Data from: Trophic structure alters consequences of environmental warming

Climate warming can directly affect traits and demographic rates of organisms. However, individuals are embedded in complex networks of ecological interactions with other members of the community, allowing for a range of direct and indirect effects that depend on the trophic structure of the community. Here we show that effects of warming (i.e. increase in mean temperature) on a given species can strongly depend on the community context and trophic complexity of the system. Specifically, we manipulated the presence/ absence of two competing tadpole species and their dragonfly predators to simulate different food webs of increasing complexity that were exposed to ambient or warmed conditions. We found that warming dramatically reduced herbivore (tadpole) survival in the absence of strong interspecific competition and predation, but it had no measureable effect on demographic rates on the dominant competitor in more complex communities where it was exposed to interspecific competition and predation. Conversely, our results also indicate that warming reduced the strength of interspecific competition and predation in our system. These results suggest that trophic complexity could potentially buffer climate change effects on populations and emphasize that we often cannot predict the effects of changes in abiotic conditions on a given population without accounting for the community context.气候变暖可直接影响生物的性状与种群统计参数。然而，生物个体嵌入于与群落其他成员构成的复杂生态相互作用网络中，由此产生一系列依赖于群落营养结构的直接与间接效应。在此我们证实，变暖（即平均温度升高）对某一特定物种的影响，在很大程度上取决于该系统的群落背景与营养复杂性。具体而言，我们通过调控两种竞争型蝌蚪物种及其蜻蜓捕食者的存在与否，模拟了复杂度依次递增的不同食物网，并将其分别置于常温对照与变暖环境中。我们发现，在缺乏强烈种间竞争与捕食作用的情境下，变暖会显著降低植食性动物（蝌蚪）的存活率；但在更为复杂的群落中，当优势竞争者面临种间竞争与捕食作用时，变暖对其种群统计参数无显著可测效应。与之相反，本研究结果同时表明，在该实验系统中，变暖会削弱种间竞争与捕食作用的强度。上述结果提示，营养复杂性或可缓冲气候变化对种群的影响，同时也强调：若不考虑群落背景，我们往往无法准确预测非生物条件变化对特定种群的效应。