Investigating the Thermal Ecology of Temperate and Tropical Isolates of the Pathogenic Amphibian Fungus Batrachochytrium dendrobaditis (Bd)

The aquatic chyrtid fungus, Batrachochytrium dendrobatidis (Bd) causes the disease chytridiomycosis and has been implicated in mass die-offs and extirpations of amphibian populations across the globe.  This fungal pathogen colonizes the most superficial layers of epidermis and, in susceptible species, Bd disrupts skin functioning, leading to a lethal disruption of electrolyte balance and mortality.  The susceptibility of species to Bd-infection and disease is highly variable, which suggests that environmental conditions could play a role in the virulence and persistence of Bd. In lab trials, short-term growth has been shown to be maximal at 17-25^°C in single Bd isolates. However, few studies have investigated the thermal ecology of multiple isolates collected from distinct climatic regions. Using Bd isolates collected from both temperate and tropical locations, from multiple geographic locations, we determined population growth rates of Bd isolates at 4°C, 12°C, 18°C, and 23°C. Additionally, we cultured Bd isolates along a thermal gradient (5-28°C) to evaluate whether certain isolates display a thermal preference. By evaluating growth rates and thermal preferences of distinct isolates, we can better understand how Bd responds to a wide variety of temperature conditions in its environment.