The purpose of this study was to determine if the thermal tolerance and physiology of the coqui frog changed along HawaiÔiÕs elevation gradient. A short acclimation experiment was used to test the baseline thermal tolerance and physiology, and an extended acclimation experiment to test the acclimation ability of the thermal tolerance and physiology metrics of the coqui frogs collected from low (m), medium (350-550 m) and high elevations (>750 m).

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USDA, Animal and Plant Health Inspection Service (APHIS)

Utah State University Department of Biology

Utah State University Ecology Center


Utah State University


For the short acclimation experiment, 30 frogs were collected from 12 field sites (four at low, four at medium, and four at high elevation) and kept them in uniform conditions for three days. Critical thermal minimum (CTmin), blood glucose, oxidative stress (dROMs) and corticosterone of coqui were measured following the three-day acclimation. For the extended acclimation experiment, 30 frogs from the same 12 field sites were collected and randomly assigned them to a cold (16 degree C) or warm (23 degree C) temperature treatment. Frogs were kept in these temperature treatments for three weeks before CTmin, glucose, dROMs, and corticosterone were measured in the same way as the short acclimation study. 306 individuals (30 females, 276 males) were collected for the short acclimation experiment, and 317 individuals (43 females, 274 males) were collected for the extended acclimation experiment. CTmin was measured by using a temperature regulated chamber device (TReCS) device in which five aluminum cradles sit on top of an aluminum heatsink. Each cradle holds a plastic tube. The cradle temperature is controlled by two peltier devices beneath each cradle. CTmin testing began at 2000h after the three day and three-week acclimation periods for the short and extended acclimation frogs, respectfully. Each trial consisted of testing the CTmin of five frogs in the TReCS. At the beginning of each trial, we placed frogs in the plastic tubes and the TReCS began cooling the cradles starting at 20-23¡C. Once a cradle temperature reached 15 ¡C, we periodically spun each tube on the cradles to flip the frog on its back and elicit a righting response. If the frog did not right itself after 30 seconds, we recorded the TReCS cradle temperature (righting loss temperature; hereafter RL-temp). RL-temp served as a close approximation of CTmin, but not an exact measurement. We also recorded the elapsed time from the start of the trial to the time of righting loss (righting-loss time; hereafter RL-time). This was also important for approximating the coqui frogÕs CTmin. We measured glucose using an Accu-Chek Active blood glucose meter. dROMs were measured using an assay kit (MC435, Diacron International, Italy), ?which detects levels of hydroperoxides that oxidize an alkyl-substituted aromatic amine (A-NH2) to assess chronic oxidative stress. Corticosterone was measured using an ?enzyme-linked immunosorbent assay (ELISA) kit (Enzo Life Sciences, ?Farmingdale, NY) following a validation protocol described by Hudson et al. (2020) for blood plasma (8 µl).



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Coqui_ThermalTolerance_data.csv (116 kB)
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README_CoquiThermalTolerance.txt (5 kB)
MD5: 35ea411bf03d7ac56a2ee960e8e7f277

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