The weaker ones? More like "die out" than evolve out. They're not going anywhere.
In various traits, there is a continuum from one end to the other (say, light skin to dark skin as an example). Under various conditions natural selection will nibble at one end of the range or the other, reducing the population of the end of the range that is less suited to the conditions. The survivors get to pass on their genes. The subsequent generation will be just slightly different, in the direction of better adapted.
Apply a few hundred thousands of years of time to many small, isolated populations, stir well.
"More like "die out" than evolve out."
Yeah! That's probably the term I should have used.
But basically tho, I'm right about the stronger ones surviving which would be natural selection? Or not?
I'm not sure I'm asking this right, so bear with me.