INVESTIGATING THE EFFECTS OF LARVAL PHENOTYPES ON TRAITS EXHIBITED AT A CRUCIAL LIFE-HISTORY SWITCH POINT

Abstract

In organisms with complex life histories, phenotypes exhibited in non-reproductive life stages are often correlated with adult performance and fitness. For example, in anurans (frogs and toads), age and size at metamorphosis is commonly correlated with age at maturity, fecundity, predator avoidance and competitive ability. However, the mechanisms that lead to variation in fitness-associated traits at metamorphosis are less well understood. This study investigated how hatchling body size and hatchling activity level affected fitness-associated traits at metamorphosis in squirrel treefrogs (Hyla squirella), and whether the effects of hatchling phenotypes varied with risk of predation. I demonstrate how hatchling phenotypes, predation risk, and interactions of the two, affected H. squirella larval survival as well as fitness-associated traits at metamorphosis. Without predation, initially small and less active hatchlings emerged with traits of better quality at metamorphosis. With predation, initially large, small and active hatchlings emerged with increased trait quality at metamorphosis, while initially less active hatchling trait quality reduced at metamorphosis. This study provides an important step towards improving our understanding of how mechanisms carry over to affect variation in the timing of and phenotypes exhibited at metamorphosis.