植物群体的遗传变异水平和遗传结构不仅是对未来变化的环境适应潜力的特征，也是适应过去（历史）环境的遗传后果。研究群体遗传结构及其影响因素（基因流）是国际上植物进化生态学和保护遗传学的热点问题之一。然而，从不同空间尺度探讨不同植物群体遗传变异的分布式样、运用不同方法估测基因流及其对遗传结构的影响的研究很少。本项目以我国横断山区三种兰科植物（无苞杓兰、西藏杓兰和黄花杓兰）为研究对象，利用微卫星标记，从地理尺度和群体内小尺度研究三种植物的群体遗传变异水平和分布式样，应用间接（FST法和SGS法）和直接方法（花粉染色法和父本分析），对比分析三种杓兰群体间和群体内的基因流格局，探讨传粉者对花粉基因流以及基因流对群体遗传结构的影响，为进一步揭示兰科植物多样的适应机制尤其是不同植物适应于不同传粉者的遗传后果以及在不同空间尺度上适应的遗传后果提供重要信息，并为兰科植物的有效保护和合理利用提供有益的资料。

Genetic diversity and population structure of flowering plants are not only indicators of potential adaptability to changing environments in the future, but also genetic consequences for adaptation to historical environments. Studies on genetic structure of plant populations and its influence factors such as gene flow have been the central themes of plant evolutionary biology and conservation genetics in the past decades. However, few attempts have been made to explore spatial patterns of genetic variation at different scales and estimate historical and ongoing gene flow using both direct and indirect methods. In this project, genetic structure and gene flow of three single-flowered species of Orchidaceae (Cypripedium bardolphianum, C. tibeticum and C. flavum) characteritzed with sympatrical distribution in Hengduan Mountains, overlapping blooming periods and pollination by different types of insects in Huanglong National Nature Reserve, are investigated using 20 SSR markers. At least 20 natural populations of each species were chosen for investigation of geographical distribution of genetic variation and historical gene flow, and a natural population in Huanglong was chosen for investigation of fine-scale spatial genetic structure (SGS) and both historical and on-going gene flow. SGS at different age stages of Huanglong population was investigated by mapping and genotyping adults (reproductive individuals) and seedlings of each species. Pattern of historical gene flow among populations of each species was indirectly estimated by the mathematical model of Wright's FST, while pattern of historical gene flow within Huanglong population was indirectly estimated using an approach that is based on the slope of the regression of pairwise kinship coefficients on spatial distance and estimates of the effective population density. Pattern of on-going gene flow within Huanglong population was directly estimated using methods of parentage analysis after excluding the impossible fathers using stained pollen and variations of dates of flowering, pollen removal and pollination between the mather and the impossible fathers. We compared genetic structure at different scales and patterns of historical and on-going gene flow among three orchid species.This project will not only enrich our understangding of population genetic consequences of different species of Orchidaceae adapted to different types of pollinators in the same community and the geographical scale, but also contribute to help to develop strategies for the conservation and sustainable utilization of these orchids in China.