The complex island archipelagoes of Wallacea and Melanesia have provided empirical data behind integral theories in evolutionary biology, including allopatric speciation and island biogeography. Yet, questions regarding the relative impact of the layered biogeographic barriers, such as deep-water trenches and isolated island systems, on faunal diversification remain underexplored. One such barrier is Wallace’s Line, a significant biogeographic boundary that largely separates Australian and Asian biodiversity. To assess the relative roles of biogeographic barriers—specifically isolated island systems and Wallace’s Line—we investigated the tempo and mode of diversification in a diverse avian radiation, Corvides (Crows and Jays, Birds-of-paradise, Vangas, and allies). We combined a genus-level dataset of thousands of ultraconserved elements (UCEs) and a species-level, 12-gene Sanger sequence matrix to produce a well-resolved supermatrix tree that we leveraged to explore the group’s historical biogeography and effects of biogeographic barriers on their macroevolutionary dynamics. The tree is well-resolved and differs substantially from what has been used extensively for past comparative analyses within this group. We confirmed that Corvides, and its major constituent clades, arose in Australia and that a burst of dispersals west across Wallace’s Line occurred after the uplift of Wallacea during the mid-Miocene. We found that dispersal across this biogeographic barrier were generally rare, though westward dispersals were two times more frequent than eastward dispersals. Wallacea’s central position between Sundaland and Sahul no doubt acted as a bridge for island-hopping dispersal out of Australia, across Wallace’s Line, to colonize the rest of Earth. In addition, we found that the complex island archipelagoes east of Wallace’s Line harbor the highest rates of net diversification and are a substantial source of colonists to continental systems on both sides of this biogeographic barrier. Our results support emerging evidence that island systems, particularly the geologically complex archipelagoes of the Indo-pacific, are drivers of species diversification.

中文翻译：

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华莱士和美拉尼西亚群岛促进全球雀形目辐射科维德更高的多样化率

华莱士和美拉尼西亚的复杂岛屿群岛为进化生物学的整体理论提供了经验数据，包括异域物种形成和岛屿生物地理学。然而，关于分层生物地理屏​​障（例如深水海沟和孤岛系统）对动物群多样化的相对影响的问题仍未得到充分探索。一个这样的障碍是华莱士线，这是一个重要的生物地理边界，在很大程度上分隔了澳大利亚和亚洲的生物多样性。为了评估生物地理屏​​障（特别是孤立的岛屿系统和华莱士线）的相对作用，我们调查了多样化的鸟类辐射中的多样化的节奏和模式，Corvides（乌鸦和鸟，天堂鸟，万加斯和盟友）。我们将包含数千个超保守元素 (UCE) 的属级数据集和物种级 12 基因 Sanger 序列矩阵相结合，生成了一个解析良好的超矩阵树，我们利用它来探索该组的历史生物地理学和生物地理障碍对他们的宏观进化动力学。该树得到了很好的解析，并且与过去在该组中广泛用于比较分析的树有很大不同。我们证实了 Corvides 及其主要成分进化枝出现在澳大利亚，并且在中新世中期华莱士隆起之后发生了跨越华莱士线向西扩散的爆发。我们发现，跨越这个生物地理屏​​障的扩散通常很少见，尽管向西扩散的频率是向东扩散的两倍。华莱士位于巽他兰和萨胡尔之间的中心位置，无疑充当了跨越华莱士线、跨越华莱士线、殖民地球其他地区的澳大利亚跳岛传播的桥梁。此外，我们发现华莱士线以东的复杂岛屿群岛拥有最高的净多样化率，并且是该生物地理屏​​障两侧大陆系统的殖民者的重要来源。我们的研究结果支持新出现的证据，即岛屿系统，特别是印度太平洋地质复杂的群岛，是物种多样化的驱动力。我们发现华莱士线以东的复杂岛屿群岛拥有最高的净多样化率，并且是该生物地理屏​​障两侧大陆系统的殖民者的重要来源。我们的研究结果支持新出现的证据，即岛屿系统，特别是印度太平洋地质复杂的群岛，是物种多样化的驱动力。我们发现华莱士线以东的复杂岛屿群岛拥有最高的净多样化率，并且是该生物地理屏​​障两侧大陆系统的殖民者的重要来源。我们的研究结果支持新出现的证据，即岛屿系统，特别是印度太平洋地质复杂的群岛，是物种多样化的驱动力。