Knox Matthew A, Andriuzzi Walter S, Buelow Heather N, Takacs-Vesbach Cristina, Adams Byron J, Wall Diana H
Department of Biology, Colorado State University, Fort Collins, CO, 80523, USA.
Hopkirk Research Institute, IVABS, Massey University, Private Bag 11-222, Palmerston North, 4474, New Zealand.
Ecol Lett. 2017 Oct;20(10):1242-1249. doi: 10.1111/ele.12819. Epub 2017 Aug 10.
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.
温度变化导致升温加剧和冻融循环（FTC）频率增加，这给高山和极地生态系统中的生物带来了巨大的生态挑战。我们进行了一项实验室微观实验，以研究温度变异性如何影响来自南极洲麦克默多干谷的土壤细菌细胞数量以及土壤小型动物（以微生物为食的线虫林赛氏斯考特线虫）的丰度和特征。冻融循环和持续冻结使线虫的体型分布向大型个体转变，这是由较小个体的较高死亡率驱动的。冻融循环降低了细菌和线虫的丰度，但在升温条件下细菌细胞数量也下降了，这表明消费者与猎物的反应脱钩。我们预测，寒冷生态系统中冻融循环的更高发生率将促使土壤微型无脊椎动物体型变大，并总体上降低它们的丰度。相比之下，没有冻融循环的温暖温度可能导致土壤细菌及其微型无脊椎动物消费者产生不同的反应，这可能会影响寒冷生态系统土壤食物网中的能量和养分转移速率。
