Exploratory and risk-taking behaviors can have significant impacts on the survival of individuals. The variation in risk-taking measured in wild species is often linked to predation pressures; however, social interactions or competition may also be driving forces in behavioral development. Laboratory studies with lizards have begun to suggest that competition for spatial and food resources may select for greater risk-taking or exploratory behaviors. The goal of this study was to test the impacts of spatial and visual isolation on behavioral development. Eastern fence lizards are not typically considered to be social animals, but frequently communicate using visual cues. Since these lizards are independent upon hatching, it is possible to manipulate their early social environment to measure its impact on behavioral development. I manipulated visual and spatial isolation to determine the level of interaction required for development of variation in exploratory and risk-taking behaviors. Following a split-clutch design, hatchlings were randomly divided into one of three housing treatments: 1) group, 2) individual (spatially but not visually isolated), and 3) isolation (spatially and visually isolated). All lizards were tested in emergence and open field tests after 4 weeks in housing treatments to measure their exploratory and risk-taking tendencies.
Lizards that were housed with conspecifics (group) explored test enclosures, emerged from shelters, and used novel perches more quickly than lizards from either the individual or isolation housing treatments. Additionally, the group-housed lizards moved more and used perches more often than lizards from the other two housing treatments. The isolation lizards took the longest to emerge from shelters and to use novel perches, but explored test enclosures just as much as the individually-housed lizards. The similarity between the individual and isolation housing treatments indicate that visual communication is less important in the development of exploratory and risk-taking behaviors than is spatial isolation. These results suggest that direct contact or competition for resources may be more impactful on behavior in this species. Other studies in lizards suggest that the effects of social isolation over longer time periods can impact foraging tasks and decrease exploratory behavior. These results have important implications for dense populations with plentiful predators. Competition may result in increased risk-taking behaviors, which would likely increase an individual’s exposure to predators. Further research into the longterm effects of early social experience, and the survival and fitness consequences of these effects, would clarify the role of competition in behavior development.