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，其中尤以短命变温动物的化性（voltinism，每年发生的世代数）决定及其相关性状的研究最为不足。本研究针对沿季节长度纬度梯度分布、呈现一化性、部分二化性或二化性物候型的网尺蛾（Chiasmia clathrata，鳞翅目：尺蛾科）幼虫，对其发育过程中的不同变异组分展开了系统研究。在特定物候型内，随季节长度增加，幼虫期延长而生长速率降低，这一结果暗示种群水平存在遗传分化；而跨不同物候型时则呈现出锯齿状渐变群。就表型可塑性而言，直接发育为生殖成虫的个体相较于进入滞育的个体，具有更短的发育时长与更高的生长速率。在二化性区域中，两种发育路径间的差异最为显著，这表明若暴露于选择压力下，直接发育的适应性关联特征会发生演化。蛹重呈现出复杂的渐变群，其变化与化性或发育路径的转变并无明确关联，这可能是发育时长与生长速率的响应间存在差异化相互作用所致。本研究结果凸显了生活史性状进化轨迹的多维性——这类轨迹既可能促进，也可能限制替代表型中整合性状的演化。