Eutrophication, biodiversity loss, and species invasions modify the relationship between host and parasite richness during host community assembly

Abstract

Through this research within host communities, the positive relationship between host and parasite species richness has become

Cascading effects of sand stabilization on pathogen communities: Connecting global and local processes

“…The global and local processes that are proposed by our results, as well as by other studies (e.g., Halliday, Heckman, et al., 2020; Titcomb et al., 2017; Young et al., 2014), indicate that in nature, cascading effects leading to changes in pathogen occurrence may be the rule rather than the exception. We have provided an example in which climatic and anthropogenic processes may together constitute a catalyst for a trophic cascade, resulting in variability among blood‐associated pathogen communities.…”

“…Many experiments have highlighted a suite of environmental conditions, host characteristics, and pathogen characteristics as candidate ecological mediators (e.g., Griffiths et al., 2015; Halliday, Heckman, et al., 2020; Hoverman et al., 2011; Liu et al., 2018). In these experiments, pathogen responses are quantified as a function of a single or several manipulated factors, such as abiotic conditions, resources, host community structure, host characteristics, and coinfecting pathogens.…”

The effect of host community functional traits on plant disease risk varies along an elevational gradient

“…Finally, to compare direct and indirect effects of environmental conditions on disease risk, we performed confirmatory path analysis using the PiecewiseSEM package ( Lefcheck, 2016 ). Specifically, we fit a structural equation model (SEM) that included the effect of elevation on soil-surface temperature, the effect of soil-surface temperature on square-root-transformed disease, the effect of soil-surface temperature on two endogenous mediators (host community species richness and pace-of-life), which together measure changes in host community structure (following Halliday et al, 2020a ; Halliday et al, 2019 ), and the effects of those two mediators on square-root-transformed community parasite load. We also tested the hypothesis that soil-surface temperature altered the relationship between host community structure and disease by fitting a second-stage moderated mediation ( Hayes, 2015 ) including the pairwise interaction between soil-surface temperature and community pace-of-life, omitting other potential interactions that were non-significant in the model testing whether effects of community structure on disease depend on environmental conditions.…”

“…Infectious disease is strongly influenced by host community structure and abiotic conditions ( Halliday et al, 2020a ; Halliday et al, 2019 ), both of which are undergoing unprecedented change as the climate is warming ( Pachauri et al, 2014 ) and biodiversity is being reshuffled ( Díaz et al, 2019 ; Hillebrand et al, 2018 ). Understanding how biotic and abiotic conditions interact to drive the emergence and spread of infectious disease is quickly emerging as one of the greatest research challenges of the 21st century and will be the key to limiting the impacts of infectious diseases on food production systems, wildlife, and humans.…”

Environmental drivers of disease depend on host community context

“…Finally, to compare direct effects of elevation on disease risk with indirect effects of elevation that are mediated by changing host community structure, we performed confirmatory path analysis using the PiecewiseSEM package (Lefcheck 2016). Specifically, we fit a structural equation model (SEM) that included a direct effect of elevation on square-root-transformed disease, the effect of elevation on three endogenous mediators (host community species richness, pace of life, and phylogenetic diversity, which together measure changes in host community structure (following Halliday et al 2019, 2020a), and the effects of those three mediators on square-root-transformed community parasite load. We also tested the hypothesis that elevation altered the relationship between host community structure and disease by fitting a second-stage moderated mediation (Hayes 2015) including the pairwise interaction between elevation and community pace of life, omitting other potential interactions that were non-significant in the model testing whether effects of community structure on disease depend on elevation.…”