Data from: Breeding system evolution influenced the geographic expansion and diversification of the core Corvoidea (Aves: Passeriformes)

Birds vary greatly in their life-history strategies, including their breeding systems, which range from brood parasitism to a system with multiple non-breeding helpers at the nest. By far the most common arrangement, however, is where both parents participate in raising the young. The traits associated with parental care have been suggested to affect dispersal propensity and lineage diversification, but to date tests of this potential relationship at broad temporal and spatial scales have been limited. Here, using data from a globally distributed group of corvoid birds in concordance with state-dependent speciation and extinction models, we suggest that pair breeding is associated with elevated speciation rates. Estimates of transition between breeding systems imply that cooperative lineages frequently evolve biparental care, whereas pair breeders rarely become cooperative. We further highlight that these groups have differences in their spatial distributions, with pair breeders over-represented on islands, and cooperative breeders mainly found on continents. Finally, we find that speciation rates appear to be significantly higher on islands compared to continents. These results imply that the transition from cooperative breeding to pair breeding was likely a significant contributing factor facilitating dispersal across tropical archipelagos, and subsequent world-wide phylogenetic expansion among the core Corvoidea.

鸟类的生活史策略差异显著，其繁殖系统类型多样，涵盖巢寄生（brood parasitism）以及巢内配备多名非繁殖辅助者的合作育雏系统等；其中最为普遍的繁殖模式为双亲共同参与幼雏抚育。此前有研究指出，与育幼行为相关的特征可能会影响物种的扩散倾向与类群分化，但截至目前，在大时空尺度下对这一潜在关联开展的实证检验仍较为有限。本研究依托全球分布的鸦下目（Corvoidea）鸟类数据集，并结合状态依赖型物种形成与灭绝模型（state-dependent speciation and extinction models）开展分析，结果显示配对育雏与更高的物种形成速率显著相关；对不同繁殖系统间转换速率的估算结果表明，合作育雏类群常会演化出双亲育雏模式，而配对育雏类群则极少转变为合作育雏模式。我们还发现，两类繁殖模式的类群在空间分布上存在显著分化：配对育雏类群在岛屿生境中占比偏高，而合作育雏类群则主要集中分布于大陆区域；进一步分析显示，岛屿环境中的物种形成速率显著高于大陆环境。上述结果表明，从合作育雏向配对育雏的演化转变，或是推动鸦下目核心类群跨热带群岛扩散，并最终实现全球范围系统发育扩张的关键驱动因素之一。