Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands.
PLoS One. 2022 Feb 2;17(2):e0243877. doi: 10.1371/journal.pone.0243877. eCollection 2022.
In many groups of animals the dominance hierarchy is linear. What mechanisms underlie this linearity of the dominance hierarchy is under debate. Linearity is often attributed to cognitively sophisticated processes, such as transitive inference and eavesdropping. An alternative explanation is that it develops via the winner-loser effect. This effect implies that after a fight has been decided the winner is more likely to win again, and the loser is more likely to lose again. Although it has been shown that dominance hierarchies may develop via the winner-loser effect, the degree of linearity of such hierarchies is unknown. The aim of the present study is to investigate whether a similar degree of linearity, like in real animals, may emerge as a consequence of the winner-loser effect and the socio-spatial structure of group members. For this purpose, we use the model DomWorld, in which agents group and compete and the outcome of conflicts is self-reinforcing. Here dominance hierarchies are shown to emerge. We analyse the dominance hierarchy, behavioural dynamics and network triad motifs in the model using analytical methods from a previous study on dominance in real hens. We show that when one parameter, representing the intensity of aggression, was set high in the model DomWorld, it reproduced many patterns of hierarchical development typical of groups of hens, such as its high linearity. When omitting from the model the winner-loser effect or spatial location of individuals, this resemblance decreased markedly. We conclude that the combination of the spatial structure and the winner-loser effect provide a plausible alternative for hierarchical linearity to processes that are cognitively more sophisticated. Further research should determine whether the winner-loser effect and spatial structure of group members also explains the characteristics of hierarchical development in other species with a different dominance style than hens.
在许多动物群体中，优势等级是线性的。是什么机制导致了这种优势等级的线性，这是一个有争议的问题。线性通常归因于认知复杂的过程，如传递推理和偷听。另一种解释是，它是通过胜利者-失败者效应发展起来的。这种效应意味着，在一场战斗决定胜负后，胜利者更有可能再次获胜，而失败者更有可能再次失败。尽管已经表明，优势等级可能通过胜利者-失败者效应发展，但这种等级的线性程度是未知的。本研究的目的是调查在群体成员的胜利者-失败者效应和社会空间结构的影响下，是否会出现类似于真实动物的相似程度的线性。为此，我们使用模型 DomWorld，其中代理分组和竞争，冲突的结果是自我强化的。在这个模型中，优势等级会出现。我们使用之前关于真实母鸡中优势的研究中的分析方法来分析模型中的优势等级、行为动态和网络三元组模式。我们表明，当模型 DomWorld 中的一个代表攻击性强度的参数设置得很高时，它再现了许多与母鸡群体典型的等级发展模式，例如其高度的线性。当从模型中省略胜利者-失败者效应或个体的空间位置时，这种相似性显著降低。我们得出结论，空间结构和胜利者-失败者效应的结合为等级线性提供了一种替代方案，而不是认知更复杂的过程。进一步的研究应该确定胜利者-失败者效应和群体成员的空间结构是否也解释了其他具有与母鸡不同优势风格的物种的等级发展特征。
