A recent global meta‐analysis reported a decrease in terrestrial but increase in freshwater insect abundance and biomass (van Klink et al., Science 368, p. 417). The authors suggested that water quality has been improving, thereby challenging recent reports documenting drastic global declines in freshwater biodiversity. We raise two major concerns with the meta‐analysis and suggest that these account for the discrepancy with the declines reported elsewhere. First, total abundance and biomass alone are poor indicators of the status of freshwater insect assemblages, and the observed differences may well have been driven by the replacement of sensitive species with tolerant ones. Second, many of the datasets poorly represent global trends and reflect responses to local conditions or nonrandom site selection. We conclude that the results of the meta‐analysis should not be considered indicative of an overall improvement in the condition of freshwater ecosystems.This article is categorized under: Water and Life > Conservation, Management, and Awareness

Culicomorpha is a particularly species‐rich clade within Diptera (true flies) that comprises c . 10% of the described diversity, including many medically important flies. Morphological studies – even when all life stages are included – yield relationships different from those derived from molecular data, notably with regard to the position of Chironomidae. Congruence amongst molecular studies has been weak due to limitations in gene‐ and family‐level taxon coverage. Here we use a whole‐transcriptome shotgun phylogenomic approach to clarify the relationships among all families of Culicomorpha. The dataset comprised 30 species (27 ingroup) and 364 888 amino acid residues for 1233 single‐copy protein‐encoding genes. Likelihood and parsimony analyses produce robust and highly congruent phylogenetic trees, with only one node in conflict. The superfamily Culicoidea is well supported and comprises Dixidae + [Corethrellidae + (Chaoboridae + Culicidae)]. As suggested previously, Chironomoidea is not monophyletic. The well supported Thaumaleidae + Simuliidae is sister group to Culicoidea, with the weakly supported Chironomidae + Ceratopogonidae probably being the sister group of all remaining Culicomorpha. We used random addition concatenation analysis (RADICAL) and four‐cluster likelihood mapping (FcLM) to assess the strengths of nodal support. The sister‐group relationship between Chironomidae + Ceratopogonidae is consistent with the FcLM results but support for this relationship emerges only when 1150 of the 1233 loci are analysed. We discuss briefly nodes that remain poorly supported even with thousands of genes and mention problems with vouchering in transcriptomic studies.

A dated molecular phylogeny is proposed for the Tanypodinae, a diverse subfamily of Chironomidae (Diptera). We used molecular data from fragments of one ribosomal gene (28S), one nuclear protein-coding gene (CAD), and one mitochondrial protein-coding gene (COI), analysed using mixed model Bayesian and maximum likelihood inference methods. All proposed tribes were sampled, namely, Anatopyniini, Clinotanypodini, Coelopyniini, Fittkauimyiini, Macropelopiini, Natarsiini, Pentaneurini, Procladiini and Tanypodini. A multilocus dataset of 1938 characters was compiled from 123 individuals including outgroups. Monophyly was supported for all tribes although some relationships were not robust. Relationships between tribes and some genus groups are highly congruent with a morphology-based estimate. Relationships within tribe Pentaneurini mostly find weak support, yet previously hypothesised groupings and monophyly or lack thereof in well-sampled genera are revealed. The tempo of diversification of the family was deduced by divergence time analysis (BEAST). Origination of a subfamily stem group in the late Jurassic to early Cretaceous was inferred, with all tribes and many genera of Pentaneurini originating and diversifying in the Cretaceous. Some nodes are biogeographically informative. Gene sections supported the backbone, but more extensive sampling is needed to estimate shallower phylogenies and to better understand the tempo and diversification of Tanypodinae.