"After all the other variants have gone by the wayside, the one best suited for a particular set of conditions remains."
Why would the other variants go by the wayside? What would cause variants that weren't suitable?
Sorry, I'm not going to get caught up in your circular question-begging this time. Playing dumb is cute for a while, but it does not lead to intelligent discourse, and it is clear that you have no intention of dealing with this with an open mind.
Suffice to say, the seed that falls in good soil will grow, that which falls on rocks will not take root, and that which falls among weeds will be choked to death. Nice discussion on evolution straight from Jesus.
A terrific example of "convergent evolution" (that is, different organisms "converge" toward a similar trait) is the fish form. Both teleost fish (salmon, tuna, etc.) and mammals (whales, dolphins) got to pretty similar body types because of environmental demands. Not exactly, though...whales tails are horizontal, fish vertical. It might have something to do with the need for the mammals to get to the surface often.