The evolutionary history of Hypericum perforatum L.

金丝桃属是一个形态上和生态上高度分化的大类群，有460多种。一些物种在欧亚大陆广泛分布，并在不受极端环境因素影响的低地栖息地占据主导地位。贯叶连翘和斑点金丝桃的分布区域有很大的重叠，但前者倾向于更干燥的生境，而后者即使在欧亚大陆北部也有分布。我们的目标是揭开这两个广泛分布的低地物种在更新世的进化史(系统地理学)，并描述反映两者之间实际和过去基因流动的遗传接触区。我们想要检验这种广泛分布的低地物种的进化情景是否证实了从木本植物、一年生植物、北极高山植物代表和其他物种的分析中揭示的避难区格局和主要迁徙路线。非常高兴的是，杂交和网状结构在穿孔藻和斑点藻不同形态和细胞型的进化中发挥了作用，而且很明显，两个物种群之间存在持续的基因组流。本项目嵌入了一个更大的研究网络，总体上关注金丝桃属的进化和系统学，但选择贯叶金丝桃及其近缘作为模式，专注于进化的重要性状和特征。这项研究的结果是讨论金丝桃属一个重要性状的进化的前提，即无融合生殖，即通过无性繁殖产生的种子进行繁殖。这项研究将提供关于1)遗传多样性中心，2)遗传变异的迁徙路线和源区，3)杂交和缝合带，以及4)多样性的时间估计的基本信息。所有这些信息都可以与实际详细分析的群体中的无融合生殖性状联系在一起，并应该回答以下问题：1)无融合生殖的多重来源和构成(在空间和时间上)，2)通过杂交桥梁传递性状，以及3)从有性繁殖到无性繁殖的适应和过渡的时间动态，以及反之亦然。

The genus Hypericum is a morphologically and ecologically highly diverged and large group of more than 460 species. Several species are wide-spread in Eurasia and dominate in lowland habitats not affected by extreme environmental factors. Hypericum perforatum and H. maculatum are representative examples with a largely overlapping distribution area, but the first one tends to prefer drier habitats, while the second species is distributed even in boreal Eurasian regions. We aim to unravel the evolutionary history of these two wide-spread lowland species during the pleistocene (phylogeography) and to characterize genetical contact zones reflecting actual and past geneflow between both. We would like to test if this evolutionary scenario of the wide-spread lowland species confirm patterns of refuge areas and principle migration routes revealed from the analysis of woody plants, annuals, arcticalpine representatives and others.It is very likey that hybridization and reticulation played a role in the evolution of different morpho- and cytotypes in H. perforatum as well as in H. maculatum, and it is also obvious, that there is ongoing geneflow between both species groups. This project is embedded in a larger research network focusing on the evolution and systematics of Hypericum in general, but selecting H. perforatum and closest relatives as model to focus on evolutionary important traits and characters. The results from this study are a prerequisite to discuss the evolution of one important trait in Hypericum, namely apomixis, the propagation via seeds produced without sexuality. This study will provide fundamental information about 1) centres of genetic diversity, 2) migration routes and source areas of genetic variation, 3) hybridization and suture zones, and 4) temporal estimates of diversification. All these information can be linked with the trait apomixis within populations actually analysed in detail and should answer questions about 1) multiple origin and constitution of apomixis (in space and time), 2) transmission of the trait via hybrid bridges, and 3) temporal dynamics of adaptation and transition from sexual to asexual propagation and wee versa.