The risk of predation is an important driver that tailors life histories in various ways. Using an evolutionary model based on hormonal control, we study how different predation regimes affect adaptive risk‐taking and growth in fish populations. Growth, metabolism and foraging in the modelled fish are regulated by three simplified hormone functions: growth hormone, orexin, and thyroid hormone. A dynamic state‐dependent optimization model finds optimal hormone profiles for adaptive growth strategies in juvenile fish. We consider a gradient from species where behaviour and metabolic activity have large consequences for risk (typically benthic and camouflaged species), to the opposite endpoint where behaviour may modify predation risk to a smaller degree (as in the pelagic). Along this gradient, the model predicts changes in the pace of life from slow to fast, enacted by up‐regulation of the three hormone functions which in turn increase foraging and metabolism and change the priorities of energy reserves versus growth. Under all types of predation risk investigated, growth is faster when food availability is higher. Energy reserves are maintained primarily during periods of poor food availability and are used to accelerate growth during periods when food availability is high. The thyroid hormone function is up‐regulated predominantly when food availability is high and has an important role in trade‐offs balancing energetic gain and survival. At the individual time scale, the hormone system improves organismic flexibility and robustness. Over the phylogenetic time scale, hormone system adaptations have also restricted the phenotypic plasticity of individuals.

中文翻译：

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表型的激素调节成为环境适宜的生活节奏综合征


被捕食的风险是以各种方式改变生命史的重要驱动因素。使用基于激素控制的进化模型，我们研究了不同的捕食方式如何影响鱼类种群的适应性冒险和生长。模型鱼的生长、新陈代谢和觅食由三种简化的激素功能调节：生长激素、食欲素和甲状腺激素。动态状态依赖优化模型找到了幼鱼适应性生长策略的最佳激素分布。我们考虑从行为和代谢活动对风险产生重大影响的物种（通常是底栖和伪装物种）到行为可能在较小程度上改变捕食风险（如中上层物种）的相反终点的梯度。沿着这个梯度，该模型预测了生活节奏从慢到快的变化，这是通过三种激素功能的上调来实现的，这反过来又增加了觅食和新陈代谢，并改变了能量储备与生长的优先顺序。根据所调查的所有类型的捕食风险，当食物供应量较高时，生长速度会更快。能源储备主要在粮食供应不足期间维持，并在粮食供应充足期间用于加速生长。当食物供应量较高时，甲状腺激素功能主要上调，并且在平衡能量增益和生存方面发挥着重要作用。在个体时间尺度上，激素系统提高了机体的灵活性和稳健性。在系统发育时间尺度上，激素系统的适应也限制了个体的表型可塑性。