Mixture or mosaic? Genetic patterns in UK grey squirrels support a human-mediated ‘long-jump’ invasion mechanism

Aim Clarifying whether multiple introductions of a species remain relatively isolated or merge and interbreed is essential for understanding the dynamics of invasion processes. Multiple introductions from different sources can result in a mixture of genetically distinct populations, increasing the total genetic diversity. This mixing can resolve the ‘genetic paradox’, whereby in spite of the relatively small numbers of introduced individuals, the augmented diversity due to this mixing increases adaptability and the ability of the species to spread in new environments. Here, we aim to assess whether the expansion of a successful invader, the Eastern grey squirrel, was partly driven by the merger of multiple introductions and the effects of such a merger on diversity. Location UK, Ireland. Methods We analysed the genetic variation at 12 microsatellite loci of 381 individuals sampled from one historical and 14 modern populations of grey squirrels. Results Our data revealed that current UK population structure resembles a mosaic, with minimal interpopulation mixing and each element reflecting the genetic make-up of historic introductions. The genetic diversity of each examined population was lower than a US population or a historical UK population. Numbers of releases in a county did not correlate with county-level genetic diversity. Inbreeding coefficients remain high, and effective population sizes remain small. Main conclusions Our results support the conclusion that rapid and large-scale expansion in this species in the UK was not driven by a genetic mixing of multiple introduced populations with a single expansion front, but was promoted by repeated translocations of small propagules. Our results have implications for the management of grey squirrels and other invasive species and also demonstrate how invaders can overcome the genetic paradox, if spread is facilitated by human-mediated dispersal

Immune interactions and heterogeneity in transmission drives the pathogen-mediated invasion of grey squirrels in the UK

Mathematical models highlighted the importance of pathogen-mediated invasion, with the replacement of red squirrels by squirrelpox virus (SQPV) carrying grey squirrels in the UK, a well-known example. In this study, we combine new epidemiological models, with a range of infection characteristics, with recent longitudinal field and experimental studies on the SQPV dynamics in red and grey squirrel populations to better infer the mechanistic basis of the disease interaction. A key finding is that a model with either partial immunity or waning immunity and reinfection, where individuals become seropositive on the second exposure to infection, that up to now has been shown in experimental data only, can capture the key aspects of the field study observations. By fitting to SQPV epidemic observations in isolated red squirrel populations, we can infer that SQPV transmission between red squirrels is significantly (4×) higher than the transmission between grey squirrels and as a result our model shows that disease-mediated replacement of red squirrels by greys is considerably more rapid than replacement in the absence of SQPV. Our findings recover the key results of the previous model studies, which highlights the value of simple strategic models that are appropriate when there are limited data, but also emphasise the likely complexity of immune interactions in wildlife disease and how models can help infer disease processes from field data.</p

Seguimiento de poblaciones con baja densidad: una perspectiva de qué nivel de declive poblacional podemos detectar con certeza

Monitoring of mammal species is an important part in detecting changes in their status. Efforts are based on a variety of direct and indirect methods and many low density populations are monitored through field signs. We present data on the endangered European red squirrel from Kidland Forest in the UK. We used cone transects to both record changes in seed availability and to monitor population trends. We examined the difficulty of accurately detecting population change when populations are low and field signs are patchily distributed. Current efforts would be sufficient to detect significant population declines of 50–75% in years with a modest squirrel population but not when they fall below one squirrel for every 20 ha of forest. The findings emphasise that monitoring aims have to be clearly defined with an awareness and understanding of what level of change the adopted methodological approach can reliably detect. We propose that mammal monitoring schemes need to be based on a pilot scheme to determine effect size and planned accordingly. Key words: Squirrel, Sciurus vulgaris, Conservation, Power analysis.El seguimiento de las especies de mamíferos es una parte importante de la detección de los cambios producidos en su estatus. Los esfuerzos van dirigidos hacia diversos métodos directos e indirectos, y muchas poblaciones que presentan una densidad baja se monitorizan mediante rastros o signos de campo. En este trabajo presentamos datos de una especie en peligro, la ardilla roja, del bosque de Kidland en el Reino Unido. Se realizaron transectos de detección de piñas o conos para registrar tanto los cambios en la disponibilidad de semillas como para monitorizar las tendencias de la población. Examinamos la dificultad que presenta detectar con precisión los cambios poblacionales, cuando las poblaciones son pequeñas y los restos alimentarios de presencia están distribuidos de forma desigual. Los esfuerzos normales deberían ser suficientes para detectar disminuciones poblacionales significativas del 50–75% en años con una población de ardillas modesta, pero no cuando la densidad está por debajo de una ardilla cada 20 ha de bosque. Nuestros hallazgos enfatizan que los esfuerzos de seguimiento deben estar claramente definidos, con el conocimiento y la comprensión de qué nivel de cambio puede realmente detectar de forma fiable el enfoque metodológico adoptado. Proponemos que los seguimientos de mamíferos deben estar basados en un esquema piloto, con el fin de determinar el efecto del tamaño, y ser planificados consecuentemente. Palabras clave: Ardilla, Sciurus vulgaris, Conservación, Análisis de potencia

Sarcopenia in Children With End-Stage Liver Disease on the Transplant Waiting List

Sarcopenia predicts morbidity and mortality in adults with end-stage liver disease (ESLD) and is determined by total psoas muscle area (tPMA) measurement from computed tomography (CT) imaging. Recently developed pediatric age- and sex-specific tPMA growth curves provide the opportunity to ascertain prevalence and impact of sarcopenia in children awaiting liver transplantation (LT). This retrospective single-center study evaluated sarcopenia in children between 1 and 16 years with ESLD and a clinically indicated abdominal CT less than 3 months before first isolated LT. Sarcopenia was defined as tPMA z score less than −2 measured at the intervertebral L4-5 level. Patient demographic, biochemical, and outcome data were recorded. tPMA was compared with other measures of nutritional status using univariate and multivariate logistic analyses. Outcome measures included 1-year morbidity events and mortality after LT. CT images from 25 (64% female) children with median age of 5.50 (interquartile range [IQR], 3.75-11.33) years were reviewed. Ten children (40%) had a tPMA z score less than −2. Sarcopenia was associated with lower z scores for weight (odds ratio [OR], 0.38; P = 0.02), height (OR, 0.32; P = 0.03), and nutritional support before LT (OR, 12.93; P = 0.01). Sarcopenic children had a longer duration of pediatric intensive care unit (PICU) stay (3.50 [IQR, 3.00-6.00] versus 2.00 [IQR, 2.00-3.50] days; P = 0.03). Sarcopenia was prevalent in 40% of children with ESLD awaiting LT, and lower tPMA z score was associated with deficient anthropometrics and need for nutritional support before LT. Post-LT PICU duration was increased in children with sarcopenia, reflecting adverse outcomes associated with muscle loss. Further studies are needed to elucidate the underlying mechanisms of sarcopenia in children with ESLD

Implications of squirrelpox virus for successful red squirrel translocations within mainland UK

Remnant red squirrel populations in the UK mainland are threatened by squirrelpox viral disease and the reservoir of the squirrelpox virus, the invasive grey squirrel, is expanding its range. Until this threat can be effectively mitigated, there is a high risk from disease outbreaks, following proposed conservation translocation of red squirrels

Spongiibacter marinus gen. nov., sp. nov., a halophilic marine bacterium isolated from the boreal sponge Haliclona sp. 1

Strain HAL40bT was isolated from the marine sponge Haliclona sp. 1 collected at the Sula Ridge off the Norwegian coast and characterized by physiological, biochemical and phylogenetic analyses. The isolate was a small rod with a polar flagellum. It was aerobic, Gram-negative and oxidase- and catalase-positive. Optimal growth was observed at 20–30 °C, pH 7–9 and in 3 % NaCl. Substrate utilization tests were positive for arabinose, Tween 40 and Tween 80. Enzyme tests were positive for alkaline phosphatase, esterase lipase (C8), leucine arylamidase, acid phosphatase, naphthol-AS-BI-phosphohydrolase and N-acetyl-β-glucosaminidase. The predominant cellular fatty acid was C17 : 1 ω8, followed by C17 : 0 and C18 : 1 ω7. Analysis by matrix-assisted laser desorption/ionization time-of-flight MS was used to characterize the strain, producing a characteristic low-molecular-mass protein pattern that could be used as a fingerprint for identification of members of this species. The DNA G+C content was 69.1 mol%. Phylogenetic analysis supported by 16S rRNA gene sequence comparison classified the strain as a member of the class Gammaproteobacteria. Strain HAL40bT was only distantly related to other marine bacteria including Neptunomonas naphthovorans and Marinobacter daepoensis (type strain sequence similarity >90 %). Based on its phenotypic, physiological and phylogenetic characteristics, it is proposed that the strain should be placed into a new genus as a representative of a novel species, Spongiibacter marinus gen. nov., sp. nov.; the type strain of Spongiibacter marinus is HAL40bT (=DSM 17750T =CCUG 54896T)

Long-Term US Industrial Energy Use and CO2 Emissions

We present a description and scenario results from our recently-developed long-term model of United States industrial sector energy consumption, which we have incorporated as a module within the ObjECTS-MiniCAM integrated assessment model. This new industrial model focuses on energy technology and fuel choices over a 100 year period and allows examination of the industrial sector response to climate policies within a global modeling framework. A key challenge was to define a level of aggregation that would be able to represent the dynamics of industrial energy demand responses to prices and policies, but at a level that remains tractable over a long time frame. In our initial results, we find that electrification is an important response to a climate policy, although there are services where there are practical and economic limits to electrification, and the ability to switch to a low-carbon fuel becomes key. Cogeneration of heat and power using biomass may also play a role in reducing carbon emissions under a policy constraint

The even darker side of the eastern gray squirrel (Sciurus carolinensis): a review of global introductions, invasion biology, and pest management strategies

Huynh, H.M., Bertolino, S., Lurz, P.W.W., Koprowski, J.L., Williams, G.R., Thompson, C.W., McAlpine, D.F