Functional Diversity as a New Framework for Understanding the Ecology of an Emerging Generalist Pathogen
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Emerging infectious disease outbreaks are increasingly suspected to be a consequence of human pressures exerted on natural ecosystems. Previously, host taxonomic communities have been used as indicators of infectious disease emergence, and the loss of their diversity has been implicated as a driver of increased presence. The mechanistic details in how such pathogen–host systems function, however, may not always be explained by taxonomic variation or loss. Here we used machine learning and methods based on Gower’s dissimilarity to quantify metrics of invertebrate functional diversity, in addition to functional groups and their taxonomic diversity at sites endemic and non-endemic for the model generalist pathogen Mycobacterium ulcerans, the causative agent of Buruli ulcer. Changes in these metrics allowed the rapid categorisation of the ecological niche of the mycobacterium’s hosts and the ability to relate specific host traits to its presence in aquatic ecosystems. We found that taxonomic diversity of hosts and overall functional diversity loss and evenness had no bearing on the mycobacterium’s presence, or whether the site was in an endemic area. These findings, however, provide strong evidence that generalist environmentally persistent bacteria such as M. ulcerans can be associated with specific functional traits rather than taxonomic groups of organisms, increasing our understanding of emerging disease ecology and origin.
Keywordsfunctional diversity biodiversity Buruli ulcer mycobacterium dilution effect
This work has benefited from a 3-year Bournemouth University PhD fellowship grant to Aaron Morris. AM, REG and JFG have benefited from an ‘Investissement d’Avenir’ grant managed by Agence Nationale de la Recherche (CEBA, Ref. ANR-10-LABX-2501). JFG is sponsored by the Institut de Recherche pour le Développement (IRD) and the Centre National de la Recherche Scientifique, and REG by IRD. The work and support of R.K. Kimbirauskas, M.D. McIntosh, T. White, and R. Kolar for invertebrate field collections and identification is gratefully acknowledged. MEB, RWM, PLCS and HW were funded by Grant Number R01TW007550 from the Fogarty International Center through the NIH/NSF Ecology of Infectious Diseases Program. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Fogarty International Center or the National Institutes of Health.
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