There are three kinds of natural selection
- Disruptive
- directional
- stabilizing
Directional Selection is: when individuals that display a more extreme form of a trait have greater fitness than individuals with an average form of the trait. selection will favor extreme phenotype in one or other direction of a phenotypic distribution.
Example: Animals and plant breeders used this to get extreme yield of resistant breeders.
Stabilizing or centripetal Selection is: when the individuals with the average form of a trait have the highest fitness. And extreme phenotypes have less fitness.
Example: In humans, the birth weight of the baby that is favoured is 8 ponds less or more than that is harmful and selection will not favour it.
Disruptive Selection is: when individuals with either extreme variations of a trait have greater fitness than individuals with the average form of the trait.
Reference: This content is taken from Strickberg book on Evolution
Courtesy: Video from YouTube for educational purpose.