| Plastic phenotypic responses of organisms to key environmental variables are well documented and ecologically important. Less is known about how these responses depend on additional variables that shape either selection or constraints, particularly interactions between biotic and abiotic factors. I studied how multiple abiotic and biotic factors combine to affect the Neotropical treefrog Dendropsophus ebraccatus through its egg, larval, and adult stages. This rainforest frog lays eggs on vegetation above ponds. Embryos develop for 3--4 days, then hatch and fall into the water. Eggs are highly susceptible to desiccation. Rainfall patterns affect D. ebraccatus egg survival both directly and by shaping predator effects. Variation in the egg environment---desiccation, hydration, and flooding---affects hatching timing and hatchling phenotype with carryover effects on tadpole vulnerability to predators and size at metamorphosis. Larval D. ebraccatus develop predator-specific coloration and morphology, growing large red tails in response to dragonfly larvae and shallow clear tails with fish. However, expression of inducible phenotypes depends on the growth environment. Fast-growing tadpoles in warmer water initially respond to predators but converge on the predator-free morphology as they increase in size. In cooler waters, where slower growth extends risk, tadpoles continue to invest in predator-induced morphology. Adult D. ebraccatus adaptively alter their reproductive mode in response to habitat quality. They lay eggs terrestrially on leaves in shaded ponds but in unshaded ponds, where terrestrial eggs desiccate rapidly, they lay eggs aquatically. Dendropsophus ebraccatus is the first vertebrate documented to lay both aquatic and terrestrial eggs. This demonstrates that such plasticity is possible, motivating re-evaluation of reproductive biology in other taxa and opening new opportunities for research on reproductive mode evolution. Dendropsophus ebraccatus is sister to a clade of terrestrial-breeding frogs with aquatic-breeding outgroups. Reproductive mode plasticity may represent a retained ancestral state intermediate in the evolution of terrestrial reproduction. My research reveals that observed plastic responses of organisms depend on multiple, interacting environmental factors, and both optimal plastic strategies and organismal capacities for response are environmentally contingent. Understanding developmental ecology requires integrating the complexity of environmental variation and contingent responses into our understanding of phenotypic plasticity. |
