Data from: Rapid independent trait evolution despite a strong pleiotropic genetic correlation

Genetic correlations are the most commonly studied of all potential constraints on adaptive evolution. We present a comprehensive test of constraints caused by genetic correlation, comparing empirical results to predictions from theory. The additive genetic correlation between the filament and corolla tube in wild radish flowers is very high in magnitude, estimated with good precision (0.85 ± 0.06), and is caused by pleiotropy. Thus, evolutionary changes in the relative lengths of these two traits should be constrained. Still, artificial selection produced rapid evolution of these traits in opposite directions, so that the difference between them in one replicate increased by six standard deviations relative to controls in only nine generations. This would result in a 54% increase in relative fitness based on a previous estimate of natural selection in this population, and would produce the phenotypes found in the most extreme species in the family Brassicaceae in less than 100 generations. These responses were within theoretical expectations and much slower than if the genetic correlation was zero; thus, there was evidence for constraint. These results, coupled with comparable results from other species, show that evolution can be rapid despite the constraints caused by genetic correlations.

遗传相关（genetic correlation）是适应性进化的各类潜在限制因素中研究最为广泛的一类。本研究针对遗传相关性引发的进化限制开展了系统性检验，将实验观测结果与理论预测进行了比对。野萝卜（wild radish）花朵的花丝（filament）与花冠筒（corolla tube）之间的加性遗传相关（additive genetic correlation）强度极高，估计精度良好（0.85 ± 0.06），且该相关由多效性（pleiotropy）所致。因此，这两个性状的相对长度进化改变理应受到限制。尽管如此，人工选择仍使这两个性状朝相反方向快速演化：仅历经9代繁育，其中一个实验重复组的两性状差值较对照组提升了6个标准差。依据该种群此前的自然选择估计结果，这一变化将使相对适合度提升54%，且仅需不足100代即可演化出十字花科（Brassicaceae）中极端物种所具备的表型。这些演化响应符合理论预期，且远低于遗传相关为零时的演化速率，由此证实了进化限制的存在。结合其他物种的同类研究结果，本研究表明即便存在遗传相关性引发的进化限制，演化仍可快速进行。