Data from: Guppies occupy consistent positions in social networks: mechanisms and consequences

The social network approach has focused increasing attention on the complex web of relationships found in animal groups and populations. As such, network analysis has been used frequently to identify the role that particular individuals play in their social interactions and this approach has led to the question of whether, and in what context, individuals consistently occupy certain positions within their network. Here we investigated the social networks of guppies, Poecilia reticulata, in the wild and tested whether 1) individual fish occupy consistent positions in their network and 2) whether these positions are robust to experimental manipulations to their habitat. Our habitat manipulations involved increasing and decreasing the surface area of their pools as well as translocating an entire pool population between different pools in situ. We found that guppies did indeed consistently occupy positions within their social networks, irrespective of the type of manipulation and that individual network positions vary between individuals. Our results suggest that at least 2 factors contribute to the observed individual variation in network position including 1) the tendency to be social and 2) sex-specific social preferences. Finally, we used a simulation to explore the implications of individuals consistently occupying different network positions regarding the exposure of fish to parasites and predators. The time until infection decreased with increasing rank of individual betweenness and the predation risk increased with decreasing rank of the individual node strength thus illustrating the potential ecological and evolutionary consequences of consistent network positions.

社会网络研究范式愈发受到学界关注，其核心聚焦于动物类群与种群内部错综复杂的关系网络。正因如此，网络分析手段常被用于识别特定个体在社会互动中所扮演的角色，该研究方向也催生了一个核心科学问题：个体是否会在其社会网络中持续占据特定位置，以及在何种情境下会呈现这一特征。本研究针对野生环境下的孔雀鱼（guppies, Poecilia reticulata）社会网络展开实地调查，验证了两项核心假设：1）单个鱼类是否会在其社会网络中保持稳定的位置；2）这些位置是否会在对其栖息环境进行实验干预后依然保持稳健。本次栖息地干预实验包括调整其栖息池的表面积（分别进行增大与缩减处理），以及在原位环境下将单个栖息池的完整种群转移至其他池体。研究结果显示，无论干预类型如何，孔雀鱼确实会在其社会网络中持续占据特定位置，且不同个体的网络位置存在显著差异。本研究结果表明，至少有两种因素会导致个体在网络位置上的差异：1）社交倾向程度；2）基于性别的社交偏好。最后，本研究通过模拟实验，探讨了个体持续占据不同网络位置对鱼类接触寄生虫与捕食者的风险所产生的影响。个体中介中心性（betweenness）排名越高，其感染所需的时间越短；而个体节点强度（node strength）排名越低，其面临的捕食风险则越高。这一结果阐明了个体持续占据稳定网络位置所可能带来的生态与进化层面的潜在影响。