survival of the fitted...

Rolling through a lovely conversation with a lovely lady some days ago something sort of wandered into my head. A lot of environmentalists believe in evolution. And a lot of Christians seem to ignore the whole dominion thing and take more of "it's all going to burn" approach to the environment. That seems a bit backward to me for this reason:

If species can mutate into other species, and over time a one-celled organism can evolve into such diverse creatures as sperm whales, ocelots, and honeysuckles, why should we care if a few go extinct. Even if all the kinds of living things in all the world were to disappear but one, then why couldn't that one species evolve into a proper panoply of life?

It seems to me that of all people creationists, who believe that what we have is what we have, should be concerned about preserving species.