From specialist to generalist: biotic and abiotic reservoirs of fungal pathogens

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Ecology and Evolution

Emerging fungal infectious diseases threaten human health, jeopardize agriculture and economic security, and pose a major threat to wildlife biodiversity. While most research in disease ecology is aimed atbacterial and viral pathogens, where within- and among-host interactions are central to understandingdisease dynamics, it is becoming evident that fungal pathogens require a shifting of thisa aradigm to include a more ecosystem-centric view. Many fungal pathogens have broad host ranges, long-lived environmental stages, and the potential for saprotrophic growth. New models are needed for this type of pathogen, in order to improve our ability to understand the dynamics and impacts of this unique, diverse,and abundant group of pathogens. The overall aim of this project is to expand our understanding of the dynamics of emerging fungal pathogens both amongst and outside of their hosts. Laboratory and field experiments and field surveys will be conducted to develop and fit disease models, utilizing the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), as the primary model system. Recent evidence that Bd can infect a wide diversity of organisms (in addition to amphibians), and that Bd has the ability to form biofilms (which may enhance its potential for environmental persistence), makes this an ideal model system for this project. The fungal disease models will be applied to the data collected through a meta-analysis to generalize the results to other emerging fungal pathogens (e.g. Batrachochytrium salomandrovirons, white-nose syndrome, and snake fungal disease).

Intellectual Merit:

Fungal disease models will be developed and parameterized, including generalist pathogens, external pathogen reservoirs (including the possibility of incorporation of the pathogen into biofilms), and the potential for saprotrophic pathogen growth. The models will be used to explore the implications of these features of fungal pathogens on pathogen prevalence and disease severity in target host species, in the both the amphibian/Bd system and in other emerging fungal pathogen systems. Specifically, the research team will (1) perform an in-depth analysis of alternative hosts and environmental reservoirs where Bd may persist outside of the host, (2) test experimentally the role of these alternative hosts and environmental reservoirs on survival and reproduction of Bd, persistence of Bd in the environment, and in transmission of the pathogen to amphibians, (3) test how Bd biofilm formation affects Bd persistence and reproduction, (4) explore how Bd biofilms persist in extreme environments (i.e., temperatures) and if this affects the infectiousness of Bd using novel approaches (metagenomics, metatranscriptomics, metaproteomics), (5) improve the fungal-based disease model to include an ecosystem-centric approach using Bd as a case study, and (6) create an emerging fungal database, conduct a metanalysis, and fit our disease models to other emerging fungal diseases.

Broader Impacts:

This collaborative project bridges together a diverse group of multidisciplinary scientists, many of whom are from underrepresented groups in science, at different stages in their career and diverse educational institutions. The interdisciplinary nature of this research creates partnerships spanning ecology, microbiology, mathematics, and engineering. The project will train a diverse group of future leaders that will have the skills necessary to integrate knowledge across disciplines. Fungal and fungus-like pathogens reduce crop yields in many agricultural systems, so this project will benefit human society and agriculture through improving knowledge of this type of pathogen. This project will also (i) improve ecosystem health and help protect biodiversity increasing our understanding of fungal pathogens by identifying the causal agents for chytrid persistence; (ii) develop a non-vertebrate species as a new model organism to test various hypothesis about fungal pathogens of amphibian, (iii) to create a working group of global experts on emerging fungal pathogens and perform a meta-analysis examining the mechanism for host extirpation or host-pathogen coexistence, (iv) to broaden the participation of underrepresented groups in STEM, and (v) to reach a larger community of the public through social media.