The phylogeny of the Orthoptera (Insecta) as deduced from mitogenomic gene sequences

Abstract

Abstract Background The phylogeny of the Orthoptera was analyzed based on 6 datasets from 47 orthopteran mitochondrial genomes (mitogenomes). The phylogenetic signals in the mitogenomes were rigorously examined under analytical regimens of maximum likelihood (ML) and Bayesian inference (BI), along with how gene types and different partitioning schemes influenced the phylogenetic reconstruction within the Orthoptera. The monophyly of the Orthoptera and its two suborders (Caelifera and Ensifera) was consistently recovered in the analyses based on most of the datasets we selected, regardless of the optimality criteria. Results When the seven NADH dehydrogenase subunits were concatenated into a single alignment (NADH) and were analyzed; a near-identical topology to the traditional morphological analysis was recovered, especially for BI_NADH. In both the concatenated cytochrome oxidase (COX) subunits and COX + cytochrome b (Cyt b) datasets, the small extent of sequence divergence seemed to be helpful for resolving relationships among major Orthoptera lineages (between suborders or among superfamilies). The conserved and variable domains of ribosomal (r)RNAs performed poorly when respectively analyzed but provided signals at some taxonomic levels. Conclusions Our findings suggest that the best phylogenetic inferences can be made when moderately divergent nucleotide data from mitogenomes are analyzed, and that the NADH dataset was suited for studying orthopteran phylogenetic relationships at different taxonomic levels, which may have been due to the larger amount of DNA sequence data and the larger number of phylogenetically informative sites.