Hutchinson Matthew C, Dobson Andrew P, Pringle Robert M
Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA.
Institute of Evolutionary Biology and Environmental Studies, Universität Zürich, Zürich, Switzerland.
Ecol Lett. 2022 Apr;25(4):992-1008. doi: 10.1111/ele.13948. Epub 2021 Dec 30.
Diet composition is among the most important yet least understood dimensions of animal ecology. Inspired by the study of species abundance distributions (SADs), we tested for generalities in the structure of vertebrate diets by characterising them as dietary abundance distributions (DADs). We compiled data on 1167 population-level diets, representing >500 species from six vertebrate classes, spanning all continents and oceans. DADs near-universally (92.5%) followed a hollow-curve shape, with scant support for other plausible rank-abundance-distribution shapes. This strong generality is inherently related to, yet incompletely explained by, the SADs of available food taxa. By quantifying dietary generalisation as the half-saturation point of the cumulative distribution of dietary abundance (sp50, minimum number of foods required to account for 50% of diet), we found that vertebrate populations are surprisingly specialised: in most populations, fewer than three foods accounted for at least half the diet. Variation in sp50 was strongly associated with consumer type, with carnivores being more specialised than herbivores or omnivores. Other methodological (sampling method and effort, taxonomic resolution), biological (body mass, frugivory) and biogeographic (latitude) factors influenced sp50 to varying degrees. Future challenges include identifying the mechanisms underpinning the hollow-curve DAD, its generality beyond vertebrates, and the biological determinants of dietary generalisation.
饮食组成是动物生态学中最重要但却最不为人所理解的方面之一。受物种丰度分布（SADs）研究的启发，我们通过将脊椎动物的饮食特征化为饮食丰度分布（DADs）来测试其结构的普遍性。我们收集了1167个种群水平的饮食数据，这些数据代表了来自六个脊椎动物类别的500多种物种，涵盖了所有大陆和海洋。DADs几乎普遍（92.5%）呈空心曲线形状，几乎没有其他合理的秩-丰度分布形状的支持。这种强烈的普遍性与可用食物类群的SADs内在相关，但尚未得到充分解释。通过将饮食泛化量化为饮食丰度累积分布的半饱和点（sp50，即占饮食50%所需的最少食物种类数），我们发现脊椎动物种群的饮食令人惊讶地具有特异性：在大多数种群中，少于三种食物占了至少一半的饮食。sp50的变化与消费者类型密切相关，食肉动物比食草动物或杂食动物更具特异性。其他方法学（采样方法和工作量、分类分辨率）、生物学（体重、食果性）和生物地理学（纬度）因素在不同程度上影响了sp50。未来的挑战包括确定空心曲线DAD的潜在机制、其在脊椎动物之外的普遍性以及饮食泛化的生物学决定因素。
