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 southwest to northeast 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 Al...在过去25年间，印度-马来亚生物区（Indo-Malayan bioregion）已成为全球发现新型脊椎动物物种最具突破性的区域之一，例如中南大羚（saola）、克氏鹎（khanyou）与裸脸鹎（bare-faced bulbul）。然而，学界对该区域现存生物多样性的形成过程仍知之甚少。我们对一类亲缘关系紧密的雀形目鸟类（passerines）——绿鹎属（Alophoixus）鹎类——的系统地理学历史（phylogeographic history）进行了重构。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）单次拓殖至马来半岛大陆，随后类群沿西南向东北方向依次分化；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较弱或古老的基因交流。我们还检测到两个亚种（subspecies）存在种群扩张的迹象，其中一个亚种参与了分布环的闭合过程。因此，我们的分析表明，Alophoixus属鹎类的物种分化模式……