Data from: The roles of genetic drift and natural selection in quantitative trait divergence along an altitudinal gradient in Arabidopsis thaliana

Understanding how natural selection and genetic drift shape biological variation is a central topic in biology, yet our understanding of the agents of natural selection and their target traits is limited. We investigated to what extent selection along an altitudinal gradient or genetic drift contributed to variation in ecologically relevant traits in Arabidopsis thaliana. We collected seeds from 8 to 14 individuals from each of 14 A. thaliana populations originating from sites between 800 and 2700 m above sea level in the Swiss Alps. Seed families were grown with and without vernalization, corresponding to winter-annual and summer-annual life histories, respectively. We analyzed putatively neutral genetic divergence between these populations using 24 simple sequence repeat markers. We measured seven traits related to growth, phenology and leaf morphology that are rarely reported in A. thaliana and performed analyses of altitudinal clines, as well as overall QST-FST comparisons and correlation analyses among pair-wise QST, FST and altitude of origin differences. Multivariate analyses suggested adaptive differentiation along altitude in the entire suite of traits, particularly when expressed in the summer-annual life history. Of the individual traits, a decrease in rosette leaf number in the vegetative state and an increase in leaf succulence with increasing altitude could be attributed to adaptive divergence. Interestingly, these patterns relate well to common within- and between-species trends of smaller plant size and thicker leaves at high altitude. Our results thus offer exciting possibilities to unravel the underlying mechanisms for these conspicuous trends using the model species A. thaliana.

解析自然选择与遗传漂变如何塑造生物变异，是生物学领域的核心议题之一，但目前学界对自然选择的作用媒介及其所作用的靶标性状的认知仍存在局限。本研究针对沿海拔梯度的选择作用与遗传漂变在多大程度上驱动拟南芥（Arabidopsis thaliana）的生态相关性状变异展开了探究。我们从瑞士阿尔卑斯山区海拔800至2700米的14个拟南芥种群中，各选取8至14株供试个体收集种子。将所得种子家系分别置于春化（vernalization）与非春化条件下培养，分别对应越冬型与越夏型两种生活史策略。我们利用24个简单序列重复（simple sequence repeat）标记，对这些种群间的推定中性遗传分化开展了分析。我们测定了7个与生长、物候及叶片形态相关、且此前在拟南芥中鲜有报道的性状，并开展了海拔渐变群分析；同时进行了整体QST-FST比较，以及两两QST、FST与起源地海拔差异间的相关性分析。多变量分析结果显示，整套被测性状均存在沿海拔梯度的适应性分化，尤其在越夏型生活史处理下表现得更为显著。针对单个性状的分析显示，随着海拔升高，营养生长期莲座叶（rosette leaf）数量减少、叶片肉质性（leaf succulence）提升这两个性状的变异可归因于适应性分化。值得注意的是，上述模式与跨物种及种内普遍观测到的"高海拔地区植株体型更小、叶片更厚"的趋势高度契合。因此，本研究结果为利用模式物种拟南芥解析上述显著趋势的内在调控机制提供了极具前景的研究路径。