[wolf78]

you couldn’t go from a chihuahua to an alsation for instance.

Of course you can't just "go" from a chihuaha to an alsatian, because going isn't a scientific term, just like you can't "go" from caucasiod to mongoloid humans. You can however breed chihuahuas and alsatians, because they are the same species, just different races.

Only if the offspring gradually becomes infertil, you are witnessing a seperation of species. Example: horse / donkey -> mule.

[chuck_the_tv_out]

“you couldn’t go from a chihuahua to an alsation for instance”

indeed. because the alsation code has been lost. you could never get an alsation from breeding chihuahua together, because you have selected out an extreme portion of the dog DNA.