Inhibition of optimal behavior by social transmission in the guppy depends on shoaling

Previous research has suggested social learning of foraging behavior can inhibit learning of the optimal behavior pattern. Based on their transmission chain design, we used small groups of guppies (Poecilia reticulata) to determine the degree to which the optimal behavior pattern was inhibited by socially learned information. A founder group was trained to take a long, energetically costly route to a food source. The members of this group were gradually replaced with naive conspecifics, Replicating the findings of the earlier researchers, it was clear that the behavior of the founders strongly influenced the behavior of the naive fish, probably through a process of local enhancement. When tested as a group, the naive fish chose the long route to the food source significantly more often than chance. Each naive fish was also tested in isolation. When tested alone, there was a significant tendency to choose the short route despite following the long route when tested as a group. These results suggest social learning does not inhibit learning of optimal behavior patterns but that a trade-off occurs when tested in the group condition. It is possible that the advantages for an individual fish of swimming with the shoal, and thus following the socially learned route, may have outweighed the potential energetic costs of taking this longer route.