Data from: Adaptive value of phenological traits in stressful environments: predictions based on seed production and laboratory natural selection

Phenological traits often show variation within and among natural populations of annual plants. Nevertheless, the adaptive value of post-anthesis traits is seldom tested. In this study, we estimated the adaptive values of pre- and post-anthesis traits in two stressful environments (water stress and interspecific competition), using the selfing annual species Arabidopsis thaliana. By estimating seed production and by performing laboratory natural selection (LNS), we assessed the strength and nature (directional, disruptive and stabilizing) of selection acting on phenological traits in A. thaliana under the two tested stress conditions, each with four intensities. Both the type of stress and its intensity affected the strength and nature of selection, as did genetic constraints among phenological traits. Under water stress, both experimental approaches demonstrated directional selection for a shorter life cycle, although bolting time imposes a genetic constraint on the length of the interval between bolting and anthesis. Under interspecific competition, results from the two experimental approaches showed discrepancies. Estimation of seed production predicted directional selection toward early pre-anthesis traits and long post-anthesis periods. In contrast, the LNS approach suggested neutrality for all phenological traits. This study opens questions on adaptation in complex natural environment where many selective pressures act simultaneously.

物候性状在一年生植物的自然种群内部及种群间普遍存在变异。然而，花后性状的适应价值却鲜有研究验证。本研究以自交一年生物种拟南芥（Arabidopsis thaliana）为研究材料，在水分胁迫与种间竞争两种胁迫环境中，评估花前与花后性状的适应价值。通过估算种子产量并开展实验室自然选择（laboratory natural selection, LNS）实验，我们针对两种胁迫环境各设置四个强度梯度，解析了两种胁迫条件下作用于拟南芥物候性状的选择强度与类型（定向选择、歧化选择与稳定选择）。胁迫类型及其强度均可影响选择的强度与类型，物候性状间的遗传约束同样会对选择产生影响。在水分胁迫环境下，两种实验方法均检测到针对更短生活周期的定向选择，尽管抽薹时间对抽薹至开花的间隔时长存在遗传约束。在种间竞争环境中，两种实验方法的结果存在分歧。种子产量估算实验预测，选择倾向于早花前性状与长花后周期的方向；而实验室自然选择实验则显示所有物候性状均受中性选择作用。本研究为解析多重选择压力共同作用下的复杂自然环境中的适应性机制提出了新的待解问题。