Data from: Multicontinental community phylogenetics of avian mixed-species flocks reveal the role of the stability of associations and of kleptoparasitism

If understood as a way to forage socially without incurring intra-specific competition for mates or other resources, mixed-species foraging flocks are predicted to be composed of functionally similar species. In the most intensively studied mixed-species foraging system, understory forest birds, relevant functional traits are however extremely difficult to measure and best replaced by phylogenetic relatedness. A multicontinental analysis of flock phylogenetic structure revealed departures from the expected phylogenetic clustering. Long-lasting associations (> one day) were phylogenetically overdispersed, indicating that these associations are affected by competitive exclusion or by mutualistic interactions. However, where kleptoparasites occurred, this effect disappeared completely, as expected if the dilution of kleptoparasitism risk compensated competition between related species. Mixed-species flocks should not be analyzed as a homogeneous phenomenon.

若将混合物种觅食群（mixed-species foraging flocks）理解为一种可在不引发配偶或其他资源种内竞争的前提下开展社会性觅食的策略，则这类群落理论上应由功能相似的物种组成。在研究最为深入的混合物种觅食系统——林下鸟类群落中，相关功能性状（functional traits）的量化难度极大，因此最适宜采用系统发育亲缘关系（phylogenetic relatedness）作为其替代指标。一项覆盖多大陆的觅食群系统发育结构分析表明，其结果与预期的系统发育聚集模式存在偏差。持续时长超过一日的长期关联类群呈现出系统发育离散特征，这暗示这类物种关联会受到竞争排除或互利共生相互作用的调控。然而，当盗食寄生者（kleptoparasites）存在时，这一效应会完全消失——这与预期相符：盗食寄生风险的稀释效应能够补偿近缘物种间的竞争冲突。不应将混合物种觅食群作为均质化现象进行统一分析。