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Background The Hemiptera (aphids, cicadas, and true bugs) are a key insect order, with high diversity for feeding ecology and excellent experimental tractability for molecular genetics. Building upon recent sequencing of hemipteran pests such as phloem-feeding aphids and blood-feeding bed bugs, we present the genome sequence and comparative analyses centered on the milkweed bug Oncopeltus fasciatus , a seed feeder of the family Lygaeidae. Results The 926-Mb Oncopeltus genome is well represented by the current assembly and official gene set. We use our genomic and RNA-seq data not only to characterize the protein-coding gene repertoire and perform isoform-specific RNAi, but also to elucidate patterns of molecular evolution and physiology. We find ongoing, lineage-specific expansion and diversification of repressive C2H2 zinc finger proteins. The discovery of intron gain and turnover specific to the Hemiptera also prompted the evaluation of lineage and genome size as predictors of gene structure evolution. Furthermore, we identify enzymatic gains and losses that correlate with feeding biology, particularly for reductions associated with derived, fluid nutrition feeding. Conclusions With the milkweed bug, we now have a critical mass of sequenced species for a hemimetabolous insect order and close outgroup to the Holometabola, substantially improving the diversity of insect genomics. We thereby define commonalities among the Hemiptera and delve into how hemipteran genomes reflect distinct feeding ecologies. Given Oncopeltus ’s strength as an experimental model, these new sequence resources bolster the foundation for molecular research and highlight technical considerations for the analysis of medium-sized invertebrate genomes.

Offshore environments are increasingly invaded by man-made structures that form hard-substrate habitats for many marine species. Examples include oil and gas platforms, wind turbines and shipwrecks. One of the hypothesised effects is an increased genetic connectivity among natural populations due to new populations growing on man-made structures that may act as stepping stones. However, few data are available on genetic connectivity among organisms inhabiting artificial offshore structures. Here, we present a study on the common fouling amphipod Jassa herdmani from offshore structures in the southern North Sea. Partial mitochondrial DNA sequences (cytochrome-c-oxidase 1, N = 514) were obtained from artificial structures at 17 locations in the southern North Sea, including 13 shipwrecks, 2 wind turbines and 2 platforms. Samples from these locations were significantly differentiated, meaning that strong population structure exists for this species in the area. Levels of intraspecific variation were consistent with stable population sizes. No evidence was found for isolation by distance. Using coalescent simulations, the oldest population subdivision events were estimated to date back to the time the study area was flooded following the Last Glacial Maximum. We therefore tentatively conclude that J. herdmani may have colonised man-made structures from previously existing populations on the sea floor, and that the increase in offshore installations has not led to an overall increase in genetic connectivity for this species.