In tropical sky-islands, cold-affinity populations tend to become isolated at highlands during the interglacial periods, and to expand into the lowlands where they become more connected during the glacial periods. Although this has been widely studied in trees, it is poorly understood how fungal symbionts can differentiate among mountains (allopatrically), or within a single mountain (parapatrically) due to climate fluctuations. Here, we conducted population genomic analyses on the ectomycorrhizal fungus Laccaria trichodermophora in three tropical sky-islands using Genotyping by Sequencing (GBS) at low DNA concentrations. There were no significant differences between altitudes within a single mountain, but we observed significant genetic differentiation among populations from different mountains, supporting the allopatric differentiation hypothesis. Our results indicate that L. trichodermophora populations are under a sky-island population dynamics that started during the Pleistocene climate fluctuations.

在热带的天空岛上，冷亲和种群在冰期之间倾向于在高地处变得孤立，并扩展到低地，在冰期期间它们之间的联系更加紧密。尽管对此进行了广泛的研究，但由于气候波动，真菌共生体如何在山间（异位地）或在单个山内（副生地）之间进行区分却知之甚少。在这里，我们对外生菌根真菌Laccaria trichodermophora进行了人口基因组分析在低DNA浓度下使用测序基因分型法（GBS）在三个热带天空群岛中发现 同一座山的海拔高度之间没有显着差异，但是我们观察到了来自不同山地的种群之间存在显着的遗传分化，支持了异源分化假说。我们的结果表明，L。trichodermophora种群处于更新世气候波动期间开始的天空岛种群动态之下。