Phylogeny and biogeography of the American live oaks (Quercus subsection Virentes): a genomic and population genetics approach

The nature and timing of evolution of niche differentiation among closely related species remains an important question in ecology and evolution. The American live oak clade, Virentes, which spans the unglaciated temperate and tropical regions of North America and Mesoamerica, provides an instructive system in which to examine speciation and niche evolution. We generated a fossil-calibrated phylogeny of Virentes using RADseq data to estimate divergence times and used nuclear microsatellites, chloroplast sequences and an intron region of nitrate reductase (NIA-i3) to examine genetic diversity within species, rates of gene flow among species and ancestral population size of disjunct sister species. Transitions in functional and morphological traits associated with ecological and climatic niche axes were examined across the phylogeny. We found the Virentes to be monophyletic with three subclades, including a southwest clade, a southeastern US clade and a Central American/Cuban clade. Despi...近缘物种间生态位分化的演化本质与时间进程，始终是生态学与进化生物学领域的重要研究议题。分布于北美及中美洲未受冰川覆盖的温带与热带区域的美洲活栎分支（Virentes），为物种形成与生态位演化研究提供了极具指导意义的研究体系。本研究通过限制性位点关联DNA测序（RADseq）数据构建了Virentes的化石校准系统发育树以估算分化时间，并利用核微卫星、叶绿体序列以及硝酸还原酶内含子区域（NIA-i3），分析了物种种内遗传多样性、物种种间基因流速率以及间断分布姊妹物种的祖先种群规模。本研究针对系统发育树各分支，分析了与生态及气候生态位维度相关的功能与形态性状演化过渡。本研究发现Virentes为单系群，包含三个亚分支：西南分支、美国东南部分支以及中美洲/古巴分支。尽管……