Shared genetic patterns within a community of ecologically distinct species may reflect the role of past geoclimatic events imprinting species evolutionary history. Although Pleistocene glaciations are the most important processes evoked as drivers of these shared patterns, in some regions Quaternary volcanic activity should also be considered as a potential process shaping genetic diversity distribution. Additionally, phenotypic attributes related to dispersal and persistence may affect the time and manner in which species respond to geoclimatic changes. We performed a comparative phylogeographical study within a plant community of the South American Arid Diagonal to assess whether genetic patterns are better explained by climatic changes or volcanisms, taking into account the possible influence of life form and dispersal syndromes of the focal species. Chloroplast intergenic spacers were sequenced for five plant species. Genealogy, divergence time estimates, demographic and range expansion analyses were performed. Approximate Bayesian computation was used to test plausible shared phylogeographic scenarios. Climatically stable areas during the last glacial period were inferred with distribution modeling. Results showed that most species were split into northern and southern lineages separated by a phylogeographic break at around 37.5 °S, with the northern populations being genetically less diverse, inhabiting both climatically stable and unstable areas, but being severely affected by intense Plio-Pleistocene magmatic activity; the southern populations, less influenced by volcanism, appeared to be genetically more diverse and occupied climatically stable areas through time. Most recent range expansions and effective population size increases occurred after most of the volcanic episodes, before and during the Last Glacial Maximum. All species shared the same geographic origin of the detected spatial expansion. Overall, our results suggest a preponderant effect of Quaternary volcanism rather than climatic oscillations on the evolutionary history of this xerophytic community. Additionally, we found evidence that autecological traits would have modulated the community historical responses.

在生态上不同的物种群落中共享的遗传模式可能反映了过去的地球气候事件在影响物种进化历史的过程中的作用。尽管更新世冰川是引起这些共享模式的最重要过程，但在某些地区，第四纪火山活动也应被视为影响遗传多样性分布的潜在过程。此外，与扩散和持久性有关的表型属性可能会影响物种响应地球气候变化的时间和方式。我们在南美干旱对角线的一个植物群落中进行了比较植物地理学研究，以评估遗传模式是否能通过气候变化或火山作用得到更好的解释，考虑到焦点物种的生命形式和传播综合症的可能影响。对五个植物物种的叶绿体基因间隔子进行了测序。进行了族谱，发散时间估计，人口统计和范围扩展分析。近似贝叶斯计算用于测试合理的共享系统地理学方案。利用分布模型推断出上一个冰期的气候稳定区域。结果表明，大多数物种在大约37.5°S时被系统地理学断裂分为北部和南部谱系，北部种群的遗传多样性较差，居住在气候稳定和不稳定的地区，但受到强烈的上新世-上新世岩浆的严重影响活动; 南部人口，较少受到火山影响，随着时间的流逝，似乎在遗传上更加多样化，并占据了气候稳定的地区。最近的范围扩展和有效种群数量的增加发生在大多数火山事件之后，最后一次冰河期末之前和之中。所有物种都共享检测到的空间扩展的相同地理起源。总体而言，我们的结果表明，第四纪火山作用的优势在于气候变化，而不是气候振荡。此外，我们发现证据表明，自律学特征会调节社区的历史反应。所有物种都共享检测到的空间扩展的相同地理起源。总体而言，我们的结果表明，第四纪火山作用的优势在于气候变化，而不是气候振荡。此外，我们发现证据表明，自律学特征会调节社区的历史反应。所有物种都共享检测到的空间扩展的相同地理起源。总体而言，我们的结果表明，第四纪火山作用的优势在于气候变化，而不是气候振荡。此外，我们发现证据表明，自律学特征会调节社区的历史反应。