Document Type



Doctor of Philosophy (PhD)



First Advisor's Name

Maureen A. Donnelly

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Steven F. Oberbauer

Second Advisor's Committee Title

Committee member

Third Advisor's Name

René M. Price

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Joseph R. Mendelson, III

Fourth Advisor's Committee Title

Committee member

Fifth Advisor's Name

Craig Guyer

Fifth Advisor's Committee Title

Committee member


tropical mountains, alpine ecology, climate change, Peru, anurans, frogs

Date of Defense



Understanding biological responses to climate change is a primary concern in conservation biology. Of the ecosystems being rapidly impacted by climate change, those in the high-elevation tropics are among the most poorly studied. The tropical Andean biosphere includes record elevations above 5000 meters, where extreme environmental conditions challenge many organisms. In the Cordillera Vilcanota of southern Peru, frogs including Pleurodema marmoratum and Telmatobius marmoratus have expanded their ranges to 5244 – 5400 m into habitats created by glacial recession, making them among the highest recorded amphibians on Earth. To understand how hydrologic alterations from loss of glacial meltwater and climatic fluctuations affect these amphibians, I conduct a 36-month field study of reproductive phenology and develop a method to distinguish glacial meltwater-fed ponds and precipitation-fed ponds utilizing natural variation in stable isotopes of water (18O, 2H, and d-excess). My results suggest that some ponds critical for breeding populations may have lost their connection to glacial runoff. Ongoing deglaciation may transform these ponds from permanent to ephemeral habitats, leading to the extirpation of the fully aquatic species, T. marmoratus. The 2015/2016 El Niño delayed the onset of the 2015 wet season and shortened the P. marmoratum breeding and tadpole development period in ephemeral ponds. I examine regional patterns of amphibian occupancy and prevalence of the deadly amphibian pathogen Batrachochytrium dendrobaditis in unexplored high-elevation zones that were until recent decades covered by permanent ice. Next, I examine adaptive strategies that allow these two frog species to persist in the harsh high-elevation environment. Pleurodema marmoratum withstands the daily freeze-thaw cycle by utilizing a wide thermal tolerance range (from below 0ºC to CTmax > 32ºC) and I report the first evidence of frost tolerance in a tropical frog. My research compares divergent strategies allowing two anuran species to persist through disease and variable, extreme conditions in high-mountain environments, providing a better understanding of responses to and consequences of climate change for some of the world's highest life forms.




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