Paraphyletic species no more - genomic data resolve a Pleistocene radiation and validate morphological species of the Melanoplus scudderi complex (Insecta: Orthoptera)

Rapid speciation events, with taxa generated over a short time period, are among the most investigated biological phenomena. However, molecular systematics often reveals contradictory results compared with morphological/phenotypical diagnoses of species under scenarios of recent and rapid diversification. In this study, we used molecular data from an average of over 29- 000 loci per sample from RADseq to reconstruct the diversification history and delimit the species boundary in a short- winged grasshopper species complex (Melanoplus scudderi group), where Pleistocene diversification has been hypothesized to generate more than 20 putative species with distinct male genitalic shapes. We found that, based on a maximum likelihood molecular phylogeny, each morphological species indeed forms a monophyletic group, contrary to the result from a previous mitochondrial DNA sequence study. By dating the diversification events, the species complex is estimated to have diversified during the Late Pleistocene, supporting the recent radiation hypothesis. Furthermore, coalescent- based species delimitation analyses provide quantitative support for independent genetic lineages, which corresponds to the morphologically defined species. Our results also showed that male genitalic shape may not be predicted by evolutionary distance among species, not only indicating that this trait is labile, but also implying that selection may play a role in character divergence. Additionally, our findings suggest that the rapid speciation events in this flightless grasshopper complex might be primarily associated with the fragmentation of their grassland habitats during the Late Pleistocene. Collectively, our study highlights the importance of integrating multiple sources of information to delineate species, especially for a species complex that diversified rapidly, and whose divergence may be linked to ecological processes that create geographic isolation (i.e. fragmented habitats), as well as selection acting on characters with direct consequences for reproductive isolation (i.e. genitalic divergence).Genomic data validate morphological species designations in Melanoplus grasshoppers from the southeastern U.S.A.The difference in male genitalic shape, which is evolutionarily labile, can be a good diagnostic character to distinguish species of recent and rapid diversification origin.Fragmentation of grassland habitats in the Late Pleistocene might have facilitated rapid speciation events in the flightless Melanoplus grasshoppers.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/155980/1/syen12415-sup-0001-SupInfo.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155980/2/syen12415_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/155980/3/syen12415.pd

Paraphyletic species no more – genomic data resolve a Pleistocene radiation and validate morphological species of the Melanoplus scudderi complex (Insecta: Orthoptera)

Rapid speciation events, with taxa generated over a short time period, are among the most investigated biological phenomena. However, molecular systematics often reveals contradictory results compared with morphological/phenotypical diagnoses of species under scenarios of recent and rapid diversification. In this study, we used molecular data from an average of over 29 000 loci per sample from RADseq to reconstruct the diversification history and delimit the species boundary in a short-winged grasshopper species complex (Melanoplus scudderi group), where Pleistocene diversification has been hypothesized to generate more than 20 putative species with distinct male genitalic shapes. We found that, based on a maximum likelihood molecular phylogeny, each morphological species indeed forms a monophyletic group, contrary to the result from a previous mitochondrial DNA sequence study. By dating the diversification events, the species complex is estimated to have diversified during the Late Pleistocene, supporting the recent radiation hypothesis. Furthermore, coalescent-based species delimitation analyses provide quantitative support for independent genetic lineages, which corresponds to the morphologically defined species. Our results also showed that male genitalic shape may not be predicted by evolutionary distance among species, not only indicating that this trait is labile, but also implying that selection may play a role in character divergence. Additionally, our findings suggest that the rapid speciation events in this flightless grasshopper complex might be primarily associated with the fragmentation of their grassland habitats during the Late Pleistocene. Collectively, our study highlights the importance of integrating multiple sources of information to delineate species, especially for a species complex that diversified rapidly, and whose divergence may be linked to ecological processes that create geographic isolation (i.e. fragmented habitats), as well as selection acting on characters with direct consequences for reproductive isolation (i.e. genitalic divergence).This research was funded by the National Science Foundation (NSF DEB 16‐55607, to LLK), a grant from the Orthopterists' Society (to JGH), the National Institute of Food and Agriculture, and the Hubbell Orthopteran Research Endowment, Museum of Zoology, University of Michigan. JO's research visit to the University of Michigan was funded by a fellowship from the University of Castilla‐La Mancha

Molecular phylogeny and taxonomic synopsis of the angraecoid genus Ypsilopus (Orchidaceae, Vandeae)

Previous phylogenetic analyses focused on angraecoid orchids suggested that the genus Ypsilopus was paraphyletic and that some species of Tridactyle and Rangaeris belong to a clade that included Ypsilopus. These studies, based on three to four genes, sampled few taxa in each genus, and did not include the type of Rangaeris, nor did they take morphological variation into account. To delineate Ypsilopus more precisely, we reconstructed phylogenetic relationships of the genus and seven other closely related genera by analysing sequence variation at the nuclear ribosomal internal transcribed spacer (ITS‐1) and at five plastid markers (matK, rps16, trnC‐petN intergenic spacer, trnL‐trnF intergenic spacer, ycf1), from 42 specimens representing 36 taxa. Trees based on maximum likelihood and Bayesian inference confirm that two species of Tridactyle are nested with three Ypsilopus species, including the type of the latter, and two species of Rangaeris are grouped with this clade. Moreover, we examined morphological variation among all species belonging to these three genera, highlighting morphological features that characterize Ypsilopus, and we used these data to assign the two species of Tridactyle included in the molecular analyses, three other species of Tridactyle not included in the molecular analyses and two species of Rangaeris to Ypsilopus. New combinations for Tridactyle citrina, T. furcistipes, T. sarcodantha, T. tanneri, T. tricuspis, Rangaeris amaniensis and R. schliebenii in Ypsilopus are thus proposed, and one new section (i.e., Ypsilopus sect. Barombiella) is described. Keys to the species of Ypsilopus and closely related genera are provided, along with a table of characters that can be used to differentiate these species