Meeting Abstract
Batrachochytrium dendrobatidis (Bd), the amphibian chytrid fungus, is considered one of the deadliest pathogens on the planet and is associated with hundreds of amphibian declines and extinctions. Bd growth and amphibian immunity are both temperature-dependent and thus temperature likely influences Bd outbreaks. In the past, most Bd models have assumed that amphibians are susceptible at temperatures where Bd grows best in culture (~20 °C), but here, we show that susceptibility varies based on the temperature to which host species are adapted. Two species from warm climates were susceptible to Bd at cold temperatures (10-18 °C), while a cold-tolerant montane species was most susceptible under warm conditions (26-28 °C). In addition, we tested for the relationship between temperature and Bd prevalence in the field by accumulating prevalence records for 4,775 amphibian populations from 250 published articles and extracting climate data specific to the location and date that each population was sampled. On average, peak pathogen growth occurred at a temperature only slightly cooler than in culture (~18 °C). However, amphibian populations from cool climates (averaging <15 °C) experienced peak prevalence at relatively warm temperatures (~23 °C) while those from warm climates (>20 °C) peaked at cooler temperatures (~16 °C), suggesting that Bd outbreaks may depend on characteristics of hosts and Bd growth in culture might not accurately reflect growth in the field. Researches must parameterize spatial models of Bd distribution to account for how Bd grows on hosts (as opposed to in culture), and should consider species-level traits when modeling susceptibility of a specific species.
