In Many Areas of the Rocky Mountains, Both Squirrel and Bird

Multiple Choice

In many areas of the Rocky Mountains, both squirrel and bird species extract and eat the pine seeds from cones of lodgepole pines.In a few areas, however, birds called red crossbills are the only consumers of the pine seeds.Where this one-on-one relationship occurs, both the birds and the pine trees have changed over generations.The crossbills have developed deeper, shorter, and straighter bills that are more efficient at extracting pine seeds, and the pines have developed larger, thicker scales on the cones that defend the seeds from extraction.This bird-tree interaction is an example of _______ due to _______.

A) plant defenses; predation
B) evolution; parasitism
C) coevolution; herbivory
D) adaptation; mutualism
E) resource partitioning; competition