Exploring neuronal markers and early social environment influence in divergent quail lines selected for social motivation

Abstract Vertebrates, including humans exhibit a wide range of social behaviors that are crucial for the adaptation and survival of most species. The brain organization and function are shaped by genetic and environmental factors, although their precise contributions have been poorly explored in the context of artificial selection. We used divergent lines of quail selected on their high versus low level of motivation to approach a group of conspecifics (S+ and S-, respectively) to investigate the influence of genetic selection and early social environment on sociability. We observed distinct sex- and brain-region-specific expression patterns of three neuronal markers: mesotocin, and vasotocin, the avian homologues of mammalian oxytocin and vasopressin, as well as aromatase, the enzyme that converts androgens into estrogens. These markers displayed pronounced and neuroanatomically specific differences between S+ and S- quail. Additionally, we assessed the influence of early social environment on social skills in adolescent birds. Mixing S+ and S- resulted in more S- males approaching the group without affecting the sociability of S+ or other behaviors, suggesting that the early social environment may influence the results of genetic selection. In conclusion, the divergent quail lines offer a valuable model for unraveling the neuronal and behavioral mechanisms underlying social behaviors.