Laboratory of Ecology, Department of Biological and Environmental Sciences and Technologies, University of the Salento, 73100, Lecce, Italy; NBFC, National Biodiversity Future Center, 90133, Palermo, Italy.
Laboratory of Ecology, Department of Biological and Environmental Sciences and Technologies, University of the Salento, 73100, Lecce, Italy.
J Therm Biol. 2024 Aug;124:103941. doi: 10.1016/j.jtherbio.2024.103941. Epub 2024 Aug 10.
The responses of organisms to climate change are mediated primarily by its impact on their metabolic rates, which, in turn, drive various biological and ecological processes. Although there have been numerous seminal studies on the sensitivity of metabolic rate to temperature, little is empirically known about how this rate responds to seasonal temperature ranges and beyond under conservative IPCC climate change scenarios. Here, we measured the SMR of the aquatic amphipod, Gammarus insensibilis, which served as our subject species, with body masses ranging from 0.20 to 7.74 mg ash free weight. We assessed the response of the SMR across nine temperature levels ranging from 12 to 30.2 °C. These temperatures match seasonal temperature norms, with an incremental increase of 0.6-1.2 °C above each seasonal baseline, as projected for the years 2040 and 2100 under the modest climate change scenarios. Overall, our findings showed that the effect of temperature on SMR varies with body mass, as indicated by a negative size-temperature interaction, with larger conspecifics exhibiting less sensitivity to temperature changes than smaller ones. From the cold to warm season, the SMR increased by an average of 14% °C, with increases of 18.4% °C in smaller individuals and 11.4% °C in larger ones. The SMR of smaller individuals peaked at a 0.6 °C increase from the current summer baseline (15.08% °C, Q10 = 4.2), while in larger ones it peaked with a 1.2 °C increase beyond autumn temperatures (14.9% °C, Q10 = 3.9). However, at temperatures reflecting global warming that exceed summer temperatures, the SMR of larger individuals levelled off, while that of smaller ones continued to increase. Overall, our findings suggest that smaller-sized individuals have a broader thermal window for SMR performance, while the SMR of larger-sized ones will become increasingly constrained at summer temperatures as those summer temperatures become hotter.
生物体对气候变化的反应主要受其对代谢率的影响所介导，而代谢率又驱动着各种生物和生态过程。尽管已经有许多关于代谢率对温度敏感性的开创性研究，但实际上我们对于代谢率如何响应季节性温度范围以及在保守的 IPCC 气候变化情景下超出该范围的情况知之甚少。在这里，我们测量了水生端足目动物无节幼体（Gammarus insensibilis）的标准代谢率（SMR），该动物的体重范围为 0.20 至 7.74 毫克无灰重。我们评估了 SMR 在 12 至 30.2°C 的九个温度水平上的响应。这些温度与季节性温度规范相匹配，每个季节的基线温度都升高了 0.6-1.2°C，这是根据 2040 年和 2100 年适度气候变化情景下的预测得出的。总的来说，我们的研究结果表明，温度对 SMR 的影响因体重而异，这表现为负的大小-温度相互作用，体型较大的同种动物对温度变化的敏感性低于体型较小的动物。从冷季到暖季，SMR 平均增加了 14%°C，其中较小个体的增加幅度为 18.4%°C，较大个体的增加幅度为 11.4%°C。较小个体的 SMR 在比当前夏季基线高出 0.6°C 的温度时达到峰值（15.08%°C，Q10=4.2），而在较大个体中，在超过秋季温度 1.2°C 时达到峰值（14.9%°C，Q10=3.9）。然而，在反映夏季温度升高的全球变暖温度下，较大个体的 SMR 趋于平稳，而较小个体的 SMR 继续增加。总的来说，我们的研究结果表明，较小体型的个体有更宽的 SMR 表现热窗，而较大体型的个体的 SMR 将在夏季温度变得更高时受到越来越多的限制。
