What characterizes directional selection?

Directional selection is a type of natural selection that occurs when one extreme phenotype is favored over others, leading to a shift in the population's trait distribution in that direction. This means that individuals with a particular extreme trait have a higher chance of survival and reproduction, allowing that trait to become more common in future generations.

For example, if a species of birds has a range of beak sizes and the environment changes to favor larger beaks (perhaps due to a shift in available food sources), birds with larger beaks will likely survive better and produce more offspring, resulting in a larger proportion of the population exhibiting larger beaks over time.

In contrast, the other options describe different aspects of natural selection. Favoring the average phenotype would be indicative of stabilizing selection, which tends to reduce variation and maintain the status quo of traits rather than shifting them in one direction. The option about favoring multiple phenotypes equally relates to disruptive selection, where individuals at both extremes of a trait distribution are favored, which can lead to increased diversity rather than a directional shift. Finally, promoting genetic diversity is not a characteristic of directional selection; instead, directional selection often results in reduced genetic diversity as specific traits become more prevalent at the expense of others. Thus, the correct