Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Water Availability and Temperature as Modifiers of Evaporative Water Loss in Tropical Frogs.
Juarez BH
,
Quintanilla-Salinas I
,
Lacey MP
,
O'Connell LA
.
???displayArticle.abstract???
Water plays a notable role in the ecology of most terrestrial organisms due to the risks associated with water loss. Specifically, water loss in terrestrial animals happens through evaporation across respiratory tissues or the epidermis. Amphibians are ideal systems for studying how abiotic factors impact water loss since their bodies often respond quickly to environmental changes. While the effect of temperature on water loss is well known across many taxa, we are still learning how temperature in combination with humidity or water availability affects water loss. Here, we tested how standing water sources (availability) and temperature (26 and 36°C) together affect water loss in anuran amphibians using a Bayesian framework. We also present a conceptual model for considering how water availability and temperature may interact, resulting in body mass changes. After accounting for phylogenetic and time autocorrelation, we determined how different variables (water loss and uptake rates, temperature, and body size) affect body mass in three species of tropical frogs (Rhinella marina, Phyllobates terribilis, and Xenopus tropicalis). We found that all variables impacted body mass changes, with greater similarities between P. terribilis and X. tropicalis, but temperature only showed a notable effect in P. terribilis. Furthermore, we describe how the behavior of P. terribilis might affect its water budget. This study shows how organisms might manage water budgets across different environments and is important for developing models of evaporative water loss and species distributions.
Fig. 1A conceptual model of how body mass may change due to interactions between water availability and temperature. These examples are not exhaustive. We assume mass gain is only possible in water and relatively higher temperatures always result in greater mass loss. Outcomes (O) 1–5 show treatment effects (solid blue lines) for water at 26°C. For simplicity, we only show two 36°C (dashed red) lines near the lower slope = 0 limit for each potential outcome, corresponding to the lack of an interaction with temperature for O1 and O4. 36°C treatments may also yield results as shown in O1–5, representing an interaction (if statistically distinct from the 26°C effect). O1 and O4 show no temperature interaction and only a small effect of water availability, resulting in mass gain or mass loss. O2 shows no marginal effect of water. O3 and O5 show stronger possible temperature interactions (relative to 36°C). Relative to O5, O3 shows more body mass is lost without water, and only a small body mass increase when in water.
Fig. 2Raw body mass data were collected over 1 h for each water availability and temperature treatment. Each panel is a different species. Red hues correspond to 36°C, and blue hues correspond to 26°C. Circles show water presence and triangles show water absence treatments. We assumed even sampling at 20 min intervals for plotting purposes, but we analyzed the real times at which measurements were taken (see the “Methods” section).
Fig. 3Prior and posterior distributions of model effects. Posterior distributions (left) are shown in blue, and prior distributions (right) are shown in yellow. Snout-vent length is a measure of body size in amphibians. All prior distributions shown here were normally distributed. Please see text for how we chose to specify the mean and variance for each prior.
Fig. 4Posterior distributions of the marginal effect of temperature by species and water treatment. These effects correspond to body mass. The height of each distribution corresponds to the probability density. The vertical line denotes an effect of 0.
