AUTHOR=Belasen Anat M. , Russell Imani D. , Zamudio Kelly R. , Bletz Molly C. 

TITLE=Endemic Lineages of Batrachochytrium dendrobatidis Are Associated With Reduced Chytridiomycosis-Induced Mortality in Amphibians: Evidence From a Meta-Analysis of Experimental Infection Studies

JOURNAL=Frontiers in Veterinary Science

VOLUME=Volume 9 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/veterinary-science/articles/10.3389/fvets.2022.756686

DOI=10.3389/fvets.2022.756686

ISSN=2297-1769

ABSTRACT=Emerging infectious wildlife diseases have caused devastating declines, particularly when pathogens are introduced in naïve host populations. The outcome of disease emergence in any population will be dictated by a series of factors including pathogen virulence, host susceptibility, and prior coevolutionary opportunity between hosts and pathogens. Historical coevolution can lead to lowered pathogen virulence and/or increased host resistance that allows stable persistence of both host and pathogen. In some cases, adaptive coevolution can occur on relatively short time scales following introduction of a novel pathogen. Here, we performed a meta-analysis of experimental infection studies to examine whether the potential for long- or short-term coevolution determines the outcome of amphibian chytridiomycosis infections. We hypothesized that the opportunity for host-pathogen coevolution leads to reduced susceptibility to lethal chytridiomycosis in amphibian hosts infected with Batrachochytrium dendrobatidis (Bd). We performed a meta-analysis of multi-strain Bd infection experiments to test whether: (1) amphibians exhibit lower mortality rates when infected with strains belonging to endemic Bd lineages relative to the global panzootic lineage (Bd-GPL), hypothetically owing to long coevolutionary histories between endemic Bd lineages and their amphibian hosts; and (2) amphibians exhibit lower mortality rates when infected with local Bd-GPL strains compared with non-local Bd-GPL strains, hypothetically owing to recent selection for tolerance or resistance to local Bd-GPL strains. We found that in a majority of cases, amphibians in endemic Bd treatments experienced reduced mortality relative to those in Bd-GPL treatments. However, we detected no overall difference in amphibian mortality between local and non-local Bd-GPL treatments. Taken together, our results suggest that long-term historical coexistence is associated with less severe disease, potentially due to coevolutionary selection for hypovirulence in endemic Bd lineages.