Investigating the potential of American Bullfrogs (Lithobates catesbeianus) to serve as disease reservoirs in Vermont and Brazilian amphibian communities
Conference Year
January 2019
Abstract
Ranaviruses are a group of emerging pathogens negatively impacting amphibian communities around the globe. This disease has the capability of causing sudden and mass amphibian mortality events; yet, the factors that influence it are not entirely understood, especially in areas where diversity and endemism are at their highest. The Atlantic rainforest of Brazil is one such area; however, neither amphibian diversity nor amphibian pathogen distribution and impacts are well-characterized. We have previously documented ranaviruses in relatively low prevalences across Vermont; however, the American Bullfrog (Lithobates catesbeianus) communities have consistently had high ranavirus prevalence, with individuals retaining high amounts of virus. Although native to the northeast United States, L. catesbeianus is invasive in Brazil and has already negatively impacted native amphibian communities. American Bullfrogs have been suggested as a reservoir for other amphibian diseases, such as the chytrid fungus, due to the species’ ability to withstand the onset of disease once infected. Additionally, ranaviruses have been detected in American Bullfrogs farmed in captive facilities in Brazil. Yet, it is unknown if wild Bullfrogs are infected and whether they are serving as disease reservoirs. The goal of this study was to determine whether ranavirus had spilled over from Bullfrog facilities into the natural Bullfrog populations in Brazil, and whether these individuals can retain large amounts of virus, similar to what we observed in its native range in Vermont. We collected a total of 58 L. catesbeianus liver samples in multiple sites near the Atlantic Rainforest. These samples were tested for ranavirus using quantitative PCR to amplify a conserved region in its major capsid protein. We expect that ranavirus has indeed infiltrated the natural communities and believe L. catesbeianus has the capability of being infected with the virus without showing any clinical signs, thus amplifying disease transmission in native anurans. If so, the American Bullfrog invasion poses an even greater threat to the biodiversity of the Atlantic Rainforest than previously supposed. These results will further our understanding of amphibian conservation efforts and allow us to identify areas of conservation priority.
Primary Faculty Mentor Name
Nicholas J. Gotelli
Faculty/Staff Collaborators
Dr. Karla M. Campião (Collaborator at Universidade Federal do Panara)
Status
Graduate
Student College
College of Arts and Sciences
Program/Major
Biology
Primary Research Category
Biological Sciences
Investigating the potential of American Bullfrogs (Lithobates catesbeianus) to serve as disease reservoirs in Vermont and Brazilian amphibian communities
Ranaviruses are a group of emerging pathogens negatively impacting amphibian communities around the globe. This disease has the capability of causing sudden and mass amphibian mortality events; yet, the factors that influence it are not entirely understood, especially in areas where diversity and endemism are at their highest. The Atlantic rainforest of Brazil is one such area; however, neither amphibian diversity nor amphibian pathogen distribution and impacts are well-characterized. We have previously documented ranaviruses in relatively low prevalences across Vermont; however, the American Bullfrog (Lithobates catesbeianus) communities have consistently had high ranavirus prevalence, with individuals retaining high amounts of virus. Although native to the northeast United States, L. catesbeianus is invasive in Brazil and has already negatively impacted native amphibian communities. American Bullfrogs have been suggested as a reservoir for other amphibian diseases, such as the chytrid fungus, due to the species’ ability to withstand the onset of disease once infected. Additionally, ranaviruses have been detected in American Bullfrogs farmed in captive facilities in Brazil. Yet, it is unknown if wild Bullfrogs are infected and whether they are serving as disease reservoirs. The goal of this study was to determine whether ranavirus had spilled over from Bullfrog facilities into the natural Bullfrog populations in Brazil, and whether these individuals can retain large amounts of virus, similar to what we observed in its native range in Vermont. We collected a total of 58 L. catesbeianus liver samples in multiple sites near the Atlantic Rainforest. These samples were tested for ranavirus using quantitative PCR to amplify a conserved region in its major capsid protein. We expect that ranavirus has indeed infiltrated the natural communities and believe L. catesbeianus has the capability of being infected with the virus without showing any clinical signs, thus amplifying disease transmission in native anurans. If so, the American Bullfrog invasion poses an even greater threat to the biodiversity of the Atlantic Rainforest than previously supposed. These results will further our understanding of amphibian conservation efforts and allow us to identify areas of conservation priority.