MAPLE, M.M.: Direct and indirect effects of maternal rearing site choice on tadpole survival in the strawberry arrow poison frog, Dendrobates pumilio

Parental choice of early offspring environments can have important fitness consequences for their young, especially in taxa with otherwise limited parental investment. The pathways by which site variables influence fitness will determine the strength of selection for site choice. In 1995 and 1996, I investigated the direct and indirect effects of rearing site choice in Dendrobates pumilio, a frog with extended parental care. Female D. pumilio deposit their tadpoles in Dieffenbachia and bromeliad axils that vary in age, water volume, pH, mean temperature, and temperature variance. The results of this study indicate that female D. pumilio actively discriminate among abundantly available rearing sites when depositing their tadpoles and that these site choices may have both direct and indirect consequences for tadpole survival. Females consistently chose younger rearing sites with greater water volumes in both years, and selected on mean temperature in 1995. Although the fitness consequences of water volume and axil age could not be assessed in this study, these axil characters are expected to have direct effects on offspring survival. Variance in axil temperature had an indirect effect on tadpole fitness via its effect on tadpole growth in 1996; however, females showed no preference for temperature variance when depositing their tadpoles. These results are consistent with the prediction that mothers showing extended parental care will more likely discriminate among sites (if they discriminate at all) based on characters having direct effects on offspring survival than among sites based on characters with only indirect effects.