Data from: Genetic and phenotypic variation in juvenile development in relation to temperature and developmental pathway in a geometrid moth

Life histories show genetic population-level variation due to spatial variation in selection pressures. Phenotypic plasticity in life histories is also common, facilitating fine-tuning of the phenotype in relation to the prevailing selection regime. In multivoltine (≥ 2 generations / year) insects, individuals following alternative developmental pathways (diapause / direct development) experience different selection regimes. We studied the genetic and phenotypic components of juvenile development in Cabera exanthemata (Lepidoptera: Geometridae) in a factorial split-brood experiment. F2 offspring of individuals originating from populations in northern and central Finland were divided among manipulations defined by temperature (14ºC / 20ºC) and day length (24h / 15h). Short day length invariably induced diapause, whereas continuous light almost invariably induced direct development in both regions, although northern populations are strictly univoltine in the wild. Individuals from northern Finland had higher growth rates, shorter development times and higher pupal masses than individuals from central Finland across the conditions, indicating genetic differences between regions. Individuals that developed directly into adults tended to have higher growth rates, shorter development times and higher pupal masses than those entering diapause, indicating phenotypic plasticity. Temperature-induced plasticity was substantial; growth rate was much higher, development time much shorter and pupal mass higher at 20ºC than at 14ºC. The degree of plasticity in relation to developmental pathway was pronounced at 20ºC in growth rate and development time and at 14ºC in pupal mass, emphasizing multidimensionality of reaction norms. The observed genetic variation and developmental plasticity seem adaptive in relation to time-stress due to seasonality.

生命史（life histories）因选择压力的空间异质性而呈现种群水平的遗传变异。表型可塑性（phenotypic plasticity）在生命史特征中亦十分常见，可帮助表型根据主导性选择格局进行精细调控。在多化性（multivoltine，即每年至少发生2个世代）昆虫中，采取不同发育路径（滞育（diapause）/直接发育（direct development））的个体所面临的选择格局存在差异。本研究以赤尺蛾（Cabera exanthemata，鳞翅目（Lepidoptera）尺蛾科（Geometridae））为研究对象，采用析因分群实验设计（factorial split-brood experiment），探究其幼体发育的遗传与表型组分。研究采集芬兰北部与中部种群的个体，获得其F2代后代，并将后代分配至由温度（14℃/20℃）和光照时长（24h/15h）设置的各实验处理组中。短光照时长始终诱导滞育，而持续光照在两个种群中几乎均诱导直接发育——尽管野生状态下北部种群严格为一化性（univoltine，每年仅发生1个世代）。在所有实验处理条件下，芬兰北部种群的个体均表现出更快的生长速率、更短的发育时长以及更大的蛹重，这表明不同区域的种群间存在遗传分化。与进入滞育的个体相比，直接发育为成虫的个体通常具有更快的生长速率、更短的发育时长以及更大的蛹重，这体现了表型可塑性。温度诱导的表型可塑性十分显著：与14℃相比，20℃条件下个体的生长速率更快、发育时长更短、蛹重更大。与发育路径相关的可塑性程度在20℃条件下对生长速率和发育时长的影响尤为显著，而在14℃条件下对蛹重的影响更为突出，这凸显了反应规范（reaction norms）的多维性。本研究观测到的遗传变异与发育可塑性，似乎与季节性带来的时间压力相适应。