Data from: Quantifying species contributions to ecosystem processes: a global assessment of functional trait and phylogenetic metrics across avian seed-dispersal networks

Quantifying the role of biodiversity in ecosystems not only requires understanding the links between species and the ecological functions and services they provide, but also how these factors relate to measurable indices, such as functional traits and phylogenetic diversity. However, these relationships remain poorly understood, especially for heterotrophic organisms within complex ecological networks. Here, we assemble data on avian traits across a global sample of mutualistic plant–frugivore networks to critically assess how the functional roles of frugivores are associated with their intrinsic traits, as well as their evolutionary and functional distinctiveness. We find strong evidence for niche complementarity, with phenotypically and phylogenetically distinct birds interacting with more unique sets of plants. However, interaction strengths—the number of plant species dependent on a frugivore—were unrelated to evolutionary or functional distinctiveness, largely because distinct frugivores tend to be locally rare, and thus have fewer connections across the network. Instead, interaction strengths were better predicted by intrinsic traits, including body size, gape width and dietary specialization. Our analysis provides general support for the use of traits in quantifying species ecological functions, but also highlights the need to go beyond simple metrics of functional or phylogenetic diversity to consider the multiple pathways through which traits may determine ecological processes.

量化生物多样性（biodiversity）在生态系统中的作用，不仅需要厘清物种与其所提供的生态功能与服务之间的关联，还需明晰这些要素与可测量指标（如功能性状（functional traits）和系统发育多样性）之间的联系。然而，目前人们对这些关系的认知仍较为匮乏，尤其是复杂生态网络中的异养生物（heterotrophic organisms）。在此研究中，我们基于全球范围的互利共生植物-食果动物网络样本，整合了鸟类性状数据，以批判性评估食果动物的功能角色与其内在性状、进化及功能独特性之间的关联。我们发现了生态位互补（niche complementarity）的有力证据：表型与系统发育独特的鸟类会与更多独特的植物类群产生互作。不过，互作强度——即依赖某一食果动物的植物物种数量——与进化或功能独特性并无关联，这主要是因为独特的食果动物往往在本地较为稀有，因此在整个网络中的连接数更少。取而代之的是，互作强度可通过内在性状得到更好的预测，包括体型大小、口裂宽度（gape width）与食性特化程度。本研究分析为利用性状量化物种生态功能提供了普适性支持，同时也强调，我们需要超越简单的功能或系统发育多样性指标，去探究性状决定生态过程的多重路径。