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.

中文翻译：

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环境变暖增加了河流食物网中高周转能量通道的重要性

气温升高正在改变地球生态系统的群落和营养网络。虽然变暖对食物网的总体影响通常取决于具体情况，但预计气温升高将以两种基本方式改变群落：（1）减少平均体型；（2）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、食物网稳定性以及塑造群落组装的确定性和随机生态过程的相对重要性。在这里，我们量化了跨越广泛的自然温度梯度（5-27°C）的河流食物网中有机物通量的模式和相对分布。然后，我们将这些模式与平均体型和种群生物量周转的物种和群落特征分布联系起来（磷:乙）在流内和跨流。我们预测 (1) 温暖河流中的群落会表现出更小的体型和更高的体型。压力：B(2) 较温暖的社区内的有机物通量将越来越倾向于更小、更高的区域压力：B人口。在整个温度梯度上，较温暖的群落的特点是体型较小（每°C约9%）和较高的体型。压力：B（每摄氏度周转速度加快约 7%）种群数量平均。此外，较温暖河流内的有机物通量越来越倾向于较高的压力：B人口，证明变暖可以在绝对和相对意义上重组有机物通量。随着变暖，有机物通量的相对分布通过物种的随机排序而出现的可能性降低，这表明随着温度的升高，对驱动高周转的性状进行了更强的选择。我们的研究表明，全球变暖将有利于通过“更小、更快”的人口来实现能量通量，而且这些变化可能比之前想象的更容易预测。