Minute moss beetles in the Southern Hemisphere: Molecular phylogeny,historical biogeography and habitat shifts (Coleoptera: Hydraenidae)

Minute moss beetles (Hydraenidae) are one of the most speciose and widespread families of aquatic Coleoptera, with an estimated 4000 extant species, found in the majority of aquatic habitats from coastal rock pools to mountain streams and from the Arctic Circle to the Antarctic islands. Molecular phylogenetic works have improved our understanding of the evolutionary history of the megadiverse Hydraena, Limnebius and Ochthebius in recent years, but most genera in the family have not yet been included in any phylogenetic analyses, particularly most of those which are restricted to the Southern Hemisphere. Using a multimarker molecular matrix, sampling over 40% of described species richness and 75% of currently recognized genera, we infer a comprehensive molecular phylogeny of these predominantly Gondwanan Hydraenidae. Whilst the genera we focus on are morphologically diverse, and currently classified across all four hydraenid subfamilies, our phylogenetic analyses suggest that these Gondwanan genera may instead constitute a single clade. As a result of our findings, the African genus Oomtelecopon Perkins syn.n. is shown to nest within Coelometopon Janssens, the New Zealand Homalaena Ordish syn.n. and Podaena Ordish syn.n. are synonymised with Orchymontia Broun, and the South African Pterosthetops Perkins syn.n. is synonymised with Prosthetops Waterhouse, resulting in Pterosthetopini Perkins syn.n. being synonymised with Prosthetopini Perkins. Mesoceratops Bilton & Jäch gen.n. is erected to accommodate six former members of Mesoceration Janssens, which is shown to be polyphyletic. We propose the replacement name Orchymontia ordishi Jäch & Bilton nom.n. for Homalaena dilatata Ordish, 1984 (now a junior homonym); altogether 39 new combinations are proposed. Our Bayesian divergence times infer an origin for this ‘Gondwana group’ of genera in Africa plus Madagascar in the mid-Cretaceous and suggest that both vicariant and dispersal processes, together with extinctions, have shaped the biogeographic history of these beetles in the Southern Hemisphere during the Cretaceous, resulting in geographically conserved extant lineages. Finally, we reconstruct ancestral habitat shifts across our phylogeny, revealing numerous changes in habitat occupancy in these genera, including multiple origins of fully terrestrial, humicolous taxa in different regions.     

Using genotyping‐by‐sequencing to predict gender in animals

Gender assignment errors are common in some animal species and lead to inaccuracies in downstream analyses. Procedures for detecting gender misassignment are available for array‐based SNP data but are still being developed for genotyping‐by‐sequencing (GBS) data. In this study, we describe a method for using GBS data to predict gender using X and Y chromosomal SNPs. From a set of 1286 X chromosomal and 23 Y chromosomal deer (Cervus sp.) SNPs discovered from GBS sequence reads, a prediction model was built using a training dataset of 422 Red deer and validated using a test dataset of 868 Red deer and Wapiti deer. Prediction was based on the proportion of heterozygous genotypes on the X chromosome and the proportion of non‐missing genotypes on the Y chromosome observed in each individual. The concordance between recorded gender and predicted gender was 98.6% in the training dataset and 99.3% in the test dataset. The model identified five individuals across both datasets with incorrect recorded gender and was unable to predict gender for another five individuals. Overall, our method predicted gender with a high degree of accuracy and could be used for quality control in gender assignment datasets or for assigning gender when unrecorded, provided a suitable reference genome is available.     

Thermal tolerance and geographical range size in the Agabus brunneus group of European diving beetles (Coleoptera: Dytiscidae)

Aim Within clades, most taxa are rare, whilst few are common, a general pattern for which the causes remain poorly understood. Here we investigate the relationship between thermal performance (tolerance and acclimation ability) and the size of a species’ geographical range for an assemblage of four ecologically similar European diving beetles (the Agabus brunneus group) to examine whether thermal physiology relates to latitudinal range extent, and whether Brown’s hypothesis and the environmental variability hypothesis apply to these taxa. Location Europe. Methods In order to determine the species tolerances to either low or high temperatures we measured the lethal thermal limits of adults, previously acclimated at one of two temperatures, by means of thermal ramping experiments (± 1°C min^?1). These measures of upper and lower thermal tolerances (UTT and LTT respectively) were then used to estimate each species’ thermal tolerance range, as total thermal tolerance polygons and marginal UTT and LTT thermal polygons. Results Overall, widespread species have higher UTTs and lower LTTs than restricted ones. Mean upper lethal limits of the Agabus brunneus group (43 to 46°C), are similar to those of insects living at similar latitudes, whilst mean lower lethal limits (?6 to ?9°C) are relatively high, suggesting that this group is not particularly cold‐hardy compared with other mid‐temperate‐latitude insects. Widespread species possess the largest thermal tolerance ranges and have a relatively symmetrical tolerance to both high and low temperatures, when compared with range‐restricted relatives. Over the temperature range employed, adults did not acclimate to either high or low temperatures, contrasting with many insect groups, and suggesting that physiological plasticity has a limited role in shaping distribution. Main conclusions Absolute thermal niche appears to be a good predictor of latitudinal range, supporting both Brown’s hypothesis and the environmental variability hypothesis. Restricted‐range species may be more susceptible to the direct effect of climate change than widespread species, notwithstanding the possibility that even ‘thermally‐hardy’, widespread species may be influenced by the indirect effects of climate change such as reduction in habitat availability in Mediterranean areas.     

Experimental simulation of environmental warming selects against pigmented morphs of land snails

In terrestrial snails, thermal selection acts on shell coloration. However, the biological relevance of small differences in the intensity of shell pigmentation and the associated thermodynamic, physiological, and evolutionary consequences for snail diversity within the course of environmental warming are still insufficiently understood. To relate temperature‐driven internal heating, protein and membrane integrity impairment, escape behavior, place of residence selection, water loss, and mortality, we used experimentally warmed open‐top chambers and field observations with a total of >11,000 naturally or experimentally colored individuals of the highly polymorphic species Theba pisana (O.F. MÜller, 1774). We show that solar radiation in their natural Mediterranean habitat in Southern France poses intensifying thermal stress on increasingly pigmented snails that cannot be compensated for by behavioral responses. Individuals of all morphs acted neither jointly nor actively competed in climbing behavior, but acted similarly regardless of neighbor pigmentation intensity. Consequently, dark morphs progressively suffered from high internal temperatures, oxidative stress, and a breakdown of the chaperone system. Concomitant with increasing water loss, mortality increased with more intense pigmentation under simulated global warming conditions. In parallel with an increase in mean ambient temperature of 1.34°C over the past 30 years, the mortality rate of pigmented individuals in the field is, currently, about 50% higher than that of white morphs. A further increase of 1.12°C, as experimentally simulated in our study, would elevate this rate by another 26%. For 34 T. pisana populations from locations that are up to 2.7°C warmer than our experimental site, we show that both the frequency of pigmented morphs and overall pigmentation intensity decrease with an increase in average summer temperatures. We therefore predict a continuing strong decline in the frequency of pigmented morphs and a decrease in overall pigmentation intensity with ongoing global change in areas with strong solar radiation.     

Genomic structure and expression analysis of the spastic paraplegia gene, SPG7

SPG7 is a newly identified gene involved in an autosomal recessive form of hereditary spastic paraplegia (HSP), a genetically heterogeneous group of neurodegenerative disorders. This gene encodes a protein characterized as a nuclear-encoded mitochondrial metalloprotease. The present report describes the genomic structure of the SPG7 gene. It is organized into 17 exons ranging from 78 to 242 bp and spans approximately 52 kb within three overlapping cosmids. The exon/intron boundaries and all splice junctions are consistent with the published consensus sequences for donor and acceptor sites. The provided genomic structure of SPG7 should facilitate the screening for mutations in this gene in patients with HSP and other related mitochondrial disease syndromes. SPG7 has been mapped to chromosome 16q24.3, a region of frequent loss of heterozygosity (LOH) seen in sporadic breast and prostate cancer. We have performed single-strand conformation polymorphism analysis of ten exons of this gene in a number of sporadic breast cancer samples showing LOH at 16q24.3. No mutations were detected; only single nucleotide polymorphisms were observed in exon 11, intron 7, intron 10 and intron 12. An expression analysis study has revealed the differential expression of SPG7 mRNA in various tissues and at different developmental stages. Electronic Publication     

Laboratory Diagnosis and Characterization of Fungal Disease in Patients with Cystic Fibrosis (CF): A Survey of Current UK Practice in a Cohort of Clinical Microbiology Laboratories

There is much uncertainty as to how fungal disease is diagnosed and characterized in patients with cystic fibrosis (CF). A 19-question anonymous electronic questionnaire was developed and distributed to ascertain current practice in clinical microbiology laboratories providing a fungal laboratory service to CF centres in the UK. Analyses of responses identified the following: (1) current UK laboratory practice, in general, follows the current guidelines, but the scope and diversity of what is currently being delivered by laboratories far exceeds what is detailed in the guidelines; (2) there is a lack of standardization of fungal tests amongst laboratories, outside of the current guidelines; (3) both the UK CF Trust Laboratory Standards for Processing Microbiological Samples from People with Cystic Fibrosis and the US Cumulative Techniques and Procedures in Clinical Microbiology (Cumitech) Guidelines 43 Cystic Fibrosis Microbiology need to be updated to reflect both new methodological innovations, as well as better knowledge of fungal disease pathophysiology in CF; (4) there is a need for clinical medicine to decide upon a stratification strategy for the provision of new fungal assays that will add value to the physician in the optimal management of CF patients; (5) there is also a need to rationale what assays should be performed at local laboratory level and those which are best served at National Mycology Reference Laboratory level; and (6) further research is required in developing laboratory assays, which will help ascertain the clinical importance of ‘old’ fungal pathogens, as well as ‘emerging’ fungal pathogens.