Latitudinal environmental niches and riverine barriers shaped the phylogeography of the central Chilean endemic Dioscorea humilis (Dioscoreaceae)

The effects of Pleistocene glaciations and geographical barriers on the phylogeographic patterns of lowland plant species in Mediterranean-climate areas of Central Chile are poorly understood. We used Dioscorea humilis (Dioscoreaceae), a dioecious geophyte extending 530 km from the Valparaíso to the Bío-Bío Regions, as a case study to disentangle the spatio-temporal evolution of populations in conjunction with latitudinal environmental changes since the Last Inter-Glacial (LIG) to the present. We used nuclear microsatellite loci, chloroplast (cpDNA) sequences and environmental niche modelling (ENM) to construct current and past scenarios from bioclimatic and geographical variables and to infer the evolutionary history of the taxa. We found strong genetic differentiation at nuclear microsatellite loci between the two subspecies of D. humilis, probably predating the LIG. Bayesian analyses of population structure revealed strong genetic differentiation of the widespread D. humilis subsp. h...

智利中部地中海气候区域内，低地植物物种的系统地理格局（phylogeographic patterns）受更新世冰期（Pleistocene glaciations）与地理屏障（geographical barriers）的影响机制迄今仍未得到充分阐明。本研究以匍匐薯蓣（Dioscorea humilis，薯蓣科（Dioscoreaceae））为案例物种——该物种为雌雄异株地下芽植物（dioecious geophyte），分布范围从瓦尔帕莱索大区延伸至比奥比奥大区，跨度达530公里——以期厘清自末次间冰期（Last Inter-Glacial, LIG）至今，伴随纬度环境变化的种群时空演化进程。研究采用核微卫星位点（nuclear microsatellite loci）、叶绿体（cpDNA）序列与生态位模型（environmental niche modelling, ENM），基于生物气候与地理变量构建当前及历史气候场景，进而推断该类群的演化历史。结果显示，匍匐薯蓣的两个亚种在核微卫星位点上存在显著遗传分化，其分化时间大概率早于末次间冰期。种群结构贝叶斯分析揭示，广布的匍匐薯蓣原亚种（D. humilis subsp. h...）存在显著遗传分化……