Question

which of the following can result in a population looking more similar over time and can be described as selection against both extremes of a trait?

○ directional selection
○ stabilizing selection
○ disruptive selection
○ species selection

Explanation:

To solve this, we analyze each option:

• Directional selection: Favors one extreme of a trait, shifting the population's trait distribution in one direction. Doesn't make the population more similar by selecting against extremes.
• Stabilizing selection: Selects against both extreme phenotypes of a trait, favoring the intermediate ones. This leads to the population becoming more similar over time as the extremes are reduced.
• Disruptive selection: Favors both extreme phenotypes, leading to a population with two distinct groups (more diversity, not similarity).
• Species selection: Acts on entire species, not on the traits within a population to make it more similar.

So, stabilizing selection matches the description of selecting against both extremes and making the population more similar.

Answer:

B. stabilizing selection