End of Evolution

Has anyone ever read a sci-fi story where evolution stops?

I was thinking in particular of a world settled by anti-darwinists (called "Kansas" of course) where scientists make a breakthrough discovery of a cure for the common cold... which lasts year after year. Eventually, the world thrives, probably based on other "crutches" of not having to worry about species change; but over the long haul some sort of natural calamity casuses a chain of events that would otherwise have been resolved through natural selection and speciation, and instead the climate crashes.

It might actually be funnier if it were set in the real Kansas, wouldn't it?

(if there isn't such a story, you're welcome to steal the idea, as long as I get a mention in the credits. :)