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Karen M. Warkentin - One of the best experts on this subject based on the ideXlab platform.
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Egg clutch dehydration induces early hatching in red-eyed treefrogs, Agalychnis callidryas
PeerJ, 2017Co-Authors: María José Salica, James R. Vonesh, Karen M. WarkentinAbstract:Terrestrial eggs have evolved repeatedly in tropical anurans exposing embryos to the new threat of dehydration. Red-eyed treefrogs, Agalychnis callidryas, lay eggs on plants over water. Maternally provided water allows shaded eggs in humid sites to develop to hatching without rainfall, but unshaded eggs and those in less humid sites can die from dehydration. Hatching responses of amphibian eggs to dry conditions are known from two lineages with independent origins of terrestrial eggs. Here, we experimentally tested for dehydration-induced early hatching in another lineage (Agalychnis callidryas, Phyllomedusidae), representing a third independent origin of terrestrial eggs. We also investigated how dehydration affected egg and clutch structure, and egg mortality. We collected clutches from a pond in Gamboa, Panama, and randomly allocated them to wet or dry treatments at age 1 day. Embryos hatched earlier from dry clutches than from wet clutches, accelerating hatching by ∼11%. Clutch thickness and egg diameter were affected by dehydration, diverging between treatments over time. Meanwhile, mortality in dry clutches was six-fold higher than in control clutches. With this study, early hatching responses to escape mortality from egg dehydration are now known from three anuran lineages with independent origins of terrestrial eggs, suggesting they may be widespread. Further studies are needed to understand how terrestrial amphibian eggs can respond to, or will be affected by, rapid changes in climate over the next decades.
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How embryos escape from danger: the mechanism of rapid, plastic hatching in red-eyed treefrogs.
The Journal of experimental biology, 2016Co-Authors: Kristina L Cohen, Marc A Seid, Karen M. WarkentinAbstract:Environmentally cued hatching allows embryos to escape dangers and exploit new opportunities. Such adaptive responses require a flexibly regulated hatching mechanism sufficiently fast to meet relevant challenges. Anurans show widespread, diverse cued hatching responses, but their described hatching mechanisms are slow, and regulation of timing is unknown. Arboreal embryos of red-eyed treefrogs, Agalychnis callidryas, escape from snake attacks and other threats by very rapid premature hatching. We used videography, manipulation of hatching embryos and electron microscopy to investigate their hatching mechanism. High-speed video revealed three stages of the hatching process: pre-rupture shaking and gaping, vitelline membrane rupture near the snout, and muscular thrashing to exit through the hole. Hatching took 6.5-49 s. We hypothesized membrane rupture to be enzymatic, with hatching enzyme released from the snout during shaking. To test this, we displaced hatching embryos to move their snout from its location during shaking. The membrane ruptured at the original snout position and embryos became trapped in collapsed capsules; they either moved repeatedly to relocate the hole or shook again and made a second hole to exit. Electron microscopy revealed that hatching glands are densely concentrated on the snout and absent elsewhere. They are full of vesicles in embryos and release most of their contents rapidly at hatching. Agalychnis callidryas' hatching mechanism contrasts with the slow process described in anurans to date and exemplifies one way in which embryos can achieve rapid, flexibly timed hatching to escape from acute threats. Other amphibians with cued hatching may also have novel hatching mechanisms.
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Appendix F. Differences in size and developmental stage between early induced hatchlings and modal spontaneous hatchlings in six phyllomedusine treefrogs (Agalychnis and Pachymedusa).
2016Co-Authors: Ivan Gomez-mestre, John J. Wiens, Karen M. WarkentinAbstract:Differences in size and developmental stage between early induced hatchlings and modal spontaneous hatchlings in six phyllomedusine treefrogs (Agalychnis and Pachymedusa)
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Froglet metabolic rates
2016Co-Authors: Sarah S. Bouchard, Chelsea Jenney R. O'leary, Lindsay J. Wargelin, Julie F. Charbonnier, Karen M. WarkentinAbstract:This file contains metabolic rates of Agalychnis callidryas froglets that were reared as larvae in mesocosms at different densities. The data include metamorph ID, tank (mesocosm) number, body size, and rates of oxygen consumption
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Onset of metamorph feeding
2016Co-Authors: Sarah S. Bouchard, Chelsea Jenney R. O'leary, Lindsay J. Wargelin, Julie F. Charbonnier, Karen M. WarkentinAbstract:This file contains information on the rate at which Agalychnis callidryas metamorphs initiated feeding upon emergence from mesocosms where they were reared at different larval densities. Data include size at emergence and the time required for tail resorption and the production of the first fecal pellet. The file also contains the number of insect heads egested in each fecal pellet for varying periods of time post-metamorphosis
Ivan Gomez-mestre - One of the best experts on this subject based on the ideXlab platform.
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Appendix F. Differences in size and developmental stage between early induced hatchlings and modal spontaneous hatchlings in six phyllomedusine treefrogs (Agalychnis and Pachymedusa).
2016Co-Authors: Ivan Gomez-mestre, John J. Wiens, Karen M. WarkentinAbstract:Differences in size and developmental stage between early induced hatchlings and modal spontaneous hatchlings in six phyllomedusine treefrogs (Agalychnis and Pachymedusa)
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Appendix E. Examples of egg clutches of phyllomedusine hylid frogs, Agalychnis and Pachymedusa, showing differences between highly gelatinous and minimally gelatinous clutches.
2016Co-Authors: Ivan Gomez-mestre, John J. Wiens, Karen M. WarkentinAbstract:Examples of egg clutches of phyllomedusine hylid frogs, Agalychnis and Pachymedusa, showing differences between highly gelatinous and minimally gelatinous clutches
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EVOLUTION OF ADAPTIVE PLASTICITY: RISK‐SENSITIVE HATCHING IN NEOTROPICAL LEAF‐BREEDING TREEFROGS
Ecological Monographs, 2008Co-Authors: Ivan Gomez-mestre, John J. Wiens, Karen M. WarkentinAbstract:Adaptive plasticity at switch points in complex life cycles (e.g., hatching, metamorphosis) is well known, but the evolutionary history of such plasticity is not. Particularly unclear is how a single plastic response (e.g., shifts in hatching timing) evolves to respond to different threats and cues (e.g., abiotic and biotic). We conducted a comparative phylogenetic study of hatching plasticity in a group of frogs with arboreal embryos to determine when risk-accelerated hatching evolved in the clade, whether responses to two common egg-stage risks (snake predation and flooding) evolved independently, and whether the overall capacity for hatching plasticity was evolutionarily more conservative than responses to specific cues. Red-eyed treefrogs (Agalychnis callidryas) hatch early to escape from several egg-stage risks but otherwise hatch later, improving larval survival with predators. We reconstructed a phylogeny for Agalychnis and related genera based on three mitochondrial and four nuclear genes. We quantified onset of hatching competence, spontaneous hatching timing, responses to egg-stage risks, and costs of premature hatching in Agalychnis and Pachymedusa. We also assessed hatching plasticity in a basal phyllomedusine, Cruziohyla calcarifer. The capacity to hatch ;30% before the spontaneous hatching age appears ancestral for phyllomedusines, with little change over ;34-50 million years among the species examined. A strong hatching response to flooding, with no mortality of hatching-competent eggs, is similarly ancient and conserved. Premature hatchlings of Agalychnis and Pachymedusa are more vulnerable to fish predation than are full-term hatchlings, indicating a conserved risk trade-off across hatching that would make plasticity advantageous. In contrast, the hatching response to snake attack has undergone major changes at least twice in the Agalychnis-Pachymedusa clade, with two species showing substantially lower escape success than the others. Responses to different threats have thus evolved independently. The capacity for switch point plasticity may be evolutionarily more stable than the response to individual stage-specific threats.
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To hatch and hatch not: similar selective trade-offs but different responses to egg predators in two closely related, syntopic treefrogs
Oecologia, 2007Co-Authors: Ivan Gomez-mestre, Karen M. WarkentinAbstract:Risk-sensitive hatching is adaptive for species facing a trade-off between egg-stage and post-hatching risks, and environmental variation in one or both stages. Such plasticity has been found in amphibians, fishes, reptiles and spiders, with red-eyed treefrogs (Agalychnis callidryas) being the best-studied case. We assessed hatching plasticity and egg- and larval-stage risks in a closely related, syntopic species, the gliding leaf-frog (Agalychnis spurrelli). We found a lower hatching response to egg-eating snakes in A. spurrelli (9–28% of embryos escaped) than in A. callidryas (59–80% escaped). Levels of snake predation were similarly high for clutches of both species monitored at a pond in Costa Rica, and in fish predation experiments early-hatched A. spurrelli tadpoles were more vulnerable than later hatchlings, as has been shown for A. callidryas. A. spurrelli thus face a risk trade-off similar to A. callidryas, and likely would benefit from predator-induced hatching; their lower responsiveness to snakes appears nonadaptive. A. spurrelli embryos showed a stronger hatching response (57% hatched in 1 h) to submergence underwater than to snake attacks even though submergence is a less frequent risk. This suggests they have a greater capacity for early hatching than is expressed in the context of snake attacks, but have much lower sensitivity to snake cues than to flooding cues. Development in A. spurrelli is accelerated compared to syntopic A. callidryas, and spontaneous hatching is earlier and more synchronous. This is congruent with predictions based on selection by egg predators in the absence of a strong escape hatching response.
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Development, Surface Exposure, and Embryo Behavior Affect Oxygen Levels in Eggs of the Red‐Eyed Treefrog, Agalychnis callidryas
Physiological and biochemical zoology : PBZ, 2005Co-Authors: Karen M. Warkentin, Ivan Gomez-mestre, J. Gregory McdanielAbstract:Abstract Oxygen stress can slow development, induce hatching, and kill eggs. Terrestrial anamniote embryos face a potential conflict between oxygen uptake and water loss. We measured oxygen levels within eggs to characterize the respiratory environment for embryos of the red‐eyed treefrog, Agalychnis callidryas, a Neotropical frog with arboreal egg masses and plastic hatching timing. Perivitelline oxygen partial pressure (Po2) was extremely variable both within and among eggs. Po2 increased with air‐exposed surface of the egg and declined over the developmental period before hatching competence. Through the plastic hatching period, however, average Po2 was stable despite continued rapid development. Development was synchronous across a wide range of perivitelline Po2 (0.5–16.5 kPa), and hatching‐competent embryos tolerated Po2 as low as 0.5 kPa without hatching. The variation in Po2 measured over short periods of time within individual eggs was as great as that measured across development or surface expos...
C. Shaw - One of the best experts on this subject based on the ideXlab platform.
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identification of a new myotropic decapeptide from the skin secretion of the red eyed leaf frog Agalychnis callidryas
PLOS ONE, 2020Co-Authors: Mei Zhou, Tianbao Chen, Lei Wang, Yitian Gao, Wenqing Yang, C. ShawAbstract:Bradykinin-related peptides (BRPs) family is one of the most significant myotropic peptide families derived from frog skin secretions. Here, a novel BRP callitide was isolated and identified from the red-eyed leaf frog, Agalychnis callidryas, with atypical primary structure FRPAILVRPK-NH2. The mature peptide was cleaved N-terminally at a classic propeptide convertase cleavage site (-KR-) and at the C-terminus an unusual -GKGKGK sequence was removed using the first G residue as an amide donor for the C-terminally-located K residue. Thereafter, the synthetic replicates of callitide were assessed the myotropic activity and showed a significant contraction of balder, with the 0.63 nM EC50 value, more potent than most discovered myotropic peptides. The binding mode was further speculated by molecular docking and stimulation. The result indicated that the C-terminal of callitide might selectively bind to bradykinin receptor B2 (BKRB2). Further investigation of the callitide needs to be done in the future to be exploited as potential future drug leads.
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unravelling the skin secretion peptides of the gliding leaf frog Agalychnis spurrelli hylidae
Biomolecules, 2019Co-Authors: Carolina Proanobolanos, Mei Zhou, Tianbao Chen, Lei Wang, Ailin Blascozuniga, Jose Rafael Almeida, Miguel Angel Llumiquinga, Miryan Rivera, C. ShawAbstract:Frog skin secretions contain medically-valuable molecules, which are useful for the discovery of new biopharmaceuticals. The peptide profile of the skin secretion of Agalychnis spurrelli has not been investigated; therefore, the structural and biological characterization of its compounds signify an inestimable opportunity to acquire new biologically-active chemical scaffolds. In this work, skin secretion from this amphibian was analysed by molecular cloning and tandem mass spectrometry. Although the extent of this work was not exhaustive, eleven skin secretion peptides belonging to five peptide families were identified. Among these, we report the occurrence of two phyllokinins, and one medusin-SP which were previously reported in other related species. In addition, eight novel peptides were identified, including four dermaseptins, DRS-SP2 to DRS-SP5, one phylloseptin-SP1, and three orphan peptides. Phylloseptin-SP1 and dermaseptins-SP2 were identified in HPLC fractions based on their molecular masses determined by MALDI-TOF MS. Among the antimicrobial peptides, dermaseptin-SP2 was the most potent, inhibiting Escherichia coli, Staphylococcus aureus, and ORSA with a minimum inhibitory concentration (MIC) of 2.68 μM, and Candida albicans with an MIC of 10.71 μM, without haemolytic effects. The peptides described in this study represent but a superficial glance at the considerable structural diversity of bioactive peptides produced in the skin secretion of A. spurrelli.
Luis Miguel Gutiérrez-pesquera - One of the best experts on this subject based on the ideXlab platform.
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Critical Thermal Limits Do Not Vary between Wild-caught and Captive-bred Tadpoles of Agalychnis spurrelli (Anura: Hylidae)
Diversity, 2020Co-Authors: Pol Pintanel, Miguel Tejedo, Freddy Almeida-reinoso, Andrés Merino-viteri, Luis Miguel Gutiérrez-pesqueraAbstract:Captive-bred organisms are widely used in ecology, evolution and conservation research, especially in scenarios where natural populations are scarce or at risk of extinction. Yet, it is still unclear whether captivity may alter thermal tolerances, crucial traits to predict species resilience to global warming. Here, we study whether captive-bred tadpoles of the gliding treefrog (Agalychnis spurrelli) show different thermal tolerances than wild-caught individuals. Our results show that there are no differences between critical thermal limits (CTmax and CTmin) of captive-bred and wild-caught tadpoles exposed to three-day acclimatization at 20 °C. Therefore, we suggest that the use of captive-bred amphibians is valid and may be appropriate in experimental comparisons to thermal physiological studies of wild populations.
Geert P. J. Janssens - One of the best experts on this subject based on the ideXlab platform.
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Pearson´s correlations between blood values and colouration of the combined Agalychnis spp. data from Costa Rica.
2017Co-Authors: Andrea Brenes-soto, Ellen S. Dierenfeld, Geert P. J. JanssensAbstract:Pearson´s correlations between blood values and colouration of the combined Agalychnis spp. data from Costa Rica.
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Pearson´s correlations between morphometric measurements and colouration of the combined Agalychnis spp. data from Costa Rica.
2017Co-Authors: Andrea Brenes-soto, Ellen S. Dierenfeld, Geert P. J. JanssensAbstract:Pearson´s correlations between morphometric measurements and colouration of the combined Agalychnis spp. data from Costa Rica.
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Average values of body condition, blood values and colouration of three groups of free ranging Agalychnis spp.
2017Co-Authors: Andrea Brenes-soto, Ellen S. Dierenfeld, Geert P. J. JanssensAbstract:Average values of body condition, blood values and colouration of three groups of free ranging Agalychnis spp.
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Pearson´s correlations between morphometric measurements and blood values of the combined Agalychnis spp. data from Costa Rica.
2017Co-Authors: Andrea Brenes-soto, Ellen S. Dierenfeld, Geert P. J. JanssensAbstract:Pearson´s correlations between morphometric measurements and blood values of the combined Agalychnis spp. data from Costa Rica.
