Department of Organismic and Evolutionary Biology and Center for Brain Science, Harvard University, Cambridge, USA.
Department of Biological and Experimental Psychology, Queen Mary University of London, London, UK.
Sci Rep. 2020 Mar 11;10(1):4480. doi: 10.1038/s41598-020-61410-7.
Theory predicts that social interactions can induce an alignment of behavioral asymmetries between individuals (i.e., population-level lateralization), but evidence for this effect is mixed. To understand how interaction with other individuals affects behavioral asymmetries, we systematically manipulated the social environment of Drosophila melanogaster, testing individual flies and dyads (female-male, female-female and male-male pairs). In these social contexts we measured individual and population asymmetries in individual behaviors (circling asymmetry, wing use) and dyadic behaviors (relative position and orientation between two flies) in five different genotypes. We reasoned that if coordination between individuals drives alignment of behavioral asymmetries, greater alignment at the population-level should be observed in social contexts compared to solitary individuals. We observed that the presence of other individuals influenced the behavior and position of flies but had unexpected effects on individual and population asymmetries: individual-level asymmetries were strong and modulated by the social context but population-level asymmetries were mild or absent. Moreover, the strength of individual-level asymmetries differed between strains, but this was not the case for population-level asymmetries. These findings suggest that the degree of social interaction found in Drosophila is insufficient to drive population-level behavioral asymmetries.
理论预测，社会互动可以诱导个体之间行为不对称的一致性（即群体水平的侧化），但这一效应的证据参差不齐。为了了解与其他个体的相互作用如何影响行为不对称，我们系统地操纵了黑腹果蝇的社会环境，测试了个体果蝇和双体（雌雄、雌雌和雄雄对）。在这些社会环境中，我们在五个不同的基因型中测量了个体和群体在个体行为（盘旋不对称，翅膀使用）和对偶行为（两只果蝇之间的相对位置和方向）中的不对称性。我们推断，如果个体之间的协调驱动行为不对称的一致性，那么在社会环境中应该比在孤独个体中观察到更高的群体水平的一致性。我们观察到其他个体的存在会影响果蝇的行为和位置，但对个体和群体不对称性有意外的影响：个体水平的不对称性很强，并且受到社会环境的调节，但群体水平的不对称性较弱或不存在。此外，个体水平不对称性的强度在菌株之间存在差异，但群体水平不对称性则不然。这些发现表明，在果蝇中发现的社会互动程度不足以驱动群体水平的行为不对称性。
