Vorhees Ashley S, Gray Emilie M, Bradley Timothy J
Department of Ecology and Evolutionary Biology, University of California, Irvine, CA 92697, USA.
Physiol Biochem Zool. 2013 Jan-Feb;86(1):73-81. doi: 10.1086/668851. Epub 2012 Dec 14.
The abundance and success of widely distributed species across variable environments make them suitable models for exploring which traits will be important for resilience to climate change. Using a widespread mosquito species, Culex tarsalis, we have investigated population-level variation in the critical thermal maximum (CT(max)) and the metabolic response to temperature (MR-T). Adult female C. tarsalis were sampled from three sites representing thermally distinct habitats in California, and flow-through respirometry was used to determine CT(max) and MR-T relationships. CT(max) differed significantly among the three populations and correlated positively with maximum temperatures at each site but not with mean temperatures. Culex tarsalis from our cool-temperature, high-altitude site had significantly higher metabolic rates at each test temperature compared with the two populations from warmer sites, consistent with previous examples of thermal compensation in ectothermic animals inhabiting cold climates. The MR-T slope was steepest in mosquitoes inhabiting the site with the lowest temperature variability, while shallower slopes were exhibited by mosquitoes from the two sites with higher thermal variability. Our results show the extent to which local populations may differentiate within their respective environments and suggest that plasticity in thermal tolerance traits may play a role in mediating resilience to climate change. Furthermore, our study highlights the importance of thermal variability and extremes rather than average temperatures for the evolution of thermal traits.
广泛分布于各种不同环境中的物种数量众多且十分成功，这使得它们成为探索哪些性状对于适应气候变化具有重要意义的合适模型。我们以一种广泛分布的蚊虫物种——致倦库蚊（Culex tarsalis）为研究对象，调查了其临界热最大值（CT(max)）的种群水平差异以及对温度的代谢反应（MR-T）。从加利福尼亚州三个代表不同热环境栖息地的地点采集成年雌性致倦库蚊样本，并采用流动式呼吸测定法来确定CT(max)和MR-T之间的关系。三个种群的CT(max)存在显著差异，且与每个地点的最高温度呈正相关，但与平均温度无关。与来自温暖地区的两个种群相比，我们从低温、高海拔地点采集的致倦库蚊在每个测试温度下的代谢率都显著更高，这与之前栖息在寒冷气候中的变温动物热补偿的例子一致。MR-T斜率在栖息于温度变异性最低地点的蚊子中最为陡峭，而来自温度变异性较高的两个地点的蚊子的斜率则较浅。我们的研究结果表明了当地种群在各自环境中可能产生分化的程度，并表明热耐受性状的可塑性可能在介导对气候变化的适应能力方面发挥作用。此外，我们的研究强调了温度变异性和极端温度而非平均温度对于热性状进化的重要性。
