Changes in population genetics in which extreme values for a trait are selected over intermediate values, is known as

Changes in population genetics in which extreme values for a trait are selected over intermediate values are known as Disruptive selection.
Disruptive selection also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values.
In this case, the variance of the trait increases, and the population is divided into two distinct groups. The effect of selection is to promote certain alleles, traits, and individuals that have a higher chance to survive and reproduce in their specific environment.