Save for a rainy day? Simulating how current investment in escaping decisions may affect future reproductive success of males

In many species, males defending mating territories face a trade-off between survival and reproductive opportunities when escaping predators. To avoid missing mating chances, males often take greater risks in the presence of females. Because female receptivity varies seasonally, males that adjust their escape decisions according to the reproductive period may gain a selective advantage, yet the evolution of this behavioral modulation remains unexplored. We developed an individual-based simulation model to investigate how different escape strategies evolve. Males adopted one of four strategies: (i) adjusting flight initiation distance (FID) based on female presence, (ii) modifying FID according to the reproductive period, (iii) adjusting FID based on both female presence and reproductive period, or (iv) maintaining a fixed FID. Our results show that males that modulate their FID in response to female presence or during the reproductive period are favoured under conditions where delaying escape significantly increases the likelihood of retaining females, and when the correlation between FID and survival is weak. In contrast, when FID strongly predicts survival and delayed escape has a limited effect on female retention, males with fixed FID dominated the population. These results highlight the significance of context-dependent flexibility in shaping the evolution of escape decisions.

在诸多物种中，守卫交配领地的雄性在躲避捕食者时，往往面临生存与繁殖机会之间的权衡取舍。为避免错失交配机会，雄性在雌性存在时通常甘愿承担更高风险。由于雌性的繁殖接受性随季节发生变化，若雄性能够依据繁殖周期调整逃避决策，或可获得选择优势，但这类行为调控的演化机制仍有待探索。我们构建了基于个体的模拟模型（individual-based simulation model），以探究不同逃避策略的演化路径。雄性可采用四种策略之一：(i) 依据雌性存在与否调整逃逸起始距离（flight initiation distance, FID）；(ii) 根据繁殖周期调整FID；(iii) 同时结合雌性存在状态与繁殖周期调整FID；或(iv) 维持固定的FID。研究结果表明，当延迟逃逸能显著提升留住雌性的概率，且逃逸起始距离与生存的相关性较弱时，能够依据雌性存在状态或繁殖周期调整FID的雄性更受选择青睐。与之相反，当FID可强烈预测生存概率，且延迟逃逸对留住雌性的作用有限时，采用固定FID策略的雄性将在种群中占据主导地位。本研究结果凸显了情境依赖的灵活性在塑造逃避决策演化过程中的重要意义。