Toward an insect evolution resolution: Insects are the most diverse group of animals, with the largest number of species. However, many of the evolutionary relationships between insect species have been controversial and difficult to resolve. Misofet al.performed a phylogenomic analysis of protein-coding genes from all major insect orders and close relatives, resolving the placement of taxa. The authors used this resolved phylogenetic tree together with fossil analysis to date the origin of insects to ~479 million years ago and to resolve long-controversial subjects in insect phylogeny.Science, this issue p.763

Phylogenetic relationships among subgroups of cockroaches and termites are still matters of debate. Their divergence times and major phenotypic transitions during evolution are also not yet settled. We addressed these points by combining the first nuclear phylogenomic study of termites and cockroaches with a thorough approach to divergence time analysis, identification of endosymbionts, and reconstruction of ancestral morphological traits and behaviour. Analyses of the phylogenetic relationships within Blattodea robustly confirm previously uncertain hypotheses such as the sister-group relationship between Blaberoidea and remaining Blattodea, andLamproblattabeing the closest relative to the social and wood-feedingCryptocercusand termites. Consequently, we propose new names for various clades in Blattodea:Cryptocercus+ termites = Tutricablattae; Lamproblattidae + Tutricablattae = Kittrickea; and Blattoidea + Corydioidea = Solumblattodea. Our inferred divergence times contradict previous studies by showing that most subgroups of Blattodea evolved in the Cretaceous, reducing the gap between molecular estimates of divergence times and the fossil record. On a phenotypic level, the blattodean ground-plan is for egg packages to be laid directly in a hole while other forms of oviposition, including ovovivipary and vivipary, arose later. Finally, other changes in egg care strategy may have allowed for the adaptation of nest building and other novelties.

Viruses with circular ssDNA genomes that encode a replication initiator protein (Rep) are among the smallest viruses known to infect both eukaryotic and prokaryotic organisms. In the past few years an overwhelming diversity of novel circular Rep-encoding ssDNA (CRESS-DNA) viruses has been unearthed from various hosts and environmental sources. Since there is limited information regarding CRESS-DNA viruses in invertebrates, this study explored the diversity of CRESS-DNA viruses circulating among insect populations by targeting dragonflies (Epiprocta), top insect predators that accumulate viruses from their insect prey over space and time. Using degenerate PCR and rolling circle amplification coupled with restriction digestion, 17 CRESS-DNA viral genomes were recovered from eight different dragonfly species collected in tropical and temperate regions. Nine of the genomes are similar to cycloviruses and represent five species within this genus, suggesting that cycloviruses are commonly associated with insects. Three of the CRESS-DNA viruses share conserved genomic features with recently described viruses similar to the mycovirus Sclerotinia sclerotiorum hypovirulence-associated DNA virus 1, leading to the proposal of the genus Gemycircularvirus. The remaining viruses are divergent species representing four novel CRESS-DNA viral genera, including a gokushovirus-like prokaryotic virus (microphage) and three eukaryotic viruses with Reps similar to circoviruses. The novelty of CRESS-DNA viruses identified in dragonflies using simple molecular techniques indicates that there is an unprecedented diversity of ssDNA viruses among insect populations.

We present a supermatrix approach to the phylogeny of Insecta that stemmed from a talk given at the 2nd Dresden Meeting on Insect Phylogeny (2005). The data included a fragment of the 28S (D1–D8) and complete sequences for the 18S, histone (H3), EF-1α, COI, COII, the 12S and 16S plus the intervening tRNA, and 170 morphological characters. Ribosomal RNA sequences were manually aligned to secondary structure. Two separate Bayesian likelihood analyses were performed, as well as a weighted parsimony analysis, on combined data. Partitioned datasets were also explored. Expected clades like Hexapoda, Insecta, Dicondylia, Pterygota, Neoptera, Dictyoptera, Paraneoptera, and Endopterygota were consistently recovered. However, conflicting hypotheses from independent datasets, as well as a lack of quantitative support from the combined supermatrix, suggest that the elucidation of relationships between non-holometabolous neopteran orders is far from resolved. Substitution rate heterogeneity among lineages, missing intermediate taxa, near simultaneous divergences, flawed phylogenetic models and nucleotide compositional bias are discussed as possible causes for unresolved interordinal relationships. The capacity of this dataset to convey information, its inherent limitations, and the role and responsibility of the systematist in interpreting data are explored

Among terrestrial arthropods, the dragonfly species Pantala flavescens is remarkable due to their nearly global distribution and extensive migratory ranges; the largest of any known insect. Capable of migrating across oceans, the potential for high rates of gene flow among geographically distant populations is significant. It has been hypothesized that P. flavescens may be a global panmictic population but no sufficient genetic evidence has been collected thus far. Through a population genetic analysis of P. flavescens samples from North America, South America, and Asia, the current study aimed to examine the extent at which gene flow is occurring on a global scale and discusses the implications of the genetic patterns we uncovered on population structure and genetic diversity of the species. This was accomplished using PCR-amplified cytochrome oxidase one (CO1) mitochondrial DNA data to reconstruct phylogenetic trees, a haplotype network, and perform molecular variance analyses. Our results suggested high rates of gene flow are occurring among all included geographic regions; providing the first significant evidence that Pantala flavescens should be considered a global panmictic population.