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

密切相关的物种之间的基因流动往往与物种形成或单一事件有关，但很少被认为是以重复或规则的方式塑造物种遗传结构的因素。我们的目的是调查的地理模式的遗传变异在分类困难的属蓝藻（菊科，矢车菊亚科）与叶绿体和核DMA标记。应用广泛的地理学方法，包括基于聚结的分析，我们想重建分歧的过程和迁移内和跨物种的边界。网状进化和不完全分化的证据提供了各种加入显示非凡水平的叶绿体DNA多态性。我们还想评估的适用性，一个地理学的方法来重建模式和四倍体的起源地。在形态、生态和分布上相似的四倍体物种之间叶绿体谱系的差异表明，在建立和传播中具有共同的潜在力量的重复起源，或者二倍体向四倍体的大量渐渗。我们的研究结果将允许在不同的时间尺度在多年生自交不亲和草本植物的物种形成过程中的基因流的作用的一般评价。

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.