Data from: Latitudinal and voltinism compensation shape thermal reaction norms for growth rate

Latitudinal variation in thermal reaction norms of key fitness traits may inform about the response of populations to climate warming, yet their adaptive nature and evolutionary potential is poorly known. We assessed the contribution of quantitative genetic, neutral genetic and environmental effects to thermal reaction norms of growth rate for populations of the damselfly Ischnura elegans. Among populations, reaction norms differed primarily in elevation suggesting that time constraints associated with shorter growth seasons in univoltine, high-latitude as well as multivoltine, low-latitude populations selected for faster growth rates. Phenotypic divergence among populations is consistent with selection rather than drift as QST was greater than FST in all cases. QST estimates increased with experimental temperature and were influenced by genotype by environment interactions. Substantial additive genetic variation for growth rate in all populations suggests that evolution of trait means in different environments is not constrained. Heritability of growth rates was higher at high temperature, driven by increased genetic rather than environmental variance. While environment-specific non-additive effects also may contribute to heritability differences among temperatures, maternal effects did not play a significant role (where these could be accounted for). Genotype by environment interactions strongly influenced the adaptive potential of populations, and our results suggest the potential for microevolution of thermal reaction norms in each of the studied populations. In summary, the observed latitudinal pattern in growth rates is adaptive and results from a combination of latitudinal and voltinism compensation. Combined with the evolutionary potential of thermal reaction norms, this may affect populations’ ability to respond to future climate warming.

关键适合度性状（fitness traits）的热反应规范（thermal reaction norms）的纬度变异，可为种群应对气候变暖的响应提供科学参考，但其适应性本质与进化潜力却鲜为人知。我们针对蓝尾豆娘（Ischnura elegans）的不同种群，评估了数量遗传（quantitative genetic）、中性遗传（neutral genetic）与环境效应对其生长速率热反应规范的贡献。种群间的热反应规范差异主要体现为截距（即整体表现水平）的不同，这表明高纬度一化性（univoltine）种群与低纬度多化性（multivoltine）种群的生长季均较短，由此产生的时间约束对更快的生长速率施加了定向选择。种群间的表型分化（phenotypic divergence）符合选择作用而非遗传漂变（genetic drift）的预期，因为所有场景下的数量遗传分化指数（QST, quantitative genetic differentiation）均大于遗传分化固定指数（FST, fixation index）。QST估计值随实验温度升高而增加，且受基因型×环境互作（genotype by environment interactions）的影响。所有种群中均存在显著的生长速率加性遗传变异（additive genetic variation），这意味着不同环境下的性状均值进化并不受约束。受遗传方差（而非环境方差）升高的驱动，高温下的生长速率遗传力（heritability）更高。尽管环境特异性的非加性效应也可能导致不同温度下的遗传力差异，但母体效应（maternal effects）并未发挥显著作用（在可评估的范围内）。基因型×环境互作强烈影响种群的适应性进化潜力，我们的研究结果表明，本次研究所涉的所有种群均存在热反应规范的微进化（microevolution）潜力。综上，观测到的生长速率纬度格局具有适应性，是纬度梯度与化性（voltinism）补偿共同作用的结果。结合热反应规范的进化潜力，这可能会影响种群应对未来气候变暖的能力。