Social competence is influenced by early but not late life social experience in a cooperatively breeding fish

Social species rely on acquiring appropriate social skills to navigate their social environment. Developmental plasticity allows individuals to develop an appropriate phenotype by receiving cues from their social and nonsocial environment. However, committing to a specific phenotype early in life may prove maladaptive if there is a mismatch between the early and future environment. To address potential mismatches, multiple or extended sensitive periods provide opportunities for individuals to gather the necessary information in changing and predictable environments. Cooperative breeders, like the highly social cichlid Neolamprologus pulcher, typically experience changing environments especially during dispersal. While we know that early development is critical for the acquisition of social competence, it remains uncertain whether a second or extended sensitive period exists around the time of dispersal decisions in cooperative breeders. Here we manipulated the early and late life social environment of N. pulcher and asked whether individuals retain plasticity to adjust their social phenotype around sexual maturation. Juveniles were raised for 2 months with or without adults and tested for social competence. Shortly before reaching sexual maturity, they were randomly assigned to be housed alone, with siblings or with a social group for an additional 2 months before undergoing further social competence testing. Aggressive and submissive behaviours were assessed in two social contexts. Fish raised with a large group exhibited greater social competence compared to those raised only among siblings, regardless of subsequent social experiences. This suggests that either early life cues reliably predict future environments in nature or that constraints on late life plasticity exist.