Evolution of Acoustic Communication in Insects

Tympanal organs for hearing in the far field have evolved on multiple occasions among insects and are currently found in seven orders. Many, if not most, cases of insect hearing probably originated as a means for detecting and avoiding predators. In particular, sensitivity to ultrasound appears to have coevolved with echolocation signaling by insectivorous bats. However, on an overall scale, hearing is relatively rare among insects in comparison with other modalities of perception, including detection of substrate vibration. Sound signaling in insects, which typically occurs in the context of mating communication, is rarer still and is known in only five orders. Phylogenetic analyses suggest that acoustic communication in the Lepidoptera and in the suborder Caelifera (grasshoppers) of the Orthoptera originated via a “sensory bias” mechanism. Hearing was ancestral and sound signaling by males subsequently arose on multiple, independent occasions. On the other hand, acoustic communication in the Cicadidae and in the suborder Ensifera (crickets, katydids) of the Orthoptera may have originated via coevolution between female perception and male signaling. The diversity of songs among acoustic insects may reflect genetic drift and reproductive character displacement. There is little evidence, however, that insect songs are adapted to specific physical environments. In one clade of acoustic insects, the diversification of song is associated with an unusually high rate of population differentiation and speciation, which may be facilitated by a genomic co-localization of loci influencing female response/preference and male signaling. The extent to which co-localization is a general factor in speciation remains to be explored.