What type of selection occurs when individuals with intermediate phenotypes have higher fitness?

Stabilizing selection occurs when individuals with intermediate phenotypes have higher fitness.

This form of natural selection favors organisms near the population average while selecting against extremes. Over generations, the trait’s average may remain relatively stable, but the overall range of variation becomes narrower.

A classic example is human birth weight. Very small newborns may have difficulty surviving, while very large babies can face greater risks during delivery. Babies in an intermediate weight range historically tended to have better survival prospects, producing a pattern consistent with stabilizing selection.

It is often confused with directional selection, which favors one extreme and shifts the population average. Disruptive selection does the opposite of stabilizing selection: it favors both extremes over intermediate forms. Stabilizing selection can preserve a well-adapted average even while genetic variation remains in the population.