Escuela Nacional de Estudios Superiores Unidad Morelia, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex-Hacienda de San José de la Huerta, Morelia, Michoacán, México.
Laboratorio Nacional de Análisis y Síntesis Ecológica, Escuela Nacional de Estudios Superiores, Unidad Morelia, Universidad Nacional Autónoma de México, Antigua Carretera a Pátzcuaro No. 8701, Col. Ex-Hacienda de San José de la Huerta, Morelia, Michoacán, México.
J Hered. 2018 Jun 27;109(5):530-542. doi: 10.1093/jhered/esy011.
Lower Central America is an important area to study recent population history and diversification of Neotropical species due to its complex and dynamic geology and climate. Phylogeographic studies in this region are few in comparison with other regions and even less for tree species. The aim of the present study was to characterize the phylogeographic structure in 2 partially co-distributed endemic oak species (Quercus costaricensis and Q. bumelioides) of the Costa Rican mountains using chloroplast short sequence repeats (cpSSRs), and to test for the effect of geological and palaeoclimatic processes on their population history. Genetic diversity and structure, haplotype networks, patterns of seed-mediated gene flow and historical demography were estimated for both species. Results suggested contrasting patterns. Quercus costaricensis exhibited high values of genetic diversity, a marked phylogeographic structure, a north-to-south genetic diversity gradient and evidence of a demographic expansion during the Quaternary. Quercus bumelioides did not show significant genetic structure and the haplotype network and historical demography estimates suggested a recent population expansion probably during the Pleistocene-Holocene transition. The phylogeographic structure of Q. costaricensis seems to be related to Pleistocene altitudinal migration due to its higher altitudinal distribution. Meanwhile, historical seed-mediated gene flow through the lower altitudinal distribution of Q. bumelioides may have promoted the homogenization of genetic variation. Population expansion and stable availability of suitable climatic areas in both species probably indicate that palaeoclimatic changes promoted downwards altitudinal migration and formation of continuous forests allowing oak species to expand their distribution into the Panamanian mountains during glacial stages.
中美洲低地由于其复杂和动态的地质和气候条件，是研究新热带物种近期种群历史和多样化的重要区域。与其他地区相比，该地区的系统地理学研究较少，对于树种的研究则更少。本研究的目的是利用叶绿体短序列重复（cpSSR）来描述哥斯达黎加山区两种部分共分布的特有栎属物种（Q. costaricensis 和 Q. bumelioides）的系统地理学结构，并检验地质和古气候过程对其种群历史的影响。对这两个物种的遗传多样性和结构、单倍型网络、种子介导的基因流模式和历史动态进行了估计。结果表明存在相反的模式。Q. costaricensis 表现出较高的遗传多样性、显著的系统地理学结构、由北向南的遗传多样性梯度以及第四纪发生的种群扩张证据。Q. bumelioides 没有表现出显著的遗传结构，单倍型网络和历史动态估计表明，最近的种群扩张可能发生在更新世-全新世过渡期。Q. costaricensis 的系统地理学结构似乎与更新世的海拔迁移有关，因为它的海拔分布更高。同时，Q. bumelioides 较低海拔分布的历史种子介导的基因流可能促进了遗传变异的同质化。两种物种的种群扩张和稳定的适宜气候区域的存在，可能表明古气候变化促进了海拔的向下迁移和连续森林的形成，使栎属物种能够在冰川时期将其分布扩展到巴拿马山脉。
