Data from: Latitudinal clines in alternative life histories in a geometrid moth

The relative roles of genetic differentiation and developmental plasticity in generating latitudinal gradients in life histories remain insufficiently understood. In particular, this applies to determination of voltinism (annual number of generations) in short-lived ectotherms, and the associated trait values. We studied different components of variation in development of Chiasmia clathrata (Lepidoptera: Geometridae) larvae that originated from populations expressing univoltine, partially bivoltine or bivoltine phenology along a latitudinal gradient of season length. Indicative of population-level genetic differentiation, larval period became longer while growth rate decreased with increasing season length within a particular phenology, but saw-tooth clines emerged across the phenologies. Indicative of phenotypic plasticity, individuals that developed directly into reproductive adults had shorter development times and higher growth rates than those entering diapause. The most marked differences between the alternative developmental pathways were found in the bivoltine region suggesting that the adaptive correlates of the direct development evolve if exposed to selection. Pupal mass followed a complex cline without clear reference to the shift in voltinism or developmental pathway probably due to varying interplay between the responses in development time and growth rate. The results highlight the multidimensionality of evolutionary trajectories of life history traits, which either facilitate or constrain the evolution of integrated traits in alternative phenotypes.

遗传分化与发育可塑性（developmental plasticity）在塑造生活史纬度梯度中的相对作用，迄今尚未得到充分阐明。具体而言，这一问题在短命外温动物（ectotherms）的年世代数（voltinism）及其相关性状值的决定机制中尤为突出。本研究以网尺蛾（*Chiasmia clathrata*，鳞翅目（Lepidoptera）：尺蛾科（Geometridae））的幼虫为研究对象，这些幼虫采自沿季节长度纬度梯度分布、分别表现为一化性、部分二化性或二化性物候的种群，我们分析了其发育过程中的不同变异组分。在特定物候型内，幼虫期随季节长度增加而延长、生长速率随之降低，这一现象指示了种群水平的遗传分化；而不同物候型间则呈现出锯齿状的梯度分布模式。直接发育为生殖成虫的个体，相较于进入滞育（diapause）的个体，发育时长更短、生长速率更高，这体现了表型可塑性（phenotypic plasticity）。不同发育路径间最显著的差异出现在二化性区域，这表明直接发育的适应性关联性状在经受选择压力时会发生演化。蛹重呈现出复杂的梯度分布模式，并未与年世代数或发育路径的转变呈现明确关联，这可能是发育时长与生长速率的响应间存在动态相互作用所致。本研究结果凸显了生活史性状演化轨迹的多维性，这类多维性既可能促进也可能限制不同表型下整合性状的演化。