In the Grand Canyon,in the southwestern U.S.,there are many species of squirrels,including the Albert Squirrel and a "subspecies," the Kaibab Squirrel (isolation is not complete,according to the biological species definition by Ernst Mayr).The two populations of squirrels can interbreed to produce fertile offspring,but the populations exist on different portions of the rim of the Grand Canyon,separated by the canyon and the Colorado River.This is an example of
A) sympatric speciation. B) postzygotic speciation. C) prezygotic specation. D) parapatric speciation. E) allopatric speciation.