Meeting Abstract

P1.136  Tuesday, Jan. 4  Variation in field hydration state among species of Australian hylid frogs TRACY, C.R.*; TIXIER, T.; LE NOENE, C.; MARTIN, S.; CHRISTIAN, K.A.; Charles Darwin University chris.tracy@cdu.edu.au

Frogs species face interesting and different challenges to maintaining hydration state, depending on ecological habit (e.g. arboreal, terrestrial, aquatic). We have previously shown that ecological habit correlates with thermoregulatory behaviors and water balance physiology among species of hylid frogs in Northern Australia. However, to date, there are very few data on the hydration levels that frogs maintain in the field and these studies generally do not relate hydration state with habit or seasonal difference in water availability. Therefore, we measured the hydric state of 15 species of frogs from around Darwin, Northern Territory, Australia to determine the influences of ecological habit and season on the hydric state these frogs maintain. As predicted, frogs in the dry season were significantly less hydrated than they were in the wet season, and showed significantly higher variation among individuals, suggesting that maintaining hydration is more challenging in the dry season. Furthermore, ecological habit had a significant effect on hydric state, with terrestrial species being significantly less hydrated in the wet season than arboreal or aquatic species; during the dry season, aquatic species (that sought refuge in cracking mud after the pond dried) were significantly less hydrated than terrestrial or arboreal species. These data suggest that hydration behaviors and voluntary tolerance of dehydration vary with habitat usage, even within closely related species in the same family or genus.