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Drivers and consequences of coevolution in protective symbiosis

Periodic Reporting for period 2 - COEVOPRO (Drivers and consequences of coevolution in protective symbiosis)

Reporting period: 2020-08-01 to 2022-01-31

All organisms in nature are targets for parasite attack. Symbiotic microbial species living within hosts can provide a strong barrier against infection, beyond the host’s own immune response. We now know that ‘protective microbes’ are key components of plant, animal, and human microbiota, determining host health in the face of parasite infection. The realisation that these microbes can evolve challenges our understanding of how hosts may resist infections diseases across evolutionary time. Thus far in the project, we have shown that the microbiota can facilitate infection and indeed worsen disease severity, advancing our thinking on microbiota-pathogen relationships. We have also discovered new ways in which microbes can evolve along the mutualist-parasite continuum to protect their host. We are currently using experimental evolution, followed by detailed genomic analysis, to understand the evolutionary and ecological dynamics of symbiotic interactions. We also evaluating the outputs with a view to pushing the conceptual boundaries for thinking about 'protective microbes' in environmental and clinical settings.
Given severe delays due to the pandemic, the main results achieved so far are minimal. Completed are the evolution experiments tackling the impacts of evolving protective microbes for host-paraiste coevolution, as well as the impacts of parasite heterogenetiy and the microbiota on mutualism coevolution. Genomic analysis and a full assessment of the phenotypic results are ongoing.
All of these achievements thus far have been unplanned/unexpected as they sprung from discussions/thinking that occurred during the lab lockdowns during the pandemic's first wave. Given the focus of the field on examining the protective impact of host microbiota against pathogen infection, our pursuit to understand the ability of microbiota and its components to facilitate or promote infection advances our thinking on microbiota-disease relationships, particularly in the context of health. We have written a review (Stevens et al 2021 PLoS Pathogens) which discusses the mechanisms underlying the facilitation as well as the evolutionary implications. Moreover, another review (Drew et al. 2021 Nature Review Microbiology) we have written has highlighted the diversity of ways in which microbes can evolve along the mutualist-parasite continuum, contributing to our understanding of the evolutionary and ecological dynamics in symbiotic relationships.