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 dif...

遗传分化（genetic differentiation）与发育可塑性（developmental plasticity）在塑造生活史（life histories）纬度梯度（latitudinal gradients）中的相对作用，迄今仍未得到充分阐明。针对短命外温动物（ectotherms）的化性（voltinism，即年世代数）及其相关性状值（trait values）的确定这一特定问题，现有认知仍存在显著缺口。我们以沿季节长度纬度梯度分布、分别表现为一化性（univoltine）、部分二化性（partially bivoltine）或二化性（bivoltine）物候（phenology）的双斑长尺蛾（*Chiasmia clathrata*，鳞翅目Lepidoptera：尺蛾科Geometridae）幼虫的发育变异各组分为研究对象展开探究。在特定物候类群内，幼虫期（larval period）随季节长度增加而延长，生长速率（growth rate）随之降低，这一结果印证了种群水平的遗传分化；而不同物候类群之间则呈现出锯齿状渐变群（saw-tooth clines）。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）。最为显著的差异……