Date of Award
Master of Science
Batrachochytrium dendrobatidis (Bd) has contributed to population declines and extinction of amphibians worldwide. Disease-caused extinction is rare, but may occur where reservoirs exist or where transmission is independent of host density. Because some species persist after Bd epizootic events, they may act as potential reservoirs of the infection. I studied seasonal and elevational patterns of prevalence and intensity of Bd infection in eight pond-breeding species that persisted after an epizootic event at three low- and three mid-elevation ponds in Central America. I visited each pond three times over the rainy season to sample for Bd and to quantify frog density. I recorded air and water temperature at each pond. I analyzed 1,288 samples and detected Bd in all six ponds and in six of the eight species. Elevation and time affected Bd prevalence (F2,7 = 8.90, p = 0.01) and Bd intensity (F2,8 = 9.09, p = 0.008). Frog density was not correlated with Bd prevalence (F1,7= 4.75, p= 0.06), and temperature did not affect prevalence or intensity of the infection. Bd is enzootic at all 6 sites and six pond-breeding species are reservoirs. The presence of abundant reservoirs at enzootic conditions explains the persistence of Bd in areas where other species declined without showing evidence of recovery. Low intensities of infection explain the survivorship of these reservoir species. I suggest that temperature might not be the principal factor molding Bd dynamics in the humid Neotropical forests, and present evidence that ponds are ecosystems where frogs might clean or reduce their infections
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