Loss of small glaciers will diminish beta diversity in Pyrenean streams at two levels of biological organization

Aim Small (< 1 km²) alpine glaciers are likely to disappear in this century, resulting in decreased regional habitat heterogeneity in associated streams. Both heterogeneity within and spatial isolation among glacier‐influenced streams can enhance beta diversity of stream‐dwelling organisms. We measured beta at both community and population‐genetic levels within and among streams currently influenced by small Pyrenean glaciers. We aimed to evaluate whether patterns are analogous between the two levels, to apply various approaches for characterizing beta, and to infer the outcome of future glacier loss on regional biodiversity. Location Four glacier‐fed basins in the Parc National des Pyrénées, France. Methods We classified each of 18 stream reaches across the basins into either high‐, mid‐ or low‐‘glaciality’ (glacial influence) groups according to four physicochemical characteristics. At each reach, we collected macroinvertebrate communities and evaluated mitochondrial DNA haplotypes for 11–13 individuals of Baetis alpinus Pictet. Using taxa/haplotypes as basic units, we evaluated community and population‐genetic beta diversity simultaneously. We measured beta diversity in three major ways: as multivariate (Sørensen's dissimilarity, Jost D) and ‘classical’ (gamma/alpha) variation to compare among glaciality groups, and as turnover along the glaciality gradient within each basin. Results For most approaches at both organizational levels, beta was greatest among high‐glaciality reaches, absolute values of variation of beta in high‐glaciality streams were strikingly similar between levels, and the steepest turnover within basins occurred between high‐ and mid‐glaciality reaches. Therefore, high‐glaciality reaches contained assemblages and populations that were unique both within that stream type (among basins) and compared with other stream types within basins. Main conclusions Parallel beta diversity patterns at population‐genetic and community levels suggested that environmental drivers influence these levels analogously. Extreme conditions (e.g. low temperature, high instability, isolation) in high‐glaciality streams probably enhance beta at both levels. Stream beta diversity is likely to decrease substantially with continued glacial reduction in this system.     

Late Embryogenesis Abundant (LEA) proteins confer water stress tolerance to mammalian somatic cells

Late Embryogenesis Abundant (LEA) proteins are commonly found in plants and other organisms capable of undergoing severe and reversible dehydration, a phenomenon termed “anhydrobiosis”. Here, we have produced a tagged version for three different LEA proteins: pTag-RAB17-GFP-N, Zea mays dehydrin-1dhn, expressed in the nucleo-cytoplasm; pTag-WCOR410-RFP, Tricum aestivum cold acclimation protein WCOR410, binds to cellular membranes, and pTag-LEA-BFP, Artemia franciscana LEA protein group 3 that targets the mitochondria. Sheep fibroblasts transfected with single or all three LEA proteins were subjected to air drying under controlled conditions. After rehydration, cell viability and functionality of the membrane/mitochondria were assessed. After 4 h of air drying, cells from the un-transfected control group were almost completely nonviable (1% cell alive), while cells expressing LEA proteins showed high viability (more than 30%), with the highest viability (58%) observed in fibroblasts expressing all three LEA proteins. Growth rate was markedly compromised in control cells, while LEA-expressing cells proliferated at a rate comparable to non-air-dried cells. Plasmalemma, cytoskeleton and mitochondria appeared unaffected in LEA-expressing cells, confirming the protection conferred by LEA proteins on these organelles during dehydration stress. This is likely to be an effective strategy when aiming to confer desiccation tolerance to mammalian cells.     

Examining the effects of chronic,lake-wide elevated temperatures on behavioural expression in largemouth bass,Micropterus salmoides

Many behaviours have differential fitness consequences across thermal and ecological contexts, indicating that both ecological shifts and warming temperatures induced by climatic change may alter how organisms behave. However, empirical evidence of temperature-driven behavioural selection in natural systems is lacking. We compared behaviours and behavioural syndromes related to activity, exploration, boldness and aggression in populations of largemouth bass (Micropterus salmoides) from ambient lakes to the those from artificially warmed, power plant cooling lakes to investigate changes in behaviours associated with warmer environments. Activity, exploration, boldness and aggression of juvenile largemouth bass were assessed in laboratory conditions using a novel environment assay and a risky situation assay. We found that activity and exploratory behaviours were higher and decreased through first year ontogeny in populations from heated lakes, whereas these behaviours were lower and showed no relationship through ontogeny in populations from ambient lakes. We attribute these differences to the changes in food source availability in heated lakes associated with temperature-driven ecological effects. Bold and aggressive behaviours tended to differ between populations, as did correlations between behaviours, but did not differ between ambient and heated lakes. The findings of this work identify that large ecological changes associated with warming environments, such as food availability, may drive changes in some aspects of behavioural expression in largemouth bass but that other aspects of behavioural expression may be driven by lake-specific factors not related to warming.     

Effects of climate warming on host–parasitoid interactions

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The effect of acclimation temperature on thermal activity thresholds in polar terrestrial invertebrates

In the Maritime Antarctic and High Arctic, soil microhabitat temperatures throughout the year typically range between ?10 and +5 °C. However, on occasion, they can exceed 20 °C, and these instances are likely to increase and intensify as a result of climate warming. Remaining active under both cool and warm conditions is therefore important for polar terrestrial invertebrates if they are to forage, reproduce and maximise their fitness. In the current study, lower and upper thermal activity thresholds were investigated in the polar Collembola, Megaphorura arctica and Cryptopygus antarcticus, and the mite, Alaskozetes antarcticus. Specifically, the effect of acclimation on these traits was explored. Sub-zero activity was exhibited in all three species, at temperatures as low as ?4.6 °C in A. antarcticus. At high temperatures, all three species had capacity for activity above 30 °C and were most active at 25 °C. This indicates a comparable spread of temperatures across which activity can occur to that seen in temperate and tropical species, but with the activity window shifted towards lower temperatures. In all three species following one month acclimation at ?2 °C, chill coma (=the temperature at which movement and activity cease) and the critical thermal minimum (=low temperature at which coordination is no longer shown) occurred at lower temperatures than for individuals maintained at +4 °C (except for the CTmin of M. arctica). Individuals acclimated at +9 °C conversely showed little change in their chill coma or CTmin. A similar trend was demonstrated for the heat coma and critical thermal maximum (CTmax) of all species. Following one month at ?2 °C, the heat coma and CTmax were reduced as compared with +4 °C reared individuals, whereas the heat coma and CTmax of individuals acclimated at +9 °C showed little adjustment. The data obtained suggest these invertebrates are able to take maximum advantage of the short growing season and have some capacity, in spite of limited plasticity at high temperatures, to cope with climate change.     

Advancing the long view of ecological change in tundra systems

Despite uncertainties related to sustained funding, ideological rivalries and the turnover of research personnel, long-term studies and studies espousing a long-term perspective in ecology have a history of contributing landmark insights into fundamental topics, such as population- and community dynamics, species interactions and ecosystem function. They also have the potential to reveal surprises related to unforeseen events and non-stationary dynamics that unfold over the course of ongoing observation and experimentation. The unprecedented rate and magnitude of current and expected abiotic changes in tundra environments calls for a synthetic overview of the scope of ecological responses these changes have elicited. In this special issue, we present a series of contributions that advance the long view of ecological change in tundra systems, either through sustained long-term research, or through retrospective or prospective modelling. Beyond highlighting the value of long-term research in tundra systems, the insights derived herein should also find application to the study of ecological responses to environmental change in other biomes as well.     

青藏高原高寒草甸植被特征与温度、水分因子关系

以广布于青藏高原的高寒草甸为研究对象,进行模拟增温实验,探讨高寒草甸植被特征与温度、水分因子关系,并试图论证高寒草甸植被是否符合生物多样性代谢理论.结果表明:①高寒草甸植被物种多样性的对数与绝对温度的倒数呈显著线性递减关系,空气-地表-浅层土壤(0-20 cm)温度(R2 ＞0.6,P＜0.01)较深层土壤(40-100 cm)温度(R2＜0.5,P＜0.05)对物种多样性影响大;其植被新陈代谢平均活化能为0.998-1.85 eV,高于生物多样性代谢理论预测值0.6-0.7 eV,这是高寒草甸植被对长期低温环境适应进化的结果.②除趋势对应分析和冗余分析显示,温度对植被地上部分影响较大,而土壤水分对全株影响均较大,适当的增温与降水均可极显著促进高寒草甸植被生长.③逐步回归和通径分析显示,40 cm、60 cm深度土壤水分对植被地上部分产生直接影响,20 cm高度空气相对湿度和40 cm深度土壤温度对其产生间接影响;40 cm深度土壤温度和60 cm深度土壤水分对植被地下部分产生直接影响,红外地表温度对其产生间接影响.深层土壤温度和水分对高寒草甸植被具有影响作用,这可能与增温后冻土的融化有关,但其机理尚待进一步研究.     

中国北方春小麦生育期变化的区域差异性与气候适应性

利用北方18个农业气象观测站春小麦主要发育期和气象观测等资料,通过相关性分析等方法,研究了北方春小麦生育期间气候和发育期变化特点及发育期变化区域差异性形成原因。结果表明,我国北方春小麦生长季普遍增温,大部分观测站春小麦生育期间和灌浆期的平均气温显著升高,有效积温显著增加,生育期显著缩短。然而,稳定通过0 ℃初日没有显著提前,表明增温主要发生在生长季后期。春小麦主要发育期和生育期与不同生育阶段的平均气温和有效积温的相关性分析表明,后期增温并没有完全显著提前成熟期,春小麦生育期缩短是播种期推迟和成熟期提前共同作用的结果。春小麦生育期间的平均气温与生育期的相关性比有效积温与生育期的相关性更高,能更好地定量刻画北方春小麦生长发育客观规律。春小麦品种改良变换、播种期调整以及其它适应性措施的实施以及措施实施程度在区域上的差异性是春小麦生育期变化区域差异的主要原因。北方春小麦生长发育的区域性差异是各自适应气候变化的结果。     

Warm springs reduce parasitism of the cereal leaf beetle through phenological mismatch

Variation in weather among years may affect biological control of insect pests by influencing how well matched in phenology specialist parasitoids are with their pest hosts. A 10‐year study in western North America (Utah) revealed greater change with warm versus cool springs in the life cycle timing of the cereal leaf beetle (CLB), Oulema melanopus (L.), than of its principal enemy, the parasitoid wasp Tetrastichus julis (Walker). The beetle laid eggs, and larval populations developed in crop fields earlier on a calendar‐day basis, but nonetheless after more degree‐days had accumulated, in warmer than in cooler springs. The phenology of parasitism by wasps, in contrast, varied little among springs in relation to accumulated degree‐days. Consequently, in warmer springs, larval phenology of the CLB was delayed relative to adult parasitoid activity, and parasitism was reduced. Presently, a significant degree of biological control of the CLB results from parasitism by T. julis. By promoting phenological mismatch between host and parasitoid, however, a warming climate could weaken this biological control of the insect pest.     

One‐year experiment on the physiological response of the Mediterranean crustose coralline alga,Lithophyllum cabiochae,to elevated pCO2 and temperature

The response of respiration, photosynthesis, and calcification to elevated pCO₂ and temperature was investigated in isolation and in combination in the Mediterranean crustose coralline alga Lithophyllum cabiochae. Algae were maintained in aquaria during 1 year at near‐ambient conditions of irradiance, at ambient or elevated temperature (+3°C), and at ambient (ca. 400 μatm) or elevated pCO₂ (ca. 700 μatm). Respiration, photosynthesis, and net calcification showed a strong seasonal pattern following the seasonal variations of temperature and irradiance, with higher rates in summer than in winter. Respiration was unaffected by pCO₂ but showed a general trend of increase at elevated temperature at all seasons, except in summer under elevated pCO₂. Conversely, photosynthesis was strongly affected by pCO₂ with a decline under elevated pCO₂ in summer, autumn, and winter. In particular, photosynthetic efficiency was reduced under elevated pCO₂. Net calcification showed different responses depending on the season. In summer, net calcification increased with rising temperature under ambient pCO₂ but decreased with rising temperature under elevated pCO₂. Surprisingly, the highest rates in summer were found under elevated pCO₂ and ambient temperature. In autumn, winter, and spring, net calcification exhibited a positive or no response at elevated temperature but was unaffected by pCO₂. The rate of calcification of L. cabiochae was thus maintained or even enhanced under increased pCO₂. However, there is likely a trade‐off with other physiological processes. For example, photosynthesis declines in response to increased pCO₂ under ambient irradiance. The present study reports only on the physiological response of healthy specimens to ocean warming and acidification, however, these environmental changes may affect the vulnerability of coralline algae to other stresses such as pathogens and necroses that can cause major dissolution, which would have critical consequence for the sustainability of coralligenous habitats and the budgets of carbon and calcium carbonate in coastal Mediterranean ecosystems.