Large and small scale evolutionary processes in the floodplain plant Cnidium dubium: From biogeography to population dynamics in fragmented river landscapes

蛇床是一种受威胁的河流廊道植物，具有独特的大小尺度分布格局。由于这种模式，该物种注定要阐明自末次冰期以来的大规模地理历史以及小规模堤坝对洪泛平原破碎的影响。有关该物种的地理学历史的工作已经完成，有证据表明该物种可能是冰川遗迹。在小规模上，我们假设水播过程和干扰过程是塑造动态河流景观中植物遗传格局的主要因素，并且堤坝对洪泛区的破碎化对植物种群动态有很大影响。与拟议的研究，我们要测试的假设，最近的洪泛区（仍然淹没在高水位的时候）的人口表现出较高的克隆多样性，以及较低的遗传分化相比，较老的洪泛区（不再淹没），主要是在最近的洪泛区的遗传多样性增加，从上游到下游的人口。我们的目标是有助于更好地了解草本植物物种的进化过程中，河流景观的变化。

Cnidium dubium is a threatened river corridor plant species with a peculiar large and small scale distribution pattern. Due to this pattern, the species is predestined to shed light on both the biogeographical history since the last glacial period on the large scale as well as on the impacts of floodplain fragmentation by dykes on the small scale. The work related to the biogeographic history is already accomplished with evidence that the species could be a glacial relic. On the small scale we assume that hydrochory and disturbance processes are major factors shaping plant genetic patterns in dynamic river landscapes and that the fragmentation of floodplains by dykes has strong effects on plant population dynamics. With the proposed study, we want to test the hypotheses that the populations of the recent floodplain (still inundated in times of high water) show a higher clonal diversity as well as a lower genetic differentiation in comparison with those of the older floodplain (not flooded anymore) and that mainly in the recent floodplain genetic diversity increases from upstream to downstream populations. The goal is to contribute to a better understanding of the evolutionary processes of herbaceous plant species in response to river landscape alterations.