Data from: Evaluating mechanisms of diversification in a Guineo-Congolian tropical forest frog using demographic model selection

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.

热带森林生物多样性的积累可通过多种异域分化（allopatric）与邻域分化（parapatric）模式实现，涵盖森林避难所（forest refugia）、河流屏障（riverine barriers）与生态梯度（ecological gradients）等机制。学界围绕核心物种分化过程尚存广泛争议，尤以西非下几内亚森林区域为甚——该区域兼具复杂的地形地貌格局与历史避难所分布。本研究以加蓬林蛙（*Scotobleps gabonicus*）为研究对象，利用基因组数据探究其潜在物种分化机制：首先明确种群结构，随后开展种群历史模型选择与空间显式分析。研究结果显示，绝大多数种群分化事件均可由契合森林避难所假说的异域分化模型得到最优解释，即种群先经历隔离分化，后续伴随分布扩张与基因交流。这些种群分化事件同步发生，且与基于生态位模型推断的气候稳定区域的预测结果一致。尽管森林避难所在加蓬林蛙的种内分化中发挥了关键作用，本研究同时发现景观特征与历史避难所间存在潜在交互作用的证据，其中包括大型河流与喀麦隆火山带（Cameroonian Volcanic Line）等海拔屏障。本研究阐述了在模型检验框架中利用全基因组变异区分不同异域分化假说的优势，同时也指出了地理采样与分子采样范围有限所带来的研究局限。尽管系统地理学格局通常具有物种特异性，且与物种生活史特征相关，但要区分共享历史过程与物种对环境、气候及地质因素介导的分化所产生的特异性响应，仍需开展更多结合基因组数据的比较研究。