Meeting Abstract

P3.16  Wednesday, Jan. 6  Determining patterns of behavioral hydroregulation in three families of amphibians PILIKIAN, T.*; TRACY, C.R.; BAHLMAN, A.; Univ. of Nevada, Reno; Univ. of Nevada, Reno; Univ. of Nevada, Reno pilikian@biodiversity.unr.edu

Amphibians lose water at high rates to the environment by cutaneous evaporative water loss, and are thus limited to habitats with water or high moisture. Not all evaporative water loss rates are created equal; the rate at which dehydration occurs depends on multiple factors such as body size, ambient temperature, physical activity levels, and cutaneous resistance to water loss. Little is known about the degree at which amphibians hydroregulate, or maintain sufficient hydration for optimum performance. We conducted a lab experiment to examine differences in hydroregulation between three families (Ranidae, Hylidae, and Bufonidae) of varying degrees of terrestriality. Individuals at Standard Mass (100% hydration with an empty bladder) were placed in arenas with access to water for voluntary rehydration. Using video surveillance, activity levels and the duration of time until voluntary rehydration were recorded. Data will be plotted against dehydration rates specific to each individual, and preferred ‘set point’ hydration ranges will be determined for each family. We expect the data to show that Ranidae, an obligate aquatic family, will more closely control hydration than the semi-aquatic family Hylidae. We also predict that Bufonidae, a terrestrial family, will maintain the lowest degree of hydroregulation of the three families. If our hypotheses are supported, we will lend more insight to the importance of phylogenetics in amphibian hydroregulation. If our hypotheses are not supported, this study will provide evidence that hydroregulation in amphibians is controlled by factors unrelated to family characteristics.