Mortality risk of spatial positions in animal groups: The danger of being in the front
Mortality risk of spatial positions in animal groups: The danger of being in the front
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DOI：
10.1163/156853997x00403
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发表时间：
1997-11-01
期刊：
影响因子：
1.3
通讯作者：
Rubenstein, D
中科院分区：
文献类型：
--
作者：
Bumann, D;Krause, J;Rubenstein, D
通过引入有向运动的食饵群和捕食者，我们改进了汉密尔顿（1971）的自私群体模型。这种修改的后果，关于差分捕食风险相比，汉密尔顿的原始模型（使用固定的猎物组）和测试的经验数据。在模型1中，我们复制了汉密尔顿的原始捕食系统。在模型2和3中，猎物群体是移动的，捕食者是移动的（模型2）或固定的（模型3）。我们的研究结果表明，除了汉密尔顿的模型预测的正风险梯度从中心到外围的固定群体，可能有另一个正的风险梯度从后部到前部的移动群体。此外，模型2和模型3表明，如果风险最小化是唯一相关的因素，移动群体通常应表现出细长的形状（沿着运动轴的长度大于宽度）。此外，较小的个体间的距离预测前个人比其他地方的个人在组中。基于鱼群三维结构的经验数据（使用蟑螂，Rutilus rutilus）与上述两个预测一致。第二个实验涉及湖鲢鱼，Semotilus atromaculatus，作为猎物和岩石鲈鱼，Ambloplites rupestris，作为捕食者，提供了直接支持的假设，即个人在前面的位置组发生了显着更高的捕食风险比鱼在后方的位置。最后，我们讨论了不同的群体位置的背景下，潜在的觅食收益，提供了一个动态模型的基础上，在群体生活的动物的位置偏好的差异风险。
We modified Hamilton's (1971) selfish herd model by introducing directional movement to the prey groups and the predators. The consequences of this modification with regards to differential predation risks are compared to Hamilton's original model (using stationary prey groups) and tested against empirical data. In model 1, we replicated Hamilton's original predator-prey system. In models 2 and 3, prey groups were mobile and predators were mobile (model 2) or stationary (model 3). Our results indicate that additional to the positive risk gradient from centre to periphery predicted by Hamilton's model for stationary groups, there might be another positive risk gradient from the rear to the front part in moving groups. Furthermore, models 2 and 3 suggest that moving groups should generally exhibit an elongated shape (longer than wide along the axis of locomotion) if risk minimisation is the only factor concerned. Also smaller inter-individual distances are predicted for front individuals than individuals elsewhere in the group. Empirical data based on the three-dimensional structure of fish shoals (using roach, Rutilus rutilus) were consistent with the above two predictions. A second experiment which involved lake chub, Semotilus atromaculatus, as prey and rock bass, Ambloplites rupestris, as predators, provided direct support for the hypothesis that individuals in front positions of groups incurred a significantly higher predation risk than fish in rear positions. Finally, we discuss the differential risks of different group positions in the context of potential foraging gains which provides the basis for a dynamic model of position preferences in group-living animals.