Divergence of courtship and mating behaviors among endemic Hawaiian swordtail crickets

Abstract

Crickets in the family Gryllidae are well known for their elaborate mating behaviors; however, behavior of the subfamily Trigonidiinae is poorly understood. A large portion of this clade is endemic to Hawaii, including three genera: Trigonidium , Laupala and Prolaupala . The only Hawaiian genus that has been studied is Laupala , which exhibits unusual nuptial feeding in the form of spermless 'micro' spermatophores. Microspermatophore donation has been suggested to increase sperm transfer, constituting a novel mechanism of mating effort in crickets. We observed mating from representatives of each genus to investigate behavioral diversity and reconstruct character state evolution. We found that Prolaupala species produce microspermatophores during a behavioral sequence very similar to Laupala . Trigonidium do not produce microspermatophores, but exhibit other behavioral strategies that likely function to improve insemination, such as prolonged copulation and post-copulatory guarding. We also observed spermatophore and copulation characteristics that were previously considered unique to other gryllids. Behavioral diversity among the Hawaiian fauna reflects the evolutionarily labile nature of gryllid mating behavior and convergence of behavioral strategies in response to sexual selection. Furthermore, our results suggest that microspermatophore donation may be a common mating effort strategy within Trigonidiinae.