What type of selection occurs when one extreme phenotype is favored?

What type of selection occurs when one extreme phenotype is favored?

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

Answer: (C)

Directional selection occurs when one extreme phenotype is favored in a population, which leads to a shift in the frequency of alleles in that direction over time. In this process, individuals that exhibit the favored trait have a higher fitness and are more likely to survive and reproduce compared to individuals with other phenotypes. As a result, the traits that result in this extreme phenotype become more common in the gene pool. For instance, if a characteristic, such as larger size in a species of birds, offers a survival advantage (perhaps due to better access to food), those individuals with larger body sizes will have greater reproductive success in the environment. Over generations, this leads to a noticeable increase in the frequency of that trait within the population. Other options represent different mechanisms of selection. Stabilizing selection favors intermediate phenotypes and reduces variation, while disruptive selection favors both extreme phenotypes over the average. Neutral selection describes a scenario where traits do not affect fitness significantly. Understanding these distinctions highlights why directional selection is specifically characterized by the favoring of one extreme phenotype.

Directional selection occurs when one extreme phenotype is favored in a population, which leads to a shift in the frequency of alleles in that direction over time. In this process, individuals that exhibit the favored trait have a higher fitness and are more likely to survive and reproduce compared to individuals with other phenotypes. As a result, the traits that result in this extreme phenotype become more common in the gene pool.

For instance, if a characteristic, such as larger size in a species of birds, offers a survival advantage (perhaps due to better access to food), those individuals with larger body sizes will have greater reproductive success in the environment. Over generations, this leads to a noticeable increase in the frequency of that trait within the population.

Other options represent different mechanisms of selection. Stabilizing selection favors intermediate phenotypes and reduces variation, while disruptive selection favors both extreme phenotypes over the average. Neutral selection describes a scenario where traits do not affect fitness significantly. Understanding these distinctions highlights why directional selection is specifically characterized by the favoring of one extreme phenotype.