Abstract：
Warming temperatures are altering communities and trophic networks across Earth\'s ecosystems. While the overall influence of warming on food webs is often context-dependent, increasing temperatures are predicted to change communities in two fundamental ways: (1) by reducing average body size and (2) by increasing individual metabolic rates. These warming-induced changes have the potential to influence the distribution of food web fluxes, food web stability, and the relative importance of deterministic and stochastic ecological processes shaping community assembly. Here, we quantified patterns and the relative distribution of organic matter fluxes through stream food webs spanning a broad natural temperature gradient (5-27°C). We then related these patterns to species and community trait distributions of mean body size and population biomass turnover (P:B) within and across streams. We predicted that (1) communities in warmer streams would exhibit smaller body size and higher P:B and (2) organic matter fluxes within warmer communities would increasingly skew toward smaller, higher P:B populations. Across the temperature gradient, warmer communities were characterized by smaller body size (~9% per °C) and higher P:B (~7% faster turnover per °C) populations on average. Additionally, organic matter fluxes within warmer streams were increasingly skewed toward higher P:B populations, demonstrating that warming can restructure organic matter fluxes in both an absolute and relative sense. With warming, the relative distribution of organic matter fluxes was decreasingly likely to arise through the random sorting of species, suggesting stronger selection for traits driving high turnover with increasing temperature. Our study suggests that a warming world will favor energy fluxes through \"smaller and faster\" populations, and that these changes may be more predictable than previously thought.
摘要：
变暖的温度正在改变地球生态系统中的群落和营养网络。虽然变暖对食物网的总体影响通常取决于环境，预计温度升高将以两种基本方式改变社区：（1）通过减少平均体型和（2）通过增加个体代谢率。这些变暖引起的变化有可能影响食物网通量的分布，食物网稳定性，以及确定性和随机生态过程对社区聚集的相对重要性。这里,我们量化了跨自然温度梯度（5-27°C）的食物网的有机物通量的模式和相对分布。然后，我们将这些模式与河流内部和河流之间的平均体型和种群生物量周转（P：B）的物种和群落特征分布相关联。我们预测（1）温暖溪流中的社区将表现出较小的体型和较高的P：B，以及（2）温暖社区中的有机物通量将越来越偏向较小，较高的P：B群体。穿过温度梯度，较温暖的社区的特征是平均体型较小（每°C〜9％）和P：B较高（每°C的周转快〜7％）。此外,较温暖的溪流中的有机物通量越来越向较高的P：B种群倾斜，证明变暖可以在绝对和相对意义上重组有机质通量。随着变暖，通过物种的随机分类，有机物通量的相对分布可能会逐渐减少，表明随着温度的升高，对驱动高周转的性状的选择更强。我们的研究表明，变暖的世界将有利于通过“更小，更快的人口”的能量通量，这些变化可能比以前想象的更可预测。
