Directional selection in the modern horse is demonstrated by
A) populations consisting of only very dark and very light colored horses.
B) the rapid decrease in size over the last 200 years.
C) the gradual increase in size over millions of years.
D) fossils which show the horse has not changed in millions of years.
E) the extinction of other horse species.

Question

Quizplus · Accepted Answer

Directional selection is a form of natural selection in which an extreme phenotype is favored over other phenotypes, causing the allele frequency to shift over time in the direction of that phenotype. The gradual increase in size over millions of years in the modern horse is an example of directional selection, where larger size was likely favored in various environmental contexts, leading to the modern horse's increased size compared to its ancestors.

Directional Selection in the Modern Horse Is Demonstrated by