How can natural selection change the distribution of a trait?

If a trait is seen more useless than over traits, through evolution that trait will become more enhanced while other trait diminish.

Explanation:

For example, if a fish wants to live on land, through evolution the fish will develop lungs and a nose in exchange for gills.

glacial erosion, the picking up and movement of earth beneath a glacier, is also referred to as plucking. erosion and transportation of individual pieces of bedrock, especially large "joint block occur as a result of this glacial erosion. plucking is type of erosion in which rocks become frozen into the bottom and sides of the glacier.as the glacier moves downhill it 'plucks' the rocks frozen into the glacier from the ground.