Data from: A continent-scale test of multiple hypotheses on the abundances of Neotropical birds

Explaining variation in the abundance of species remains a challenge in ecology. We sought to explain variation in abundance of Neotropical forest birds using a dataset of population densities of 596 species. We tested a priori hypotheses for the roles of species traits, environmental factors, and species interactions. Specifically, we focused on four factors: 1) body mass (trait); 2) habitat type (environmental factor), 3) net primary productivity (NPP; environmental factor); and 4) species richness of competitors (species interaction). Body size explained much variation in density, although only when analyzed at higher taxonomic levels. Habitat type was a strong predictor of density. The relationship between density and productivity was weak. Densities were related negatively to the species richness of heterospecifics, however – this trend was particularly strong within closely related groups. Our results show that the influence of energetic factors such as body size and productivity depends on phylogeny, and they act through indirect relations with other variables; alternative ecological factors such as habitat structure and species interactions play a more direct and stronger role in determining abundance than previously thought.阐明物种种群丰度的变异机制，仍是生态学研究中的一大挑战。本研究依托涵盖596个物种种群密度的数据集，旨在阐释新热带界森林鸟类的丰度变异规律。我们针对物种性状、环境因子与物种间相互作用的作用效应，检验了先验假说。具体而言，本研究重点关注四类因子：1）体重（物种性状）；2）生境类型（环境因子）；3）净初级生产力（Net Primary Productivity，NPP，环境因子）；4）竞争者物种丰富度（物种间相互作用）。 体重能够解释大量种群密度变异，但该效应仅在较高分类阶元水平上分析时才显著。生境类型对种群密度具有极强的预测能力。种群密度与生产力之间的相关性较弱。然而，种群密度与异种物种丰富度呈显著负相关，且该负相关趋势在亲缘关系较近的类群中尤为明显。 本研究结果表明，体重、生产力这类能量因子对种群丰度的影响依赖于物种系统发育关系，且其作用通过与其他变量的间接关联实现；相较于此前认知，生境结构、物种间相互作用等其他生态因子，在决定物种种群丰度时发挥了更为直接且更强的调控作用。