Northern ecosystems are experiencing rapid and large-scale changes driven by accelerated warming, which have profound effects on the terrestrial and freshwater biodiversity. A comprehensive understanding of the distribution of aquatic biodiversity of subarctic ecosystems is therefore needed to better predict future trajectories of their unique biodiversity. In this study, we examined the functional diversity of chironomid communities in subarctic lakes across a 1000 m-elevation gradient, reflecting gradual changes in temperature and landscape characteristics. Using fuzzy correspondence analyses, we investigated spatial variability in trait composition of chironomid communities from 100 lakes in northern Sweden, and tested the hypotheses that (1) climate directly and indirectly shapes chironomid trait composition across the studied gradient, and (2) that generalist taxa with smaller body size and broader food preferences are more able to persist in cold environments. Our results showed that complex interplays between direct (e.g. temperature) and indirect climate processes (e.g. elevation-driven changes in vegetation/habitats) affect the functional diversity of chironomid communities. Specifically, traits such as larval size, food preference and feeding habits were well separated along the gradient, and this pattern revealed that low elevation lakes with forested catchments tended to have more sediment-feeding taxa and larger larvae than those above the tree line. As expected, food resource availability in lakes is strongly linked to vegetation composition/cover, and traits related to resource exploitation in chironomid communities are therefore well constrained by landscape characteristics. Furthermore, our findings suggested that short life cycles could facilitate the development of viable population in northern and high-elevation lakes where the short ice-free period is a limiting factor, thus contradicting patterns showing smaller organisms in warmer environments reported for other invertebrates. As a consequence of climate warming, the highest elevation lakes in subarctic landscapes will likely lose their typical cold-adapted chironomid taxa along with their functional attributes leading to potential impacts on the food web structure and the overall functioning of northern lake ecosystems.

北部生态系统正经历着加速变暖的迅速而大规模的变化，这对陆地和淡水生物多样性产生了深远的影响。因此，需要全面了解亚北极生态系统水生生物多样性的分布，以更好地预测其独特生物多样性的未来轨迹。在这项研究中，我们检查了海拔1000 m梯度下亚弧湖中手足类动物群落的功能多样性，反映了温度和景观特征的逐渐变化。使用模糊对应分析，我们研究了瑞典北部100个湖泊的拟南芥群落特征组成的空间变异性，并检验了以下假设：（1）气候在研究的梯度上直接或间接地塑造了拟南芥特征组成，（2）具有较小体型和较宽泛食物偏爱的通才分类群在寒冷环境中更能持久。我们的结果表明，直接（例如温度）和间接气候过程（例如海拔驱动的植被/栖息地变化）之间复杂的相互作用影响了手足动物群落的功能多样性。具体而言，幼虫大小，食物偏爱和进食习惯等特征沿坡度很好地分开，并且这种模式表明，与林线上方相比，具有林木集水区的低海拔湖泊往往具有更多的以泥沙为食的分类单元和较大的幼虫。如预期的那样，湖泊中粮食资源的可获得性与植被组成/覆盖率密切相关，因此，与手足类动物群落资源开发有关的特征受到景观特征的制约。此外，我们的研究结果表明，较短的生命周期可以促进北部和高海拔湖泊中无冰期短的限制因素的生存种群的发展，因此与其他无脊椎动物报道的在较温暖环境中显示较小生物的模式相矛盾。气候变暖的结果是，亚北极景观中海拔最高的湖泊可能会失去其典型的冷适应性天目分类单元及其功能属性，从而对食物网结构和北部湖泊生态系统的整体功能产生潜在影响。我们的发现表明，较短的生命周期可以促进北部和高海拔湖泊中无冰期短的限制因素的生存种群的发展，因此与其他无脊椎动物报道的在较温暖的环境中显示较小生物的模式相矛盾。气候变暖的结果是，亚北极景观中海拔最高的湖泊可能会失去其典型的冷适应天龙座类群及其功能属性，从而对食物网结构和北部湖泊生态系统的整体功能产生潜在影响。我们的发现表明，较短的生命周期可以促进北部和高海拔湖泊中无冰期短的限制因素的生存种群的发展，因此与其他无脊椎动物报道的在较温暖的环境中显示较小生物的模式相矛盾。气候变暖的结果是，亚北极景观中海拔最高的湖泊可能会失去其典型的冷适应天龙座类群及其功能属性，从而对食物网结构和北部湖泊生态系统的整体功能产生潜在影响。