Which type of selection favors individuals at both extremes of variation, with reduced middle variation?

• A. Disruptive selection
• B. Natural selection
• C. Directional selection
• D. Stabilizing selection

Answer: (A)

This question tests how natural selection can shape the distribution of a trait in a population. Disruptive selection occurs when individuals with extreme values at both ends of variation have higher fitness than those with intermediate values. As a result, the middle forms are less common and the population splits into two groups with extreme traits, creating reduced middle variation and a bimodal distribution.

Context helps: this tends to happen when two different ecological niches or resources favor different extremes—for example, two seed sizes that favor beaks at opposite ends of the range. Over time, the extremes become more common while intermediates decline.

For comparison, directional selection increases one extreme, speeding it up in frequency; stabilizing selection favors intermediates and reduces variation; natural selection is the overall process describing how traits that affect fitness spread or disappear.