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.

南美山地是植物多样性的热点区域。目前学界对于该区域植物多样性的起源与演化过程，以及地理与环境因子在当地类群分化中所扮演的角色仍不甚明晰。鼠刺属（Escallonia）是一类在形态与生态上均具丰富多样性的灌木与乔木类群，广泛分布于上述山地，其为研究塑造该区域极具特色、多样且濒危的植物区系的历史成因提供了理想契机，同时也可用于评估非生物因子在类群分化过程中的作用。本研究采用最大简约法、最大似然法及贝叶斯系统发育分析方法，对两个核基因座与一个叶绿体基因座的中性DNA序列数据进行了分析。本研究通过贝叶斯方法解析基因树的地理结构，并借助系统发育校正的生物气候变量方差分解，分析基因树的生态气候格局。本研究得出如下结论：① 鼠刺属为单系类群；② 其系统发育结构呈现显著的地理与气候分异特征；③ 鼠刺属大概率起源于热带安第斯山脉；④ 类群普遍缺乏物种排他性。地理隔离在鼠刺属演化早期发挥了重要作用，其分隔的种群后续大概率在隔离状态下发生分化。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：沿海拔分布的环境梯度是否对近期的类群分化事件产生了影响，或是物种已演化出更广泛的环境耐受能力。