物种的自然居群可遗传的表观遗传变异能影响其适应与分化，进而对物种的进化过程产生重要影响。然而，目前关于自然居群表观遗传变异的发生机制及其进化意义却依然知之甚少。莲两生态型（热带莲和温带莲）具有独特的地理分布及显著的表型分化，是研究非模式植物自然居群适应不同环境的表观遗传学机制的良好材料。本项目拟对世界分布范围内莲两生态型的自然居群代表植物材料进行全基因组甲基化测序，研究自然居群的DNA甲基化变异模式并区分遗传变异和表观遗传变异的相对贡献；鉴定基因组中与环境因子显著关联的表观遗传修饰位点和相应的功能基因，揭示自然选择在莲两生态型的形成及表观遗传分化过程中的作用，为我们更全面、深入理解该物种的生态适应性及进化的表观遗传学机制提供基础资料，也为该重要经济植物野生资源的挖掘利用及遗传育种提供理论指导。

The heritable epigenetic variation among natural populations could affect the processes of adaptation and divergence, thus influence the course of evolution in species. But little is known of the origin and its evolutionary significance of the epigenetic variation in natural population. In order to reveal the mechanism of epigenetic variation in response to various environments in natural populations of non-model species, we will use the two distinct ecotypes, temperate and tropical lotus (Nulembo nucifera) as a model system. In this study, using the Whole-Genome Bisulfite Sequencing technique and basing on the species-wide sampling of the two ecotypes, we study the patterns of epigenetic variation in natural populations, disentangle the epigenetic from genetic variations, identify the genomic context of the epigenetic variants that are significantly associated with the climate variables, to reveal the role of natural selection in shaping the epigenetic divergence between these two ecotypes. The insights gained in this study will not only enrich our knowledge on the mechanism of adaptive evolution of the sacred lotus, but also provide some baseline data for the utilization of wild resources and genetic breeding of this economic important crop.