(Not) far from home: No sex bias in dispersal, but limited genetic patch size, in an endangered species, the Spotted Turtle (Clemmys guttata).

Sex-biased dispersal is common in many animals, with male-biased dispersal often found in studies of mammals and reptiles, including interpretations of spatial genetic structure, ostensibly as a result of male-male competition and a lack of male parental care. Few studies of sex-biased dispersal have been conducted in turtles, but a handful of studies, in saltwater turtles and in terrestrial turtles, have detected male-biased dispersal as expected. We tested for sex-biased dispersal in the endangered freshwater turtle, the spotted turtle (Clemmys guttata) by investigating fine-scale genetic spatial structure of males and females. We found significant spatial genetic structure in both sexes, but the patterns mimicked each other. Both males and females typically had higher than expected relatedness at distances <25 km, and in many distance classes greater than 25 km, less than expected relatedness. Similar patterns were apparent whether we used only loci in Hardy-Weinberg equilibrium (n = 7) or also included loci with potential null alleles (n = 5). We conclude that, contrary to expectations, sex-biased dispersal is not occurring in this species, possibly related to the reverse sexual dimorphism in this species, with females having brighter colors. We did, however, detect significant spatial genetic structure in males and females, separate and combined, showing philopatry within a genetic patch size of <25 km in C. guttata, which is concerning for an endangered species whose populations are often separated by distances greater than the genetic patch size.

Use of standardized methods to improve extinction-risk classification.

Standardized classification methods based on quantifiable risk metrics are critical for evaluating extinction threats because they increase objectivity, consistency, and transparency of listing decisions. Yet, in the United States, neither federal nor state agencies use standardized methods for listing species for legal protection, which could put listing decisions at odds with the magnitude of the risk. We used a recently developed set of quantitative risk metrics for California herpetofauna as a case study to highlight discrepancies in listing decisions made without standardized methods. We also combined such quantitative metrics with classification tree analysis to attempt to increase the transparency of previous listing decisions by identifying the criteria that had inherently been given the most weight. Federally listed herpetofauna in California scored significantly higher on the risk-metric spectrum than those not federally listed, whereas state-listed species did not score any higher than species that were not state listed. Based on classification trees, state endemism was the most important predictor of listing status at the state level and distribution trend (decline in a species' range size) and population trend (decline in a species' abundance at localized sites) were the most important predictors at the federal level. Our results emphasize the need for governing bodies to adopt standardized methods for assessing conservation risk that are based on quantitative criteria. Such methods allow decision makers to identify criteria inherently given the most weight in determining listing status, thus increasing the transparency of previous listing decisions, and produce an unbiased comparison of conservation threat across all species to promote consistency, efficiency, and effectiveness of the listing process.

Uso de Métodos Estandarizados para Mejorar la Clasificación del Riesgo de Extinción Resumen Los métodos estandarizados de clasificación basados en medidas cuantificables del riesgo de extinción son sumamente importantes para evaluar las amenazas de extinción ya que incrementan la objetividad, consistencia y transparencia de las decisiones de listado. Aún así, en los Estados Unidos, ni las agencias federales ni las estatales usan métodos estandarizados para enlistar a las especies para su protección legal, lo que podría poner en discrepancia a las decisiones de listado con la magnitud del riesgo. Usamos un conjunto de medidas cuantitativas del riesgo, desarrollado recientemente para la herpetofauna de California, como un estudio de caso que nos permitiera resaltar las discrepancias en las decisiones de listado hechas sin métodos estandarizados. También combinamos dichas medidas cuantitativas con un análisis de árbol de clasificación para intentar incrementar la transparencia de las decisiones de listado previas al identificar los criterios a los cuales se les había otorgado mayor peso inherentemente. La herpetofauna de California que se encontraba enlistada a nivel federal tuvo un puntaje significativamente más alto en el espectro de la medida del riesgo que aquellas especies que no estaban enlistadas, mientras que las especies enlistadas a nivel estatal no tuvieron un puntaje más alto que aquellas especies que no estaban enlistadas a nivel estatal. Con base en los árboles de clasificación, el endemismo estatal fue el indicador más importante del estado de listado a nivel estatal y tanto la tendencia de distribución (declinación del tamaño de la extensión de una especie) y como la tendencia poblacional (declinación de la abundancia de una especie en sitios localizados) fueron los indicadores más importantes a nivel federal. Nuestros resultados enfatizan la necesidad que tienen los cuerpos de gobierno de adoptar los métodos estandarizados que están basados en criterios cuantitativos para la evaluación del riesgo de conservación. Dichos métodos permiten que quienes toman las decisiones identifiquen los criterios a los cuales se les otorga inherentemente el mayor peso al determinar el estado de listado, lo que incrementa la transparencia de las decisiones previas de listado, y produce una comparación sin sesgos de la amenaza de conservación en todas las especies para promover la regularidad, eficiencia y efectividad de los procesos de listado.

Amphibian responses to livestock use of wetlands: new empirical data and a global review.

Pastureland currently occupies 26% of Earth's ice-free land surface. As the global human population continues to increase and developing countries consume more protein-rich diets, the amount of land devoted to livestock grazing will only continue to rise. To mitigate the loss of global biodiversity as a consequence of the ever-expanding amount of land converted from native habitat into pastureland for livestock grazing, an understanding of how livestock impact wildlife is critical. While previous reviews have examined the impact of livestock on a wide variety of taxa, there have been no reviews examining how global livestock grazing affects amphibians. We conducted both an empirical study in south-central Florida examining the impact of cattle on amphibian communities and a quantitative literature review of similar studies on five continents. Our empirical study analyzed amphibian community responses to cattle as both a binary (presence/absence) variable, and as a continuous variable based on cow pie density. Across all analyses, we were unable to find any evidence that cattle affected the amphibian community at our study site. The literature review returned 46 papers that met our criteria for inclusion. Of these studies, 15 found positive effects of livestock on amphibians, 21 found neutral/mixed effects, and 10 found negative effects. Our quantitative analysis of these data indicates that amphibian species that historically occurred in closed-canopy habitats are generally negatively affected by livestock presence. In contrast, open-canopy amphibians are likely to experience positive effects from the presence of livestock, and these positive effects are most likely to occur in locations with cooler climates and/or greater precipitation seasonality. Collectively, our empirical work and literature review demonstrate that under the correct conditions well-managed rangelands are able to support diverse assemblages of amphibians. These rangeland ecosystems may play a critical role in protecting future amphibian biodiversity by serving as an "off-reserve" system to supplement the biodiversity conserved within traditional protected areas.