Data from: Allometric and trait-based patterns in parasite stoichiometry

We measured the elemental content (%C, N, and P) and ratios (C:N, C:P, N:P) of a diverse assemblage of parasitic helminths to ask whether taxonomy or traits were related to stoichiometric variation among species. We sampled 27 macroparasite taxa, spanning 4 phyla, infecting vertebrate and invertebrate hosts from freshwater ecosystems in New Jersey. Macroparasites varied widely in elemental content, exhibiting 4.7-fold variation in %N, 4.6-fold variation in %P, and 11.5-fold variation in N:P. Across all species, parasite %P scaled negatively and C:P scaled positively with body size. Similar relationships between parasite P content and body size occurred at the phylum level and within individual species. The allometric scaling of P across species supports the growth rate hypothesis, which predicts that smaller taxa require more P to support relatively higher growth rates. Life cycle stage was related to %N and C:N, with non-reproductive parasite stages lower in %N and higher in C:N than actively reproducing parasites. Parasite phylum, functional feeding group, and trophic level did not explain elemental variation among species. Organismal stoichiometry is linked to ecological function, and wide variation in macroparasite stoichiometry likely generates diverse patterns in host-parasite nutrient dynamics and variable relationships between parasitism and nutrient cycling.

本研究测定了多样寄生蠕虫类群的元素含量（%C、%N和%P）及元素比值（C:N、C:P、N:P），旨在探究物种间化学计量学（stoichiometry）变异与分类学地位或功能性状是否存在关联。本研究共采样了涵盖4个门的27种大型寄生蠕虫（macroparasite）类群，这些类群寄生于新泽西州淡水生态系统中的脊椎动物与无脊椎动物宿主体内。大型寄生蠕虫的元素含量差异显著，其中%N的变异幅度达4.7倍，%P达4.6倍，N:P比值达11.5倍。在所有物种中，寄生蠕虫的%P与体型呈负相关，C:P与体型呈正相关。在门分类阶元以及单个物种种内，寄生蠕虫的P含量与体型间均呈现类似的关联关系。跨物种的P元素异速缩放（allometric scaling）结果支持生长速率假说（growth rate hypothesis），该假说预测体型更小的类群需要更多的P元素以支撑相对更高的生长速率。生命周期阶段与%N及C:N比值存在关联：相较于活跃繁殖的寄生阶段，非繁殖期寄生阶段的%N含量更低，C:N比值更高。寄生蠕虫的门级分类地位、功能摄食类群及营养级，并不能解释物种间的元素含量变异。生物体化学计量学（organismal stoichiometry）与生态功能密切相关，而大型寄生蠕虫化学计量学的广泛变异，可能会导致宿主-寄生虫营养动态呈现多样模式，同时使寄生作用与营养循环间的关联存在差异。