Data from: Complex phylogeographic patterns indicate Central American origin of two widespread Mesoamerican Quercus (Fagaceae) species

The northern Neotropical region is characterized by a heterogeneous geological and climatic history. Recent studies have shown contrasting patterns regarding the role of geographic elements as barriers that could have determined phylogeographic structure in various species. Recently, the phylogeography and biogeography of Quercus species have been studied intensively, and the patterns observed so far suggest contrasting evolutionary histories for Neotropical species in comparison with their Holarctic relatives. The goal of this study was to describe the phylogeographic structure of two Neotropical oak species (Quercus insignis and Quercus sapotifolia) in the context of the geological and palaeoclimatic history of the northern Neotropics. Populations through the distribution range of both species were collected and characterized using nine chloroplast DNA microsatellite loci. Both oak species showed high levels of genetic diversity and strong phylogeographic structure. The distribution of genetic variation in Q. insignis suggested an influence of two major barriers, the Isthmus of Tehuantepec and the Nicaraguan Depression, while Q. sapotifolia exhibited a genetic structure defined by the heterogeneity of the Chortis highlands. The haplotype networks of both species indicated complex histories, suggesting that colonization from the Sierra Madre de Chiapas to central Mexico and from the north of the Nicaraguan Depression to the Costa Rican mountains may have occurred during different stages, and apparently more than one time. In conclusion, the phylogeographic structure of Neotropical oak species seems to be defined by a combination of geological and climatic events.新热带北部区域以异质性的地质与气候演化历史为典型特征。近期研究表明，地理要素作为潜在屏障对多个物种种群系统发育地理结构的塑造作用呈现出截然不同的模式。近年来，针对栎属（Quercus）物种的系统发育地理学与生物地理学研究已得到广泛开展，目前观测到的格局显示，新热带栎属物种与其全北界近缘类群的演化历史存在显著差异。本研究旨在结合新热带北部区域的地质与古气候历史，解析两种新热带栎属物种——大果栎（Quercus insignis）与萨波蒂栎（Quercus sapotifolia）的系统发育地理结构。研究人员采集了两个物种整个分布范围内的种群，并通过9个叶绿体DNA微卫星位点对其进行遗传特征分析。两种栎属物种均表现出较高的遗传多样性水平与显著的系统发育地理结构。大果栎的遗传变异分布格局表明，特万特佩克地峡（Isthmus of Tehuantepec）与尼加拉瓜洼地（Nicaraguan Depression）这两大地理屏障对其产生了影响；而萨波蒂栎的遗传结构则由乔蒂斯高地（Chortis highlands）的环境异质性所塑造。两种物种的单倍型网络均呈现出复杂的演化历史，提示从恰帕斯马德雷山脉（Sierra Madre de Chiapas）至墨西哥中部，以及从尼加拉瓜洼地北部至哥斯达黎加山地的殖民事件可能发生于不同阶段，且并非仅发生一次。综上，新热带栎属物种的系统发育地理结构似乎是地质与气候事件共同作用的结果。