Data from: Where are we now? Bergmann's Rule sensu lato in insects

Bergmann's rule states that individuals of a species/clade at higher altitudes or latitudes will be larger than species at lower ones. A systemic review of the known literature on inter- and intraspecific variation in insect size along latitudinal or altitudinal clines was done to see how often such clines appeared and if they reflected class-wide, species-specific, or experimentally biased tendencies. Nearly even numbers of studies showed Bergmann clines and Converse Bergmann clines, where insects get smaller as latitude/altitude increases. In fact, the majority of studies suggested no clines at all. Small ranges may have obscured certain clines, while giant ranges may have introduced artifacts. Researchers examining interspecific patterns found clines less frequently than those examining intraspecific patterns due to variation among species within the clades, which renders interspecific studies unhelpful. Bergmann's Rule does not apply to hexapods with nearly the same consistency as it does to endothermic vertebrates. The validity of Bergmann's Rule for any group and range of insects is highly idiosyncratic and partially depends on the study design. We conclude that studies of "Bergmann's Rule" should focus within species and look at widespread but contiguous populations to account for all sources of variation while minimizing error.

贝格曼法则（Bergmann's Rule）指出，栖息于更高海拔或纬度的物种/支系个体，体型要大于低海拔或低纬度的同类。本研究对已发表的、关于昆虫体型沿纬度或海拔梯度存在种间与种内变异的相关文献开展系统性综述，旨在探究此类体型梯度的出现频率，以及其是否反映了类群共性、物种特异性或实验偏倚带来的趋势。显示存在贝格曼梯度与反向贝格曼梯度（即昆虫体型随纬度/海拔升高而减小）的研究数量近乎相当。事实上，绝大多数研究并未观测到此类体型梯度。采样范围过小可能掩盖部分梯度模式，而采样范围过大则可能引入人为伪迹。相较于种内格局研究，分析种间模式的研究者更少发现体型梯度，这是由于支系内各物种间存在变异，使得种间研究的结论参考价值有限。贝格曼法则并不像适用于恒温脊椎动物那样，能稳定地推广至六足动物。针对任意昆虫类群与研究范围的贝格曼法则有效性，均具有高度的特异性，且在一定程度上取决于研究设计方案。综上，有关“贝格曼法则”的研究应聚焦于物种内部，并选取分布广泛且连续的种群作为研究对象，以便在尽可能降低误差的同时，全面考量所有变异来源。