Data from: Decoupled responses of soil bacteria and their invertebrate consumer to warming, but not freeze-thaw cycles, in the Antarctic Dry Valleys

Altered temperature profiles resulting in increased warming and freeze–thaw cycle (FTC) frequency pose great ecological challenges to organisms in alpine and polar ecosystems. We performed a laboratory microcosm experiment to investigate how temperature variability affects soil bacterial cell numbers, and abundance and traits of soil microfauna (the microbivorous nematode Scottnema lindsayae) from McMurdo Dry Valleys, Antarctica. FTCs and constant freezing shifted nematode body size distribution towards large individuals, driven by higher mortality among smaller individuals. FTCs reduced both bacterial and nematode abundance, but bacterial cell numbers also declined under warming, demonstrating decoupled consumer–prey responses. We predict that higher occurrence of FTCs in cold ecosystems will select for large body size within soil microinvertebrates and overall reduce their abundance. In contrast, warm temperatures without FTCs could lead to divergent responses in soil bacteria and their microinvertebrate consumers, potentially affecting energy and nutrient transfer rates in soil food webs of cold ecosystems.

升温加剧与冻融循环（freeze–thaw cycle, FTC）频率升高所导致的温度格局改变，给高山与极地生态系统中的生物带来了严峻的生态挑战。本研究通过实验室微宇宙实验，探究了温度动态变化对南极麦克默多干谷土壤细菌细胞数量，以及土壤微型动物（食微线虫Scottnema lindsayae）的丰度与功能性状的影响。研究发现：冻融循环与持续低温使线虫体型分布向大型个体偏移，这一现象由小型个体更高的死亡率所驱动；冻融循环会同时降低细菌与线虫的丰度，但升温环境下细菌细胞数量也会出现下降，表明消费者与猎物的响应存在解耦现象。我们预测，寒冷生态系统中冻融循环发生频率的升高，将促使土壤微型无脊椎动物向大型体型方向演化，并整体降低其种群丰度。与之相反，无冻融循环的升温环境可能会使土壤细菌及其微型无脊椎动物消费者产生差异化响应，进而可能影响寒冷生态系统土壤食物网的能量与养分传递速率。