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，分布于更高海拔或纬度的物种种群/支系个体，体型要大于低海拔或低纬度区域的同类。本研究对已发表的有关昆虫体型沿纬度或海拔梯度发生种间与种内变异的文献开展了系统综述，旨在探究此类梯度模式的出现频次，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。几乎同等数量的研究分别报道了贝格曼梯度与逆贝格曼梯度（Converse Bergmann clines）——即随着纬度或海拔升高，昆虫体型逐渐变小。实际上，绝大多数研究均未发现此类梯度模式。研究范围过小可能掩盖了部分梯度模式，而范围过大则可能引入人为伪迹。相较于种间模式研究，种内模式研究因支系内物种间的变异，更难发现梯度模式，这使得种间研究的参考价值有限。贝格曼法则并不像适用于恒温脊椎动物（endothermic vertebrates）那样，普遍适用于六足动物（hexapods）。针对任何类群与研究范围的昆虫而言，贝格曼法则的适用性均具有高度的个体特异性，且部分取决于研究设计。本研究认为，有关“贝格曼法则”的研究应聚焦于物种内部，并关注分布广泛且连续的种群，以纳入所有变异来源同时最大限度降低误差。