Data from: Seasonality maintains alternative life history phenotypes

Many organisms express discrete alternative phenotypes (polyphenisms) in relation to predictable environmental variation. However, the evolution of alternative life history phenotypes remains poorly understood. Here, we analyze the evolution of alternative life histories in seasonal environments by using temperate insects as a model system. Temperate insects express alternative developmental pathways of diapause and direct development, the induction of a certain pathway affecting fitness through its life history correlates. We develop a methodologically novel and holistic simulation model and optimize development time, growth rate, body size, reproductive effort and adult lifespan simultaneously in both developmental pathways. The model predicts that direct development should be associated with shorter development time (duration of growth) and adult life span, higher growth rate and reproductive effort, smaller body size as well as lower fecundity compared to the diapause pathway, because the two generations divide the available time unequally. These predictions are consistent with many empirical data. Our analysis shows that seasonality alone can explain the evolution of alternative life histories.

诸多生物会依据可预测的环境变化，表达出离散型交替表型（polyphenisms）。然而，学界对交替生活史表型的演化机制仍缺乏深入认知。本研究以温带昆虫作为模式系统，分析季节性环境下交替生活史的演化规律。温带昆虫存在滞育（diapause）与直接发育两类交替发育路径，特定发育路径的诱导会通过其生活史关联性状影响个体适合度。我们构建了一种方法学上兼具创新性与整体性的模拟模型，并同时对两类发育路径下的发育时长、生长速率、体型大小、繁殖投入以及成虫寿命进行优化。该模型预测，相较于滞育路径，直接发育路径将伴随更短的发育时长（即生长周期）与成虫寿命、更高的生长速率与繁殖投入、更小的体型以及更低的繁殖力，其原因在于两代昆虫可利用的时间分配不均。上述预测与诸多实证研究结果相符。本研究分析表明，仅季节性因素即可解释交替生活史的演化过程。