Data from: The complex phylogeography of the Indo-Malayan Alophoixus bulbuls with the description of a putative new ring species complex

The Indo-Malayan bioregion has provided some of the most spectacular discoveries of new vertebrate species (e.g. saola, khanyou, bare-faced bulbul) over the last 25 years. Yet, very little is known about the processes that led to the current biodiversity in this region. We reconstructed the phylogeographic history of a group of closely related passerines, the Alophoixus bulbuls. These birds are continuously distributed in Indo-Malaya around the Thailand lowlands such that their distribution resembles a ring. Our analyses revealed a single colonization event of the mainland from Sundaland with sequential divergence of taxa from South West to North East characterized by significant gene flow between parapatric taxa, and reduced or ancient gene flow involving the two taxa at the extremities of the ring. We detected evidence of population expansion in two subspecies, including one that was involved in the closing of the ring. Hence, our analyses indicate that the diversification pattern of Alophoixus bulbuls fits a ring species model driven by geographic isolation. To our knowledge, the Alophoixus bulbuls represent the first case of a putative broken ring species complex in Indo-Malaya. We also discuss the implications of our results on our understanding of the biogeography in Indo-Malaya.

过去25年间，印度-马来亚生物区（Indo-Malayan bioregion）内陆续发现了诸多极具标志性的脊椎动物新物种，例如中南大羚（saola）、khanyou、裸脸鹎（bare-faced bulbul）。然而，学界对塑造该区域现有生物多样性的演化过程仍知之甚少。本研究重建了一类近缘雀形目鸟类（passerines）——阿劳鹎属鹎类（Alophoixus bulbuls）的系统地理学历史（phylogeographic history）。该类鸟类在印度-马来亚区域内沿泰国低地呈连续分布，其分布格局近似环状。分析结果显示，该类群从巽他陆块（Sundaland）向马来亚大陆仅发生过一次殖民事件，类群分化沿西南向东北方向依次进行，邻域类群（parapatric taxa）间存在显著的基因流（gene flow），而分布环两端的两个类群间仅存在微弱或古老的基因交流。研究还检测到两个亚种存在种群扩张的信号，其中一个亚种参与了该分布环的闭合过程。因此，本研究结果表明，阿劳鹎属鹎类的分化模式符合地理隔离驱动的环物种模型。据我们所知，阿劳鹎属鹎类是印度-马来亚区域内首个被认定为破碎环物种复合体的类群。本研究还探讨了本次研究结果对学界理解印度-马来亚区域生物地理学的启示意义。