Data from: Genetic and ecotypic differentiation in a Californian plant polyploid complex (Grindelia, Asteraceae)

Studies of ecotypic differentiation in the California Floristic Province have contributed greatly to plant evolutionary biology since the pioneering work of Clausen, Keck, and Hiesey. The extent of gene flow and genetic differentiation across interfertile ecotypes that span major habitats in the California Floristic Province is understudied, however, and is important for understanding the prospects for local adaptation to evolve or persist in the face of potential gene flow across populations in different ecological settings. We used microsatellite data to examine local differentiation in one of these lineages, the Pacific Coast polyploid complex of the plant genus Grindelia (Asteraceae). We examined 439 individuals in 10 different populations. The plants grouped broadly into a coastal and an inland set of populations. The coastal group contained plants from salt marshes and coastal bluffs, as well as a population growing in a serpentine grassland close to the coast, while the inland group contained grassland plants. No evidence for hybridization was found at the single location where adjacent populations of the two groups were sampled. In addition to differentiation along ecotypic lines, there was also a strong signal of local differentiation, with the plants grouping strongly by population. The strength of local differentiation is consistent with the extensive morphological variation observed across populations and the history of taxonomic confusion in the group. The Pacific Clade of Grindelia and other young Californian plant groups warrant additional analysis of evolutionary divergence along the steep coast-to-inland climatic gradient, which has been associated with local adaptation and ecotype formation since the classic studies of Clausen, Keck, and Hiesey.自Clausen、Keck与Hiesey的开创性研究以来，针对加利福尼亚植物区系省（California Floristic Province）生态型分化的研究，极大地推动了植物进化生物学领域的发展。不过，跨越该植物区系省主要生境的可互交生态型之间的基因流程度与遗传分化水平，目前仍未得到充分研究；而理解不同生态环境下种群间存在潜在基因流时，本地适应演化或维持的前景，恰恰依赖于对该问题的阐释。本研究以其中一个演化支系——菊科（Asteraceae）胶草属（Grindelia）的太平洋海岸多倍体复合体（Pacific Coast polyploid complex）为研究对象，利用微卫星（microsatellite）标记数据探究其本地分化情况。我们对10个不同种群的439个个体进行了分析，供试植株大致可划分为海岸种群组与内陆种群组两类：海岸种群组包含来自盐沼、海岸悬崖以及邻近海岸的蛇纹岩草原（serpentine grassland）生境的植株，而内陆种群组则均为草原生境植株。在两组相邻种群的采样点中，未发现任何杂交现象的证据。除沿生态型分化的特征外，还存在显著的本地分化信号：供试植株的聚类结果与种群来源高度吻合。本地分化的强度与各种群间广泛存在的形态变异，以及该类群长期存在的分类学混乱历史相吻合。胶草属太平洋演化支（Pacific Clade）以及其他年轻的加利福尼亚植物类群，亟需针对沿海岸至内陆陡峭气候梯度的演化分化展开进一步研究——自Clausen、Keck与Hiesey的经典研究以来，该气候梯度便被认为与本地适应及生态型形成密切相关。