AP BIOLOGY

Detailed explanation-1: -Stabilizing selection: Stabilizing selection occurs when the population stabilizes on a particular trait value and genetic diversity decreases.

Detailed explanation-2: -Stabilizing selection causes the narrowing of the phenotypes seen in a population. This is because the extreme phenotypes are selected against, causing reduced survival in organisms with those traits.

Detailed explanation-3: -Both stabilizing selection and directional selection will generally decrease genetic diversity. The former reduces diversity by favouring the average phenotype (and associated genotype) over either extreme.

Detailed explanation-4: -In that way, like all forms of selection, the cause of stabilizing selection is the increased fitness and reproductive success that the median individuals have. The extreme versions or traits have a disadvantage, in one way or another.