Fight-flight or freeze-hide? Personality and metabolic phenotype mediate physiological defense responses in a benthic fish

Please refer to the ReadMe file and associated manuscript for details about the data and the statistical analyses.Abstract of the manuscript:1. Survival depends on appropriate behavioural and physiological responses to danger. In addition to active “fight-flight” defence responses, a passive “freeze-hide” response is adaptive in some contexts. However, the physiological mechanisms determining which individuals choose a given defence response remain poorly understood. 2. We examined the relationships among personality, metabolic performance and physiological stress responses across an environmental gradient in the olive flounder, Paralichthys olivaceus. 3. We employed four behavioural assays to document the existence of two distinct behavioural types (“bold” and “shy”) in this species. We then found consistent metabolic differences between individuals of a given behavioural type across an environmental gradient: shy individuals had overall lower aerobic scope, maximum metabolic rate and standard metabolic rate than bold individuals in both high (25ppt) and low (3ppt) salinity. 4. These behavioural and metabolic differences translated into divergent physiological responses during acute stress: shy individuals adopted a passive “freeze-hide” response by reducing their oxygen consumption rates (akin to shallow breathing) whereas bold individuals adopted an active “fight-flight” response by increasing their rates of respiration. These distinct defence strategies were repeatable within individuals between salinity treatments. 5. Although it has been suggested theoretically, this is the first empirical evidence that the metabolic response to stressful situations differs between bold and shy individuals. Our results emphasize the importance of incorporating physiological measures to understand the mechanisms driving persistent inter-individual differences in animals.<br>有关数据与统计分析的详细信息，请参阅ReadMe文件及相关手稿。手稿摘要如下：1. 生存依赖于对危险作出恰当的行为与生理响应。除了主动的“战斗-逃跑”防御策略外，被动的“冻结-藏匿”响应在部分情境下也具有适应性。然而，目前学界对决定个体选择特定防御策略的生理机制仍知之甚少。2. 本研究以褐牙鲆（*Paralichthys olivaceus*）为研究对象，探究了环境梯度下动物个性、代谢表现与生理应激响应之间的关联。3. 本研究通过四项行为学测定，证实该物种存在两种截然不同的行为类型——“大胆型”与“胆怯型”。进一步研究发现，在环境梯度下，同一行为类型的个体间代谢特征存在稳定差异：在高盐（25ppt）与低盐（3ppt）环境中，胆怯型个体的有氧代谢范围、最大代谢率及标准代谢率均显著低于大胆型个体。4. 上述行为与代谢差异在急性应激过程中转化为不同的生理响应：胆怯型个体通过降低耗氧率（类似浅呼吸）采取被动的“冻结-藏匿”策略，而大胆型个体则通过提升呼吸速率采取主动的“战斗-逃跑”策略。且这两种差异化的防御策略在不同盐度处理组的个体间均具有可重复性。5. 尽管已有理论提出相关假说，但本研究首次通过实验证据证实，大胆型与胆怯型个体在应激情境下的代谢响应存在显著差异。本研究结果凸显了纳入生理指标的重要性，有助于解析驱动动物个体间持久差异的内在机制。