Isolation and Genetic Characterization of Amphibian Chytrid Strains in Central Texas
Date
2017-08
Authors
Marshall, Thomas L.
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Abstract
Chytridiomycosis, an emerging infectious disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is a major contributor to declines in amphibian populations worldwide. Bd was first described in the 1990s, and there is still much to learn about its regional diversity and origin. The Global Panzootic Lineage (Bd-GPL) has been responsible for devastating amphibian population declines and extinctions in Central and South America, Australia, and the western U.S. On the other hand, a few localized endemic lineages have been discovered in regions such as Brazil and Asia, which are areas that have not experienced such severe disease outbreaks. There are still several geographic sampling gaps in the analysis of the global distribution of Bd, and relatively few studies have focused on regions in which Bd exhibits low virulence, thus creating a bias in our current knowledge of the pathogen’s diversity. One such region that has not seen disease-associated declines is the state of Texas. This pathogen has been detected from amphibians in the state, although strains had not been characterized genetically prior to this study. Here, we isolated, cultured, and genotyped strains of Bd in Central Texas and compared them to a panel of previously genotyped strains distributed across the globe. Our results support the hypothesis that Bd is an introduced pathogen in the region. We found a diversity of Bd genotypes yet did not detect geographically based genetic structure in Texas and across North America. Strains in Central Texas are genetically similar to those in the western U.S. that have caused amphibian population declines, which raises questions about the roles that climate and host resistance play in shaping Bd-amphibian disease dynamics in North America.
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Keywords
Chytrid, Amphibians, Emerging infectious diseases, Batrachochytrium dendrobatidis, Fungal diseases, Genetics
Citation
Marshall, T. L. (2017). <i>Isolation and genetic characterization of amphibian chytrid strains in Central Texas</i> (Unpublished thesis). Texas State University, San Marcos, Texas.