Which type of selection tends to favor one extreme phenotype over the mean or other extreme phenotypes?

Directional selection is a process in evolution where one extreme phenotype is favored over others, leading to a shift in the population's trait distribution towards that extreme. This type of selection occurs in response to environmental changes or pressures that favor individuals exhibiting a specific trait that enhances their survival or reproductive success. For example, if an environment changes such that larger body size provides a survival advantage (e.g., in a colder climate where larger animals retain heat better), individuals with this larger size will be more likely to survive and reproduce, thereby shifting the overall population towards this trait.

In contrast, stabilizing selection tends to favor the mean phenotype and reduce variation in traits, while disruptive selection favors the extreme phenotypes at both ends of the distribution, potentially leading to two or more distinct forms. Artificial selection, on the other hand, is the human-directed breeding process that selects for specific traits rather than natural environmental pressures. Thus, directional selection specifically captures the idea of favoring one extreme phenotype, which is why this answer is the most accurate in context.