Carry‐over Effects of Size at Metamorphosis in Red‐eyed Treefrogs: Higher Survival but Slower Growth of Larger Metamorphs

The development of antipredator traits is dependent on the frequency and intensity of predator exposure over evolutionary and ecological time. We hypothesized that prey species would respond with increasing accuracy when exposed to predators across generational, ontogenetic, and immediate time scales. We assessed larval Pacific chorus frog (PSRE; Pseudacris regilla) individuals that varied in population sympatry, embryonic conditioning, and immediate exposure to stocked populations of rainbow trout (Oncorhynchus mykiss). Using PSRE populations from sites with and without resident rainbow trout, we conditioned embryos to trout odor, PSRE alarm cues, trout odor in combination with alarm cues, or control water. After being hatched and reared in control water, individuals were exposed to the four predator cue treatments using a fully factorial design. Tadpoles from populations with resident rainbow trout did not behave or develop differently than tadpoles originating from fishless sites. However, we found evidence that PSRE reduced predation risk with a combination of carry‐over effect (i.e., transfer of information across life history stages) and within‐life stage phenotypically plastic mechanisms. We found both developmental and behavioral carry‐over effects: tadpoles conditioned with trout odor as embryos grew more slowly and took refuge more often than control animals. Within‐life‐stage behavioral plasticity was observed in tadpoles from all treatment groups, responding to predator cues with increased refuge use. Potentially additive effects of predator exposure on prey response should be considered when predicting the ability of prey to recognize novel threats.

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“…, Tarvin et al. ), we predict a subsequent reduction in individual fitness (Fig. ; Rowe and Ludwig , Ludwig and Rowe ).…”

Section: Discussionmentioning

confidence: 51%

“…, Tarvin et al. , Van Allen and Rudolf ). However, carry‐over effects may represent an important alternate prey response mechanism as they are driven by ontogenetic exposure regimes.…”

Section: Introductionmentioning

confidence: 99%

Evaluating adaptive, carry‐over, and plastic antipredator responses across a temporal gradient in Pacific chorus frogs

Garcia

Bredeweg

Urbina

et al. 2019

Ecology

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“…Tarvin et al . () found that larger A. callidryas froglets from low larval densities lost significant mass for a period of 1–3 weeks. This mass loss can be explained by the marked delay in the onset of feeding that we found for large individuals.…”

Section: Discussionmentioning

confidence: 99%

“…Such measures accurately reflect froglet intake because small and large froglets do not preferentially select small or large leafhoppers or fruit flies when ad libitum food is provided following our methods (Tarvin et al . ).…”

Section: Methodsmentioning

confidence: 97%

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Post‐metamorphic carry‐over effects of larval digestive plasticity

et al. 2015

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1.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. 2. 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. 3. 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. 4. 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 postmetamorphosis. 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. 5. 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. 6. 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.

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Examination of the link between life stages uncovered the mechanisms by which habitat characteristics affect odonates

et al. 2017

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Abstract. The larval and adult stages of amphibious animals are affected by both aquatic and terrestrial habitat characteristics, and each stage also affects the other. However, this link between life stages has been largely overlooked in previous studies. We examined the effect of aquatic and terrestrial habitat characteristics on the diversity of larval and adult odonates, taking into account the link between the two life stages. Species diversity of adult and larval odonates and aquatic plants, as well as patterns of land use, was investigated in 63 irrigation ponds. We created structural equation models, with paths from land use and aquatic plants characteristics to larval and adult stages of odonates, as well as between the two stages, and chose the best model based on the lowest Akaike information criterion. Adult odonates, but not larvae, were affected by aquatic and terrestrial habitat characteristics, suggesting that the former is the key stage for odonate communities. We observed a positive relationship between the diversity of aquatic plants and larval odonates, but this was in fact due to the effects of aquatic plants on adults, which carried over to the larval stage. Our study showed that a consideration of the link between life stages is crucial for a complete understanding of the relationship between habitat characteristics and amphibious animal populations.

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Carry‐over Effects of Size at Metamorphosis in Red‐eyed Treefrogs: Higher Survival but Slower Growth of Larger Metamorphs

Cited by 40 publications

References 61 publications

Evaluating adaptive, carry‐over, and plastic antipredator responses across a temporal gradient in Pacific chorus frogs

Evaluating adaptive, carry‐over, and plastic antipredator responses across a temporal gradient in Pacific chorus frogs

Post‐metamorphic carry‐over effects of larval digestive plasticity

Examination of the link between life stages uncovered the mechanisms by which habitat characteristics affect odonates

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