Density-dependence in the terrestrial stage of the wood frog, Rana sylvatica

In organisms with complex life cycles, populations may be regulated and experience selection in one or more stages. Amphibians experience a shift from an aquatic to a terrestrial environment during metamorphosis, which produces substantial changes in population density, individual mobility, and selection regime. Although density-dependent growth and survivorship have been well documented in larval anurans, effects of post-metamorphic density and individual variation remain largely unexplored. However, amphibian population models suggest that post-metamorphic survivorship may be more important for population viability than are larval/reproductive parameters. The results of this experimental manipulation of juvenile wood frog (Rana sylvatica) density in field enclosures corroborates long-term survey data demonstrating strong density-dependent survivorship immediately following metamorphosis in this species. In addition, morphological growth patterns in surviving juveniles were affected by their plasticity responses to the larval environment. These results suggest that post-metamorphic density could produce potentially strong selection on juvenile phenotypes entering the terrestrial environment, highlighting the need for a broader understanding of consecutive phases within complex life cycles.