Molecular phylogenetic evidence for multiple dispersal events in gomphocerine grasshoppers

Abstract

The gomphocerine grasshoppers, comprising over 1000 species, occur on all continents excepting Australia and Madagascar. This work provides an independent examination of previous accounts of their taxonomic relationships and intercontinental connections, focusing on selected North American and Eurasian taxa. Our study is based on portions of four mitochondrial genes (coding for cytochrome b, cytochrome oxidase subunits I and II, and NADH dehydrogenase subunit V) which were sequenced and phylogenetically analyzed using weighted and unweighted maximum parsimony, maximum likelihood and Bayesian methods. Maximum resolution was achieved using weighted parsimony (counting transversions at third codon positions only) and Bayesian methods, and treating all four sequences, totalling 1892 bp, as a unit. The subfamily is provisionally accepted as monophyletic. The tribe Chrysochraontini is monophyletic, whereas the monophyletic status of Aulocarini and Dociostaurini is unclear. Tribes, Arcypterini, Chorthippini and Gomphocerini, are not monophyletic and require further scrutiny. Regarding biogeographic origins of the subfamily, our molecular data generally support Vickery's assertion that there were multiple periods of dispersal, most likely from Eurasia to North America. Assigning the range 50 to 70 Mya to the time of gomphocerine divergence, we provide estimates of the times of these biogeographic events.