School of Biological Sciences, University of Bristol, Bristol, U.K.
Department of Life Sciences, University of the West Indies at St. Augustine, St. Augustine, Trinidad and Tobago.
Sci Adv. 2017 May 3;3(5):e1602682. doi: 10.1126/sciadv.1602682. eCollection 2017 May.
Collective decisions play a major role in the benefits that animals gain from living in groups. Although the mechanisms of how groups collectively make decisions have been extensively researched, the response of within-group dynamics to ecological conditions is virtually unknown, despite adaptation to the environment being a cornerstone in biology. We investigate how within-group interactions during exploration of a novel environment are shaped by predation, a major influence on the behavior of prey species. We tested guppies () from rivers varying in predation risk under controlled laboratory conditions and find the first evidence of differences in group interactions between animals adapted to different levels of predation. Fish from high-predation habitats showed the strongest negative relationship between initiating movements and following others, which resulted in less variability in the total number of movements made between individuals. This relationship between initiating movements and following others was associated with differentiation into initiators and followers, which was only observed in fish from high-predation rivers. The differentiation occurred rapidly, as trials lasted 5 min, and was related to shoal cohesion, where more diverse groups from high-predation habitats were more cohesive. Our results show that even within a single species over a small geographical range, decision-making in a social context can vary with local ecological factors.
集体决策在动物从群体生活中获得的益处中起着重要作用。尽管已经广泛研究了群体如何集体做出决策的机制，但群体内部动态如何适应生态条件实际上是未知的，尽管适应环境是生物学的基石。我们研究了在探索新环境期间，捕食对群体内部相互作用的影响，捕食是对猎物物种行为的主要影响因素。我们在受控实验室条件下测试了来自不同捕食风险河流的孔雀鱼（Poecilia reticulata），并首次发现了适应不同捕食水平的动物之间群体相互作用差异的证据。来自高捕食栖息地的鱼类表现出发起运动和跟随他人之间最强的负相关关系，这导致个体之间的总运动次数变化较小。发起运动和跟随他人之间的这种关系与分化为发起者和追随者有关，而只有来自高捕食河流的鱼类才观察到这种关系。这种分化发生得很快，因为试验持续了 5 分钟，与鱼群的凝聚力有关，来自高捕食栖息地的更多样化的鱼群更具凝聚力。我们的研究结果表明，即使在一个小地理范围内的单一物种中，社会环境中的决策也可能因当地生态因素而异。
