A decade ago, the General Stress Paradigm (GSP) aimed to develop a predictive framework linking predator effects to ecosystem function. The GSP was based on the notion that animals, across taxa, exhibit similar physiological responses to predation risk that divert resources from growth and reproduction [which require N-rich biomolecules (i.e., protein)] to emergency functions [which require C-rich biomolecules (e.g., carbohydrates)]. The GSP predicts that stressed prey should have a greater dietary demand for C-rich resources, a higher body C:N ratio, and elevated N excretion. Now, ten years later, we aim to revisit the GSP- using quantitative meta-analysis to test the original predictions of the GSP and how 1) predator hunting mode, 2) multiple stressors, and 3) prey dietary shifts affect prey stoichiometric responses to predation-risk. Our dataset was consistent with previous work showing that predation-risk increases prey glucocorticoid levels and metabolic rates and decreases prey growth rates. We found that predation-risk tended to decrease the fat, carbohydrate, and protein content of prey bodies; increased the C:P and N:P of prey bodies; but had no effect on the C, N, P or C:N content of prey bodies. Additionally, we found no effect of predation risk on the N content of prey excretions. Prey responses to predation risk were unaffected by multiple stressors or the prey's ability to shift their diet, but predator hunting mode did affect the nature of prey stoichiometric responses. Specifically, ambush predators decreased prey macronutrient content and suppressed prey growth, while active predators had no effect on prey macronutrient content and a smaller effect on prey growth than ambush predators. The significant effects of predation risk were supported by robust fail-safe numbers, despite the high between comparison heterogeneity that was found in all analyses. Our findings highlight the need to 1) test the underlying mechanisms and emerging patterns of the GSP in diverse taxa, 2) explore the mismatch between prey macronutrient content and elemental stoichiometry, and 3) expand the conceptual framework to include more inducible defenses (e.g., behavioral and morphological) and predator traits.

中文翻译：

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捕食风险对猎物化学计量的影响：荟萃分析

十年前，一般压力范式 (GSP) 旨在开发一个预测框架，将捕食者效应与生态系统功能联系起来。普惠制基于这样一种观点，即动物在整个分类群中对捕食风险表现出相似的生理反应，将资源从生长和繁殖 [需要富含 N 的生物分子（即蛋白质）] 转移到紧急功能 [需要富含 C 的生物分子（例如，碳水化合物）]。GSP 预测，压力大的猎物应该对富含 C 的资源有更大的饮食需求、更高的身体 C:N 比和更高的 N 排泄。现在，十年后，我们的目标是重新审视 GSP-使用定量荟萃分析来测试 GSP 的原始预测以及如何 1) 捕食者狩猎模式，2) 多重压力源，以及 3) 猎物饮食变化影响猎物对以下物质的化学计量反应捕食风险。我们的数据集与之前的工作一致，表明捕食风险增加了猎物的糖皮质激素水平和代谢率，并降低了猎物的生长速度。我们发现捕食风险往往会降低猎物身体的脂肪、碳水化合物和蛋白质含量；增加猎物体的 C:P 和 N:P；但对猎物的 C、N、P 或 C:N 含量没有影响。此外，我们发现捕食风险对猎物排泄物的 N 含量没有影响。猎物对捕食风险的反应不受多重压力因素或猎物改变饮食能力的影响，但捕食者狩猎模式确实影响了猎物化学计量反应的性质。具体来说，伏击捕食者减少了猎物的常量营养素含量并抑制了猎物的生长，而主动捕食者对猎物常量营养素含量没有影响，对猎物生长的影响比伏击捕食者小。尽管在所有分析中发现比较异质性很高，但强大的故障安全数字支持了捕食风险的显着影响。我们的研究结果强调需要 1) 测试不同分类群中 GSP 的潜在机制和新兴模式，2) 探索猎物常量营养素含量与元素化学计量之间的不匹配，以及 3) 扩展概念框架以包括更多诱导防御（例如，行为和形态）和捕食者特征。