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物种分化起到了重要驱动作用。然而，更新世气候变化与生态因子同样可能塑造该火山带沿线植物的遗传结构。本研究以鹦鹉槲寄生（Psittacanthus calyculatus）为对象，分析其谱系地理学格局，以明确上述不同因素的相对贡献。
研究区域：跨墨西哥火山带（Trans-Mexican Volcanic Belt，TMVB）
研究方法：本研究共获取370个个体的核基因组与叶绿体基因组序列数据，对该物种分布范围内的35个种群开展遗传分化分析。通过对P. calyculatus的序列进行系统发育、种群遗传学及空间遗传分析，并结合生态位模型与贝叶斯推断方法，解析上述种群的遗传变异结构。
研究结果：分析结果显示，该物种存在显著的种群遗传结构，可划分为3个遗传类群，分别对应瓦哈卡（Oaxaca）种群以及跨墨西哥火山带中东部、西部种群。研究检测到显著的种群扩张遗传信号，物种分布模型预测的东-西扩张方向，以及近似贝叶斯计算分析结果，均强烈支持P. calyculatus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：P. calyculatus的遗传分化可由两种共同作用机制解释：（1）与冰期-间冰期旋回及环境因子相关的地理隔离，驱动其与同属物种向旱生植被生境发生遗传分化；（2）跨墨西哥火山带的东-西方向入侵过程，表明定殖事件与冰期-间冰期旋回模型均在其演化进程中发挥了重要作用。