• Energy Research

AbstractSpecies may circumvent the impacts of climate warming if the habitats they use reduce ambient temperature. In this study, we identified which frog species from a tropical montane rain forest in the Philippines may be vulnerable to climate warming. To do so, we selected five anuran species that utilize four breeding habitats and identified the sensitivity and exposure of tadpoles and direct‐developer eggs to heat by measuring their critical thermal maximums (CTmax) and the habitat‐specific temperatures they experience. Our study species included two direct‐developer frogs—one species that lays its eggs on exposed leaves, and another that lays its eggs in ferns—and three species that produce aquatic free‐swimming tadpoles—two stream breeders, and one phytotelm (tree hole) breeder. We compared thermal tolerances derived from microclimates of breeding habitats with tolerances derived from macroclimate (i.e., non‐buffered air temperature taken from the rain forest canopy). We also examined whether differences in CTmax existed across life‐history stages (egg, metamorph/young‐of‐year, and adult) for the two direct‐developer frog species. Habitats buffered ambient temperature and expanded thermal tolerances of all frog species. We found that direct‐developers, however, are more vulnerable to increased temperatures than aquatic breeders—indicated by their high sensitivity to temperature, and exposure to high temperatures. Direct‐developer eggs were more sensitive to warming than both metamorph and adult life‐history stages. Thermally buffered microhabitats may represent the only protection against current and impending climate warming. Our data highlight the importance of considering sensitivity and exposure in unison when deciphering warming vulnerability of frogs.

Assessing Biodiversity Declines Understanding human impact on biodiversity depends on sound quantitative projection. Pereira et al. (p. 1496 , published online 26 October) review quantitative scenarios that have been developed for four main areas of concern: species extinctions, species abundances and community structure, habitat loss and degradation, and shifts in the distribution of species and biomes. Declines in biodiversity are projected for the whole of the 21st century in all scenarios, but with a wide range of variation. Hoffmann et al. (p. 1503 , published online 26 October) draw on the results of five decades' worth of data collection, managed by the International Union for Conservation of Nature Species Survival Commission. A comprehensive synthesis of the conservation status of the world's vertebrates, based on an analysis of 25,780 species (approximately half of total vertebrate diversity), is presented: Approximately 20% of all vertebrate species are at risk of extinction in the wild, and 11% of threatened birds and 17% of threatened mammals have moved closer to extinction over time. Despite these trends, overall declines would have been significantly worse in the absence of conservation actions.

AbstractExtreme weather events, such as unusually hot or dry conditions, can cause death by exceeding physiological limits, and so cause loss of population. Survival will depend on whether or not susceptible organisms can find refuges that buffer extreme conditions. Microhabitats offer different microclimates to those found within the wider ecosystem, but do these microhabitats effectively buffer extreme climate events relative to the physiological requirements of the animals that frequent them? We collected temperature data from four common microhabitats (soil, tree holes, epiphytes, and vegetation) located from the ground to canopy in primary rainforests in the Philippines. Ambient temperatures were monitored from outside of each microhabitat and from the upper forest canopy, which represent our macrohabitat controls. We measured the critical thermal maxima (CTmax) of frog and lizard species, which are thermally sensitive and inhabit our microhabitats. Microhabitats reduced mean temperature by 1–2 °C and reduced the duration of extreme temperature exposure by 14–31 times. Microhabitat temperatures were below the CTmax of inhabitant frogs and lizards, whereas macrohabitats consistently contained lethal temperatures. Microhabitat temperatures increased by 0.11–0.66 °C for every 1 °C increase in macrohabitat temperature, and this nonuniformity in temperature change influenced our forecasts of vulnerability for animal communities under climate change. Assuming uniform increases of 6 °C, microhabitats decreased the vulnerability of communities by up to 32‐fold, whereas under nonuniform increases of 0.66 to 3.96 °C, microhabitats decreased the vulnerability of communities by up to 108‐fold. Microhabitats have extraordinary potential to buffer climate and likely reduce mortality during extreme climate events. These results suggest that predicted changes in distribution due to mortality and habitat shifts that are derived from macroclimatic samples and that assume uniform changes in microclimates relative to macroclimates may be overly pessimistic. Nevertheless, even nonuniform temperature increases within buffered microhabitats would still threaten frogs and lizards.

La perte d'habitat, le changement climatique, la surexploitation, la maladie et d'autres facteurs ont été hypothétisés dans le déclin mondial de la biodiversité des amphibiens. Cependant, l'importance relative et les synergies entre les différents facteurs sont encore mal comprises. Nous présentons la plus grande analyse mondiale d'environ 45 % des amphibiens connus (2 583 espèces) pour quantifier les influences du cycle biologique, du climat, de la densité humaine et de la perte d'habitat sur les déclins et le risque d'extinction. L'inférence bayésienne multimodèle révèle que les grandes espèces d'amphibiens ayant une faible aire de répartition géographique et une saisonnalité prononcée de la température et des précipitations sont les plus susceptibles d'être inscrites sur la Liste rouge de l'UICN. La perte élevée d'habitat et les densités humaines sont également corrélées à un risque élevé de menace. La taille de l'aire de répartition, la perte d'habitat et une saisonnalité plus extrême des précipitations ont contribué au déclin du risque chez les 2 454 espèces qui ont décliné entre 1980 et 2004, comparativement aux espèces qui étaient stables (n = 1 545) ou qui avaient augmenté (n = 28). Ces résultats empiriques montrent que les espèces d'amphibiens à aire de répartition restreinte devraient être ciblées de toute urgence pour la conservation. La pérdida de hábitat, el cambio climático, la sobreexplotación, las enfermedades y otros factores se han planteado como hipótesis en el declive global de la biodiversidad de los anfibios. Sin embargo, la importancia relativa y las sinergias entre los diferentes impulsores siguen siendo poco conocidas. Presentamos el análisis global más grande de aproximadamente el 45% de los anfibios conocidos (2.583 especies) para cuantificar las influencias de la historia de vida, el clima, la densidad humana y la pérdida de hábitat en las disminuciones y el riesgo de extinción. La inferencia bayesiana multimodelo revela que las especies de anfibios grandes con un rango geográfico pequeño y una estacionalidad pronunciada en la temperatura y la precipitación tienen más probabilidades de ser incluidas en la Lista Roja de la UICN. La pérdida elevada de hábitat y la densidad humana también se correlacionan con un alto riesgo de amenaza. El tamaño del rango, la pérdida de hábitat y la estacionalidad más extrema en las precipitaciones contribuyeron a disminuir el riesgo en las 2.454 especies que disminuyeron entre 1980 y 2004, en comparación con las especies que eran estables (n = 1.545) o habían aumentado (n = 28). Estos resultados empíricos muestran que las especies de anfibios con rangos restringidos deben ser objeto de protección urgente. Habitat loss, climate change, over-exploitation, disease and other factors have been hypothesised in the global decline of amphibian biodiversity. However, the relative importance of and synergies among different drivers are still poorly understood. We present the largest global analysis of roughly 45% of known amphibians (2,583 species) to quantify the influences of life history, climate, human density and habitat loss on declines and extinction risk. Multi-model Bayesian inference reveals that large amphibian species with small geographic range and pronounced seasonality in temperature and precipitation are most likely to be Red-Listed by IUCN. Elevated habitat loss and human densities are also correlated with high threat risk. Range size, habitat loss and more extreme seasonality in precipitation contributed to decline risk in the 2,454 species that declined between 1980 and 2004, compared to species that were stable (n = 1,545) or had increased (n = 28). These empirical results show that amphibian species with restricted ranges should be urgently targeted for conservation. تم افتراض فقدان الموائل وتغير المناخ والإفراط في الاستغلال والمرض وعوامل أخرى في التراجع العالمي للتنوع البيولوجي البرمائي. ومع ذلك، لا تزال الأهمية النسبية وأوجه التآزر بين الدوافع المختلفة غير مفهومة بشكل جيد. نقدم أكبر تحليل عالمي لما يقرب من 45 ٪ من البرمائيات المعروفة (2583 نوعًا) لتحديد تأثيرات تاريخ الحياة والمناخ والكثافة البشرية وفقدان الموائل على الانخفاضات ومخاطر الانقراض. يكشف الاستدلال البايزي متعدد النماذج أن الأنواع البرمائية الكبيرة ذات النطاق الجغرافي الصغير والموسمية الواضحة في درجة الحرارة وهطول الأمطار من المرجح أن تكون مدرجة في القائمة الحمراء من قبل الاتحاد الدولي لحفظ الطبيعة. كما يرتبط ارتفاع فقدان الموائل والكثافات البشرية بمخاطر التهديد العالية. ساهم حجم النطاق وفقدان الموائل والموسمية الأكثر تطرفًا في هطول الأمطار في انخفاض المخاطر في 2454 نوعًا انخفضت بين عامي 1980 و 2004، مقارنة بالأنواع التي كانت مستقرة (العدد = 1545) أو زادت (العدد = 28). تُظهر هذه النتائج التجريبية أنه يجب استهداف الأنواع البرمائية ذات النطاقات المحدودة بشكل عاجل للحفظ.