Allometric relationships between cutaneous surface area and body mass in anuran amphibians

Klein, Wilfried; Dabés, Lucianne; Bonfim, Vanessa Maria Gomes; Magrini, Leandro; Napoli, Marcelo Felgueiras

doi:10.1016/j.jcz.2016.04.007

Cited by 14 publications

(19 citation statements)

References 54 publications

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“…We simulated animals of three body sizes: small, medium and large, in a range that is representative for lizards (5, 100 and 200 g) and anurans (5, 50 and 100 g) (Meiri, 2010;Oliveira, São-Pedro, Santos-Barrera, Penone, & Costa, 2017). We modelled their geometric relationships, that is, length-to-mass and surface area-to-mass, using allometric functions representative for each group (Klein, Dabés, Bonfim, Magrini, & Napoli, 2016;Meiri, 2010).…”

Section: Modelling T B and Ewlmentioning

confidence: 99%

A mechanistic model to scale up biophysical processes into geographical size gradients in ectotherms

Rubalcaba

Gouveia

Olalla‐Tárraga

2019

Global Ecol Biogeogr

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Aim Understanding the mechanisms behind broad‐scale gradients in animal body size remains challenging. In contrast to endotherms, the extent to which biophysical properties of ectotherms scale up into interspecific size gradients at macroecological scales remains elusive. Our aim here is to investigate what latitudinal body size gradients are expected to emerge from first biophysical principles regarding heat and water balances in terrestrial vertebrate ectotherms. Location Nearctic and Western Palaearctic. Time period Theoretical model under current climatic conditions. Major taxa studied Terrestrial vertebrate ectotherms. Methods We developed a biophysical model to derive heat balances and rates of water loss of lizard‐like reptiles and anuran‐like amphibians from microclimatic variables. We projected geographically model predictions for different size classes to explore how body temperature (Tb) and cutaneous evaporative water loss (EWL) are influenced by body size at macroscales. Results Large‐bodied ectotherms (over 100 g) attain a slightly higher Tb and conserve it for longer than small animals (5 g), owing to the lower convective heat dissipation and their greater thermal inertia. While large animals are more at risk of overheating in warm regions, all organisms, irrespective of body size, are constrained by low temperatures experienced at boreal latitudes. Furthermore, because of the nonlinear decrease in EWL with increasing size, larger size allows reduction of water loss of small wet‐skinned ectotherms in more evaporative environments. Main conclusions Size differences in heat balance offer a mechanistic explanation for the pattern of increasing body size northwards, as well as for the associated decrease in species richness. Water conservation is also identified as a potential mechanism for larger body sizes in dryer areas in wet‐skinned ectotherms such as amphibians. Moreover, our model reveals nonlinear relationships involving size and optimum states of thermal and hydric functions, accounting for complexities that are unnoticeable by traditional, correlative investigations.

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Section: Modelling T B and Ewlmentioning

confidence: 99%

A mechanistic model to scale up biophysical processes into geographical size gradients in ectotherms

Rubalcaba

Gouveia

Olalla‐Tárraga

2019

Global Ecol Biogeogr

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“…To express EWL Skin as an area-specific rate (µg H 2 O cm −2 s −1 ), absolute EWL Skin (µgH 2 O s −1 ) was divided by 2/3 of the toad's estimated total skin surface area (A s ). A s was estimated from body mass as described by Klein et al (2016) specifically for the Bufonidae family: A s =7.956Mass 0.6772 . Equating A s to 2/3 accounts for the fact that only a portion of the skin surface area was exposed to air during the experiments (see Withers et al, 1982Withers et al, , 1984.…”

Section: List Of Abbreviationsmentioning

confidence: 99%

Temperature and dehydration effects on metabolism, water uptake, and the partitioning between respiratory and cutaneous evaporative water loss in a terrestrial toad

Senzano

Andrade

2018

Journal of Experimental Biology

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Terrestrial anurans often experience fluctuations in body temperature and hydration state, which are known to influence evaporative water loss through the skin (EWL Skin ) and lungs (EWL Resp ). These effects arise from associated changes in skin permeability, metabolism and lung ventilation. Herein, we determined the rates of EWL Skin and EWL Resp in the terrestrial toad Rhinella diptycha at different temperatures and hydration states. We measured oxygen uptake rates to verify whether alterations in the partitioning between EWL Skin and EWL Resp were associated with metabolism-induced changes in pulmonary gas exchange. We also measured the influence of hydration and temperature on water uptake (WU) through the skin. Finally, as estimates of skin resistance to evaporation (R s ) are usually inferred from total evaporative water loss (EWL Total ), under the assumption of negligible EWL Resp , we calculated the potential error in accepting this assumption for different temperature and hydration states. EWL Skin and EWL Resp increased with temperature, but this response was greater for EWL Resp , which was attributed to the temperature-induced elevation in metabolism and lung ventilation. Dehydration caused a decrease in the relative contribution of EWL Skin to EWL Total , mirrored by the concurrent increase in the contribution of EWL Resp , at all temperatures. Thus, R s increased with dehydration. WU rates were dictated by dehydration with little influence of temperature. The partitioning between EWL Skin and EWL Resp was affected by both temperature and hydration state and, under some conditions, considering EWL Resp as negligible led to significant errors in the assessment of skin resistance to evaporation.

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“…Thus, the LR50 for adults is more than 5 times the label rate of both fungicide formulations. The body mass and total surface area (calculated using the formula for bufonids proposed by Klein et al [45]) of the adults tested in the present study were both more than an order of magnitude higher than the juvenile amphibians tested (mean mass of adult vs juvenile A. cognatus ¼ 64.5 vs 1.1 g, respectively, and mean total surface area of adult vs juvenile A. cognatus ¼ 135.0 vs 8.5 cm 2 , respectively), and the corresponding surface area to mass ratios for adult and juvenile A. cognatus were 2.1 versus 7.7 cm 2 /g, respectively. Thus, even in a worst-case exposure, mortality of large-bodied adult amphibians is predicted to be low.…”

Section: Discussionmentioning

confidence: 99%

Factors influencing the toxicity of Headline® fungicides to terrestrial stage toads

Cusaac

Mimbs

Belden

et al. 2017

Enviro Toxic and Chemistry

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Amphibians are susceptible to exposure from contaminants via multiple pathways. Pyraclostrobin fungicides have been shown to be toxic to terrestrial amphibians at environmentally relevant concentrations; however, these studies did not account for factors that may influence exposure and effects, such as fungicide formulation, age of the individual, exposure route, and physiological state of the individual. We examined Headline® and Headline AMP® fungicide toxicity to adult Anaxyrus cognatus and Anaxyrus woodhousii by direct overspray, as well as acute toxicity of Headline AMP to juvenile A. cognatus through direct overspray, previously exposed soils, and diet. We also assessed effects of hydration state on fungicide toxicity in juvenile A. cognatus and sublethal effects of fungicide exposure on prey-orientation ability of juvenile A. cognatus. Neither formulation of Headline caused mortality of adult A. cognatus and A. woodhousii at up to 5 times the maximum label rate in North American corn (1052 and 879 mL formulation/ha for Headline AMP and Headline fungicides, respectively, corresponding to 1.52 and 2.2 μg pyraclostrobin/cm , respectively). Exposures of juvenile A. cognatus to Headline AMP via direct overspray and previously exposed soils (2 types) resulted in median lethal rate (LR50) values of 2.4, 3.34, and 3.61 μg pyraclostrobin/cm , respectively. Dietary Headline AMP exposure was not toxic, prey-orientations were not influenced by exposure, and effects were similar between dehydrated and hydrated treatments (LR50 = 2.4 and 2.3 μg pyraclostrobin/cm , respectively). These results, combined with exposure concentrations reported in previous studies, suggest that risk of acute mortality for amphibians in terrestrial environments is low and is dictated by body size and site-specific factors influencing exposure. Environ Toxicol Chem 2017;36:2679-2688. © 2017 SETAC.

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Allometric relationships between cutaneous surface area and body mass in anuran amphibians

Cited by 14 publications

References 54 publications

A mechanistic model to scale up biophysical processes into geographical size gradients in ectotherms

A mechanistic model to scale up biophysical processes into geographical size gradients in ectotherms

Temperature and dehydration effects on metabolism, water uptake, and the partitioning between respiratory and cutaneous evaporative water loss in a terrestrial toad

Factors influencing the toxicity of Headline® fungicides to terrestrial stage toads

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