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

Abstract1. 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 high trophic levels and with smaller body size, regardless of geographic location. 4. Carnivores may have higher nutrient content and lower carbon:nutrient ratios than their prey, as organisms optimize growth by choosing the most nutrient-rich resources to consume and then preferentially retain nutrients over carbon in their bodies. Smaller organisms grow proportionally faster than large organisms, and so are predicted to have higher nutrient requirements to fuel RNA and protein synthesis. Geography influenced the magnitude, more than the direction, of the ecological and/or phylogenetic effects on elemental composition. 5. Overall, our results show that both ecological (i.e., trophic group) and evolutionary drivers explain among-taxa variation in the elemental content of invertebrates, whereas intraspecific variation is mainly a function of body size. Our findings also demonstrate that restricting analyses of macroinvertebrate stoichiometry solely to either the local scale or species level affects inferences of the patterns in invertebrate elemental content, and their underlying mechanisms., Usage notesStoichiometry.Invertebrates.2018Data on elemental content of aquatic macroinvertebrates from tank bromeliads across Central-South America

摘要
1. 生物间的化学计量（Stoichiometry）差异可影响生态系统内的营养级相互作用与养分循环速率。然而，目前学界对这类化学计量差异的根本成因，以及其在大范围地理尺度上的一致性仍所知有限。
2. 本研究对采自中美洲与南美洲5个相距甚远的采样点的140株积水凤梨（tank bromeliads）生境中的872个水生大型无脊椎动物（aquatic macroinvertebrates）个体（隶属于71个物种）的元素（碳、氮、磷）组成展开分析，旨在达成两大研究目标：其一，检验系统发育、营养级及体型缩放假说，以阐释不同生物元素组成存在差异的原因；其二，明确元素组成的分布模式究竟具备普适性，还是依赖于特定环境背景。
3. 分类学因素对元素组成的变异解释度最高，尽管系统发育信号较弱，且仅局限于区域空间尺度与科级分类层级。无论地理区位如何，营养级较高、体型较小的生物均呈现出最高的元素含量与最低的碳养分比。
4. 食肉动物相较于其猎物可能拥有更高的养分含量与更低的碳养分比，这是由于生物会通过选择养分丰度最高的资源进行取食，并优先在体内留存养分而非碳，以此实现生长最优化。体型较小的生物相较于大型个体的生长速率更快，因此为满足核糖核酸（RNA）与蛋白质合成的需求，其养分需求量理应更高。地理因素对元素组成的生态及/或系统发育效应的影响更多体现在强度维度，而非方向维度。
5. 总体而言，本研究结果显示，生态因素（即营养类群）与进化驱动因素共同解释了无脊椎动物类群间的元素含量变异，而种内变异则主要由体型大小决定。本研究发现还证实，若仅在局域尺度或物种水平上开展大型无脊椎动物化学计量学分析，将会干扰对无脊椎动物元素组成模式及其潜在机制的推断。

使用说明：化学计量学（Stoichiometry）、无脊椎动物，2018年。数据集涵盖横跨中美洲至南美洲的积水凤梨生境中的水生大型无脊椎动物元素含量数据。