The use of fumigants and anticoagulant rodenticides on game estates in Great Britain

Several studies have highlighted the potential risk to nontarget wildlife associated with accidental exposure to vertebrate control agents. In order to provide information that may assist in the mitigation of this problem, we questioned 215 gamekeepers in Great Britain about the use of vertebrate control agents on the land for which they were responsible. Fumigants were used to control Rabbits Oryctolagus cuniculus by 59% of gamekeepers. Use of fumigants was more common than on farms in general. 91% of gamekeepers reported the use of rodenticides, 95% of which were anticoagulants. Patterns of rodenticide use were similar to those on arable farms, though chlorophacinone and warfarin were used more commonly on game estates. Future studies of the exposure of nontarget wildlife to anticoagulants should be expanded to include these compounds. Rodenticides were apparently used in accordance with label recommendations in most cases. However, better information and guidelines for users may improve standards of agent application and reduce potential risks to nontarget wildlife.     

Phylogenetic analysis of five medically important Candida species as deduced on the basis of small ribosomal subunit RNA sequences.

The classification of species belonging to the genus Candida Berkhout is problematic. Therefore, we have determined the small ribosomal subunit RNA (srRNA) sequences of the type strains of three human pathogenic Candida species; Candida krusei, C. lusitaniae and C. tropicalis. The srRNA sequences were aligned with published eukaryotic srRNA sequences and evolutionary trees were inferred using a matrix optimization method. An evolutionary tree comprising all available eukaryotic srRNA sequences, including two other pathogenic Candida species, C. albicans and C. glabrata, showed that the yeasts diverge rather late in the course of eukaryote evolution, namely at the same depth as green plants, ciliates and some smaller taxa. The cluster of the higher fungi consists of 10 ascomycetes and ascomycete-like species with the first branches leading to Neurospora crassa, Pneumocystis carinii, Candida lusitaniae and C. krusei, in that order. Next there is a dichotomous divergence leading to a group consisting of Torulaspora delbrueckii, Saccharomyces cerevisiae, C. glabrata and Kluyveromyces lactis and a smaller group comprising C. tropicalis and C. albicans. The divergence pattern obtained on the basis of srRNA sequence data is also compared to various other chemotaxonomic data.     

TDFCAM: A method for estimating stable isotope trophic discrimination in wild populations

1. Stable isotope mixing models (SIMMs) are widely used for characterizing wild animal diets. Such models rely upon using accurate trophic discrimination factors (TDFs) to account for the digestion, incorporation, and assimilation of food. Existing methods to calculate TDFs rely on controlled feeding trials that are time-consuming, often impractical for the study taxon, and may not reflect natural variability of TDFs present in wild populations.
2. We present TDF_CAM as an alternative approach to estimating TDFs in wild populations, by using high-precision diet estimates from a secondary methodological source—in this case nest cameras—in lieu of controlled feeding trials, and provide a framework for how and when it should be applied.
3. In this study, we evaluate the TDF_CAM approach in three datasets gathered on wild raptor nestlings (gyrfalcons Falco rusticolus; peregrine falcons Falco perigrinus; common buzzards Buteo buteo) comprising contemporaneous δ¹³C & δ¹⁵N stable isotope data and high-quality nest camera dietary data. We formulate Bayesian SIMMs (BSIMMs) incorporating TDFs from TDF_CAM and analyze their agreement with nest camera data, comparing model performance with those based on other relevant TDFs. Additionally, we perform sensitivity analyses to characterize TDF_CAM variability, and identify ecological and physiological factors contributing to that variability in wild populations.
4. Across species and tissue types, BSIMMs incorporating a TDF_CAM outperformed any other TDF tested, producing reliable population-level estimates of diet composition. We demonstrate that applying this approach even with a relatively low sample size (n < 10 individuals) produced more accurate estimates of trophic discrimination than a controlled feeding study conducted on the same species. Between-individual variability in TDF_CAM estimates for ∆¹³C & ∆¹⁵ N increased with analytical imprecision in the source dietary data (nest cameras) but was also explained by natural variables in the study population (e.g., nestling nutritional/growth status and dietary composition).
5. TDF_CAM is an effective method of estimating trophic discrimination in wild animal populations. Here, we use nest cameras as source dietary data, but this approach is applicable to any high-accuracy method of measuring diet, so long as diet can be monitored over an interval contemporaneous with a tissue's isotopic turnover rate.

     

Impacts of climate change on the global potential distribution of two notorious invasive crayfishes

1. Invasive alien species and climate change are two of the most serious global environmental threats. In particular, it is of great interest to understand how changing climates could impact the distribution of invaders that pose serious threats to ecosystems and human activities.
2. In this study, we developed ensemble species distribution models for predicting the current and future global distribution of the signal crayfish Pacifastacus leniusculus and the red swamp crayfish Procambarus clarkii, two of the most highly problematic invaders of freshwater ecosystems worldwide. We collected occurrence records of the species, from native and alien established ranges worldwide. These records in combination with averaged observations of current climatic conditions were used to calibrate a set of 10 distinct correlative models for estimating the climatic niche of each species. We next projected the estimated niches into the geographical space for the current climate conditions and for the 2050s and 2070s under representative concentration pathway 2.6 and 8.5 scenarios.
3. Our species distribution models had high predictive abilities and suggest that annual mean temperature is the main driver of the distribution of both species. Model predictions indicated that the two crayfish species have not fully occupied their suitable climates and will respond differently to future climate scenarios in different geographic regions. Suitable climate for P. leniusculus was predicted to shift poleward and to increase in extent in North America and Europe but decrease in Asia. Regions with suitable climate for P. clarkii are predicted to widen in Europe but contract in North America and Asia.
4. This study highlights that invasive species with different thermal preference are likely to respond differently to future climate changes. Our results provide important information for policy makers to design and implement anticipated measures for the prevention and control of these two problematic species.