Department of Biology, University of Virginia, Charlottesville, VA, USA.
School of Biosciences, Ecology and Evolutionary Biology, University of Sheffield, Sheffield, UK.
Nat Ecol Evol. 2022 Oct;6(10):1449-1457. doi: 10.1038/s41559-022-01837-5. Epub 2022 Aug 18.
The adaptive nature of phenotypic plasticity is widely documented. However, little is known about the evolutionary forces that shape genetic variation of plasticity within populations. Whether genetic variation in plasticity is driven by stabilizing or diversifying selection and whether the strength of such forces remains constant through time, remain open questions. Here, we address this issue by assessing the evolutionary forces that shape genetic variation in antipredator developmental plasticity of Daphnia pulex. Antipredator plasticity in D. pulex is characterized by the growth of a pedestal and spikes in the dorsal head region upon exposure to predator cue. We characterized genetic variation in plasticity using a method that describes the entire dorsal shape amongst >100 D. pulex strains recently derived from the wild. We observed the strongest reduction in genetic variation in dorsal areas where plastic responses were greatest, consistent with stabilizing selection. We compared mutational variation (V) to standing variation (V) and found that V/V is lowest in areas of greatest plasticity, again consistent with stabilizing selection. Our results suggest that stabilizing selection operates directly on phenotypic plasticity in Daphnia and provide a rare glimpse into the evolution of fitness-related traits in natural populations.
表型可塑性的适应性是被广泛记录的。然而，对于塑造种群内可塑性遗传变异的进化力量知之甚少。可塑性的遗传变异是由稳定选择还是多样化选择驱动的，以及这些力量的强度是否随时间保持不变，这些仍然是悬而未决的问题。在这里，我们通过评估塑造多刺裸腹溞（Daphnia pulex）防御性发育可塑性遗传变异的进化力量来解决这个问题。多刺裸腹溞的防御性可塑性的特征是在暴露于捕食者线索时，头部背部区域生长出一个基座和刺。我们使用一种方法来描述最近从野外衍生的 100 多个多刺裸腹溞菌株的整个背部形状，从而确定了可塑性的遗传变异。我们观察到在最大的可塑性反应的背部区域，遗传变异的减少最大，这与稳定选择一致。我们将突变变异 (V) 与现有变异 (V) 进行了比较，发现最大可塑性区域的 V/V 最低，这再次与稳定选择一致。我们的结果表明，稳定选择直接作用于多刺裸腹溞的表型可塑性，并为自然种群中与适应性相关的特征的进化提供了罕见的视角。
