Table 3 data

<br><b>• Background and Aims </b>Freshwater nitrogen inputs are increasing globally, altering the structure and function of wetland ecosystems adapted to low nutrient conditions. Carnivorous wetland plants of the genus <i>Utricularia </i>are hypothesized to reduce their reliance on carnivory and increase their assimilation of environmental nutrients when the supply of ambient nutrients increases. Despite success in using stable isotope approaches to quantify carnivory of terrestrial carnivorous plants, quantifying carnivory of aquatic <i>Utricularia </i>requires improvement.<b>• Methods </b>We developed stable isotope mixing models to quantify aquatic plant carnivory and used these models to measure dietary changes of three <i>Utricularia </i>species, <i>Utricularia australis</i>, <i>U. gibba </i>and <i>U. uliginosa</i>, in 11 wetlands across a 794-km gradient in eastern Australia. Diet was assessed using multiple models that compared variations in the natural-abundance nitrogen isotope composition (δ15N) of <i>Utricularia </i>spp. with that of non-carnivorous plants, and environmental and carnivorous nitrogen sources.<b>• Key Results </b>Carnivory supplied 40–100 % of plant nitrogen. The lowest carnivory rates coincided with the highest availability of ammonium and dissolved organic carbon.<b>• Conclusions </b>Our findings suggest that <i>Utricularia </i>populations may adapt to high nutrient environments by shifting away from energetically costly carnivory. This has implications for species conservation as anthropogenic impacts continue to affect global wetland ecosystems.• 研究背景与目的 全球范围内淡水氮输入持续增加，改变了适应低营养条件的湿地生态系统的结构与功能。狸藻属（Utricularia）的食虫湿地植物被假设为：当环境营养供给提升时，会降低对食虫习性的依赖，并增加对环境营养的吸收。尽管利用稳定同位素方法量化陆生食虫植物的食虫习性已获得成功，但水生狸藻属植物的食虫习性量化仍有待完善。 • 研究方法 本研究开发了稳定同位素混合模型以量化水生植物的食虫习性，并利用该模型测量了澳大利亚东部794公里梯度范围内11处湿地中3种狸藻属植物——南方狸藻（Utricularia australis）、姬狸藻（Utricularia gibba）和沼泽狸藻（Utricularia uliginosa）——的食性变化。研究通过多种模型评估食性：将狸藻属植物的自然丰度氮同位素组成（δ15N）与非食虫植物、环境氮源以及食虫来源的氮同位素组成差异进行对比。 • 主要结果 食虫习性可为植物提供40%~100%的氮素来源。最低的食虫率与最高的铵盐及溶解有机碳可获得性相契合。 • 研究结论 本研究结果表明，狸藻属种群可通过摒弃能量成本高昂的食虫习性，以适应高营养环境。随着人为活动持续影响全球湿地生态系统，该发现对物种保护具有重要的参考价值。