The distribution of arthropod species on a 400 m elevational gradient (equivalent to a temperature decrease of 2.5°C) on Snowdon, North Wales, was examined and compared with the British distribution. Preferred temperature, an indication of optimal body temperature (Tb), and supercooling point (SCP), an indication of cold tolerance, of several species on the gradient were determined experimentally. The alpine beetle species Patrobus assimilis and Nebria rufescens had low preferred Tb, of 5.6 and 7.1°C respectively, whereas the more widespread upland species had higher preferred Tb, between 12.9 and 15.5°C. The SCP of both alpine and widespread beetles were similar, being between -6.9 and -5.8°C. The alpine species, which were smaller, were freeze intolerant, whereas the widespread species, which were larger, were freeze tolerant. On the national scale there was significant correlation between preferred Tb and species elevation, but no correlation with SCP. It is concluded that the alpine species survive on Snowdon because their optimal Tb is close to the ambient temperature at the time of day and year when they are active and because they are able to tolerate winter temperatures, by a combination of cold tolerance and shelter. Although a species' optimal niche will tend to shift upwards as mean temperatures rise with global climatic change, complex microclimatic and biotic factors make changes in distribution difficult to predict.
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.