Low Tolerance of Embryonic Desiccation in the Terrestrial Nesting Frog Bryobatrachus nimbus (Anura: Myobatrachinae)

Mitchell, Nicola J.

doi:10.1643/0045-8511(2002)002[0364:ltoedi]2.0.co;2

Cited by 28 publications

(35 citation statements)

References 15 publications

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“…In our study, embryos incubated in atmospheres of decreasing ψ v showed significant declines in whole-egg mass, perivitelline membrane diameter, capsule thickness, dry mass and total length. In particular, tail lengths were significantly shorter for embryos reared in the driest conditions, similar to B. nimbus hatching-stage embryos where a decline in total length at lower ψ π was due to proportionally shorter tails (Mitchell, 2002). Smaller larvae have lower foraging efficiency and may develop more slowly, but in the case of terrestrial embryos, higher rates of yolk assimilation associated with high ψ during incubation may also allow hatchlings to metamorphose earlier and, hence, spend less time in a vulnerable stage of their life cycle (Arnold, 1983).…”

Section: Fitness Consequences Of Development In Dehydrating Atmospheresmentioning

confidence: 73%

“…In terrestrial breeding species without parental care, selection of nest sites with adequate water availability is critical, as eggs lose water freely from their jelly capsule and are at risk of desiccation (Bradford and Seymour, 1988;Mitchell, 2002). The jelly capsule consists of a matrix of acid mucopolysaccharides, which swells in the presence of water to form a liquid water reservoir (Salthe, 1963;Beattie, 1980) and buffers embryonic water loss in the short term (days).…”

Section: Introductionmentioning

confidence: 99%

“…However, high mortality can result from prolonged incubation in terrestrial environments with less than optimal water availability (Martin and Cooper, 1972;Bradford and Seymour, 1988). Further, the growth rate of embryos that develop terrestrially is reduced in dry conditions and embryos have a lower tissue water content, metabolise less yolk and may have lower mass-specific rates of oxygen consumption (Taigen et al, 1984;Bradford and Seymour, 1988;Mitchell, 2002).…”

Section: Introductionmentioning

confidence: 99%

“…Embryos developing within smaller capsules have a reduced surface area for gas exchange and may risk becoming hypoxic, especially during the later stages of development when V O 2 is relatively high. Other damaging effects, including body asymmetry and head depression, may result from development in a dehydrated egg if the embryo is unable to rotate freely within the perivitelline space, and tail lesions can occur if the embryo adheres to the perivitelline membrane (Bradford and Seymour, 1988;Mitchell, 2002). In anuran species in which embryos hatch into a water body to become free-swimming, feeding tadpoles, such developmental anomalies will potentially be detrimental to swimming performance and may enhance predation risk.…”

Section: Introductionmentioning

confidence: 99%

“…Depending on soil matric and osmotic properties (which were not measured), these humidities could potentially result in relatively low water potentials and consequently low water availability to the embryos. The survival limit of terrestrial anuran embryos incubated on filter paper substrates ranges between -25 kPa (Bryobatrachus nimbus) and -400 kPa (Pseudophryne bibronii) (Bradford and Seymour, 1988;Mitchell, 2002).…”

Section: Introductionmentioning

confidence: 99%

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Phenotypic differences in terrestrial frog embryos: effect of water potential and phase

Andrewartha

Mitchell

Frappell

2008

Journal of Experimental Biology

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SUMMARYThe terrestrial embryos of many amphibians obtain water in two ways; in a liquid phase from the substrate on which eggs are deposited, and in a vapour phase from the surrounding atmosphere. We tested whether the mode of water flux (liquid or vapour) affected the morphology and metabolic traits of the terrestrial Victorian smooth froglet (Geocrinia victoriana) embryos by incubating eggs both with a liquid water source and at a range of vapour water potentials. We found that embryos incubated with a liquid water source (ψ π =0 kPa) were better hydrated than embryos incubated with a vapour water source (ψ v =0 kPa), and grew to a larger size. Eggs incubated in atmospheres with lower ψ v values showed significant declines in mass and in the thickness of the jelly capsule, while embryos primarily showed reductions in dry mass, total length, tail length and fin height. The most significant deviations from control (ψ v =0 kPa) values were observed when the ψ v of the incubation media was less than the osmotic water potential (ψ π ) of the embryonic interstitial fluid (approximately -425 kPa). Despite the caveat that a ψ v of 0 kPa is probably difficult to achieve under our experimental conditions, the findings indicate the importance for eggs under natural conditions of contacting liquid water in the nesting substrate to allow swelling of the capsule.

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Section: Fitness Consequences Of Development In Dehydrating Atmospheresmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Phenotypic differences in terrestrial frog embryos: effect of water potential and phase

Andrewartha

Mitchell

Frappell

2008

Journal of Experimental Biology

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Reproductive colonization of land by frogs: Embryos and larvae excrete urea to avoid ammonia toxicity

Narvaez

Warkentin

2022

Ecology and Evolution

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Vertebrate colonization of land has occurred multiple times, including over 50 origins of terrestrial eggs in frogs. Some environmental factors and phenotypic responses that facilitated these transitions are known, but responses to water constraints and risk of ammonia toxicity during early development are poorly understood. We tested if ammonia accumulation and dehydration risk induce a shift from ammonia to urea excretion during early stages of four anurans, from three origins of terrestrial development. We quantified ammonia and urea concentrations during early development on land, under well‐hydrated and dry conditions. Where we found urea excretion, we tested for a plastic increase under dry conditions and with ammonia accumulation in developmental environments. We assessed the potential adaptive role of urea excretion by comparing ammonia tolerance measured in 96h‐LC50 tests with ammonia levels in developmental environments. Ammonia accumulated in foam nests and perivitelline fluid, increasing over development and reaching higher concentrations under dry conditions. All four species showed high ammonia tolerance, compared to fishes and aquatic‐breeding frogs. Both nest‐dwelling larvae of Leptodactylus fragilis and late embryos of Hyalinobatrachium fleischmanni excreted urea, showing a plastic increase under dry conditions. These two species can develop the longest on land and urea excretion appears adaptive, preventing their exposure to potentially lethal levels of ammonia. Neither late embryos of Agalychnis callidryas nor nest‐dwelling larvae of Engystomops pustulosus experienced toxic ammonia levels under dry conditions, and neither excreted urea. Our results suggest that an early onset of urea excretion, its increase under dry conditions, and elevated ammonia tolerance can all help prevent ammonia toxicity during terrestrial development. High ammonia represents a general risk for development which may be exacerbated as climate change increases dehydration risk for terrestrial‐breeding frogs. It may also be a cue that elicits adaptive physiological responses during early development.

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Early onset of urea synthesis and ammonia detoxification pathways in three terrestrially developing frogs

Méndez-Narváez,

Warkentin

2023

J Comp Physiol B

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Low Tolerance of Embryonic Desiccation in the Terrestrial Nesting Frog Bryobatrachus nimbus (Anura: Myobatrachinae)

Cited by 28 publications

References 15 publications

Phenotypic differences in terrestrial frog embryos: effect of water potential and phase

Phenotypic differences in terrestrial frog embryos: effect of water potential and phase

Reproductive colonization of land by frogs: Embryos and larvae excrete urea to avoid ammonia toxicity

Early onset of urea synthesis and ammonia detoxification pathways in three terrestrially developing frogs

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