Functional traits and environmental conditions predict community isotopic niches and energy pathways across spatial scales

1. Despite ongoing research in food web ecology and functional biogeography, the links between food-web structure, functional traits and environmental conditions across spatial scales remain poorly understood. Trophic niches, defined as the amount of energy and elemental space occupied by species and food webs, may help bridge this divide. 2. Here, we ask how the functional traits of species, the environmental conditions of habitats and the spatial scale of analysis jointly determine the characteristics of trophic niches. We used isotopic niches as a proxy of trophic niches, and conducted analyses at spatial scales ranging from local food webs and metacommunities to geographically distant sites. 3. We sampled aquatic macroinvertebrates from 104 tank bromeliads distributed across five sites from Central to South America, and compiled the macroinvertebrates’ functional traits and stable isotope values (δ15N and δ13C). We assessed how isotopic niches within each bromeliad were influenced ...1. 尽管当前食物网生态学（food web ecology）与功能生物地理学（functional biogeography）领域已开展诸多研究，但食物网结构、功能性状与不同空间尺度下环境条件之间的关联仍未得到充分阐明。营养生态位（Trophic niche）被定义为物种及食物网所占据的能量与元素空间，或可填补这一研究缺口。 2. 本研究旨在探讨物种功能性状、栖息地环境条件与分析空间尺度如何共同决定营养生态位的特征。我们以同位素生态位（isotopic niche）作为营养生态位的替代指标，在从局域食物网、集合群落（metacommunity）到地理远距样地的多种空间尺度上开展分析。 3. 我们从分布于中美洲至南美洲5个样地的104株积水凤梨（tank bromeliad）中采集了水生大型无脊椎动物（aquatic macroinvertebrate），并整理了这些无脊椎动物的功能性状与稳定同位素值（δ¹⁵N与δ¹³C）。我们评估了每株积水凤梨内的同位素生态位如何受到……