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：墨西哥跨火山带（Trans-Mexican Volcanic Belt, TMVB）的形成对高海拔物种的种间及种内分化起到了关键驱动作用。然而，更新世气候变化与生态因子或许也推动了该火山带沿线植物的遗传结构分化。本研究以鹦鹉寄生藤（Psittacanthus calyculatus）为研究对象，分析其系统地理格局，以明确上述不同因子的相对贡献。
研究区域：墨西哥跨火山带（Trans-Mexican Volcanic Belt, TMVB）。
研究方法：本研究采集该物种分布范围内35个种群共370个个体的核DNA与叶绿体DNA序列数据，解析其种群遗传分化模式。我们采用系统发育分析、种群遗传学分析及空间遗传分析方法，结合生态位建模与贝叶斯推断手段，对P. calyculatus的序列数据进行分析，以阐明该物种各类群的遗传变异结构。
研究结果：分析结果显示，该物种存在三类遗传聚类群，分别对应瓦哈卡（Oaxaca）种群、中东部TMVB种群与西部TMVB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-西扩张趋势，以及近似贝叶斯计算分析结果，均强烈支持“更新世晚期P. calyculatus发生生境隔离，并逐步入侵TMVB”这一演化场景。
主要结论：本研究的主要结论为，P. calyculatus的遗传分化可由两种共同作用机制共同解释：（1）与冰期-间冰期旋回及环境因子相关的地理隔离，驱动该物种与其同属近缘类群产生遗传分化，并使其适应旱生植被生境；（2）该物种从东向西入侵TMVB的演化过程，表明定殖事件与冰期-间冰期旋回模型均在其演化历程中发挥了重要作用。