Abstract：
Understanding the causes of morphological variation of organisms along climatic gradients has been a central challenge in ecological research. We studied the variation of community weighted mean (CWM) and two functional diversity metrics (Rao-Q and functional richness) computed for five morphological traits of wild bees (Hymenoptera: Apoidea) related to thermal performance (namely body size, relative appendage length and hairiness), at community and interspecific levels, along an elevation gradient in a Mexical-type scrubland. At the community level we found a decreasing CWM of body size pattern with increasing elevation which is consistent with the species-energy theory (and contrary to Bergmann\'s rule). We also found an increase in the CWM of relative tibia length, which is contrary to Allen\'s rule. Additionally, we found an increase in the CWM of relative hair length towards high levels of elevation, which would be consistent with the hypothesis that hairiness plays an important role as thermal insulation. We found that functional diversity was larger at low elevations with respect to high elevation for body size and hair length, which could imply that highland communities were more sensitive towards environmental changes than lowland communities. Overall, at intraspecific level, most of species showed no pattern for any of the traits along the elevation gradient. Future research should provide further evidence on the possible behavioral or physiological mechanisms behind it.
摘要：
了解生物沿气候梯度的形态变化的原因一直是生态学研究中的主要挑战。我们研究了与热性能（即体型，相对附件长度和毛羽)，在社区和种间层面，沿着Mexical型灌木丛中的海拔梯度。在社区一级，我们发现体型模式的CWM随着海拔的增加而降低，这与物种能量理论一致（与Bergmann规则相反）。我们还发现相对胫骨长度的CWM增加，这违反了艾伦的规则。此外,我们发现相对头发长度的CWM向高海拔水平增加，这与毛羽在隔热中起重要作用的假设是一致的。我们发现，相对于高海拔而言，低海拔地区的身体大小和头发长度的功能多样性更大，这可能意味着高地社区比低地社区对环境变化更敏感。总的来说,在种内水平，大多数物种在海拔梯度上没有任何特征的模式。未来的研究应该为其背后可能的行为或生理机制提供进一步的证据。
