Lost reproductive value reveals a high burden of juvenile road mortality in a long-lived species.

Adult mortality is often the most sensitive vital rate affecting at-risk wildlife populations. Therefore, road ecology studies often focus on adult mortality despite the possibility for roads to be hazardous to juvenile individuals during natal dispersal. Failure to quantify concurrent variation in mortality risk and population sensitivity across demographic states can mislead the efforts to understand and mitigate the effects of population threats. To compare relative population impacts from road mortality among demographic classes, we weighted mortality observations by applying reproductive value analysis to quantify expected stage-specific contributions to population growth. We demonstrate this approach for snapping turtles (Chelydra serpentina) observed on roads at two focal sites in Ontario, Canada, where we collected data for both live and dead individuals observed on roads. We estimated reproductive values using stage-classified matrix models to compare relative population-level impacts of adult and juvenile mortality. Reproductive value analysis is a tractable approach to assessing demographically variable effects for applications covering large spatial scales, nondiscrete populations, or where abundance data are lacking. For one site with long-term life-history data, we compared demographic frequency on roads to expected general population frequencies predicted by the matrix model. Our application of reproductive value is sex specific but, as juvenile snapping turtles lack external secondary sex characters, we estimated the sex ratio of road-crossing juveniles after dissecting and sexing carcasses collected on roads at five sites across central Ontario, Canada. Juveniles were more abundant on roads than expected, suggesting a substantial dispersal contribution, and the road-killed juvenile sex ratio approached 1:1. A higher proportion of juveniles were also found dead compared with adults, and cumulative juvenile mortality had similar population-level importance as adult mortality. This suggests that the impact of roads needs to be considered across all life stages, even in wildlife species with slow life histories, such as snapping turtles, that are particularly sensitive to adult mortality.

Bibliometric investigation of the integration of animal personality in conservation contexts.

Consistent individual differences in behavior, commonly termed animal personality, are a widespread phenomenon across taxa that have important consequences for fitness, natural selection, and trophic interactions. Animal personality research may prove useful in several conservation contexts, but which contexts remains to be determined. We conducted a structured literature review of 654 studies identified by combining search terms for animal personality and various conservation subfields. We scored the relevance of personality and conservation issues for each study to identify which studies meaningfully integrated the 2 fields as opposed to surface-level connections or vague allusions. We found a taxonomic bias toward mammals (29% of all studies). Very few amphibian or reptile studies applied personality research to conservation issues (6% each). Climate change (21%), invasive species (15%), and captive breeding and reintroduction (13%) were the most abundant conservation subfields that occurred in our search, though a substantial proportion of these papers weakly integrated conservation and animal personality (climate change 54%, invasive species 51%, captive breeding and reintroduction 40%). Based on our results, we recommend that researchers strive for consistent and broadly applicable terminology when describing consistent behavioral differences to minimize confusion and improve the searchability of research. We identify several gaps in the literature that appear to be promising and fruitful avenues for future research, such as disease transmission as a function of sociability or exploration as a driver of space use in protected areas. Practitioners can begin informing future conservation efforts with knowledge gained from animal personality research.

Investigación bibliométrica sobre la integración de la personalidad animal a los contextos de conservación Resumen Las diferencias individuales y constantes en el comportamiento, comúnmente llamadas personalidad animal, son un fenómeno generalizado en los taxones con consecuencias importantes para la aptitud, selección natural e interacciones tróficas. Las investigaciones sobre la personalidad animal pueden ser útiles en varios contextos de conservación, aunque falta determinar cuáles son estos contextos. Realizamos una revisión literaria estructurada de 654 estudios identificados mediante la combinación de los términos de búsqueda para la personalidad animal y varios subcampos de la conservación. Puntuamos la relevancia de la personalidad y los temas de conservación en cada estudio para identificar cuáles de estos integraron significativamente a ambos campos, contrario a las conexiones a nivel superficial o alusiones vagas. Descubrimos un sesgo taxonómico por los mamíferos (29% de todos los estudios). Pocos estudios enfocados en anfibios o reptiles aplicaron un estudio de personalidad a los temas de conservación (6% para cada uno). El cambio climático (21%), las especies invasoras (15%) y la reproducción en cautiverio y las reintroducciones (13%) fueron los subcampos de conservación más abundantes que aparecieron en nuestra búsqueda, aunque una proporción significativa de estos artículos integraron muy poco a la conservación y la personalidad animal (cambio climático 54%, especies invasoras 51%, reproducción en cautiverio y reintroducciones 40%). Con base en nuestros resultados, recomendamos que los investigadores procuren tener terminologías consistentes y de aplicación generalizada cuando describan las diferencias conductuales para así minimizar las confusiones y facilitar la búsqueda durante la investigación. Identificamos varios vacíos en la literatura que prometen ser vías fructíferas para las investigaciones en el futuro, como la transmisión de enfermedades como una función sociable o la exploración como un impulsor del uso del espacio en las áreas protegidas. Los practicantes pueden comenzar por guiar los siguientes esfuerzos de conservación con el conocimiento obtenido de las investigaciones sobre la personalidad animal.

Approaches to Assessment of Muscle Mass and Myosteatosis on Computed Tomography: A Systematic Review.

BACKGROUND/OBJECTIVE: There is increasing use of computed tomography (CT) in sarcopenia research using a wide variety of techniques. We performed a systematic review of the CT literature to identify the differences between approaches used. METHODS: A comprehensive search of PubMed from 1983 to 2017 was performed to identify studies that used CT muscle measurements to assess muscle mass and myosteatosis. The CT protocols were evaluated based on anatomic landmark(s), thresholding, muscle(s) segmented, key measurement (ie, muscle attenuation, cross-sectional area, volume), derived variables, and analysis software. From the described search, 657 articles were identified and 388 studies met inclusion criteria for this systematic review. RESULTS: Muscle mass was more commonly assessed than myosteatosis (330 vs. 125). The most commonly assessed muscle or muscle groups were total abdominal wall musculature (142/330 and 49/125 for muscle mass and myosteatosis, respectively) and total thigh musculature (90/330 and 48/125). The most commonly used landmark in the abdomen was the L3 vertebra (123/142 and 45/49 for muscle mass and myosteatosis, respectively). Skeletal muscle index and intermuscular adipose tissue were the most commonly used measures of abdominal wall muscle mass (114/142) and myosteatosis (27/49), respectively. Cut points varied across studies. A significant majority of studies failed to report important CT technical parameters, such as use of intravenous contrast and slice thickness (94% and 63%, respectively). CONCLUSIONS: There is considerable variation in the CT approaches used for the assessment of muscle mass and myosteatosis. There is a need to develop consensus for CT-based evaluation of sarcopenia and myosteatosis.