[muawiyah]

It's all done very easily in a petri dish, and if you are careful with which species is going to provide the female, you can overcome size differences.

They are not in the process of speciation ~ they are in the process of being bred to make it possible for them to live around human beings.

Cordwainer Smith probably had it right ~ in the end the cats, dogs, cattle, and every other domestic animal is given enough intelligence and other features (by people) to make them barely indistinguishble from humans.

10,000 years is hardly long enough to get speciation going with your higher mammals.

[From many - one.]

By definition, if two plants or animals of appropriate sexes cannot inerbreed in the wild, they are of different species.

Fungi, Myxomycota, Archea have different rules.