The sizes of horns in males of a particular beetle have an interesting distribution: the highest frequencies are around 15 millimeters and 30 millimeters, with few individuals in between. Based on this observation, which of the following modes of selection is most likely to be operating on these horns?
A) Stabilizing selection
B) Directional selection
C) Concentrated selection
D) Disruptive selection
E) Purifying selection

Question

Quizplus · Accepted Answer

Disruptive selection favors extreme traits and can result in a bimodal distribution where there are peaks at both extremes and fewer individuals in the middle. This seems to be the case with the beetle horns, with the highest frequencies at 15mm and 30mm and few individuals in between.

The Sizes of Horns in Males of a Particular Beetle