[ketsu]

Yes, absolutely. But so what?

Species becoming reproductively isolated is not enough to demonstrate Darwinian evolution, is it?

It is. It's trivially easy to prove that phenotype changes according to environment. Once you have reproductive isolation you have evolution.

[js1138]

Don’t be to hasty in your assumptions about reproduction.

http://www.youtube.com/watch?v=-ThQQuHtzHM