Nair Arjun, Nguyen Christy, McHenry Matthew J
Department of Ecology and Evolution, University of California, Irvine, Irvine, CA, USA.
Department of Ecology and Evolution, University of California, Irvine, Irvine, CA, USA
Proc Biol Sci. 2017 Apr 12;284(1852). doi: 10.1098/rspb.2017.0359.
An escape response is a rapid manoeuvre used by prey to evade predators. Performing this manoeuvre at greater speed, in a favourable direction, or from a longer distance have been hypothesized to enhance the survival of prey, but these ideas are difficult to test experimentally. We examined how prey survival depends on escape kinematics through a novel combination of experimentation and mathematical modelling. This approach focused on zebrafish () larvae under predation by adults and juveniles of the same species. High-speed three-dimensional kinematics were used to track the body position of prey and predator and to determine the probability of behavioural actions by both fish. These measurements provided the basis for an agent-based probabilistic model that simulated the trajectories of the animals. Predictions of survivorship by this model were found by Monte Carlo simulations to agree with our observations and we examined how these predictions varied by changing individual model parameters. Contrary to expectation, we found that survival may not be improved by increasing the speed or altering the direction of the escape. Rather, zebrafish larvae operate with sufficiently high locomotor performance due to the relatively slow approach and limited range of suction feeding by fish predators. We did find that survival was enhanced when prey responded from a greater distance. This is an ability that depends on the capacity of the visual and lateral line systems to detect a looming threat. Therefore, performance in sensing, and not locomotion, is decisive for improving the survival of larval fish prey. These results offer a framework for understanding the evolution of predator-prey strategy that may inform prey survival in a broad diversity of animals.
逃避反应是猎物用来躲避捕食者的一种快速动作。据推测，以更快的速度、朝着有利的方向或在更远的距离做出这种动作能够提高猎物的存活率，但这些想法很难通过实验进行验证。我们通过实验与数学建模的新颖结合，研究了猎物的存活率如何依赖于逃避运动学。这种方法聚焦于同一物种的成年和幼年个体捕食下的斑马鱼幼虫。利用高速三维运动学来追踪猎物和捕食者的身体位置，并确定两条鱼行为动作的概率。这些测量为一个基于智能体的概率模型提供了基础，该模型模拟了动物的轨迹。通过蒙特卡洛模拟发现，这个模型对存活率的预测与我们的观察结果相符，并且我们研究了通过改变各个模型参数这些预测是如何变化的。与预期相反，我们发现提高逃避速度或改变逃避方向可能并不会提高存活率。相反，由于鱼类捕食者的接近速度相对较慢以及吸食式捕食范围有限，斑马鱼幼虫具有足够高的运动性能。我们确实发现，当猎物在更远的距离做出反应时，存活率会提高。这是一种依赖于视觉和侧线系统检测迫近威胁能力的特性。因此，对于提高幼鱼猎物的存活率而言，感知能力而非运动能力才是决定性的。这些结果为理解捕食者 - 猎物策略的进化提供了一个框架，这可能为广泛多样的动物中的猎物生存提供参考。
