those horses who have them, live longer and have more descendants. Those horses, who happen to have genes that facilitate stripes to be brighter (all mammals have genes that modify their skin and fur color), live longer and have more descendants. They basically outbreed horses. At some point of the process stripped horses (zebras) do not mate non-stripped horses any more. This process takes tens of thousands years.