Disruptive selection occurs when the environment favors extreme traits, resulting in a split of the population. Which option best captures this definition?

• A. Favors Average Traits
• B. Favors Extreme Traits
• C. Favors All Traits Equally
• D. Favors Nothing

Answer: (B)

Disruptive selection is a form of natural selection where extreme trait values have higher fitness than intermediate ones, causing the population to split into two or more distinct groups. When the environment rewards the ends of the spectrum, individuals with extreme traits become more common over time, leading to a bimodal distribution rather than one centered around an average. An example is a bird population where both very small and very large beaks are advantageous for different seed types, while mid-sized beaks don’t do as well; over generations, the extremes increase in frequency and the population splits.

That’s why the best description is the one that says extreme traits are favored. Favors average traits would reflect stabilizing selection, which narrows variation around a mean. Favors all traits equally would imply no selective pressure at all, and favors nothing would also suggest no selection acting on the trait.