Phylography and polyploid evolution in Cyanus Mill. (Centaurea L. section Cyanus Mill.)

密切相关物种之间的基因流动通常与物种形成或单一事件有关，但很少被视为以重复或规则的方式塑造物种遗传结构的因素。目的是利用叶绿体和细胞核DMA标记研究蓝藻属（Asteraceae, Centaureinae）遗传变异的地理格局。应用广泛的系统地理学方法，包括基于聚结的分析，我们希望重建物种边界内和跨物种边界的分化过程和迁移。网状进化和不完全分化的证据是由不同的材料提供的，这些材料显示了叶绿体DNA多态性的非凡水平。我们还想评估系统地理学方法的适用性，以重建模式和地方的起源的四倍体。在形态、生态和分布上相似的四倍体物种中，叶绿体谱系的差异性表明，要么是在建立和传播过程中具有共同的潜在力量的重复起源，要么是二倍体向四倍体的大量渗入。我们的结果将允许在多年生自交不亲和草本植物物种形成过程中不同时间尺度上基因流动的作用的一般评估。

Gene flow among closely related species is often associated with speciation or singular events but rarely appreciated as a factor shaping the genetic structure of species in a repeated or regular manner. Our aim is to investigate the geographic patterns of genetic variation in the taxonomically difficult genus Cyanus (Asteraceae, Centaureinae) with chloroplast and nuclear DMA markers. Applying a wide range of phylogeographic methods including coalescent-based analyses we would like to reconstruct divergence processes and migration within and across species boundaries. Evidence for reticulate evolution and incomplete differentiation is provided by various accessions displaying extraordinary levels of chloroplast DNA polymorphism. We also want to assess the applicability of a phylogeographic approach to reconstruct mode and place of the origin of tetraploids. Distinctness of chloroplast lineages among tetraploid species which are similar in morphology, ecology and distribution suggests either a repeated origin with common underlying forces in establishment and spread, or substantial introgression of diploids towards tetraploids. Our results will allow general evaluation of the role of gene flow at different time scales during speciation processes in perennial self-incompatible herbaceous plants.