基于种群克隆结构的扁秆藨草雌雄异熟同步性研究

The interaction between clonal growth and mating system is of fundamental importance to the evolution of clonal plant population. Synchronous dichogamy, by enabling all the flowers in a plant to manifest the same sexual phase simultaneously, provides a potential mechanism to avoid geitonogamous inbreeding. It is currently unknown that whether synchronicity exists beyond the ramet level. The extent of this synchronicity may also respond to the dynamics of external environmental factors or internal population clonal structure, which is also a hypothesis yet to be tested. This research plans to use a typical dichogamous clonal plant, Scirpus planiculmis (Cyperaceae), as model species, develop SNP markers by RAD sequencing，identify the clonal structure of natural populations with contrasting habitat conditions, and calculate the synchronicity metrics based on clone affiliation at four levels respectively (spikelet, inflorescence, ramet and genet). Meanwhile, a common garden experiment with controls for different levels of water depth, clone richness, and clone evenness will be implemented to explore whether the synchronicity and the product of sexual propagation will change along these gradients. The aim of this research is to find out the specific pattern and regulation mechanism of synchronous dichogamny in S planiculmis, with a discussion of its evolutionary significance. We anticipate the results could provide innovative insights on the life history traits and the gene flow process of clonal plants, while also serve as theoretical reference for ecological practice such as invasive clonal plant management.

克隆生长与交配系统的互作机制对种群的长期进化具有重要意义。同步雌雄异熟现象，使植株内的所有花朵在同一时间都表现为同一性别，减少了分株间同株异花授粉的机率，具有降低克隆植物自交率的作用。目前相关研究只关注了分株层次的同步性，并且尚未探明环境因素或种群克隆结构的变化是否会对同步程度产生影响。本研究拟以雌雄异熟的克隆植物扁秆藨草为对象，对不同生境下的自然种群，通过RAD测序开发SNP分子标记来鉴定克隆结构，基于此解析小穗、花序、分株和基株四个层次上的同步性程度；对同质园实验中的培育种群，设置不同的克隆丰富度、均匀度和水深，考察其是否会影响同步性水平以及有性繁殖产出。本研究拟解决的关键科学问题是扁秆藨草雌雄异熟的同步程度、表现式样和调节机制，并探讨其对种群交配格局的进化意义。研究结果有助于深化对克隆植物生活史特征和种群基因流过程的理解，并为入侵性克隆植物防治策略等工作提供理论参考。

克隆生长与交配系统的互作机制对种群的长期进化具有重要意义。同步雌雄异熟现象，使植株内的所有花朵在同一时间都表现为同一性别，减少了分株间同株异花授粉的机率，具有降低克隆植物自交率的作用。目前分株层次上的同步性尚无结论，并且尚未关注基株、小穗等层次上是否也存在同步性。本研究以雌雄异熟的克隆植物扁秆藨草为对象，对不同生境下的自然种群，通过2b-RAD技术开发SNP分子标记来鉴定种群克隆结构，基于此解析小穗、花序、分株和基株四个层次上的同步性程度。本研究拟解决的关键科学问题是扁秆藨草雌雄异熟的同步程度和表现式样，并探讨其对种群交配格局的进化意义。研究结果显示，不同分株之间呈现出明显的同步度，即同时为雌花或者同时为雄花，但在基株之间并无明显同步性；同一花序内，不同小穗间呈现出较好的同步性，但单一小穗内的小花之间并无明显同步性。目前考察的两种因素，水深和克隆丰富度，并未对同步性产生显著影响，但水深对有性繁殖的产出有明显效应，高水深中有性繁殖的产出显著增加，并且这种增加表现为种子数量的增加而非单个种子质量的增加。该项目成果有助于深化对克隆植物生活史特征和种群基因流过程的理解，并为相关实践性工作提供基础理论参考。