The diversity and role of the gut microbiota of insects is a rapidly growing field of entomology, primarily fueled by new metagenomic techniques. Whereas endosymbionts in the guts of xylophagous or herbivorous insects are well studied, the microbiomes in moss-eating (bryophagous) insects remain uncharacterized. Using the Illumina MiSeq platform, we determined the composition of microbiomes in the gut, abdomen and on the body surface of two bryophagous species: Simplocaria semistriata (Fabricius, 1794) and Curimopsis paleata (Erichson, 1846) (Coleoptera: Byrrhidae). Gut microbiomes differed substantially from abdominal microbiomes in the same individuals, which indicates the need to separate them during dissection. Microbiomes in the gut and abdomen differed markedly from surface microbial assemblages. Gut microbiomes in bryophages had the highest MOTU richness, diversity and relative rarity. The eudominant bacteria in the guts and abdomens of bryophages were Novosphingobium, Bradyrhizobium, Ralstonia and Caulobacter, which are responsible for the detoxification of secondary metabolites or nitrogen fixation. These are less common in the surface samples and, therefore, likely to be associated with the specific ability of bryophages to feed on mosses.
Molecular markers can be used to infer the demographic history of a given species, but many historic processes simultaneously impact multiple species. Thus, comparative historical demography has the potential to provide insight into drivers of evolution. In this study, we used nuclear DNA (nDNA) sequences to corroborate (or refute) demographic inferences based on earlier mitochondrial DNA (mtDNA) data from 16 species of Hispaniola birds. Our previously published analysis suggested population expansion in five of six migratory species (following glacial retreat in North America), with less evidence of expansion in non-migratory species. Additional molecular markers should reduce locus-specific bias, and so we generated sequence data for several nuclear loci. Test statistics associated with the nDNA provided only equivocal evidence for population expansion in 10 of the 16 species. Discordance between mtDNA and nDNA is not uncommon because the two genomes are exposed to different selective pressures and have different effective population sizes and modes of inheritance. The nDNA analyses reported here cast some doubt on our earlier mtDNA inferences. They also suggest that the signal to noise ratio of demographic statistics is typically low because of the inherent variability in selective regimes and coalescence across loci.