大序醉鱼草花部特征地理分化及适应性研究

The selection mechanism of floral evolution is one of the hottest central topics for the evolutionary biologists worldwide. Geographic variations of floral traits in flowering plants may contribute to understanding not only species adaptation and its selection mechanism, but also intraspecific genetic differentiation and speciation. Buddleja macrostachya is experiencing rapid divergence among Buddleja genra in Asia groups, which is one of the best choices for answering these scientific questions. In the previous studies, we found that B. macrostachya with divergent floral traits showed different regional distribution patterns, and spreading along with its supposed diffusion pathways. In this study, floral traits and geographic variations of B. macrostachya with dramatic intraspecific floral divergence will be studied combined with the methods of ecology, pollination biology and molecular biology. Simultaneously, natural selections from pollinators and abiotic environment were mainly taken into consideration. We primarily focused on phenotypic differentiations, genetic differentiations and geographical distribution patterns of floral traits in B. macrostachya. Furthermore, geographic variations of floral traits and these relationships with different natural selections were also discussed in order to uncover the selection mechanism of intraspecific differentiation. Finally, we hope these results could serve as a clue to ecological process and selection mechanism of intraspecific floral differentiation in Angiosperm.

探讨花进化的选择机制是进化生物学家关注的重要议题之一。被子植物花部特征的地理变异，不仅能为理解物种适应和选择机制提供独特的良机，也为研究物种种内遗传分化与物种形成提供线索。大序醉鱼草(Buddleja macrostachya)是醉鱼草属亚洲类群中分化速度最快的物种；前期的研究发现，其花部特征的分化呈明显地域分布格局，且沿其推测的物种扩散路线变化，是研究被子植物花部特征进化选择机制的理想材料。本项目拟以不同地理分布的大序醉鱼草花部特征为研究对象，以可能影响大序醉鱼草花部特征演化的传粉者和非生物环境因子为自然选择因子，采用生态学、传粉生物学及分子生物学相结合的方法，研究大序醉鱼草花部特征的表型分化、遗传分化及其地理分布格局，探讨其花部特征地域变异及其与不同选择力量的关系，揭示其物种种内花部特征地理分化的选择机制。本研究将为阐释被子植物花部特征种内分化的生态过程及进化选择机制提供科学依据。

探讨花进化的选择机制是进化生物学家关注的重要议题之一。被子植物花部特征的地理变异，不仅能为理解物种适应和选择机制提供独特的良机，也为研究物种种内遗传分化与物种形成提供线索。本研究通过比较大序醉鱼草不同表型的花气味化学特征，传粉系统，生境土壤及植物化学计量特征，以及染色体倍性和遗传结构等，初步弄清了如下问题：1. 不同表型大序醉鱼草在染色体倍性上存在差异，且首次报道了四倍体和八倍体的存在；2. 不同倍性的大序醉鱼草在花气味化学特征上存在差异；3. 不同倍性大序醉鱼草的主要传粉者类群存在差异；4. 不同倍性大序醉鱼草土壤及植物化学计量特征均偏低，且彼此之间无显著性关系；5. 不同倍性大序醉鱼草存在遗传结构上的分化。我们的结果初步解释了大序醉鱼草复合群的表型分化，遗传分化及其地理分布格局；并进一步揭示了传粉者选择在大序醉鱼草表型分化及地理分布中的关键作用。