Character Displacement and Acoustic Insects

Crickets, katydids, grasshoppers, and cicadas should be ideal for illustrating character displacement. Their species-specific calling songs are of direct importance to reproductive success, and species with similar songs and overlapping ranges should develop greater differences in their songs in areas of sympatry. Although many pairs of species have suitably similar songs and overlapping ranges and the data concerning songs are extensive for crickets and katydids, no convincing example of character displacement has been found in acoustic insects. Lack of such examples can be attributed to false premises, to divergence completed in allopatry. to elimination of geographical variation in song by gene flow between the zone of sympatry and the zones of allopatry, and to the scanty sample that has been intensively studied. 10.1093/icb/14.4.1137