Some geographic areas contain two closely related species of birds (sympatry), while other areas contain only one of the species (allopatry). Males from allopatric populations look very similar to each other, but males in the sympatric populations look different from each other and from both allopatric types of males. Which of the following outcomes is most likely if a female in a sympatric area is courted by a male that migrated into the area from an allopatric area?
A) The female is more likely to mate with the immigrant than with a male native to the area.
B) The female is less likely to mate with the immigrant than with a male native to the area.
C) The female is equally likely to mate with the immigrant or with a male native to the area.
D) The female is likely to mate with both males.

Question

Quizplus · Accepted Answer

In sympatric areas, where two closely related species of birds coexist, sexual selection often favors males that exhibit distinct traits, helping females to choose mates from their own species to avoid hybridization. An immigrant male from an allopatric area, where such distinct traits are not as pronounced due to the lack of need to differentiate from a closely related species, is likely to be less attractive to females in sympatric areas. This is because he may not exhibit the specific traits that females in sympatric populations use to choose mates from their own species.

Some Geographic Areas Contain Two Closely Related Species of Birds