Institute for Theoretical Biology, Department of Biology, Humboldt-Universität zu Berlin, Berlin, Germany.
Research Cluster of Excellence "Science of Intelligence", Technische Universität Berlin, Berlin, Germany.
Commun Biol. 2024 Nov 27;7(1):1586. doi: 10.1038/s42003-024-07267-2.
The collective dynamics of self-organised systems emerge from the decision rules agents use to respond to each other and to external forces. This is evident in groups of animals under attack from predators, where understanding collective escape patterns requires evaluating the risks and rewards associated with particular social rules, prey escape behaviour, and predator attack strategies. Here, we find that the emergence of the 'fountain effect', a common collective pattern observed when animal groups evade predators, is the outcome of rules designed to maximise individual survival chances given predator hunting decisions. Using drone-based empirical observations of schooling sardine prey (Sardinops sagax caerulea) attacked by striped marlin (Kajikia audax), we first find the majority of attacks produce fountain effects, with the dynamics of these escapes dependent on the predator's attack direction. Then, using a spatially-explicit agent-based model of predator-prey dynamics, we show that fountain manoeuvres can emerge from combining an optimal individual prey escape angle with social interactions. The escape rule appears to prioritise maximising the distance to the predator and creates conflict in the effectiveness of predators' attacks and the prey's avoidance, explaining the empirically observed predators' attack strategies and the fountain evasions produced by prey. Overall, we identify the proximate and ultimate explanations for fountain effects and more generally highlight that the collective patterns of self-organised predatory-prey systems can be understood by considering both social escape rules and attack strategies.
自组织系统的集体动力学源于个体在相互作用和对外界力量做出反应时所使用的决策规则。这在受到捕食者攻击的动物群体中表现得尤为明显，理解集体逃避模式需要评估与特定社会规则、猎物逃避行为和捕食者攻击策略相关的风险和回报。在这里，我们发现“喷泉效应”的出现是个体生存机会最大化的结果，因为捕食者的狩猎决策会影响规则的设计。我们使用基于无人机的实地观测研究了被条纹马林鱼（Kajikia audax）攻击的沙丁鱼（Sardinops sagax caerulea）鱼群，发现大多数攻击都会产生喷泉效应，而这些逃避行为的动态取决于捕食者的攻击方向。然后，我们使用捕食者-猎物动态的空间显式基于主体的模型，表明通过将最佳个体猎物逃逸角度与社会互动相结合，可以产生喷泉运动。这种逃逸规则似乎优先考虑最大化与捕食者的距离，并在捕食者的攻击效果和猎物的回避之间产生冲突，从而解释了观察到的捕食者攻击策略和猎物产生的喷泉逃避行为。总体而言，我们确定了喷泉效应的近因和远因，并强调通过考虑社会逃避规则和攻击策略，可以理解自组织捕食-猎物系统的集体模式。
