Transcriptomic data reveals nuclear-mitochondrial discordance in Gomphocerinae grasshoppers (Insecta: Orthoptera: Acrididae)

The phylogeny of many groups of Orthoptera remains poorly understood. Previous phylogenetic studies largely restricted to few mitochondrial markers found many species in the grasshopper subfamily Gomphocerinae to be para- or polyphyletic, presumably because of incomplete lineage sorting and ongoing hybridization between putatively young lineages. Resolving the phylogeny of the Chorthippus biguttulus species complex is important because many morphologically cryptic species occupy overlapping ranges across Eurasia and serve important ecological functions. We investigated whether multispecies coalescent analysis of 540 genes generated by transcriptome sequencing could resolve the phylogeny of the C. biguttulus complex and related Gomphocerinae species. Our divergence time estimates confirm that Gomphocerinae is a very young radiation, with an age estimated at 1.38 (2.35-0.77) mya for the C. biguttulus complex. Our estimated topology based on complete mitogenomes recovered some species as para- or polyphyletic. In contrast, the multispecies coalescent based on nuclear genes retrieved all species as monophyletic clusters, corroborating most taxonomic hypotheses. Our results underline the importance of using nuclear multispecies coalescent methods for studying young radiations and highlight the need of further taxonomic revision in Gomphocerinae grasshoppers.

Automated summary

The phylogeny of many groups of Orthoptera remains poorly understood. This study utilized transcriptome sequencing to investigate the phylogeny of the Chorthippus biguttulus complex and related Gomphocerinae species. The results highlight the importance of using nuclear multispecies coalescent methods for studying young radiations and underscore the need for further taxonomic revision in Gomphocerinae grasshoppers.