Mautz, William J.Haggerty, Jacqueline2017-02-022017-02-022016-12http://hdl.handle.net/10790/2945Natural variation in the environment can be tolerated by animals via behavioral modification, adaptation, or physiological or developmental plasticity. Phenotypic plasticity, or acclimation, allows individuals to adjust physiological parameters to best suit the needs of their environment. Acclimation to temperature is a feature of successful invasive species and may be a contributing factor to the expansion of the coqui frog (Eleutherodactylus coqui) in its introduced range in Hawaii. Coqui frogs have been recorded on Hawaii Island since the late 1980s and pose a noise nuisance to humans. If the frogs expand into higher elevation, montane habitats, they may disrupt the ecosystems with noise and food web disturbances. The minimum tolerance of cold temperatures of coqui frogs along an elevational gradient in East Hawaii was measured and compared. Coqui frogs were found to have a flexible range of cold temperature tolerance, with differences in cold tolerance between populations, evidence of acclimation to lower temperatures, sex-specific thermal tolerance, and a lower thermal tolerance level in Hawaii than in their native Puerto Rico. However, a higher tolerance for cold did not correlate directly with elevation and there were no appreciable differences in hematocrit, plasma osmolality, or heart mass between acclimation treatments or populations. The overall range of shift in thermal tolerance after acclimation was 2-3°C, implying the thermal flexibility of coqui frogs may enable them to further expand their habitat in Hawaii to cooler, high elevation areas. Particularly sensitive areas should be monitored and managed to minimize ecosystem threats from coqui frogs.34 pagesenConservation biologyPhysiologyEcologyAcclimationAmphibianInvasive speciesThermal biology