The joint effect of the Andes as a geographical barrier and the Quaternary glaciations as promoters of genetic divergence remains virtually unexplored in southern South America. To help fill this knowledge gap, in this study we investigated the demographic history of Centris cineraria, a solitary bee mainly distributed in Patagonia. We used mitochondrial and nuclear markers and performed phylogeographical and dating analyses, adjusted spatio-temporal diffusion and species distribution models, and used Approximate Bayesian Computation to identify likely historical demographic scenarios. Our results revealed that during glacial periods the Andes represented a barrier due to the extent of the ice-sheets and the occurrence of unsuitable habitats, while interglacials allowed for gene flow across the Andes. Secondary contact between previously isolated lineages was evident across at least two low-altitude Andean areas, the northern one being a putative glacial refugium. Our findings also suggest that C. cineraria has persisted in situ in four periglacial refugia located along a north–south transect, congruent with the maximum extent of the ice sheet during the Greatest Patagonian Glaciation. As the first phylogeographical study of Patagonian insects, our work reveals that the interaction between Quaternary climatic oscillations and the Andes as a barrier was the main driver of the spatial and demographic history of C. cineraria.

中文翻译：

---

连接，隔离和重新连接：第四纪的气候振荡和安第斯山脉塑造了巴塔哥尼亚蜜蜂Centris cineraria（Apidae）的系统地理模式

在南美洲南部，安第斯山脉作为地理障碍和第四纪冰川作为遗传差异的推动者的共同影响实际上尚未被发现。为了填补这一知识空白，在本研究中，我们调查了Centris cineraria的人口历史，一种主要分布在巴塔哥尼亚的独居蜂。我们使用线粒体和核标记，进行了地理学和年代分析，调整了时空扩散和物种分布模型，并使用近似贝叶斯计算法来确定可能的历史人口情况。我们的研究结果表明，在冰川期，由于冰盖的面积和不适当的栖息地的出现，安第斯山脉是一个障碍，而冰川间期则允许基因流过整个安第斯山脉。在至少两个低海拔的安第斯山脉地区，以前孤立的世系之间存在次要接触，北部是假定的冰川避难所。我们的研究结果还表明，瓜叶蜡毛菌已就地持续存在沿北-南样带的四个冰缘避难所，与最大巴塔哥尼亚冰川期最大的冰盖范围一致。作为对巴塔哥尼亚昆虫的第一个系统地理学研究，我们的工作表明，第四纪气候波动与安第斯山脉之间的相互作用是灰叶蝉空间和人口历史的主要驱动力。