300 million years of diversification: elucidating the patterns of orthopteran evolution based on comprehensive taxon and gene sampling.

Orthoptera is the most diverse order among the polyneopteran groups and includes familiar insects, such as grasshoppers, crickets, katydids, and their kin. Due to a long history of conflicting classification schemes based on different interpretations of morphological characters, the phylogenetic relationships within Orthoptera are poorly understood and its higher classification has remained unstable. In this study, we establish a robust phylogeny of Orthoptera including 36 of 40 families representing all 15 currently recognized superfamilies and based on complete mitochondrial genomes and four nuclear loci, in order to test previous phylogenetic hypotheses and to provide a framework for a natural classification and a reference for studying the pattern of divergence and diversification. We find strong support for monophyletic suborders (Ensifera and Caelifera) as well as major superfamilies. Our results corroborate most of the higher-level relationships previously proposed for Caelifera, but suggest some novel relationships for Ensifera. Using fossil calibrations, we provide divergence time estimates for major orthopteran lineages and show that the current diversity has been shaped by dynamic shifts of diversification rates at different geological times across different lineages. We also show that mitochondrial tRNA gene orders have been relatively stable throughout the evolutionary history of Orthoptera, but a major tRNA gene rearrangement occurred in the common ancestor of Tetrigoidea and Acridomorpha, thereby representing a robust molecular synapomorphy, which has persisted for 250 Myr.

Inside the Melanoplinae: new molecular evidence for the evolutionary history of the Eurasian Podismini (Orthoptera: Acrididae).

The Podismini are melanopline grasshoppers with a Holarctic distribution and well represented in the Eurasian fauna. To investigate their controversial taxonomy and evolutionary history, we studied 86%, 78% and 33% respectively of the Eurasian, European and Asian Palaearctic genera (Otte, 1995; Eades et al., 2013). We reconstructed parsimony, maximum likelihood and Bayesian phylogenies using fragments of four genes (ITS1, 16S, 12S, CO2). We applied a Bayesian molecular clock to estimate the times of species divergence, and the event-based parsimony method to depict the biogeographic framework of the diversification. Our results suggest that the selected Eurasian Podismini constitute a monophyletic group inside the Melanoplinae, provided it includes the North American genus Phaulotettix. The clades proposed by the present study inside the Podismini do not fit the older morphological or cytological classifications, but are in agreement with more recent proposals. Furthermore, our results can be explained by a plausible biogeographic history in which the present geographical distribution of the Eurasian Podismini resulted from known changes, to the Cenozoic climate and vegetation, induced by major geological events including the genesis of high mountain chains (e.g., Himalayas, Altay, Alps) and large deserts (e.g., Gobi, Karakoum, Taklamakan), and the opening of marginal seas (e.g., Bering, Japanese and Yellow Seas).

Evolutionary history and taxonomy of a short-horned grasshopper subfamily: the Melanoplinae (Orthoptera: Acrididae).

The Melanoplinae is one of the largest subfamilies of the Acrididae grasshoppers, with a Holarctic-Neotropical distribution. To investigate its controversial taxonomy and evolutionary history, we studied 19 species representative of its main tribes, and 7 Acridoidea outgroup species. More than 1650 base pairs of three regions of nuclear rDNA (18S, ITS1, 28S) and one mitochondrial rDNA (12S) were combined and used to construct parsimony, maximum likelihood and Bayesian phylogenies. Our results correspond with the present geographical distribution of the taxa rather than the existing taxonomy based on morphological characters. The morphologically unclassified and atypical taxa group with the Neotropical Melanoplinae. The currently recognized Melanoplinae appear to be polyphyletic due to inclusion of the Mexican genus Netrosoma. The distribution of the American and Eurasiatic Melanoplinae fauna can be explained by climatic and geological events, such as the Andean uplift, that would have affected the diversification and migration of Neotropical taxa.

Molecular taxonomy and species delimitation in Andean Schistocerca (Orthoptera: Acrididae).

The acridian genus Schistocerca comprises about 50 species which are endemic to the New World, except the Old World locust S. gregaria. Their morphological identification is rendered difficult by phase polyphenism, geographical overlap due to migrations or swarming, the difficulty to easily differentiate genitalia and the occurrence of interspecific hybrids. The three species reported from Peru include the swarming species S. interrita, a pest that can be recognized only by taxonomists. We show that it can be unambiguously identified using a mitochondrial DNA fragment known to have barcoding properties in this genus. We used several methods to delimitate Peruvian species. While S. interrita and S. pallens were well characterized, S. piceifrons peruviana was split into several taxa by a phylogeny-based method, whereas a combination of population genetics methods led one to identify only the three nominal species. A tentative reconstruction of the species history shows that several populations of S. piceifrons peruviana have recently increased in number, while exchanging some migrants, whereas an isolated population at the northern margin of the species range is substantially differentiated while exchanging no migrants with the others. This complex history has resulted in an atypical lineage pattern that appears to have confounded the standard assumptions underlying available species delimitation methods. Because of its behavioral property which tends to keep it panmictic, the identification of the swarming S. interrita remained unaffected.