Risk sensitivity of a forager with limited energy reserves in stochastic environments
Risk sensitivity of a forager with limited energy reserves in stochastic environments
复制标题
随机环境中能量储备有限的采集者的风险敏感性
DOI：
10.1111/1440-1703.1058
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发表时间：
2019
影响因子：
2
通讯作者：
Hiromu Ito
中科院分区：
文献类型：
--
作者：
城潤一郎;田畑泰彦;Hiromu Ito
长期的环境随机性已知会影响生活史特征的适应性进化。在随机环境中，行为优化有两个不同的层次，如下：第一层次，代内随机环境下的最优策略，第二层次，代际随机环境下的最优策略。本文提出了一个简单的捕食风险下的最优觅食模型，并验证了行为优化对觅食时间比的影响。在这个模型中，觅食者在觅食过程中面临捕食风险，但如果它们呆在巢穴中没有任何食物，它们是安全的。觅食时间分配策略，优化几何平均适应度（2级）进行了比较，算术平均适应度（1级），以验证代际随机性的影响，即有一个交替在好/坏的环境跨代。与以前的研究一样，使用该模型通常观察到风险规避策略（2级采用的觅食时间比1级短）。出乎意料的是，该模型显示出倾向于风险倾向策略的倾向。当食物充足而最大能量储备很小时，这种质的差异变得突出。理论研究表明，在粮食短缺期间，人们通常会采取规避风险的策略，并导致饥饿。然而，目前的研究结果表明，风险倾向的策略可能会成为最佳的储备容量有限。因此，最优策略不仅取决于个体的地位和环境条件，而且还取决于详细的选择制度。
Long‐term environmental stochasticity is known to affect the adaptive evolution of life history traits. In stochastic environments, there are two different levels of behavioral optimization, as follows: Level 1, the optimal strategy under an intrageneration stochastic environment and Level 2, the optimal strategy under an intergeneration stochastic environment. This article presents a simple optimal foraging model under predation risks and verified the effect of behavioral optimization on the foraging time ratio. In this model, foragers are exposed to predation risks during foraging but are safe if they stay in their nests without any food. The foraging time allocation strategies that optimize the geometric mean fitness (Level 2) were compared with the arithmetic mean fitness (Level 1) to verify the effects of intergenerational stochasticity, whereby there is an alternation in good/bad environments across generations. As in previous studies, risk‐averse strategies (a shorter foraging time is adopted for Level 2 than for Level 1) were commonly observed using this model. Unexpectedly, the model showed a tendency toward a preference for risk‐prone strategies. This qualitative difference became prominent when food was abundant and the maximum energy reserves were small. Theoretical studies have shown that risk‐averse strategies are commonly adopted during food shortages and result in starvation. However, the current results indicate that risk‐prone strategies may become optimal under a limited reserve capacity. Thus, the optimal strategy depends not only on the individual status and environmental conditions, but also on the detailed selection regimes.