[cookcounty]

"You're getting in some awfully deep water there. Are you willing to argue that it's possible for selection pressure to change the genotype of a species enough that the species becomes reproductively isolated?"

Yes, absolutely. But so what?

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

[tongass kid]

Have noticed it takes selective pressure to create a mule that has reproductive problems? Additionally, no selective pressure is needed to create a fine reproducing elephant. Ain't the two party system great!

[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.