中国西南地区重要木本油料植物扁核木的遗传结构及成因

扁核木(Prinsepia utilis)为中国西南地区温带森林重要的木本油料植物, 但对其野生资源种群遗传结构及成因的了解严重不足。我们采用核微卫星分子标记, 对32个扁核木自然种群共377个个体的群体演化历史进行了探讨, 并评估其遗传资源。研究发现扁核木种群自西向东可划分4个遗传群组, 即喜马拉雅、横断山以及云贵高原西部和东部群组。其中, 最大的遗传分化存在于喜马拉雅和其他区域种群间。与喜马拉雅和云贵高原东部群组相比, 横断山和云贵高原西部群组混合了其他群组的遗传成分。种群动态历史分析显示中部2个群组在喜马拉雅和云贵高原东部群组形成后形成, 不同群组间的分化均发生在更新世晚期。地理隔离和环境隔离分析表明扁核木种群间的遗传分化主要由环境差异导致。环境差异分析显示不同群组间的气候存在不同程度的差异, 其中喜马拉雅和云贵高原东部群组与中部2个群组间的差异显著。此外, 结合该物种不同时期的生态位模拟数据, 我们认为喜马拉雅和云贵高原地区的遗传资源在未来需要优先保护。

Genetic structure and its causes of an important woody oil plant in Southwest China,Prinsepia utilis (Rosaceae)

Aims: Prinsepia utilis is an important woody oil species in temperate forests in Southwest China, however, almost nothing is known about its population genetic structure and the causes. So, we aim to study its evolutionary history through multiple nuclear microsatellite loci (nSSRs).
Methods: We sampled 377 individuals from 32 natural populations across all distribution range of P. utilis. All individuals were amplified and scored using seven self-developed nSSRs markers. Genetic structure was inferred using STRUCTURE software and principal component analysis. The most possible demographic scenario and corresponding parameters were modeled and estimated in DIYABC. Genetic diversity and genetic differentiation of each population, locus and genetic cluster were calculated. Contributions of geographic distance and environmental differences to genetic differentiation were calculate through Mantel test and partial Mantel test. At last, environmental differences among different genetic clusters was evaluated through principal component analysis using 19 climatic variables.
Results: All population can be divided into four genetic groups that are Himalayas, Hengduan Mountains, west and east Yunnan-Guizhou Plateau genetic groups from west to east. The greatest genetic differentiation occurs between populations in the Himalayas and other regions. In comparison with the Himalayan and east Yunnan-Guizhou Plateau groups, the Hengduan Mountains and west Yunnan-Guizhou Plateau groups have higher proportion of genetic mixture from other groups. Population demographic history analysis indicate two central groups are formed after Himalayas and east Yunnan-Guizhou Plateau groups, all divergences are occurred in late Pleistocene. The analyses of isolation by distance and isolation by environment show that the genetic differentiation of P. utilis is mainly caused by environmental difference. Environmental difference analysis using 19 climatic variables shows various difference among groups with significant difference exist between Himalayas and east Yunnan-Guizhou Plateau groups.
Conclusion: The distinct genetic structure of P. utilis is formed through the combination of Pleistocene climatic changes, complicated environment and its own biological characters. Combined with ecological niche modeling analysis in different periods, we suggest protection of genetic resources in Himalayas and Yunnan-Guizhou Plateau should be first priority.