Two species of birds that compete for the same size of seed eventually develop different beak sizes, allowing them to compete for different sizes of seeds. What has occurred?
A)competitive exclusion only
B)character displacement only
C)directional selection only
D)competitive exclusion and character displacement
E)directional selection and character displacement

Question

Quizplus · Accepted Answer

The development of different beak sizes in two species of birds that compete for the same size of seed is an example of both directional selection and character displacement. Directional selection occurs when natural selection favors individuals with a specific trait, in this case, larger or smaller beaks depending on the size of the available seeds. Character displacement occurs when two species that compete for the same resources evolve differently to reduce competition, in this case, the different beak sizes allow the bird species to specialize in different sizes of seeds, reducing competition for resources.

Two Species of Birds That Compete for the Same Size