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 mean in one direction. So it 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 reduces variation and makes the population look more similar over time, matching the description.
• Disruptive selection: Favors both extreme phenotypes, increasing variation and making the population less similar.
• Species selection: Acts on species-level traits (like speciation rates) rather than individual traits within a population, so it's not relevant here.

Answer:

B. stabilizing selection