Data from: Phylogeography and population differentiation in the Psittacanthus calyculatus (Loranthaceae) mistletoe: a complex scenario of climate-volcanism interaction along the Trans-Mexican Volcanic Belt

Aim The formation of the Trans-Mexican Volcanic Belt (TMVB) played an important role in driving inter- and intraspecific diversification at high elevations. However, Pleistocene climate changes and ecological factors might also contribute to plant genetic structuring along the volcanic belt. Here, we analysed phylogeographic patterns of the parrot-mistletoe Psittacanthus calyculatus to determine the relative contribution of these different factors. Location Trans-Mexican Volcanic Belt Methods Using nuclear and chloroplast DNA sequence data for 370 individuals, we investigate the genetic differentiation of 35 populations across the species range. We conducted phylogenetic, population and spatial genetic analyses of P. calyculatus sequences along with ecological niche modelling and Bayesian inference methods to gain insight into the structuring of genetic variation of these populations. Results Our analyses revealed population structure with three genetic groups corresponding to individuals from Oaxaca and those from the central-eastern and western TMVB regions. A significant genetic signal of demographic expansion, an east-to-west expansion predicted by species distribution modelling, and approximate Bayesian computation analyses strongly supported a scenario of habitat isolation and invasion of TMVB by P. calyculatus during the late-Pleistocene. Main conclusions The genetic differentiation of P. calyculatus may be explained by the combined effects of (i) geographical isolation linked to the effects of the glacial/interglacial cycles and environmental factors, driving genetic differentiation from congeners into more xeric vegetation and (ii) the invasion of TMVB from east to west, suggesting a role for both colonization and glacial/interglacial cycles models.研究目的：跨墨西哥火山带（Trans-Mexican Volcanic Belt, TMVB）的形成，对高海拔区域的种间与种内分化具有重要驱动作用。然而，更新世气候变化与生态因子，或许也对该火山带沿线植物的遗传结构塑造产生了影响。本研究以具苞鹦鹉寄生（Psittacanthus calyculatus）为研究对象，分析其系统地理学格局，以明确上述各类因子的相对贡献程度。 研究区域：跨墨西哥火山带。 研究方法：本研究基于370个个体的核DNA与叶绿体DNA序列数据，对该物种分布范围内的35个种群开展遗传分化分析。我们针对具苞鹦鹉寄生的序列数据进行系统发育、种群遗传学及空间遗传分析，并结合生态位建模与贝叶斯推断方法，以深入阐明这些种群的遗传变异结构。 研究结果：本研究揭示了三类遗传聚类的种群结构，分别对应来自瓦哈卡州的个体，以及来自中东部、西部跨墨西哥火山带区域的类群。分析发现显著的种群扩张遗传信号，物种分布模型预测的东-西扩张趋势，结合近似贝叶斯计算分析结果，均强烈支持具苞鹦鹉寄生在更新世晚期通过生境隔离并入侵跨墨西哥火山带的演化场景。 主要结论：具苞鹦鹉寄生的遗传分化可由两类效应的共同作用解释：其一为与冰期/间冰期循环及环境因子相关的地理隔离，该过程驱动其与同属物种产生遗传分化，进而适应更为旱生的植被生境；其二为跨墨西哥火山带的东-西入侵过程，表明定殖事件与冰期/间冰期循环模型均在其演化中发挥了重要作用。