Technically, of course, you can't model Darwin's theory of evolution with a single character -- evolution isn't about one individual getting better, it's about a process of natural selection in a species over a period of time. To really model evolution, you'd have to play hundreds of alts, and quit them each time you ran into a problem, leaving you with just a few characters that worked really well. Wait -- maybe some of you are already doing that.
But Falstein makes good points in saying that certain elements of what Darwin described as evolution have shown up in game design as well -- the idea of specialization for certain character classes, tribal and national allegiances, and even the idea of memes (which are certainly widespread in WoW -- anyone ever heard of Chuck Norris or Leroy Jenkins?) are all drawn from Darwin's thinking and definitely embodied in the game we play.