The effect of MnSO4 concentration and selection line on behavior
Activity was a repeatable behavioral trait (Pearson’s correlation coefficient=0.437; P =0.002). There was no significant interaction between selection line and concentration neither concentration affected fish activity (Figure 2A, Table S2). Large-selected fish had overall higher activity levels than small-selected fish (t=2.633, P < 0.01; Figure 2A, Table S2) and larger fish had higher activity levels irrespective of the selection line (t=2.988,P =0.006; Table S2).
Among small- and large-selected fish, 22% and 9% of the fish, respectively, did not feed during the feeding trial. The interaction between the selection line and concentration explained differences in feeding probability (z=1.580, P =0.002; Table S2). While among large-selected fish the feeding probability increased with MnSO4 concentration, among small-selected fish the feeding probability slightly increased first but then decreased distinctively in the highest concentration (Figure 2B). Fish body size did not affect feeding probability (Table S2).