Directional selection is a type of natural selection that emphasizes one type of mutation that eventually phenotypically manifests itself within the population. The darkened wing color of the peppered moth (Biston betularia) located in industrial areas is an example of directional selection. The darker wings provided appropriate camouflage from predators as the moths dwelled on soot-covered trees.

Directional selection is commonly instigated by the human population on other species for a particular use. A plant breeder may only choose to grow seed from a plant with a particular characteristic or set of characteristics. Eventually, successive breeding of the plant will alter the population and the desired characteristic will become the common phenotype. Dog breeding is an example of directional selection applied by humans.