Body size is a crucial functional trait that influences the environmental filtering processes of animal communities. However, the role of intraspecific variations in soil invertebrate communities remains poorly understood. In this study, we investigated the influence of environmental changes on intraspecific body size variations in Collembola communities along an elevational gradient in northern Japan, using potential body length in the literature cited and realized body length actually measured. Our hypothesis posits that environmental conditions selectively filtered out smaller nymphs while sparing larger adults of Collembola, as stress tolerance, survival and mortality are directly influenced by body size in response to environmental severity. Calculating size quantiles based on observed realized individual body lengths, we found a stable size hierarchy among species across elevational sites. Species composition was significantly related with elevational gradient, with community-weighted means of smaller quantiles in body length increasing at higher elevations, while those of larger quantiles and adult body size remained unaffected. This suggests that environmental filtering predominantly influences the body size of smaller individuals, such as nymphs, but not larger adults within species. Our findings reveal asymmetric size selection among different life stages in soil animal communities.

中文翻译：

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日本北部沿海拔梯度跳虫群落种内体型大小的不对称环境选择

体型是影响动物群落环境过滤过程的重要功能特征。然而，人们对土壤无脊椎动物群落种内变异的作用仍然知之甚少。在本研究中，我们利用引用文献中的潜在体长和实际测量的体长，研究了环境变化对日本北部沿海拔梯度的跳虫群落种内体型变化的影响。我们的假设认为，环境条件选择性地过滤掉较小的若虫，同时保留较大的跳虫成虫，因为应激耐受性、生存和死亡率直接受到体型大小的影响，以应对环境的严重程度。根据观察到的个体体长计算体型分位数，我们发现不同海拔地区的物种之间存在稳定的体型等级。物种组成与海拔梯度显着相关，体长较小分位数的群落加权平均值随海拔升高而增加，而体长较大分位数和成虫体型的群落加权平均值不受影响。这表明环境过滤主要影响较小个体的体型，例如若虫，但不会影响物种内较大的成虫。我们的研究结果揭示了土壤动物群落不同生命阶段之间的不对称大小选择。