Data from: Evolution of genetic variance during adaptive radiation

Genetic correlations between traits can concentrate genetic variance into fewer phenotypic dimensions that can bias evolutionary trajectories along the axis of greatest genetic variance and away from optimal phenotypes, constraining the rate of evolution. If genetic correlations limit adaptation, rapid adaptive divergence between multiple contrasting environments may be difficult. However, if natural selection increases the frequency of rare alleles after colonisation of new environments, an increase in genetic variance in the direction of selection can accelerate adaptive divergence. Here, we explored adaptive divergence of an Australian native wildflower by examining the alignment between divergence in phenotype mean and divergence in genetic variance among four contrasting ecotypes. We found divergence in mean multivariate phenotype along two major axes represented by different combinations of plant architecture and leaf traits. Ecotypes also showed divergence in the level of genetic variance in individual traits, and the multivariate distribution of genetic variance among traits. Divergence in multivariate phenotypic mean aligned with divergence in genetic variance, with much of the divergence in phenotype among ecotypes associated with changes in trait combinations containing substantial levels of genetic variance. Overall, our results suggest that natural selection can alter the distribution of genetic variance underlying phenotypic traits, increasing the amount of genetic variance in the direction of natural selection and potentially facilitating rapid adaptive divergence during an adaptive radiation.性状间的遗传相关（genetic correlations）可将遗传方差（genetic variance）富集于更少的表型维度（phenotypic dimensions）中，进而使进化轨迹偏向遗传方差最大的轴，偏离最优表型，最终限制进化速率。若遗传相关制约了适应性进化，那么多个对比环境间的快速适应性分化（adaptive divergence）或将难以发生。然而，若自然选择（natural selection）在种群定居新环境后提升了稀有等位基因的频率，选择方向上的遗传方差增量便可加速适应性分化进程。本研究以澳大利亚本土野生花卉为研究材料，通过对比4种不同生态型（ecotypes）的表型均值分化与遗传方差分化，探究其适应性分化机制。研究发现，多变量表型（multivariate phenotype）均值沿两大主轴发生分化，该两大主轴分别对应植株构型与叶片性状的不同组合。各生态型不仅在单个性状的遗传方差水平上存在分化，在性状间遗传方差的多变量分布模式上亦存在差异。多变量表型均值的分化与遗传方差分化高度契合，生态型间的表型分化大多与携带高水平遗传方差的性状组合的变化相关。总体而言，本研究结果表明，自然选择可改变表型性状背后的遗传方差分布格局，提升自然选择方向上的遗传方差总量，从而可能在适应性辐射（adaptive radiation）过程中促进快速适应性分化。