Types of Selection Summary
Biology: Cambridge International A Level, topic 17.2.3
Summary of Selection Types
The three types of selection can be summarised in the following ways:
Stabilising selection
- Natural selection favours the average phenotype.
- The selection pressures select against the extreme phenotypes.
- Takes place in environments that do not change.
Directional selection
- Natural selection favours an extreme phenotype.
- The selection pressures select against all other phenotypes.
- Takes place after an environment has experienced a change.
Disruptive selection
- Natural selection favours the two extremes of a phenotype.
- The selection pressures select against the average phenotype.
- Takes place in an environment that favours more than one phenotype.
Test yourself on Types of Selection Summary
What is the type of selection that favours an extreme phenotype?