Witnessing others interact with a novel object has sex- and size-specific effects on neophilia in mosquitofish

Dealing with novelty can be challenging for animals. Approaching unfamiliar objects and environments allows individuals to discover and exploit new food sources and habitats, but novelty can also be dangerous and expose individuals to unfamiliar predators or toxic foods. Observing how others react to novel objects can enable an individual to indirectly assess the risks or benefits associated with particular objects without putting themselves directly in harm’s way via social transmission of information. Using the western mosquitofish (Gambusia affinis), we first manipulated whether individuals either witnessed a group of conspecifics interacting with a novel object in a beaker (shoal treatment) or witnessed the novel object alone in an empty beaker (alone treatment). Following this exposure, individuals then encountered that same object on their own and we measured how quickly they approached the object. We found that the effect of witnessing a group encounter a novel object depended on the sex and size of the focal individual. Seeing a group around a novel object caused males and similarly small-sized females to approach the object more quickly when they encountered it on their own later, compared to seeing the novel object without surrounding conspecifics. In contrast, large females were willing to approach the object regardless of the social context under which they had first encountered it. Sex, body size, and/or personality differences might affect the benefits of the social context and determine whether conspecifics attract individuals to a novel object.

对动物而言，应对新奇事物往往颇具挑战。接触陌生物体与环境，可使个体发现并利用全新的食物资源与栖息生境，但新奇事物同样潜藏风险，可能令个体暴露于陌生捕食者或有毒食物的威胁之中。通过信息的社会传递，观察同类对新奇物体的反应，能够让个体无需亲身涉险，便可间接评估特定物体对应的风险与收益。本研究以西方食蚊鱼（western mosquitofish, Gambusia affinis）为实验对象，首先通过操控设置两类实验处理：让目标个体观察到一群同种个体在烧杯中与新奇物体互动（集群处理组，shoal treatment），或让其单独观察空烧杯中的新奇物体（单独处理组，alone treatment）。完成上述暴露处理后，让个体独自接触该新奇物体，并记录其趋近该物体的速度。研究发现，观察群体接触新奇物体的效应，取决于目标个体的性别与体型大小。相较于仅观察无同种伴随的新奇物体，观察到群体围绕新奇物体的雄鱼以及体型相近的小型雌鱼，在后续独自接触该物体时，趋近速度会显著更快。与之相反，大型雌鱼的趋近行为则不受首次接触时的社会情境影响。性别、体型以及性格差异，可能会影响社会情境带来的收益，并决定同种个体是否能够吸引其他个体趋近新奇物体。