Data from: The alignment between phenotypic plasticity, the major axis of genetic variation and the response to selection

Phenotypic plasticity is the ability of a genotype to produce more than one phenotype in order to match the environment. Recent theory proposes that the major axis of genetic variation in a phenotypically plastic population can align with the direction of selection. Therefore, theory predicts that plasticity directly aids adaptation by increasing genetic variation in the direction favoured by selection and reflected in plasticity. We evaluated this theory in the freshwater crustacean Daphnia pulex, facing predation risk from two contrasting size-selective predators. We estimated plasticity in several life-history traits, the G matrix of these traits, the selection gradients on reproduction and survival, and the predicted responses to selection. Using these data, we tested whether the genetic lines of least resistance and the predicted response to selection aligned with plasticity. We found predator environment-specific G matrices, but shared genetic architecture across environments resulted in more constraint in the G matrix than in the plasticity of the traits, sometimes preventing alignment of the two. However, as the importance of survival selection increased, the difference between environments in their predicted response to selection increased and resulted in closer alignment between the plasticity and the predicted selection response. Therefore, plasticity may indeed aid adaptation to new environments.

表型可塑性（Phenotypic plasticity）指基因型（genotype）产生多种表型（phenotype）以适配环境的能力。近期有理论提出，在表型可塑性种群中，遗传变异的主轴可与选择方向相一致。据此，该理论预测，可塑性可通过增加选择偏好且在可塑性中得以体现的方向上的遗传变异，直接助力生物适应。我们以淡水甲壳类动物蚤状溞（Daphnia pulex）为研究对象，探究其面临两种截然不同的体型选择性捕食者的捕食风险时的相关情况。我们估算了多个生活史性状的可塑性、这些性状的G矩阵（G matrix）、繁殖与存活的选择梯度，以及预测的选择响应。基于上述数据，我们检验了遗传最小阻力线与预测的选择响应是否与表型可塑性相一致。研究发现存在捕食者环境特异性的G矩阵，但跨环境共享的遗传架构使得G矩阵所受的约束多于性状可塑性所受的约束，有时会阻碍二者的一致性。然而，随着存活选择的重要性提升，不同环境间的预测选择响应差异随之增大，进而使可塑性与预测选择响应之间的一致性显著提升。由此可见，表型可塑性确实可助力生物适应全新环境。