The intraspecific evolutionary history of South American xerophytic plant species has been poorly explored. The tree species Prosopis chilensis has a disjunct distribution in four South American regions: southern Peru, southern Bolivia, central–western Argentina and central Chile. Here, we combined phylogeographical (based on chloroplast and nuclear markers), morphological and climatic data to evaluate the relative contribution of historical demo-stochastic and adaptive processes in differentiating the disjunct areas of distribution. The results obtained with the two molecular markers revealed two closely related phylogroups (Northern and Southern, predominating in Bolivian Chaco and in Argentine Chaco/Monte, respectively), which would have diverged at ~5 Mya, probably associated with transgression of the Paranaense Sea. Bolivia and Argentina have a larger number of exclusive haplotypes/alleles and higher molecular diversity than Chile, suggesting a long-lasting in situ persistence in the former and a relatively recent colonization in the latter, from the Bolivian and Argentinian lineages. The two main lineages differ in morphology and climatic niche, revealing two significant, independent evolutionary units within P. chilensis promoted by local adaptation and geographical isolation.

中文翻译：

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南美不同旱生树种Prosopis chilensis（Fabaceae）的生态系统学

南美旱生植物种的种内进化历史一直没有得到很好的探索。树种Prosopis chilensis在四个南美地区分布不均：秘鲁南部，玻利维亚南部，阿根廷中西部和智利中部。在这里，我们结合了系统地理学（基于叶绿体和核标记物），形态学和气候数据，以评估历史上的随机和适应性过程在区分离散区域方面的相对贡献。用这两种分子标记获得的结果揭示了两个密切相关的系统族（北部和南部，分别在玻利维亚Chaco和阿根廷Chaco / Monte中占优势），它们在〜5 Mya处发散，可能与巴拉那海的入侵有关。与智利相比，玻利维亚和阿根廷拥有更多的独占单倍型/等位基因和更高的分子多样性，这表明其长期存在前者在玻利维亚和阿根廷的血统中就地持久存在，而后者则是相对较新的殖民地。这两个主要谱系在形态和气候生态位上有所不同，揭示了当地适应和地理隔离促进了智利假单胞菌中两个重要的，独立的进化单位。