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Environmentally cued plasticity in hatching timing is widespread in animals. As with later life-history switch points, plasticity in hatching timing may have carryover effects that affect subsequent interactions with predators and competitors. Moreover, the strength of such effects of hatching plasticity may be context dependent. We used red-eyed treefrogs, Agalychnis callidryas , to test for lasting effects of hatching timing (four or six days post-oviposition) under factorial combinations of resource levels (high or low) and predation risk (none, caged, or lethal Pantala flavescens dragonfly naiads). Tadpoles were raised in 400-L mesocosms in Gamboa, Panama, from hatching until all animals had metamorphosed or died, allowing assessment of effects across a nearly six-month period of metamorphosis. Hatching early reduced survival to metamorphosis, increased larval growth, and had context-dependent effects on metamorph phenotypes. Early during the period of metamorph emergence, early-hatched animals were larger than late-hatched ones, but this effect attenuated over time. Early-hatched animals also left the water with relatively longer tails. Lethal predators dramatically reduced survival to metamorphosis, with most mortality occurring early in the larval period. Predator effects on the timing of metamorphosis and metamorph size and tail length depended upon resources. For example, lethal predators reduced larval periods, and this effect was stronger with low resources. Predators affected metamorph size early in the period of metamorphosis, whereas resource levels were a stronger determinant of phenotype for animals that metamorphosed later. Effects of hatching timing were detectable on top of strong effects of larval predators and resources, across two subsequent life stages, and some were as strong as or stronger than effects of resources. Plasticity in hatching timing is ecologically important and currently underappreciated. Effects on metamorph numbers and phenotypes may impact subsequent interactions with predators, competitors, and mates, with potentially cascading effects on recruitment and fitness.

For animals with complex life cycles, conditions in the larval environment can have important effects that persist after metamorphosis. These carry‐over effects may influence juvenile growth plasticity and have important fitness consequences. Small juvenile red‐eyed treefrogs, Agalychnis callidryas, grow faster than larger ones. We examined to what extent this growth pattern is due to carry‐over effects of intraspecific larval competition. In particular, we assessed larval gut plasticity and determined whether carry‐over effects could persist given the extensive gut remodelling that occurs when herbivorous larvae transition to carnivorous juveniles. We reared larvae in mesocosms at low, medium and high densities and measured the size of both larval and juvenile guts, livers and fat bodies. We also monitored the timing of the onset of juvenile feeding post‐metamorphosis and, after the onset of feeding, we measured intake rate and mean diet retention time. Finally, we measured juvenile metabolic rates to determine whether any organ size plasticity contributed to metabolic carry‐over effects. Larval density had strong effects on larval morphology with higher densities increasing gut length and decreasing liver and fat body sizes. The effects of this plasticity carried over post‐metamorphosis. High larval densities produced smaller juveniles with proportionately longer guts and extremely small livers and fat bodies. There were no apparent carry‐over effects on size‐specific metabolic rate. Differences in larval density were also associated with differences in post‐metamorphic feeding. Small juveniles from high larval densities began feeding even before metamorphosis was complete, whereas large juveniles from low larval densities experienced a significant 2‐week delay. Although juvenile body mass varied over threefold across treatments, once feeding was initiated, neither intake nor mean diet retention time scaled with body size. Overall, high larval densities produced small juveniles with very low lipid reserves that may have stimulated hyperphagia relative to larger juveniles. Longer guts carried over from the larval stage could facilitate this by allowing small juveniles to elevate intake without sacrificing diet retention time. Patterns of intake coupled with differences in the onset of feeding explain the size‐dependent growth pattern previously reported in this and other species.

Life history theory predicts that organisms with complex life cycles should transition between life stages when the ratio of growth rate (g) to risk of mortality (μ) in the current stage falls below that in the subsequent stage. Empirical support for this idea has been mixed. Implicit in both theory and empirical work is that the risk of mortality in the subsequent stage is unknown. However, some embryos and larvae of both vertebrates and invertebrates assess cues of post‐transition predation risk and alter the timing of hatching or metamorphosis accordingly. Furthermore, although life history switch points of prey have traditionally been treated as discrete shifts in morphology or habitat, for many organisms they are continuous transitional periods within which the timing of specific developmental and behavioral events can be plastic. We studied red‐eyed treefrogs (Agalychnis callidryas), which detect predators of both larvae and metamorphs, to test if plastic changes during the process of metamorphosis could reconcile the mismatch between life history theory and empirical data and if plasticity in an earlier stage transition (hatching) would affect plasticity at a subsequent stage transition (metamorphosis). We reared tadpoles from hatching until metamorphosis in a full‐factorial cross of two hatching ages (early‐ vs. late‐hatched) and the presence or absence of free‐roaming predators of larvae (giant water bugs) and metamorphs (fishing spiders). Hatching age affected the times from oviposition to tail resorption and from hatching to emergence onto land, but did not alter responses to predators or developmental stage at emergence. Tadpoles did not alter their age at emergence or tail resorption in response to larval or metamorph predators, despite the fact that predators reduced tadpole density by ~30%. However, developmental stage at emergence and time needed to complete metamorphosis in the terrestrial environment were plastic and consistent with predictions of the “minimize μ/g” framework. Our results demonstrate that likely adaptive changes in life history transitions occur at previously unappreciated timescales. Consideration of plasticity in the developmental timing of ecologically important events within metamorphosis, rather than treating it as a discrete switch point, may help to reconcile inconsistencies between empirical studies of predator effects and expectations of long‐standing ecological theory.

The present study records the occurrence of Sphaenorhynchus caramaschii Toledo, Garcia, Lingnau & Haddad, 2007 for periurban areas of São Paulo and Sorocaba cities, eastern side of São Paulo state. These new records represent the northeastern known localities for this species and expand the septentrional limit of its geographic distribution. We also present comments and biological information for these recently discovered populations.