Animal behaviour can lead to varying levels of risk, and an individual's physical condition can alter the potential costs and benefits of undertaking risky behaviours. How risk‐taking behaviour depends on condition is subject to contrasting hypotheses. The asset protection principle proposes that individuals in better condition should be more risk averse, as they have higher future reproductive potential (i.e. more to lose). The state‐dependent safety hypothesis proposes that high‐condition individuals that are more likely to survive and maximise the benefits of risky situations may make apparently riskier choices, as their individual risk is in fact lower. We systematically searched for studies that experimentally manipulated animals’ nutritional or energetic condition through diet treatments, and subsequently measured risk‐taking behaviour in contexts relating to predation, novelty and exploration. Our meta‐analysis quantified condition effects on risk‐taking behaviour at both the mean and variance level. We preregistered our methods and hypotheses prior to conducting the study. Phylogenetic multilevel meta‐analysis revealed that the lower‐nutritional‐condition individuals showed on average ca. 26% greater tendency towards risk than high‐condition individuals (95% confidence interval: 15–38%; N = 126 studies, 1297 effect sizes). Meta‐regressions revealed several factors influencing the overall effect, such as the experimental context used to measure risk‐taking behaviour, and the life stage when condition was manipulated. Meta‐analysis of variance revealed no clear overall effect of condition on behavioural variance (on average ca. 3% decrease in variance in low‐ versus high‐condition groups; 95% confidence interval: −8 to 3%; N = 119 studies, 1235 effect sizes), however, the experimental context was an important factor influencing the strength and direction of the variance effect. Our comprehensive systematic review and meta‐analysis provide insights into the roles of state dependency and plasticity in intraspecific behavioural variation. While heterogeneity among effect sizes was high, our results show that poor nutritional state on average increases risk taking in ecological contexts involving predation, novelty and exploration.

中文翻译：

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营养不良促进高危行为：系统评价和荟萃分析

动物行为会导致不同程度的风险，个人的身体状况会改变进行危险行为的潜在成本和收益。冒险行为如何取决于条件取决于对比假设。资产保护原则提出，身体状况较好的人应该更规避风险，因为他们未来的生育潜力更高（即损失更大）。依赖状态的安全假设提出，更有可能生存并最大限度地利用风险情况的高条件个体可能会做出明显风险更大的选择，因为他们的个人风险实际上更低。我们系统地搜索了通过饮食治疗实验操纵动物营养或精力状况的研究，随后测量了与捕食、新奇和探索相关的环境中的冒险行为。我们的荟萃分析在均值和方差水平上量化了条件对冒险行为的影响。在进行研究之前，我们预先注册了我们的方法和假设。系统发育多级荟萃分析显示，低营养状况个体平均表现出约 风险倾向比高危个体高 26%（95% 置信区间：15-38%；N = 126 项研究，1297 个效应量）。元回归揭示了影响整体效果的几个因素，例如用于衡量冒险行为的实验环境，以及操纵条件时的生命阶段。方差的 Meta 分析显示条件对行为方差没有明确的总体影响（平均约 低条件组与高条件组的方差减少 3%；95% 置信区间：-8 至 3%；N = 119 项研究，1235 个效应大小），然而，实验环境是影响方差效应强度和方向的重要因素。我们全面的系统评价和荟萃分析提供了对状态依赖性和可塑性在种内行为变异中的作用的见解。虽然效应大小之间的异质性很高，但我们的结果表明，平均而言，营养不良状态会增加在涉及捕食、新奇和探索的生态环境中的风险承担。实验环境是影响方差效应强度和方向的重要因素。我们全面的系统评价和荟萃分析提供了对状态依赖性和可塑性在种内行为变异中的作用的见解。虽然效应大小之间的异质性很高，但我们的结果表明，平均而言，营养不良状态会增加在涉及捕食、新奇和探索的生态环境中的风险承担。实验环境是影响方差效应强度和方向的重要因素。我们全面的系统评价和荟萃分析提供了对状态依赖性和可塑性在种内行为变异中的作用的见解。虽然效应大小之间的异质性很高，但我们的结果表明，平均而言，营养不良状态会增加在涉及捕食、新奇和探索的生态环境中的风险承担。