Natural selection in populations & Other mechanisms of Evolution 11.2 & 11.3

Normal distribution Frequency is highest near the middle and decreases toward each extreme end of the range

Directional Selection Still generally represented as a bell curve, but there is a shift in the population’s phenotypic distribution

Stabilizing Selection The intermediate phenotype is favored and becomes more common in the population

Disruptive selection Both extreme phenotypes are favored, while individuals with intermediate phenotypes are selected against.

Other mechanisms for evolution

Genetic Drift Causes loss of genetic diversity in a population

Sexual selection Certain traits increase mating success