Data from: Tectonic collision and uplift of Wallacea triggered the global songbird radiation

Songbirds (oscine passerines) are the most species rich and cosmopolitan bird group, comprising almost half of global avian species diversity. Because of their diversity and ubiquity, songbirds are used extensively in studies of evolutionary ecology, diversification, and ethology. Songbirds originated in Australia, but the evolutionary trajectory from a single species in an isolated continent to worldwide proliferation is poorly understood. Prior research suggested songbird diversification scenarios that are largely uncoupled from Earth history, including extensive diversification of lineages in New Guinea prior to its emergence as a landmass and long-distance dispersal to Africa or Asia when no dispersal corridors existed. However, these results may be flawed because the studies relied on unresolved phylogenetic relationships and a controversial biogeographic time calibration. Here, we combine the first genome-scale DNA sequence data set for songbirds, fossil-based time calibrations, and geologically informed biogeographic reconstructions to provide the first well-supported evolutionary hypothesis for the group. We show that songbird diversification began in the Oligocene, but accelerated in the early Miocene, at approximately half the age of most previous estimates. This burst of diversification occurred after island formation in Wallacea, which provided the first dispersal corridor out of Australia, and resulted in independent waves of songbird expansion through Asia to the rest of the globe. Although New Guinea presently contains high songbird species richness, our data unambiguously falsify the proto-Papuan hypothesis for early songbird diversification and suggest that New Guinea has, instead, served as an “evolutionary refuge” for Australian lineages that have diversified more recently within the island. Our results reconcile songbird evolution with Earth history and link a major radiation of terrestrial biodiversity to early diversification within an isolated Australian continent.

鸣禽（oscine passerines）是物种多样性最丰富、分布最广的鸟类类群，其物种数约占全球鸟类总物种多样性的一半。鉴于其物种多样性与广泛分布的特征，鸣禽被广泛应用于进化生态学、物种分化及行为学相关研究中。鸣禽起源于澳大利亚，但人们对其从孤立大陆上的单一物种，到如今遍布全球的演化历程仍知之甚少。既往研究提出的鸣禽物种分化模式大多与地球历史进程无关，其中包括：新几内亚尚为陆地之前，其境内的支系就已发生大规模物种分化；以及在不存在扩散廊道的时期，鸣禽长距离扩散至非洲或亚洲。不过，这类研究结果可能存在瑕疵，原因在于其依赖尚未明确的系统发育关系，以及存在争议的生物地理学时间校准方案。本研究整合了首套鸣禽全基因组DNA序列数据集、基于化石的时间校准方案，以及地质学约束下的生物地理学重建结果，首次为该类群提出了证据充分的演化假说。研究表明，鸣禽的物种分化始于渐新世，但在中新世早期迎来加速，其分化时间约为多数既往研究估算时长的一半。此次物种分化爆发发生在华莱士区（Wallacea）岛屿形成之后——该区域为鸣禽提供了首个走出澳大利亚的扩散廊道，最终推动鸣禽通过亚洲向全球其他区域独立开展多波次的扩张。尽管当前新几内亚拥有极高的鸣禽物种丰富度，但本研究数据明确驳斥了鸣禽早期分化的原巴布亚假说（proto-Papuan hypothesis），并表明新几内亚实际上是澳大利亚支系的“演化避难所”，这些支系在该岛屿内发生了近期的物种分化。本研究结果将鸣禽演化与地球历史进程相统一，并将陆地生物多样性的一次大规模辐射演化，与孤立澳大利亚大陆内的早期物种分化建立了关联。