Portik Daniel M, Leaché Adam D, Rivera Danielle, Barej Michael F, Burger Marius, Hirschfeld Mareike, Rödel Mark-Oliver, Blackburn David C, Fujita Matthew K
Department of Biology, The University of Texas at Arlington, Arlington, TX, USA.
Department of Biology, University of Washington, Seattle, WA, USA.
Mol Ecol. 2017 Oct;26(19):5245-5263. doi: 10.1111/mec.14266. Epub 2017 Aug 24.
The accumulation of biodiversity in tropical forests can occur through multiple allopatric and parapatric models of diversification, including forest refugia, riverine barriers and ecological gradients. Considerable debate surrounds the major diversification process, particularly in the West African Lower Guinea forests, which contain a complex geographic arrangement of topographic features and historical refugia. We used genomic data to investigate alternative mechanisms of diversification in the Gaboon forest frog, Scotobleps gabonicus, by first identifying population structure and then performing demographic model selection and spatially explicit analyses. We found that a majority of population divergences are best explained by allopatric models consistent with the forest refugia hypothesis and involve divergence in isolation with subsequent expansion and gene flow. These population divergences occurred simultaneously and conform to predictions based on climatically stable regions inferred through ecological niche modelling. Although forest refugia played a prominent role in the intraspecific diversification of S. gabonicus, we also find evidence for potential interactions between landscape features and historical refugia, including major rivers and elevational barriers such as the Cameroonian Volcanic Line. We outline the advantages of using genomewide variation in a model-testing framework to distinguish between alternative allopatric hypotheses, and the pitfalls of limited geographic and molecular sampling. Although phylogeographic patterns are often species-specific and related to life-history traits, additional comparative studies incorporating genomic data are necessary for separating shared historical processes from idiosyncratic responses to environmental, climatic and geological influences on diversification.
热带森林中生物多样性的积累可以通过多种异域和邻域多样化模式发生，包括森林避难所、河流屏障和生态梯度。关于主要的多样化过程存在相当多的争论，特别是在西非下几内亚森林，那里地形特征和历史避难所的地理布局复杂。我们使用基因组数据来研究加蓬森林蛙（Scotobleps gabonicus）多样化的替代机制，首先确定种群结构，然后进行人口统计学模型选择和空间明确分析。我们发现，大多数种群分化最好用与森林避难所假说一致的异域模型来解释，并且涉及隔离中的分化以及随后的扩张和基因流动。这些种群分化同时发生，并且符合基于通过生态位建模推断出的气候稳定区域的预测。虽然森林避难所在加蓬森林蛙的种内多样化中发挥了重要作用，但我们也发现了景观特征与历史避难所之间潜在相互作用的证据，包括主要河流和喀麦隆火山线等海拔屏障。我们概述了在模型测试框架中使用全基因组变异来区分替代异域假说的优势，以及地理和分子采样有限的陷阱。虽然系统发育地理模式通常是物种特异性的，并且与生活史特征相关，但纳入基因组数据的额外比较研究对于将共同的历史过程与对多样化的环境、气候和地质影响的特殊反应区分开来是必要的。
