Data from: How to escape from crop-to-weed gene flow: phenological variation and isolation-by-time within weedy sunflower populations

The evolution of crop-related weeds may be constrained by recurrent gene flow from the crop. However, flowering time variation within weedy populations may open the way for weed adaptation by allowing some weeds to escape from this constraint. We investigated this link between phenology, gene flow and adaptation in weedy sunflower populations recently emerged in Europe from crop-wild hybridization. We studied jointly flowering phenology and genetic diversity for 15 microsatellite loci in six cultivated sunflower fields infested by weedy sunflower populations. The flowering overlap of cultivated and weedy sunflowers varied between and within populations: some weedy individuals were found completely isolated from the crop, the frequency of these plants being higher in populations from highly infested fields. Within weedy populations, we detected a pattern of isolation-by-time: the genetic divergence between individuals was positively correlated with their divergence in flowering period. Additionally, earlier weeds, which flowered synchronously with the crop, were genetically more similar to the cultivated varieties than late-flowering weeds. Overall our results suggest that crop-to-weed gene flow did occur but was limited by divergent phenologies. We discuss the roles of weed adaptation and population history in generating this partial reproductive isolation.与作物伴生的杂草的演化进程，或受作物来源的反复基因流（gene flow）制约。然而，杂草种群内部的开花时间变异，可通过帮助部分杂草摆脱该约束，为杂草的适应性演化开辟路径。本研究针对欧洲近期由作物与野生向日葵杂交起源的杂草向日葵种群，探究了物候学（phenology）、基因流与适应性之间的关联。我们对6个遭杂草向日葵种群侵染的栽培向日葵田开展联合研究，针对15个微卫星位点（microsatellite loci）分析了开花物候与遗传多样性。栽培与杂草向日葵的开花重叠度在种群间及种群内部存在差异：部分杂草个体完全与作物无开花重叠，这类植株在重度侵染田块的种群中出现频率更高。在杂草向日葵种群内部，我们观测到时间隔离（isolation-by-time）模式：个体间的遗传分化与二者的开花期分化呈显著正相关。此外，与作物同步开花的早花杂草，相较于晚花杂草，在遗传层面与栽培品种更为相似。综合来看，本研究结果表明作物向杂草的基因流确实存在，但受物候分化的限制。最后，我们讨论了杂草适应性与种群历史在形成该部分生殖隔离过程中所起的作用。