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，其繁殖系统亦涵盖从巢寄生（brood parasitism）到巢穴内存在多只非繁殖性育雏帮手的合作育雏系统等多种形式。不过当前最为普遍的繁殖模式，仍是双亲共同参与抚育幼雏的配对繁殖（pair breeding）系统。此前已有研究提出，与亲本抚育相关的性状会影响物种的扩散倾向与支系分化，但迄今为止，在广泛的时空尺度下验证这一潜在关联的相关研究仍较为匮乏。本研究依托全球分布的鸦总科鸟类（corvoid birds）数据集，并结合状态依赖的物种形成与灭绝模型（state-dependent speciation and extinction models），指出配对繁殖与更高的物种形成速率存在显著关联。对不同繁殖系统间转换速率的估算结果显示，合作育雏支系常演化出双亲抚育模式，而配对繁殖类群则极少转变为合作育雏。我们还发现两类繁殖模式的类群在空间分布上存在明显差异：配对繁殖类群在岛屿上的占比显著偏高，而合作育雏类群则主要分布于大陆区域。此外，我们观测到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，从合作育雏向配对繁殖的转变，可能是推动鸦总科核心类群扩散至热带群岛，并进而在全球范围内发生系统发育扩张的重要驱动因素之一。