Predictions of Disease Risk in Space and Time Based on the Thermal Physiology of an Amphibian Host-Pathogen Interaction

Julia M Sonn,Corinne L Richards-Zawacki,Paul D Mathewson,Warren P Porter

doi:10.3389/fevo.2020.576065

Julia M Sonn, Corinne L Richards-Zawacki + Show 2 more

Open Access

https://doi.org/10.3389/fevo.2020.576065

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Abstract

Emerging infectious diseases have been responsible for declines and extinctions in a growing number of species. Predicting disease variables like infection prevalence and mortality and how they vary in space and time will be critical to understanding how host-pathogen dynamics play out in natural environments and will help to inform management actions. The pandemic disease chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis (Bd), has been implicated in declines in hundreds of amphibian species worldwide. We used field-collected measurements of host body temperatures and other physiological parameters to develop a mechanistic model of disease risk in a declining amphibian, the Northern cricket frog (Acris crepitans). We first used a biophysical model to predict host body temperatures across the species range in the eastern United States. We then used empirically derived relationships between host body temperature, infection prevalence and survival to predict where and when the risk of Bd-related declines is greatest. Our model predicts that pathogen prevalence is greatest, and survival of infected A. crepitans frogs is lowest, just prior to breeding when host body temperatures are low. Taken together, these results suggest that Bd poses the greatest threat to short-lived A. crepitans populations in the northern part of this host’s range and that disease-related recruitment failure may be common. Furthermore, our study demonstrates the utility of mechanistic modeling approaches for predicting disease outbreaks and dynamics in animal hosts.

Highlights

Emerging infectious diseases threaten animals, plants and humans alike
We describe a mechanistic approach to predicting wildlife disease dynamics and illustrate its potential using the example of Northern cricket frogs (Acris crepitans), a declining North American host species susceptible to chytridiomycosis
Our findings demonstrate how a biophysical modeling approach that explicitly takes into account the environmental physiology of animal hosts can provide a more mechanistic understanding of where and when disease outbreaks may emerge and threaten biodiversity, facilitating conservation action

Summary

Introduction

Emerging infectious diseases threaten animals, plants and humans alike. Fungal pathogens in particular have been responsible for an increasing number of declines and extinctions of wildlife (Fisher et al, 2012). Thermal Physiology and Disease Risk chytridiomycosis, caused by another fungal pathogen, Batrachochytrium dendrobatidis (Bd), has been implicated in global declines in hundreds of amphibian species (Wake and Vredenburg, 2008; Murray et al, 2013; Scheele et al, 2019). Interactions between climate change and fungal disease have been implicated in the declines of both corals (Ruiz-Moreno et al, 2012) and amphibians (Lips et al, 2008; Cohen et al, 2018). We describe a mechanistic approach to predicting wildlife disease dynamics and illustrate its potential using the example of Northern cricket frogs (Acris crepitans), a declining North American host species susceptible to chytridiomycosis

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