A population of hummingbirds with a variety of beak sizes finds a new food source in a plant that has a long trumpet flower with nectar at the bottom of the trumpet. Over time, these hummingbirds develop longer beaks. This is an example of
A) directional selection.
B) stabilizing selection.
C) disruptive selection.
D) sexual selection.
E) genetic drift.

Question

Quizplus · Accepted Answer

This is an example of directional selection because the population evolves towards one extreme phenotype, in this case, longer beaks, which are favored for accessing nectar in long trumpet flowers.

A Population of Hummingbirds with a Variety of Beak Sizes