According to National Geographic, a good example of allopatric speciation is the formation of new squirrel species after the formation of the Grand Canyon. The geographic isolation of the squirrels at the north and south rims of the canyon does not allow them to breed with each other.
According to the University of California at Berkeley, allopatric speciation is one of four different types of speciation. Other types of speciation include peripatric, parapatric and sympatric. Allopatric speciation distinguishes itself from these other types of speciation by emphasizing geographic isolation as a barrier for species to breed. Lack of mating between two species causes their genetic differences to diverge further.