ABSTRACT: Species distributions are shifting in response to increased habitat temperatures as a result of ongoing climate change. Understanding variation in physiological plasticity among species and populations is important for predicting these distribution shifts. Interspecific variation in intertidal ectotherms’ short-term thermal plasticity has been well established. However, intraspecific variation among populations from differing thermal habitats remains a question pertinent to understanding the effects of climate change on species’ ranges. In this study, we explored upper thermal tolerance limits and plasticity of those limits using a foot muscle metric and 2 cardiac metrics (Arrhenius breakpoint temperature, ABT, and flatline temperature, FLT) in adult file limpets Lottia limatula. Limpets were collected from thermally different coastal and inland-estuarine habitats and held for 2 wk at 13, 17 or 21°C prior to thermal performance assays. Compared to limpets from the warm estuary site, limpets from the cold outer coast site had similar foot muscle critical thermal maxima (CT_max; 35.2 vs. 35.6°C) but lower cardiac thermal tolerances (ABT: 30.5 vs. 35.1°C). Limpets from the cold coast site had higher acclimation responses in foot muscle CT_max (0.22°C per 1°C rise in acclimation) than those of the warm estuary site (0.07°C per 1°C rise in acclimation), but lower acclimation responses in cardiac thermal tolerance (ABT: -0.85°C per 1°C rise in acclimation) than those of the estuary site (ABT: 0.10°C per 1°C rise in acclimation). Since outer coast populations had lower cardiac plasticity and higher mortalities in the warm acclimation, we predict L. limatula from colder habitats will be more susceptible to rising temperatures. Our findings illustrate the importance of population-specific variation in short-term thermal plasticity when considering the effects of climate change on ectotherms.

中文翻译：

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温度不同的足Lot的足部肌肉可塑性和心脏热极限

摘要：由于气候变化，栖息地温度升高，物种分布正在发生变化。了解物种和种群之间生理可塑性的变化对于预测这些分布变化很重要。潮间带等温线的短期热可塑性之间的种间差异已得到充分证实。然而，来自不同热生境的种群之间的种内变异仍然是与理解气候变化对物种范围的影响有关的问题。在这项研究中，我们使用足部肌肉度量标准和2个心脏度量标准（Arrhenius断点温度，ABT和扁平温度，FLT）探讨了成年文件贝贝Lottia limatula的耐热极限上限和可塑性。从热力不同的沿海和内陆河口栖息地收集帽毛，并在进行热性能分析之前于13、17或21°C保持2周。与来自温暖河口站点的帽贝相比，来自寒冷的外海岸站点的帽贝具有相似的足部肌肉临界热最大值（CT_最大值； 35.2 vs. 35.6°C），但心脏耐热性较低（ABT：30.5 vs. 35.1°C）。来自寒冷海岸地区的残肢在足部肌肉CT _max上具有更高的适应性反应（适应温度每升高1°C，温度升高0.22°C）（适应温度每升高1°C，温度升高0.07°C），但心脏热耐受性的适应性响应降低（ABT：-1.85°C，每1°C） C的上升幅度要比河口站点高（ABT：每1°C的上升幅度为0.10°C）。由于在温暖的气候条件下外海岸种群的心脏可塑性较低，而死亡率却较高，因此我们预测来自较冷栖息地的利马L.ulamatula将更容易受到温度升高的影响。我们的发现表明，当考虑气候变化对等温线的影响时，短期热可塑性中特定人群差异的重要性。