[DouglasKC]

Once two populations stop interbreeding, the first step of the speciation process has begun. Imagine that all of the dogs in the world except Great Danes and teacup chihuahuas remained. It would be chemically possible for them to interbreed, but virtually impossible for them to mechanically interbreed.

Your argument is filled with a lot of supposition and fortunate circumstances none of which can really be debated. I say that the fish will eventually breed and can never become different species.

[Soliton]

Your argument is filled with a lot of supposition and fortunate circumstances none of which can really be debated. I say that the fish will eventually breed and can never become different species.

The dog example is actually related to ring species. They exist in nature