Nuclear and chloroplast DNA phylogeography reveals Pleistocene divergence and subsequent secondary contact of two genetic lineages of the tropical rainforest tree species Shorea leprosula (Dipterocarpaceae) in Southeast Asia

Tropical rainforests in Southeast Asia have been affected by climatic fluctuations during past glacial eras. To examine how the accompanying changes in land areas and temperature have affected the genetic properties of rainforest trees in the region, we investigated the phylogeographic patterns of a widespread dipterocarp species, Shorea leprosula. Two types of DNA markers were used: expressed sequence tag-based simple sequence repeats (EST-SSRs) and chloroplast DNA (cpDNA) sequence variations. Both sets of markers revealed clear genetic differentiation between populations in Borneo and those in the Malay Peninsula and Sumatra (Malay/Sumatra). However, in the southwestern part of Borneo genetic admixture of the lineages was observed in the two marker types. Coalescent simulation based on cpDNA sequence variation suggested that the two lineages arose 0.28 to 0.09 million years before present, and that following their divergence migration from Malay/Sumatra to Borneo strongly exceeded mig...东南亚热带雨林在过往冰期时期曾经历气候波动。为探明陆地面积与温度的协同变化对该区域雨林树木遗传特性的影响，本研究针对广布龙脑香科物种薄叶娑罗双（Shorea leprosula）的系统地理（phylogeographic）格局展开了调查。本研究采用两类DNA分子标记：基于表达序列标签的简单序列重复标记（EST-SSRs）与叶绿体DNA（cpDNA）序列变异位点。两类标记均揭示，婆罗洲种群与马来半岛、苏门答腊种群（下称马来/苏门答腊种群）间存在显著遗传分化。然而在婆罗洲西南部区域，两类标记均检测到两个谱系的遗传渐渗现象。基于叶绿体DNA序列变异的溯祖模拟（coalescent simulation）分析显示，两个谱系的分化时间距今0.28至0.09百万年，且在谱系分化后，从马来/苏门答腊向婆罗洲的基因流强度远高于mig...