Data from: A multilocus phylogenetic analysis of Escallonia (Escalloniaceae): diversification in montane South America

The mountains of South America are hotspots of plant diversity. How this diversity originated and evolved, and what roles geographic and environmental factors may have played in the diversification of lineages occurring in these regions is not well understood. Escallonia, a morphologically and ecologically diverse group of shrubs and trees widely distributed in these mountains, provides an ideal opportunity for studying the historical underpinnings that have shaped the extraordinarily distinctive, diverse, and endangered flora of these regions, and for evaluating the role of abiotic factors in the process of lineage divergence. I analyzed neutral DNA sequence data from two nuclear loci and one chloroplast locus using maximum parsimony, maximum likelihood, and Bayesian phylogenetic approaches. I used a Bayesian approach to analyze the geographic structure of gene trees, and a phylogenetically controlled decomposition of the variance in bioclimatic variables to analyze the eco-climatic structure of gene trees. I found i) that Escallonia is monophyletic, ii) a remarkable level of geographical and climatic phylogenetic structure, iii) that Escallonia likely originated in the tropical Andes, and iv) a widespread absence of species exclusivity. Geography played an important role early on the history of Escallonia by separating populations that later diversify likely in isolation. Although geographic isolation was generally accompanied by changes in climate, it is not clear whether environmental gradients along elevation have influenced more recent diversification events, or species have evolved broader environmental tolerances.南美洲山地是植物多样性的热点区域。目前学界对该区域植物多样性的起源与演化路径，以及地理与环境因素在当地类群分化进程中所扮演的角色仍缺乏深入认知。鼠刺属（Escallonia）是一类形态与生态特征均具丰富多样性的灌木与乔木类群，广泛分布于上述山地，为探究塑造该区域极具特色、物种丰富且濒危的植物区系的历史成因，以及评估非生物因素在类群分化过程中的作用提供了绝佳的研究契机。本研究采用最大简约法（maximum parsimony）、最大似然法（maximum likelihood）及贝叶斯系统发育分析方法，对来自2个核基因座（nuclear loci）与1个叶绿体基因座（chloroplast locus）的中性DNA序列数据进行了分析；同时采用贝叶斯方法解析基因树的地理结构，并通过系统发育控制的生物气候变量（bioclimatic variables）方差分解，探究基因树的生态气候结构。本研究得到以下结论：① 鼠刺属为单系群（monophyletic）；② 其系统发育结构呈现出显著的地理与气候分区特征；③ 鼠刺属大概率起源于热带安第斯山脉；④ 该类群普遍存在物种排他性缺失的现象。地理隔离在鼠刺属演化早期发挥了关键作用，分离后的种群大概率在孤立状态下发生分化。尽管地理隔离通常伴随气候环境的改变，但目前仍无法明确：沿海拔梯度分布的环境因子是否对近期的类群分化事件产生了影响，或是物种本身演化出了更广泛的环境耐受能力。