Thermal tolerance and geographical range size in the Agabus brunneus group of European diving beetles (Coleoptera: Dytiscidae)

Aim Within clades, most taxa are rare, whilst few are common, a general pattern for which the causes remain poorly understood. Here we investigate the relationship between thermal performance (tolerance and acclimation ability) and the size of a species’ geographical range for an assemblage of four ecologically similar European diving beetles (the Agabus brunneus group) to examine whether thermal physiology relates to latitudinal range extent, and whether Brown’s hypothesis and the environmental variability hypothesis apply to these taxa. Location Europe. Methods In order to determine the species tolerances to either low or high temperatures we measured the lethal thermal limits of adults, previously acclimated at one of two temperatures, by means of thermal ramping experiments (± 1°C min^?1). These measures of upper and lower thermal tolerances (UTT and LTT respectively) were then used to estimate each species’ thermal tolerance range, as total thermal tolerance polygons and marginal UTT and LTT thermal polygons. Results Overall, widespread species have higher UTTs and lower LTTs than restricted ones. Mean upper lethal limits of the Agabus brunneus group (43 to 46°C), are similar to those of insects living at similar latitudes, whilst mean lower lethal limits (?6 to ?9°C) are relatively high, suggesting that this group is not particularly cold‐hardy compared with other mid‐temperate‐latitude insects. Widespread species possess the largest thermal tolerance ranges and have a relatively symmetrical tolerance to both high and low temperatures, when compared with range‐restricted relatives. Over the temperature range employed, adults did not acclimate to either high or low temperatures, contrasting with many insect groups, and suggesting that physiological plasticity has a limited role in shaping distribution. Main conclusions Absolute thermal niche appears to be a good predictor of latitudinal range, supporting both Brown’s hypothesis and the environmental variability hypothesis. Restricted‐range species may be more susceptible to the direct effect of climate change than widespread species, notwithstanding the possibility that even ‘thermally‐hardy’, widespread species may be influenced by the indirect effects of climate change such as reduction in habitat availability in Mediterranean areas.     

Variable choice affects estimations of vulnerability to climate change

For practical reasons, assessments of species' vulnerability to rising temperatures are often limited to measuring responses to a single ecological response variable, but this could result in an underestimation of vulnerability. Using the Cape Rockjumper Chaetops frenatus (‘Rockjumper’) we examined the thermal risk to nestling Rockjumpers for sublethal (i.e. reduced nestling mass gain) and lethal (i.e. increased nest predation) consequences of sustained hot weather under both current and predicted future climatic conditions (RCP 8.5). We used a direct approach to examine these risks, first as independent ecological responses and then as combined risk driven by both response variables (mass gain and predation risk). This study revealed that the inclusion of multiple climate-related responses affected the predicted vulnerability to climate change. Further, our analyses showed that increased vulnerability to climate change will vary within the Rockjumper's habitat. Our results demonstrate that the variability in predicted thermal risk depends on which response variable was used, with implications for how and where conservation practitioners direct their already limited resources.     

Extreme heat events and the vulnerability of endemic montane fishes to climate change

Identifying how close species live to their physiological thermal maxima is essential to understand historical warm‐edge elevational limits of montane faunas and forecast upslope shifts caused by future climate change. We used laboratory experiments to quantify the thermal tolerance and acclimation potential of four fishes (Notropis leuciodus, N. rubricroceus, Etheostoma rufilineatum, E. chlorobranchium) that are endemic to the southern Appalachian Mountains (USA), exhibit different historical elevational limits, and represent the two most species‐rich families in the region. All‐subsets selection of linear regression models using AIC_c indicated that species, acclimation temperature, collection location and month, and the interaction between species and acclimation temperature were important predictors of thermal maxima (T_max), which ranged from 28.5 to 37.2°C. Next, we implemented water temperature models and stochastic weather generation to characterize the magnitude and frequency of extreme heat events (T_extreme) under historical and future climate scenarios across 25 379 stream reaches in the upper Tennessee River system. Lastly, we used environmental niche models to compare warming tolerances (acclimation‐corrected T_max minus T_extreme) between historically occupied versus unoccupied reaches. Historical warming tolerances, ranging from +2.2 to +10.9°C, increased from low to high elevation and were positive for all species, suggesting that T_max does not drive warm‐edge (low elevation) range limits. Future warming tolerances were lower (?1.2 to +9.3°C) but remained positive for all species under the direst warming scenario except for a small proportion of reaches historically occupied by E. rufilineatum, indicating that T_max and acclimation potentials of southern Appalachian minnows and darters are adequate to survive future heat waves. We caution concluding that these species are invulnerable to 21st century warming because sublethal thermal physiology remains poorly understood. Integrating physiological sensitivity and warming exposure demonstrates a general and fine‐grained approach to assess climate change vulnerability for freshwater organisms across physiographically diverse riverscapes.     

Low acclimation capacity of narrow‐ranging thermal specialists exposes susceptibility to global climate change

Thermal acclimation is hypothesized to offer a selective advantage in seasonal habitats and may underlie disparities in geographic range size among closely‐related species with similar ecologies. Understanding this relationship is also critical for identifying species that are more sensitive to warming climates. Here, we study North American plethodontid salamanders to investigate whether acclimation ability is associated with species’ latitudinal extents and the thermal range of the environments they inhabit. We quantified variation in thermal physiology by measuring standard metabolic rate (SMR) at different test and acclimation temperatures for 16 species of salamanders with varying latitudinal extents. A phylogenetically‐controlled Markov chain Monte Carlo generalized linear mixed model (MCMCglmm) was then employed to determine whether there are differences in SMR between wide‐ and narrow‐ranging species at different acclimation temperatures. In addition, we tested for a relationship between the acclimation ability of species and the environmental temperature ranges they inhabit. Further, we investigated if there is a trade‐off between critical thermal maximum (CTMax) and thermal acclimation ability. MCMCglmm results show a significant difference in acclimation ability between wide and narrow‐ranging temperate salamanders. Salamanders with wide latitudinal distributions maintain or slightly increase SMR when subjected to higher test and acclimation temperatures, whereas several narrow‐ranging species show significant metabolic depression. We also found significant, positive relationships between acclimation ability and environmental thermal range, and between acclimation ability and CTMax. Wide‐ranging salamander species exhibit a greater capacity for thermal acclimation than narrow‐ranging species, suggesting that selection for acclimation ability may have been a key factor enabling geographic expansion into areas with greater thermal variability. Further, given that narrow‐ranging salamanders are found to have both poor acclimation ability and lower tolerance to warm temperatures, they are likely to be more susceptible to environmental warming associated with anthropogenic climate change.     

Regional and global climate risks for reef corals: Incorporating species-specific vulnerability and exposure to climate hazards

Climate change is driving rapid and widespread erosion of the environmental conditions that formerly supported species persistence. Existing projections of climate change typically focus on forecasts of acute environmental anomalies and global extinction risks. The current projections also frequently consider all species within a broad taxonomic group together without differentiating species-specific patterns. Consequently, we still know little about the explicit dimensions of climate risk (i.e., species-specific vulnerability, exposure and hazard) that are vital for predicting future biodiversity responses (e.g., adaptation, migration) and developing management and conservation strategies. Here, we use reef corals as model organisms (n = 741 species) to project the extent of regional and global climate risks of marine organisms into the future. We characterise species-specific vulnerability based on the global geographic range and historical environmental conditions (1900–1994) of each coral species within their ranges, and quantify the projected exposure to climate hazard beyond the historical conditions as climate risk. We show that many coral species will experience a complete loss of pre-modern climate analogs at the regional scale and across their entire distributional ranges, and such exposure to hazardous conditions are predicted to pose substantial regional and global climate risks to reef corals. Although high-latitude regions may provide climate refugia for some tropical corals until the mid-21st century, they will not become a universal haven for all corals. Notably, high-latitude specialists and species with small geographic ranges remain particularly vulnerable as they tend to possess limited capacities to avoid climate risks (e.g., via adaptive and migratory responses). Predicted climate risks are amplified substantially under the SSP5-8.5 compared with the SSP1-2.6 scenario, highlighting the need for stringent emission controls. Our projections of both regional and global climate risks offer unique opportunities to facilitate climate action at spatial scales relevant to conservation and management.     

Multiple axes of ecological vulnerability to climate change

Observed ecological responses to climate change are highly individualistic across species and locations, and understanding the drivers of this variability is essential for management and conservation efforts. While it is clear that differences in exposure, sensitivity, and adaptive capacity all contribute to heterogeneity in climate change vulnerability, predicting these features at macroecological scales remains a critical challenge. We explore multiple drivers of heterogeneous vulnerability across the distributions of 96 vegetation types of the ecologically diverse western US, using data on observed climate trends from 1948 to 2014 to highlight emerging patterns of change. We ask three novel questions about factors potentially shaping vulnerability across the region: (a) How does sensitivity to different climate variables vary geographically and across vegetation classes? (b) How do multivariate climate exposure patterns interact with these sensitivities to shape vulnerability patterns? (c) How different are these vulnerability patterns according to three widely implemented vulnerability paradigms—niche novelty (decline in modeled suitability), temporal novelty (standardized anomaly), and spatial novelty (inbound climate velocity)—each of which uses a distinct frame of reference to quantify climate departure? We propose that considering these three novelty paradigms in combination could help improve our understanding and prediction of heterogeneous climate change responses, and we discuss the distinct climate adaptation strategies connected with different combinations of high and low novelty across the three metrics. Our results reveal a diverse mosaic of climate change vulnerability signatures across the region's plant communities. Each of the above factors contributes strongly to this heterogeneity: climate variable sensitivity exhibits clear patterns across vegetation types, multivariate climate change data reveal highly diverse exposure signatures across locations, and the three novelty paradigms diverge widely in their climate change vulnerability predictions. Together, these results shed light on potential drivers of individualistic climate change responses and may help to inform effective management strategies.     

Plasticity in thermal tolerance has limited potential to buffer ectotherms from global warming

Global warming is increasing the overheating risk for many organisms, though the potential for plasticity in thermal tolerance to mitigate this risk is largely unknown. In part, this shortcoming stems from a lack of knowledge about global and taxonomic patterns of variation in tolerance plasticity. To address this critical issue, we test leading hypotheses for broad-scale variation in ectotherm tolerance plasticity using a dataset that includes vertebrate and invertebrate taxa from terrestrial, freshwater and marine habitats. Contrary to expectation, plasticity in heat tolerance was unrelated to latitude or thermal seasonality. However, plasticity in cold tolerance is associated with thermal seasonality in some habitat types. In addition, aquatic taxa have approximately twice the plasticity of terrestrial taxa. Based on the observed patterns of variation in tolerance plasticity, we propose that limited potential for behavioural plasticity (i.e. behavioural thermoregulation) favours the evolution of greater plasticity in physiological traits, consistent with the ‘Bogert effect’. Finally, we find that all ectotherms have relatively low acclimation in thermal tolerance and demonstrate that overheating risk will be minimally reduced by acclimation in even the most plastic groups. Our analysis indicates that behavioural and evolutionary mechanisms will be critical in allowing ectotherms to buffer themselves from extreme temperatures.     

Combining population genetics,species distribution modelling and field assessments to understand a species vulnerability to climate change

Climate change is recognized as a major threat to biodiversity. Multidisciplinary approaches that combine population genetics and species distribution modelling to assess these threats and recommend conservation actions are critical but rare. Combined, these methods provide independent verification and a more compelling case for developing conservation actions. This study integrates these data streams together with field assessments and spatial analyses to develop future genetic resource management recommendations. The study species was Callistemon teretifolius (Needle Bottlebrush), a shrub species endemic to the Mount Lofty and Flinders Ranges, South Australia, and potentially vulnerable to climate change. Chloroplast microsatellite and Amplified Fragment Length Polymorphism data were combined with species distribution modelling (MaxEnt), spatial analysis and field assessment to evaluate climate change vulnerability. Two major genetic groups were identified (Mount Lofty and Flinders Ranges). Populations in the Flinders Ranges, especially the Southern Flinders Ranges exhibited the highest genetic diversity, indicating a possible genetic refugium. Lower genetic diversity to the south in the Mount Lofty Ranges and north in the Gammon Ranges may be due to post‐glacial expansion into these areas from the Flinders Ranges or loss of alleles. Low levels of contemporary gene flow were identified, which suggests Callistemon teretifolius may have a limited capacity to respond to climate change through migration. Range restrictions were predicted for all future climates, especially in the north. It is likely that C. teretifolius will be adversely affected by climate change, due to limited gene flow, predicted range restriction and loss of suitable habitat. The Southern Flinders Ranges should be a priority for conservation because it contains the highest number of individuals and genetic diversity. We recommend monitoring and adaptive management involving restoration in the Southern Flinders Ranges, potentially incorporating genetic translocations from other areas to capture diversity, to assist C. teretifolius to adapt to climate change.     

A global assessment of the vulnerability of shellfish aquaculture to climate change and ocean acidification

Human‐induced climate change and ocean acidification (CC‐OA) is changing the physical and biological processes occurring within the marine environment, with poorly understood implications for marine life. Within the aquaculture sector, molluskan culture is a relatively benign method of producing a high‐quality, healthy, and sustainable protein source for the expanding human population. We modeled the vulnerability of global bivalve mariculture to impacts of CC‐OA over the period 2020–2100, under RCP8.5. Vulnerability, assessed at the national level, was dependent on CC‐OA‐related exposure, taxon‐specific sensitivity and adaptive capacity in the sector. Exposure risk increased over time from 2020 to 2100, with ten nations predicted to experience very high exposure to CC‐OA in at least one decade during the period 2020–2100. Predicted high sensitivity in developing countries resulted, primarily, from the cultivation of species that have a narrow habitat tolerance, while in some European nations (France, Ireland, Italy, Portugal, and Spain) high sensitivity was attributable to the relatively high economic value of the shellfish production sector. Predicted adaptive capacity was low in developing countries primarily due to governance issues, while in some developed countries (Denmark, Germany, Iceland, Netherlands, Sweden, and the United Kingdom) it was linked to limited species diversity in the sector. Developing and least developed nations (n = 15) were predicted to have the highest overall vulnerability. Across all nations, 2060 was identified as a tipping point where predicted CC‐OA will be associated with the greatest challenge to shellfish production. However, rapid declines in mollusk production are predicted to occur in the next decade for some nations, notably North Korea. Shellfish culture offers human society a low‐impact source of sustainable protein. This research highlights, on a global scale, the likely extent and nature of the CC‐OA‐related threat to shellfish culture and this sector enabling early‐stage adaption and mitigation.     

中国水稻生产对历史气候变化的敏感性和脆弱性

有效的适应措施需要了解两类基础信息,一是农业生产所面临的各种气候变异风险,二是作物产量对潜在气候变异风险的反应及其机制.评价作物生产对历史气候变化的敏感性和脆弱性,可以在时间上和空间上揭示气候变化的趋势及作物产量对其的反应,从而为适应行动的全面开展提供基础信息.通过分析1981-2007年水稻生育期3个气候因子(平均温度、日较差、辐射)的变化对水稻产量的影响,评估我国水稻生产对这3个气候因子变化的敏感性和脆弱性及其区域分布状况.结果表明,1981-2007年间我国大部分水稻产区生育期内3个气候因子均发生了明显变化,存在着气候变异风险,其中以最高温的变化最普遍和明显,导致水稻生产中高温热害风险增加.部分区域水稻产量变化与单一气象因子的变化存在着显著的线性相关,这些地区气候因子的变化可以一定程度地解释水稻产量变化趋势,其中产量变化对辐射变化最敏感.当水稻生育期内平均温度上升1℃、日较差升高1℃、辐射下降10％时,我国部分地区水稻产量随之发生了相应的变化,其中辐射降低导致我国水稻生产的脆弱面积最大,其次为日较差.受3种气象因子变化趋势的综合影响,约有30％的水稻产区对1981-2007年的气候变化趋势敏感,少部分地区表现为脆弱,但水稻主产区受到的影响不大,且在东北地区还集中表现出产量增加的趋势,为我国水稻发展提供了契机.     

Thermal sensitivity of a Neotropical amphibian (Engystomops pustulosus) and its vulnerability to climate change

A species’ thermal sensitivity and its exposure to climate variation are key components in the prediction of its vulnerability to climate change. We tested the thermal sensitivity of a tropical amphibian that lives in a mild constant climate in which the thermal tolerance range is expected to closely match the experienced environmental temperature. The air temperature that this species is exposed to varies between 21.9 and 31.6°C with an annual mean of 27.2°C. We estimated the microhabitat water temperature variation under vegetation shade, which buffers the temperature by 1.8°C in relation to that of the air, and with open canopy, where the water was 1.9°C warmer than the air temperature. With broods of tadpoles split into five treatments (15°C, 21°C, 28°C, 31°C, and 33°C), we estimated the critical thermal maximum (CTMax) and critical thermal minimum (CTMin) after at least 7 days of acclimation. Both CTMax (42.3°C) and CTMin (11.8°C) were more extreme than the temperature range estimated for the field. We estimated the optimum temperature (T_o = 28.8°C) and the thermal performance breadth (range: 23.3–34.1°C) based on growth rate (g/day). The animals were able to acclimate more extensively to cold than to warm temperatures. These performance curve traits closely matched the air temperature. The estimated vulnerability varied according to the microhabitat prediction model used. The combination of tadpole data on thermal sensitivity and macro‐ and microhabitat variation provides a necessary framework to understand the effects of climate change on tropical amphibians.     

Ecophysiological variation across a forest‐ecotone gradient produces divergent climate change vulnerability within species

Climate change related risks and impacts on ectotherms will be mediated by habitats and their influence on local thermal environments. While many studies have documented morphological and genetic aspects of niche divergence across habitats, few have examined thermal performance across such gradients and directly linked this variation to contemporary climate change impacts. In this study, we quantified variation in thermal performance across a gradient from forest to gallery forest‐savanna mosaic in Cameroon for a skink species (Trachylepis affinis) known to be diverging genetically and morphologically across that habitat gradient. Based on these results, we then applied a mechanistic modelling approach (NicheMapR) to project changes in potential activity, as constrained by thermal performance, in response to climate change. As a complimentary approach, we also compared mechanistic projections with climate‐driven changes in habitat suitability based on species distribution models of forest and ecotone skinks. We found that ecotone skinks may benefit from warming and experience increased activity while forest skinks will likely face a drastic decrease in thermal suitability across the forest zone. Species distribution models projected that thermal suitability for forest skinks in coastal forests would decline but in other parts of the forest zone skinks are projected to experience increased thermal suitability. The results here highlight the utility of mechanistic approaches in revealing and understanding patterns of climate change vulnerability which may not be detected with species distribution models alone. This study also emphasizes the importance of intra‐specific physiological variation, and habitat‐specific thermal performance relationships in particular, in determining warming responses.     

Distinct responses and range shifts of lizard populations across an elevational gradient under climate change

Ongoing climate change has profoundly affected global biodiversity, but its impacts on populations across elevations remain understudied. Using mechanistic niche models incorporating species traits, we predicted ecophysiological responses (activity times, oxygen consumption and evaporative water loss) for lizard populations at high-elevation (<3600 m asl) and extra-high-elevation (≥3600 m asl) under recent (1970–2000) and future (2081–2100) climates. Compared with their high-elevation counterparts, lizards from extra-high-elevation are predicted to experience a greater increase in activity time and oxygen consumption. By integrating these ecophysiological responses into hybrid species distribution models (HSDMs), we were able to make the following predictions under two warming scenarios (SSP1-2.6, SSP5-8.5). By 2081–2100, we predict that lizards at both high- and extra-high-elevation will shift upslope; lizards at extra-high-elevation will gain more and lose less habitat than will their high-elevation congeners. We therefore advocate the conservation of high-elevation species in the context of climate change, especially for those populations living close to their lower elevational range limits. In addition, by comparing the results from HSDMs and traditional species distribution models, we highlight the importance of considering intraspecific variation and local adaptation in physiological traits along elevational gradients when forecasting species' future distributions under climate change.     

Impacts of global change on species distributions: obstacles and solutions to integrate climate and land use

Aim The impact of multiple stressors on biodiversity is one of the most pressing questions in ecology and biodiversity conservation. Here we critically assess how often and efficiently two main drivers of global change have been simultaneously integrated into research, with the aim of providing practical solutions for better integration in the future. We focus on the integration of climate change (CC) and land‐use change (LUC) when studying changes in species distributions. Location Global. Methods We analysed the peer‐reviewed literature on the effects of CC and LUC on observed changes in species distributions, i.e. including species range and abundance, between 2000 and 2014. Results Studies integrating CC and LUC remain extremely scarce, which hampers our ability to develop appropriate conservation strategies. The lack of CC–LUC integration is likely to be a result of insufficient recognition of the co‐occurrence of CC and LUC at all scales, covariation and interactions between CC and LUC, as well as correlations between species thermal and habitat requirements. Practical guidelines for the study of these interactive effects include considering multiple drivers and processes when designing studies, using available long‐term datasets on multiple drivers, revisiting single‐driver studies with additional drivers or conducting comparative studies and meta‐analyses. Combining various methodological approaches, including time lags and adaptation processes, represent further avenues to improve global change science. Main conclusions Despite repeated claims for a better integration of multiple drivers, the effects of CC and LUC on species distributions and abundances have been mostly studied in isolation, which calls for a shift of standards towards more integrative global change science. The guidelines proposed here will encourage study designs that account for multiple drivers and improve our understanding of synergies or antagonisms among drivers.     

森林凋落物分解及其对全球气候变化的响应

凋落物分解是重要的森林生态系统过程之一,受到气候、凋落物质量、土壤生物群落等生物和非生物因素的综合调控．迄今,有关不同森林生态系统和不同树种地上部分的凋落物动态、凋落物分解过程中的养分释放动态、生物和非生物因素对凋落物分解的影响等研究报道较多,但对地下凋落物的分解研究相对较少．近年来,森林凋落物分解对以大气CO2浓度增加和温度升高为主要特征的全球变化的响应逐步受到重视,但其研究结果仍具有很多不确定性．因此,未来凋落物生态研究的重点应是凋落物分解对土壤有机碳固定的贡献、地上／地下凋落物的物理、化学和生物学过程及其对各种生态因子（例如冻融、干湿交替）及交互作用的响应、凋落物特别是地下凋落物分解对全球气候变化的响应机制等方面．     

Heat tolerance may determine activity time in coprophagic beetle species (Coleoptera: Scarabaeidae)

Although reports have documented loss of species diversity and ecological services caused by stressful temperature changes that result from climate change, some species cope through behavioral compensation. As temperatures and magnitudes of temperature extremes increase, animals should compensate to maintain fitness (such as through temporary behavioral shifts in activity times). Appropriate timing of activity helps avoid competition across species. Although coprophagic dung beetles exhibit species-specific temporal activity times, it is unknown whether temperature drives evolution of these species-specific temporal activity times. Using nine dung beetle species (three each of diurnal, crepuscular, and nocturnal species), we explored differences in heat stress tolerance measured as critical thermal maxima (CT_max; the highest temperature allowing activity) and heat knockdown time (HKDT; survival time under acute heat stress) across these species, and examined the results using a phylogenetically informed approach. Our results showed that day-active species had significantly higher CT_max (diurnal > crepuscular = nocturnal species), whereas crepuscular species had higher HKDT (crepuscular > nocturnal > diurnal species). There was no correlation between heat tolerance and body size across species with distinct temporal activity, and no significant phylogenetic constraint for activity. Species with higher CT_max did not necessarily have higher HKDT, which indicates that species may respond differently to diverse heat tolerance metrics. Acute heat tolerance for diurnal beetles indicates that this trait may constrain activity time and, under high acute temperatures with climate change, species may shift activity times in more benign environments. These results contribute to elucidate the evolution of foraging behavior and management of coprophagic beetle ecosystem services under changing environments.     

Microhabitats reduce animal's exposure to climate extremes

Extreme 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 (CT_max) 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 CT_max 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.     

Physiological tolerance, climate change, and a northward range shift in the spittlebug, Philaenus spumarius

Abstract.  1. Considerable evidence indicates that the Earth's climate has warmed over the past 20 years and most models predict that this process will continue or accelerate. Previous studies involving butterflies and other species have shown that ranges have shifted towards the poles although the mechanisms responsible for these range shifts have not been demonstrated conclusively.
2. Here it is reported that the range of the meadow spittlebug has moved northward along the California coast since 1988.
3. Survival and reproduction of this species in previous laboratory experiments were very sensitive to humidity and temperature. Small deviations from optimal conditions resulted in high mortality.
4. These laboratory results were corroborated by annual field censuses from one location since 1983 in which population densities of spittlebug nymphs were positively correlated with summer humidity and negatively correlated with temperature deviations from the published optimum. Thus it is shown that there are strong links between physiological tolerance and a geographic range shift associated with climatic change.     

Assessing the vulnerability of species richness to anthropogenic climate change in a biodiversity hotspot

Aim To compare theoretical approaches towards estimating risks of plant species loss to anthropogenic climate change impacts in a biodiversity hotspot, and to develop a practical method to detect signs of climate change impacts on natural populations. Location The Fynbos biome of South Africa, within the Cape Floristic Kingdom. Methods Bioclimatic modelling was used to identify environmental limits for vegetation at both biome and species scale. For the biome as a whole, and for 330 species of the endemic family Proteaceae, tolerance limits were determined for five temperature and water availability‐related parameters assumed critical for plant survival. Climate scenarios for 2050 generated by the general circulation models HadCM2 and CSM were interpolated for the region. Geographic Information Systems‐based methods were used to map current and future modelled ranges of the biome and 330 selected species. In the biome‐based approach, predictions of biome areal loss were overlayed with species richness data for the family Proteaceae to estimate extinction risk. In the species‐based approach, predictions of range dislocation (no overlap between current range and future projected range) were used as an indicator of extinction risk. A method of identifying local populations imminently threatened by climate change‐induced mortality is also described. Results A loss of Fynbos biome area of between 51% and 65% is projected by 2050 (depending on the climate scenario used), and roughly 10% of the endemic Proteaceae have ranges restricted to the area lost. Species range projections suggest that a third could suffer complete range dislocation by 2050, and only 5% could retain more than two thirds of their range. Projected changes to individual species ranges could be sufficient to detect climate change impacts within ten years. Main conclusions The biome‐level approach appears to underestimate the risk of species diversity loss from climate change impacts in the Fynbos Biome because many narrow range endemics suffer range dislocation throughout the biome, and not only in areas identified as biome contractions. We suggest that targeted vulnerable species could be monitored both for early warning signs of climate change and as empirical tests of predictions.