What type of selection might lead to the development of two distinct phenotypes within a population?

Disruptive selection is the type of natural selection that can lead to the development of two distinct phenotypes within a population. This occurs when individuals at both extremes of a trait distribution have a fitness advantage over individuals with intermediate phenotypes. As a result, the population may split into two distinct groups, each adapted to different environments or ecological niches.

For example, in a population of birds with varying beak sizes, if those with either very large or very small beaks have better access to food resources compared to those with medium-sized beaks, the population could evolve to display two different beak sizes over time, thereby creating two distinct phenotypes.

Other types of selection, such as directional and stabilizing selection, tend to favor a single phenotype or intermediate traits rather than leading to the emergence of distinct groups. Balancing selection helps maintain genetic diversity but does not necessarily result in the clear delineation of two separate phenotypes as seen with disruptive selection.