Ecological mechanisms and phylogeny shape invertebrate stoichiometry: a test using detritus-based communities across Central and South America

1. Stoichiometric differences among organisms can affect trophic interactions and rates of nutrient cycling within ecosystems. However, we still know little about either the underlying causes of these stoichiometric differences, or the consistency of these differences across large geographic extents. 2. Here we analyze elemental (carbon, nitrogen, phosphorus) composition of 872 aquatic macroinvertebrates (71 species) inhabiting tank bromeliads (n = 140) from five distantly located sites across Central and South America to (1) test phylogenetic, trophic and body size scaling explanations for why organisms differ in elemental composition, and (2) determine if patterns in elemental composition are universal or context-dependent. 3. Taxonomy explained most variance in elemental composition, even though phylogenetic signals were weak and limited to regional spatial extents and to the family level. The highest elemental contents and lowest carbon:nutrient ratios were found in organisms at hig...1. 生物间的化学计量（stoichiometric）差异可影响生态系统内的营养相互作用与养分循环速率。然而，目前我们对这类化学计量差异的潜在成因，以及这类差异在大地理尺度上的一致性，仍知之甚少。 2. 本研究针对中美洲与南美洲5个相距甚远的采样点中的140个积水凤梨（tank bromeliads）生境，分析了栖息其中的872只隶属于71个物种的水生大型无脊椎动物（aquatic macroinvertebrates）的元素（碳、氮、磷）组成，旨在达成两项研究目标：其一，验证系统发育、营养策略以及体型缩放效应对生物元素组成差异的解释力；其二，探明元素组成的分布模式究竟是通用普适的，还是存在情境依赖性。 3. 尽管系统发育信号（phylogenetic signals）较弱且仅局限于区域空间尺度与科的分类阶元，但分类学仍解释了元素组成的大部分变异。营养层级更高的生物呈现出最高的元素含量与最低的碳-养分比（carbon:nutrient ratios）……