Environmental and genetic effects on exploratory behavior of high- and low-predation guppies (Poecilia reticulata)

Abstract

Exploratory behavior—an individual’s response to novel environments, resources, or objects—should vary with the associated benefits, including new sources of food and reduced levels of competition, and the costs, such as predation pressure. Using guppies from multiple streams and rivers in Trinidad, we compared guppies from high- and low-predation populations. We found that wild-caught male and female guppies from low-predation populations were more exploratory than high-predation fish when tested in the field and in controlled laboratory conditions. We did not detect significant evidence for a genetic basis for differences in the behavior of high- and low-predation fish using a common-garden approach, but further study is required before conclusions can be made about the relative contribution of genes to population differences in exploratory behavior of guppies. Theory has assumed that predation risk is a cost that will select against high levels of exploratory behavior; this study is one of the few that has tested this assumption, and we show that exploratory behavior is indeed suppressed in guppies from high-predation localities. Exploratory behavior is a component of an individual’s responses to novel environments, resources, and objects (including potential predators) and thus can affect important decisions of animals in the wild (e.g., whether to sample new, potential sources of food, whether to disperse). We compared exploratory behavior of wild-caught guppies from sites with large, dangerous predators with those from sites with small predators that are only a threat to small individuals. Guppies co-occurring with large predators were less exploratory than those from sites with small predators. Factors contributing to this difference could include exposure to predators directly and to conspecifics’ responses to predators. Studies on general behavioral traits (e.g., temperament) combined with knowledge of animals’ environment and evolution are expanding our ability to test ideas about the origin and maintenance of intra-specific variation in fascinating and complex traits.