Dehydration-Induced Mortality and Premature Hatching in Gliding Treefrogs with Even Small Reductions in Humidity

González, Katherine; Warkentin, Karen M.; Güell, Brandon A.

doi:10.1643/h2020085

Cited by 10 publications

(9 citation statements)

References 48 publications

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“…However, the interaction between climate change and adaptive developmental plasticity remains poorly studied, with a few exceptions. For example, hatchlings of the pond‐breeding gliding tree frog, Agalychnis spurrelli , have been shown to be affected by even subtle changes in humidity, with eggs hatching prematurely in response to a reduction in humidity of only 3% (González et al, 2021). Whereas in the boreal chorus frog, Pseudacris maculata , which can breed in permanent or ephemeral water bodies, findings are more varied.…”

Section: Discussionmentioning

confidence: 99%

Hatching plasticity in a Southeast Asian tree frog mitigates submergence‐induced mortality

et al. 2023

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Environmentally cued hatching has been well‐documented in amphibians in response to a wide range of abiotic and biotic factors. The hatching of terrestrial amphibian eggs in response to flooding may be basal within the group, but amphibian lineages in tropical Asia and sub‐Saharan Africa have not received as much attention as their Neotropical counterparts. We investigated submergence‐induced hatching in Feihyla hansenae, a Rhacophorid tree frog with terrestrial eggs. We quantified natural rates of clutch submergence at our study site in Thailand. Using submergence experiments, we found that embryos are capable of hatching early to escape flooding, and that failure to hatch results in mortality. Among the embryos that were able to hatch early, only the earliest, youngest hatchlings experienced a trade‐off in body size that persisted for 6 days, while later, older hatchlings were not significantly smaller than spontaneous hatchlings under control conditions. By incorporating our natural and experimental data into Monte Carlo methods to simulate and compare survival probabilities with and without hatching plasticity, we found an overall 3.1% increase in submergence survival due to hatching plasticity. Our findings support the idea that flooding‐induced hatching is widespread across amphibians with terrestrial eggs and highlight the importance of researching understudied tropical regions. As climate change is projected to affect rainfall patterns, the ability of embryos to escape abiotic egg‐stage threats may be an indicator of species' ability to flexibly navigate a changing environment.

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Section: Discussionmentioning

confidence: 99%

Hatching plasticity in a Southeast Asian tree frog mitigates submergence‐induced mortality

et al. 2023

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“…We brought clutches on their leaves to an ambient temperature and humidity laboratory at Osa Conservation's Piro Biological Station and maintained them on plastic cards over aged tap water in cups within large plastic bins (egg humidors) with mesh windows in the lids to allow ventilation. Clutches and humidors were misted frequently with rainwater to maintain healthy levels of egg and clutch hydration (Salica et al 2017;González et al 2021). We also removed unfertilized and dead eggs at setup to reduce the risk of fungal infection.…”

Section: Egg Clutch Collection and Carementioning

confidence: 99%

“…We checked clutches every 12 hours at 06:00 and 18:00 h until all eggs hatched. At each check, we counted the number of unhatched eggs on each clutch and/or the number of hatched tadpoles in each cup, staged embryos according to Warkentin (2017), and carefully misted the clutches and their humidors to maintain humidity without disturbing the embryos (Salica et al 2017;González et al 2021). We stopped staging embryos at stage 29, once embryos became responsive to physical disturbance cues (Gomez-Mestre and Warkentin 2007; Warkentin et al 2017; this study, Fig.…”

Section: Spontaneous Hatching Timingmentioning

confidence: 99%

To hatch and hatch not: does heterochrony in onset of vestibular mechanosensing explain species differences in escape-hatching success of Agalychnis embryos in snake attacks?

Güell

Warkentin

2023

Preprint

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Phyllomedusid treefrogs hatch prematurely to escape egg predation, but escape success varies among species. Snake attacks elicited 55% less escape-hatching in spontaneously hatching Agalychnis spurrelli than in less developed A. callidryas. Agalychnis callidryas use their vestibular system and, secondarily, their lateral line to sense physical disturbances that cue hatching. Since A. spurrelli develop faster, we hypothesized that heterochronic shifts in the onset timing of vestibular mechanosensory function, relative to hatching ability, might explain their lower escape response to mechanosensory cues. To test this, we compared onset timings of hypoxia- and mechanosensory-cued hatching (MCH) and vestibular mechanosensory function in developmental series of both species. Across species, most sibships began responding to each cue at the same developmental stage and vestibular function development, measured by the vestibulo-ocular reflex (VOR), was similar. These results demonstrate that low escape-hatching success in A. spurrelli is not caused by a delay in the onset of vestibular mechanosensory function. MCH onset in A. spurrelli was associated with VOR, but with a higher threshold than in A. callidryas. The absence of MCH before strong vestibular function suggests multimodal mechanosensing may not contribute to antipredator responses of A. spurrelli embryos. Our observations of higher escape success of larger clutches in snake attacks and hatching complications in flooded A. spurrelli suggest that differences in clutch and egg capsule structure may contribute directly to species differences in escape-hatching success. Moreover, hatching complications in A. spurrelli may select against false alarms, increasing the stringency of hatching decision rules.

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“…2014 ), and two species of Agalychnis ( A. callidryas , Salica et al. 2017 ; A. spurrelli , Gonzáles et al. 2021 ).…”

Section: Introductionmentioning

confidence: 99%

Heat-Induced Hatching of Red-Eyed Treefrog Embryos: Hydration and Clutch Structure Increase Behavioral Thermal Tolerance

Guevara-Molina

Gomes

Warkentin

2022

Integrative Organismal Biology

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Climate change is increasing both environmental temperatures and droughts. Many ectotherms respond behaviorally to heat, thereby avoiding damage from extreme temperatures. Within species, thermal tolerance varies with factors such as hydration as well as ontogenetic stage. Many tropical anurans lay terrestrial eggs, relying on environmental moisture for embryonic development. These eggs are vulnerable to dehydration, and embryos of some species can hatch prematurely to escape from drying eggs. Warmer temperatures can accelerate development, and thus hatching, but excess heat can kill embryos. Thus, we hypothesize that embryos may show a behavioral thermal tolerance limit, hatching prematurely to avoid potentially lethal warming. If so, because warming and drying are often associated, we hypothesize this limit, measurable as a voluntary thermal maximum, may depend on hydration. We manipulated hydration of the terrestrial eggs of Agalychnis callidryas, in intact clutches and egg-groups isolated from clutch jelly, then warmed them to assess if embryos hatch early as a behavioral response to high temperatures and whether their thermal tolerance varies with hydration or surrounding structure. We discovered that heating induces hatching; these embryos show a behavioral escape-hatching response that enables them to avoid potentially lethal warming. Hydrated eggs and clutches lost more water and warmed more slowly than dehydrated ones, indicating that hydration buffers embryos from environmental warming via evaporative cooling. Embryos in hydrated clutches tolerated greater warming before hatching and suffered higher mortality, suggesting their behavioral thermal safety margin is small. In contrast lower thermal tolerance protected dry embryos, and those isolated from clutch jelly, from lethal warming. Heat-induced hatching offers a convenient behavioral assay for thermal tolerance of terrestrial anuran embryos and the interactive effects of warming and dehydration at an early life stage. This work expands the set of threats against which embryos use hatching in self-defense, creating new opportunities for comparative studies of thermal tolerance as well as integrative studies of self-defense mechanisms at the egg stage.

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Dehydration-Induced Mortality and Premature Hatching in Gliding Treefrogs with Even Small Reductions in Humidity

Cited by 10 publications

References 48 publications

Hatching plasticity in a Southeast Asian tree frog mitigates submergence‐induced mortality

Hatching plasticity in a Southeast Asian tree frog mitigates submergence‐induced mortality

To hatch and hatch not: does heterochrony in onset of vestibular mechanosensing explain species differences in escape-hatching success of Agalychnis embryos in snake attacks?

Heat-Induced Hatching of Red-Eyed Treefrog Embryos: Hydration and Clutch Structure Increase Behavioral Thermal Tolerance

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