In evolutionary biology, what type of natural selection favors individuals with intermediate traits?

Stabilizing selection favors individuals with intermediate traits and selects against both extremes.

This pattern tends to reduce variation around an existing population average. For example, if very small and very large newborns have lower survival than infants of intermediate birth weight, selection can favor the middle range. The exact trait and strength of selection depend on the environment.

Stabilizing selection does not mean that a population stops evolving. Allele frequencies can still change, and environmental shifts can alter which phenotypes are favored. It may also preserve a long-term average while reducing visible variation.

The three classic patterns are stabilizing, directional, and disruptive selection. Directional selection favors one extreme, whereas disruptive selection favors both extremes over intermediate forms. Stabilizing selection is therefore best identified by its preference for intermediate phenotypes.