Species’ geographic range shifts toward higher latitudes and elevations are among the most frequently reported consequences of climate change. However, the role of species interactions in setting range margins remains poorly understood. We used cage experiments in ponds to test competing hypotheses about the role of abiotic and biotic mechanisms for structuring range boundaries of an upslope range‐shifting caddisfly Limnephilus picturatus. We found that competition with a ubiquitous species Limnephilus externus significantly decreased L. picturatus survival and emergence at subalpine elevations supporting the notion that species interactions play a critical role in determining upslope range limits. However, without competitors, L. picturatus survival was greater at high‐elevation than low‐elevation sites. This was contrary to decreases in body mass (a proxy for fecundity) with elevation regardless of the presence of competitors. We ultimately show that species interactions can be important for setting upslope range margins. Yet, our results also highlight the complications in defining what may be abiotically stressful for this species and the importance of considering multiple demographic variables. Understanding how species ranges will respond in a changing climate will require quantifying species interactions and how they are influenced by the abiotic context in which they play out.

中文翻译：

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高程改变常驻物种和范围转移物种之间竞争的结果

物种向更高纬度和海拔的地理范围转移是气候变化最常报告的后果之一。但是，人们对物种相互作用在设定范围裕度中的作用还知之甚少。我们在池塘中使用网箱实验来检验关于非生物和生物机制在构造高程范围移位的线虫鳞翅目Limnephilus picturatus的范围边界中的作用的竞争性假设。我们发现一个普遍存在的物种竞争Limnephilus externus显著下跌L. picturatus在高山海拔支持的概念，即物种之间的相互作用决定上坡范围限制发挥关键作用的生存和出现。但是，没有竞争对手，L。picturatus高海拔地区的生存率高于低海拔地区。这与体重增加（代表生殖力）的降低相反，而与竞争者的存在无关。我们最终表明，物种之间的相互作用对于建立坡度范围裕度可能很重要。然而，我们的研究结果也凸显了定义什么可能对该物种造成非生物胁迫的复杂性以及考虑多个人口统计学变量的重要性。要了解物种范围如何在变化的气候中做出反应，就需要量化物种之间的相互作用，以及它们如何受到非生物环境的影响。