Data from: Selection in a fluctuating environment leads to decreased genetic variation and facilitates the evolution of phenotypic plasticity

Changes in the environment are expected to induce changes in the quantitative genetic variation, which influences the ability of a population to adapt to environmental change. Furthermore, environmental changes are not constant in time, but fluctuate. Here we investigate the effect of rapid, continuous and/or fluctuating temperature changes in the seed beetle Callosobruchus maculatus, using an evolution experiment followed by a split brood experiment. In line with expectations, individuals responded in a plastic way and had an overall higher potential to respond to selection after a rapid change in the environment. After selection in an environment with increasing temperature, plasticity remained unchanged (or decreased) and environmental variation decreased, especially when fluctuations were added; these results were unexpected. As expected, the genetic variation decreased after fluctuating selection. Our results suggest that fluctuations in the environment have major impact on the response of a population to environmental change; in a highly variable environment with low predictability a plastic response might not be beneficial and the response is genetically and environmentally canalized resulting in a low potential to respond to selection and low environmental sensitivity. Interestingly, we found greater variation for phenotypic plasticity after selection, suggesting that the potential for plasticity to evolve is facilitated after exposure to environmental fluctuations. Our study highlights that environmental fluctuations should be considered when investigating the response of a population to environmental change.环境变化预计会引发数量遗传变异（quantitative genetic variation）的改变，而该变异会影响种群适应环境变化的能力。此外，环境变化并非恒定不变，而是随时间波动。本研究以豆象（Callosobruchus maculatus）为实验对象，通过进化实验（evolution experiment）结合分窝实验（split brood experiment），探究快速、持续及/或波动的温度变化对其产生的效应。与预期一致，个体表现出表型可塑性响应，且在环境快速变化后，整体应对选择的潜力更高。在升温环境中经历选择后，表型可塑性保持不变（或有所下降），且环境变异程度降低，尤其在加入波动因素后更为显著——这一结果出乎我们的意料。正如预期，波动选择后种群的遗传变异有所下降。我们的研究结果表明，环境波动对种群响应环境变化的过程具有显著影响：在可预测性较低的高度可变环境中，表型可塑性响应可能并非有利，此时种群的性状会在遗传与发育层面被渠化，进而表现出较低的选择响应潜力与环境敏感性。有趣的是，我们发现经历选择后，表型可塑性的变异程度更高，这提示暴露于环境波动后，表型可塑性的进化潜力会得到促进。本研究强调，在探究种群对环境变化的响应时，应当将环境波动纳入考量范畴。