Constant-temperature predictions underestimate growth of a fungal amphibian pathogen under individual host thermal profiles

Greenspan, Sasha E., Roznik, Elizabeth A., Edwards, Lexie, Duffy, Richard, Berger, Lee, Bower, Deborah S., Pike, David A., Schwarzkopf, Lin, and Alford, Ross A. (2023) Constant-temperature predictions underestimate growth of a fungal amphibian pathogen under individual host thermal profiles. Journal of Thermal Biology, 111 (January 2003). 103394.

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Ectotherm body temperatures fluctuate with environmental variability and host behavior, which may influence host-pathogen interactions. Fungal pathogens are a major threat to ectotherms and may be highly responsive to the fluctuating thermal profiles of individual hosts, especially cool-loving fungi exposed to high host temperatures. However, most studies estimate pathogen thermal performance based on averages of host or surrogate environmental temperatures, potentially missing effects of short-term host temperature shifts such as daily or hourly heat spikes. We recorded individual thermal profiles of Australian rainforest frogs using temperature-sensitive radio-transmitters. We then reproduced a subset of individual thermal profiles in growth chambers containing cultures of the near-global amphibian pathogen Batrachochytrium dendrobatidis (Bd) to investigate how realistic host temperature profiles affect Bd growth. We focused on thermal profiles that exceed the thermal optimum of Bd because the effects of realistic heat spikes on Bd growth are unresolved. Our laboratory incubation experiment revealed that Bd growth varied in response to relatively small differences in heat spike characteristics of individual frog thermal profiles, such as a single degree or a few hours, highlighting the importance of individual host behaviors in predicting population-level disease dynamics. The fungus also grew better than predicted under the most extreme and unpredictable frog temperature profile, recovering from two days of extreme (nearly 32 °C) heat spikes without negative effects on overall growth, suggesting we are underestimating the growth potential of the pathogen in nature. Combined with the previous finding that Bd reduces host heat tolerance, our study suggests that this pathogen may carry a competitive edge over hosts in the face of anthropogenic climate change.

Item ID: 77255
Item Type: Article (Research - C1)
ISSN: 1879-0992
Keywords: Amphibian, Australian Wet Tropics, Batrachochytrium dendrobatidis, Thermal performance, Body temperature, Chytridiomycosis, Incubator, Incubation experiment
Copyright Information: © 2022 Elsevier Ltd. All rights reserved.
Funders: Australian Research Council (ARC)
Projects and Grants: ARC Grant DP130101635
Date Deposited: 18 Jan 2023 07:59
FoR Codes: 31 BIOLOGICAL SCIENCES > 3107 Microbiology > 310705 Mycology @ 50%
31 BIOLOGICAL SCIENCES > 3103 Ecology > 310308 Terrestrial ecology @ 50%
SEO Codes: 18 ENVIRONMENTAL MANAGEMENT > 1806 Terrestrial systems and management > 180602 Control of pests, diseases and exotic species in terrestrial environments @ 100%
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