Figure 1. Genetic variation in the social environment affects zebrafish social behavior.

The contribution of the individual genotype (G_i), the genotype of conspecifics in the social group (G_s) and the interaction between the two (G_ixG_s) to the expression of behavioral phenotypes in zebrafish was assessed by raising oxytocin receptor mutant fish and wild types (focal fish marked with *) in shoals of either mutants or wild types (A). Social preference, measured by the time fish spend near a shoal vs. empty in a choice test (B, upper panel), showed a marginally significant effect of G_s (C; Source data file Figure 1—source data 1). Social habituation, which consisted on a consecutive social preference test exhibited a G_ixG_s effect (D; Source data file Figure 1—source data 2). Social recognition, measured as the discrimination between a novel and a familiar conspecific (E, upper panel), shows a pure G effect (F; Source data file Figure 1—source data 3). Social integration, measured as distance to the centroid of the shoal (G), showed a G_ixG_s effect (H; Source data file Figure 1—source data 4). Social influence, measured by the cohesion of the remaining shoal members (I), also showed a marginally significant G_ixG_s effect (J; Source data file Figure 1—source data 5). Heatmaps show the spatial distribution of a representative oxtr^(+/+) individual fish raised in a oxtr^(+/+) group, during the entire trial, for both social preference (B, lower panel) and social recognition (E, lower panel). Data is presented as mean ± standard error of the mean (SEM). Sample sizes are nine for heterogeneous groups (i.e. focal individual with different genotype from the remaining individuals in the shoal; mutant focal in WT shoals and WT focal in mutant shoals) and 15 for homogeneous groups (i.e. focal individual with the same genotype of the remaining individuals in the shoal; mutant focal in mutant shoals and WT focal in WT shoals). Different letters indicate significant differences (p<0.05) between treatments as assessed by Tukey post-hoc tests following a two-way ANOVA (D,H,J; see Table 1). An asterisk indicates a G_i main effect in F.