Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Directional selection is a type of natural selection where one extreme phenotype is favored over others. This leads to a shift in the population's trait distribution toward that extreme.
5 Must Know Facts For Your Next Test
The average phenotype in the population changes over time.
Directional selection can lead to rapid evolutionary changes.
It often occurs when environmental conditions change or when a population colonizes a new habitat.
An example of directional selection is the increase in beak size among finches in response to food availability.
It reduces genetic diversity by favoring one extreme phenotype.
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Related terms
Stabilizing Selection: Natural selection that favors intermediate variants and acts against extreme phenotypes.
Disruptive Selection: Natural selection that simultaneously favors individuals at both extremes of the phenotypic range.
Adaptive Evolution: The process through which populations become better suited to their environment due to natural selection.