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

Previous research has suggested social learning of foragingbehavior can inhibit learning of the optimal behavior pattern.Based on their transmission chain design, we used small groupsof guppies (Poecilia reticulata) to determine the degree towhich the optimal behavior pattern was inhibited by sociallylearned information. A founder group was trained to take a long, energetically costly route to a food source. The members ofthis group were gradually replaced with naive conspecifics.Replicating the findings of the earlier researchers, it wasclear that the behavior of the founders strongly influencedthe behavior of the naive fish, probably through a process oflocal enhancement. When tested as a group, the naive fish chosethe long route to the food source significantly more oftenthan chance. Each naive fish was also tested in isolation.When tested alone, there was a significant tendency to choosethe short route despite following the long route when testedas a group. These results suggest social learning does notinhibit learning of optimal behavior patterns but that a trade-offoccurs when tested in the group condition. It is possible thatthe advantages for an individual fish of swimming with theshoal, and thus following the socially learned route, may haveoutweighed the potential energetic costs of taking this longerroute.