Convergent evolutionary selection unravels the genetic basis of audition in moths

Hearing in Lepidoptera mediates a range of ecologically important behaviours, including mate communication, predator avoidance, and acoustic signalling. In moths, the evolution of predator-prey interactions with bats has further shaped hearing through a sensory arms race, with repeated co-option of auditory organs to detect and evade echolocating predators. Despite significant prior characterization of the neurophysiology and behaviour of hearing in moths, the genetic basis of hearing is poorly understood in most insects. In this study, we identify a core set of putative auditory genes in Lepidoptera using a combination of homology-based searches from Drosophila and evolutionary rate analyses. We find 56 genes present across all species and investigate whether gene copy number varies among non-hearing and hearing lineages and among 3 different ear types. We discovered seven genes associated with ear type and one with ear presence, but did not find significant losses in gene copy number in non-hearing species. We identified three genes (btv, Dnai2, and nompB) with strong evidence of selection in hearing clades and five genes with weaker evidence of selection. We discuss the potential roles of btv, nompB, and Dnai2 in ciliary transport and the aging of hair cells, as well as the possibility of actively amplified hearing. Our study serves as a primer and resource for further gene mining and functional testing of auditory genes in moths and other insects.