Department of Biology, University of Maryland, College Park, MD, 20742, USA; Department of Biological Sciences, University of Alabama, Tuscaloosa, AL, 35487, USA.
Glob Chang Biol. 2014 Jun;20(6):1751-9. doi: 10.1111/gcb.12550. Epub 2014 Mar 25.
Reduction in body size is a major response to climate change, yet evidence in globally imperiled amphibians is lacking. Shifts in average population body size could indicate either plasticity in the growth response to changing climates through changes in allocation and energetics, or through selection for decreased size where energy is limiting. We compared historic and contemporary size measurements in 15 Plethodon species from 102 populations (9450 individuals) and found that six species exhibited significant reductions in body size over 55 years. Biophysical models, accounting for actual changes in moisture and air temperature over that period, showed a 7.1-7.9% increase in metabolic expenditure at three latitudes but showed no change in annual duration of activity. Reduced size was greatest at southern latitudes in regions experiencing the greatest drying and warming. Our results are consistent with a plastic response of body size to climate change through reductions in body size as mediated through increased metabolism. These rapid reductions in body size over the past few decades have significance for the susceptibility of amphibians to environmental change, and relevance for whether adaptation can keep pace with climate change in the future.
体型缩小是动物对气候变化的主要响应之一，但目前全球濒危两栖动物的相关证据还比较缺乏。种群平均体型的变化可能表明，由于能量限制，在气候变化下，动物通过改变资源分配和能量代谢来实现生长的可塑性响应，或者通过选择体型较小的个体来适应环境。我们比较了来自 102 个种群的 15 种盲螈（Plethodon）的历史和当代体型测量数据（共 9450 个个体），发现其中 6 种盲螈在 55 年间体型显著缩小。考虑到这段时间内实际的湿度和空气温度变化的生物物理模型表明，在三个纬度上，代谢支出增加了 7.1-7.9%，但活动的年持续时间没有变化。在经历最大干燥和变暖的南部地区，体型缩小幅度最大。我们的研究结果与体型大小对气候变化的可塑性响应一致，这种响应是通过增加代谢来介导的，从而导致体型缩小。过去几十年中，体型的这种快速缩小对两栖动物对环境变化的敏感性具有重要意义，也关系到未来适应能否跟上气候变化的步伐。
