Dark- eyed junco birds have white outer tail feathers that the males display during aggressive interactions and also during courtship displays. Males with more white in their tail are more likely to win aggressive interactions with other males, and females prefer to mate with males with more white in their tails. In the case of juncos, aggression fighting) by males is a type of selection; thus, we would expect that variation in reproductive success to be higher in and this species should exhibit _ sexual dimorphism.
A) intersexual; females; greater
B) intersexual; males; less
C) intrasexual; males; greater
D) intrasexual; females; greater
E) intrasexual; males; less

Question

Quizplus · Accepted Answer

Intrasexual selection refers to competition between members of the same sex for access to mates or resources. In this case, male juncos compete with each other for access to females. The fact that males with more white in their tails are more successful in aggressive interactions and mating indicates that there is strong intrasexual selection in this species. Since this selection is acting primarily on males, we would expect to see greater sexual dimorphism in juncos. Therefore, choice C is the best answer.

Dark- Eyed Junco Birds Have White Outer Tail Feathers That