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 resu...

表型可塑性（Phenotypic plasticity）是指某一基因型为适应环境而产生多种表型的能力。近期理论提出，表型可塑性种群中遗传变异的主轴线可与选择方向对齐。因此，理论预测，可塑性通过增加选择偏好方向上的遗传变异（该变异亦反映于可塑性中），直接助力适应性进化。我们以淡水甲壳动物蚤状溞（Daphnia pulex）为研究对象评估了这一理论——该物种面临两种具有对比性的体型选择性捕食者的捕食风险。我们估算了若干生活史性状的可塑性、这些性状的遗传矩阵（G matrix）、繁殖与存活的选择梯度，以及预测的选择响应。利用这些数据，我们检验了遗传最小阻力线与预测的选择响应是否与可塑性对齐。我们发现了捕食者环境特异性的遗传矩阵，但跨环境共享的遗传结构导致...