Shifts in temperature influence how Batrachochytrium dendrobatidis infects amphibian larvae

• Published in: PloS one Vol. 14; no. 9; p. e0222237
• Main Authors: Bradley, Paul W, Brawner, Michael D, Raffel, Thomas R, Rohr, Jason R, Olson, Deanna H, Blaustein, Andrew R
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 19-09-2019; Public Library of Science (PLoS)
• Subjects: Amphibia; Amphibians; Analysis; Anaxyrus boreas; Animals; Batrachochytrium dendrobatidis; Biology; Biology and Life Sciences; Bufonidae - microbiology; Care and treatment; Chytridiomycosis; Chytridiomycota - pathogenicity; Climate change; Climate change models; Climate models; Climate variability; Containers; Disease susceptibility; Earth Sciences; Ecology; Environmental aspects; Frogs; Fungi; Global temperature changes; Host-bacteria relationships; Hypotheses; Immunity; Infections; Infectious diseases; Influence; Laboratories; Larva - microbiology; Larvae; Medicine and Health Sciences; Mortality; Mycoses - microbiology; Mycoses - veterinary; Parasites; Pathogenic microorganisms; Pathogens; Population; Rana aurora; Ranidae - microbiology; Reptiles & amphibians; Risk factors; Sensitivity; Species; Temperature; Temperature dependence; Temperature effects; Temperature fluctuations; Toads; Oregon; United States > US; Pacific Northwest
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0222237

Many climate change models predict increases in frequency and magnitude of temperature fluctuations that might impact how ectotherms are affected by disease. Shifts in temperature might especially affect amphibians, a group with populations that have been challenged by several pathogens. Because amphibian hosts invest more in immunity at warmer than cooler temperatures and parasites might acclimate to temperature shifts faster than hosts (creating lags in optimal host immunity), researchers have hypothesized that a temperature shift from cold-to-warm might result in increased amphibian sensitivity to pathogens, whereas a shift from warm-to-cold might result in decreased sensitivity. Support for components of this climate-variability based hypothesis have been provided by prior studies of the fungus Batrachochytrium dendrobatidis (Bd) that causes the disease chytridiomycosis in amphibians. We experimentally tested whether temperature shifts before exposure to Batrachochytrium dendrobatidis (Bd) alters susceptibility to the disease chytridiomycosis in the larval stage of two amphibian species-western toads (Anaxyrus boreas) and northern red legged frogs (Rana aurora). Both host species harbored elevated Bd infection intensities under constant cold (15° C) temperature in comparison to constant warm (20° C) temperature. Additionally, both species experienced an increase in Bd infection abundance after shifted from 15° C to 20° C, compared to a constant 20° C but they experienced a decrease in Bd after shifted from 20° C to 15° C, compared to a constant 15° C. These results are in contrast to prior studies of adult amphibians highlighting the potential for species and stage differences in the temperature-dependence of chytridiomycosis.