Evolution: Abrupt Changes

[robvalue]

I don't understand your first question. Mutations that are beneficial are more likely to be promoted over time; that's the general principle of natural selection. They don't require everyone in each new generation to change at once, it will happen over time. It's just that it will happen faster if the mutation is more beneficial.

Indeed, a huge change could indeed lead to extinction instead. It will be adapt or die. Or maybe run off and find a better environment.