Question

select the correct answer. in a particular mouse species, two extremes of a phenotype are equally selected for over several generations. as a result, the genetic frequency for these two phenotypes begins to increase over the preexisting mean trait. what type of selection has occurred? a. directional b. disruptive c. bottleneck d. normal

Explanation:

Disruptive selection (also called diversifying selection) occurs when extreme phenotypes are favored over the intermediate (mean) phenotype. In the problem, two extreme phenotypes of the mouse are selected, and their frequencies increase over the mean trait, which matches the definition of disruptive selection. Directional selection favors one extreme phenotype, bottleneck is a genetic drift event (not a selection type), and "normal" (stabilizing selection) favors the mean. So the correct type is disruptive.

Answer:

B. disruptive