Question

what change is observed in a distribution curve for a trait affected by disruptive selection? (1 point)

• it shifts to the left
• it shifts to either the right or the left
• it shifts to the middle
• it shifts to the right and the left

Explanation:

Disruptive selection (also called diversifying selection) favors extreme phenotypes over intermediate ones. In terms of the distribution curve for a trait, this means the original single peak (representing the intermediate phenotype) is reduced, and two peaks form—corresponding to the favored extreme phenotypes. So the curve shifts to the right and left (as the intermediate is selected against, and extremes are selected for, creating two distinct groups). The other options: shifting only left/right is directional selection; shifting to the middle is stabilizing selection.

Answer:

D. It shifts to the right and the left (assuming the options are labeled A - D with D being "It shifts to the right and the left")