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

蛇刀草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，该物种注定要在大尺度上揭示末次冰期以来的生物地理历史，以及在小尺度上揭示堤防破碎冲积平原的影响。与生物地理历史相关的工作已经完成，有证据表明该物种可能是冰川遗迹。在小尺度上，我们假设水文和扰动过程是形成动态河流景观中植物遗传模式的主要因素，并且堤岸对洪泛平原的破碎化对植物种群动态有强烈影响。通过提出的研究，我们想要验证以下假设：与较老的冲积平原（不再被淹没）相比，最近的冲积平原（在高水位时期仍然被淹没）的种群表现出更高的克隆多样性和较低的遗传分化，主要是在最近的冲积平原上，遗传多样性从上游到下游种群增加。目的是为了更好地理解草本植物物种在响应河流景观变化时的进化过程。

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.