Data from: Water availability as an agent of selection in introduced populations of Arabidopsis thaliana: impacts on flowering time evolution

Flowering is one of the most influential events in the life history of a plant and one of the main determinants of reproductive investment and lifetime fitness. It is also a highly complex trait controlled by dozens of genes. Understanding the selective pressures influencing time to flowering, and being able to reliably predict how it will evolve in novel environments, are unsolved challenges for plant evolutionary geneticists. Using the model plant species, Arabidopsis thaliana, we examined the impact of simulated high and low winter precipitation levels on the flowering time of naturalized lines from across the eastern portion of the introduced North American range, and the fitness consequences of early versus late flowering. Flowering time order was significantly correlated across two environments—in a previous common garden experiment and in environmental chambers set to mimic mid-range photoperiod and temperature conditions. Plants in low water flowered earlier, had fewer basal branches and produced fewer fruits. Selection in both treatments favored earlier flowering and more basal branches. Our analyses revealed an interaction between flowering time and water treatment for fitness, where flowering later was more deleterious for fitness in the low water treatment. Our results are consistent with the hypothesis that differences in winter precipitation levels are one of the selective agents underlying a flowering time cline in introduced A. thaliana populations.

开花是植物生活史中最具影响力的事件之一，同时也是调控生殖投入与终生适合度的核心决定因素之一。该性状受数十个基因协同调控，属于高度复杂的生物学性状。解析影响开花时间的选择压力，并精准预测其在全新环境中的演化轨迹，是植物进化遗传学家尚未攻克的核心难题。本研究以模式植物拟南芥（Arabidopsis thaliana）为实验材料，针对北美引种分布区东部的归化株系，探究了模拟冬季高、低降水量水平对其开花时间的影响，并分析了早开花与晚开花植株的适合度差异。在两项环境体系中——即既往的同质园实验，以及设置为模拟中等光周期与温度条件的环境培养箱实验——植株的开花时间排序均呈现显著相关性。低水分处理组的植株开花更早，基部分枝数更少，结实量也更低。两组处理下的选择压力均倾向于选择早开花、基部分枝更多的植株。本研究分析还发现，开花时间与水分处理对植株适合度存在交互效应：在低水分处理组中，晚开花对适合度的负面影响更为显著。本研究结果支持以下假说：冬季降水量差异是导致引种拟南芥种群出现开花时间梯度的选择因子之一。