re: #123 b_sharp

It sounds like you are using a definition for species formed by the physical inability to interbreed. That isn’t commonly used. Speciation does incude situations represented by ring species where interbreeding is possible physically but will not happen because of some other reason.

Read John’s work.

How about creating one cat species that is deathly allergic to Purina and another to Friskies? That would be what you could call an ecological niche evolution./