中国-日本和中国-喜马拉雅植物亚区物种替代分布格局的形成机制——以青冈和滇青冈为例

Species vicarious of close related subtropical species between Sino-Japanese (SJ) and Sino-Himalayan (SH) flora sub-regions are prevalent. However, little was known on the mechanisms to shape such species geographical vicarism pattern in East Asia. Quercus glauca and Q. schottkyana (Fagaceae) are a pair of representative vicarious species with wide distribution in SJ and SH sub-regions respectively. The two species have long evolutionary history, as rich fossil records were found since Oligocene in wide range of East Asia. This two species are also the keystone species of East Asian subtropics evergreen broadleaved forests (EBLFs). Therefore, this two species offers a unique opportunity to investigate the formation and evolution of the species vicarious between SJ and SH flora sub-regions..In this study, we will couple the restriction site associated DNA sequencing (RAD-seq), species distribution and climate data to investigate (1) population genetic structure and genetic differentaition of Q. glauca and Q. schottkyana at genomic level; (2) analyze the contribution of landscape patterns of present and LGM periods to the species spatial genetic patterns; (3) reveal the divergent time between Q. glauca and Q. schottkyana, as well as the historical gene flow between them; (4) calculate the impacts of the environmental heterogeneity to the spatial genetic patterns of Q. glauca and Q. schottkyana. This investigation can provide deep insights to the mechanisms on shaping the species vicarious between SJ and SH flora sub-regions and the contributions of environmental heterogeneity to the species genetic diversity and the local adaption of the two oaks. It also can provide critical context to understand the historical dynamics of East Asia EBLFs and formation of the flora in East Asia subtropical region.

中国-日本森林亚区和中国-喜马拉雅植物亚区间近缘种地理替代现象普遍存在，但对这一替代格局的成因认识有限。青冈和滇青冈为姐妹种，替代分布于中国-日本森林亚区和中国-喜马拉雅植物亚区。它们亦是东亚亚热带常绿阔叶林的重要建群种，演化历史悠久，自渐新世以来具有丰富的化石记录，是用于研究中国-日本和中国-喜马拉雅亚区植物替代格局形成与演化的理想材料。.本研究将利用简化基因组测序方法，结合气候和分布数据，在基因组水平上：1）研究青冈和滇青冈的群体遗传结构和遗传分化；2）分析当前时期和末次盛冰期的景观格局对物种遗传多样性和遗传分化的影响；3）计算青冈和滇青冈的分化时间及历史基因流； 4）分析环境异质性对两种物种遗传格局的作用。本研究将揭示青冈和滇青冈替代分布格局的形成机制，及环境异质性对青冈滇青冈局部适应性分化的影响。研究成果还可为阐明东亚常绿阔叶林及植物区系的演化动态提供重要线索。

了解森林建群种的历史演化动态及对未来气候变化的相应对于生物多样性保护、森林管理和植被恢复都有指导作用。本项目主要研究环境变化对中国西南亚热带常绿阔叶林建群种滇青冈的遗传格局的影响。使用简化基因组测序开发了28对青冈和滇青冈通用的微卫星引物，分别对2个青冈群体和2个滇青冈群体共48个个体进行基因分型，结果显示青冈和滇青冈群体之间没有明显的遗传分化。使用双酶切简化基因组测序对22个滇青冈群体共133个个体进行基因分型，得到的变异位点在基因组中均匀分布。主成分及遗传结构分析检测到三个与地理分布相关的分组，近似贝叶斯分析显示滇青冈群体在中新世开始分化，种间分化可能由于亚洲板块和印度板块在这一时期碰撞引起。基因型环境关联分析显示年降水量和地理分布同物种空间遗传变异相关性最强。金沙江北部的滇青冈群体受未来气候变化影响最大，为了提高这一区域的遗传多样性、减缓气候变化对这一区域群体的威胁，可选用混合外源和本地种子用于这一区域森林的恢复和管理。种子萌发实验显示青冈种子在12天时开始萌发，萌发率在44天达到峰值；青冈种子淀粉含量与单宁含量显著负相关。