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.

阐释物种丰度的变异始终是生态学领域的一大研究难题。本研究依托涵盖596个物种种群密度的数据集，旨在解析新热带界森林鸟类的丰度变异规律。我们针对物种性状、环境因子以及物种间相互作用的作用机制检验了先验假说，具体聚焦四大影响因素：1）体重（物种性状）；2）栖息地类型（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）。研究结果显示，体型大小能够解释大量种群密度的变异，但该效应仅在较高分类学层级下开展分析时方可观测到。栖息地类型是种群密度的强有力预测因子。种群密度与生产力之间的关联则较为微弱。然而，种群密度与异种物种丰富度呈显著负相关关系，且这一趋势在近缘类群中尤为突出。本研究表明，体型大小、生产力这类能量相关因子的影响依赖于系统发育关系，并通过与其他变量的间接关联发挥作用；而栖息地结构、物种间相互作用等其他生态因子，在决定物种丰度方面所起到的直接作用与影响强度均超出此前的学术认知。