The community ecology of plant parasites: from coinfections to metacommunities Public Deposited

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  • March 20, 2019
Creator
  • Halliday, Fletcher
    • Affiliation: College of Arts and Sciences, Department of Biology
Abstract
  • New emerging diseases and methodological advances have generated a recent surge in disease ecology research and renewed interest in identifying the ecological processes that structure parasite communities. Yet ecologists still lack a general framework for understanding the drivers of parasite diversity. Metacommunity theory is a general ecological framework that has been used to understand patterns of community composition in many ecological systems. This dissertation leverages one key insight from metacommunity theory – that multiple processes operate across different spatial and temporal scales to control the composition of local communities – to understand parasite communities within hosts. In this work, I used experimental studies to examine the community ecology of parasites that infect wild host plants over space and time. At the smallest spatial scale, I explored how interactions among parasites in the same host leaf during coinfection alter parasite epidemics. Within host leaves, parasite growth was influenced by coinfections, but coinfections were often prevented by the sequence of parasite infection, generating priority effects within hosts. Coinfections, priority effects, and the severity of infections were altered by host immunity. Scaling up, I found that parasite phenology, which operates across host individuals, altered host susceptibility to secondary infections, parasite interactions, and ultimately the magnitude of parasite epidemics. At the largest spatial scale, I explored how characteristics of host communities influence the diversity of parasite metacommunities. Parasite diversity across host communities depended on host diversity and resource supply to hosts. Host richness alone could not explain most changes in parasite diversity. However, shifting host composition allowed disease amplification, depending on parasite transmission mode. These effects also varied over time: the structure of host communities changed in response to initial host diversity and resource supply to hosts, leading to altered parasite richness and abundance. Together, these results highlight the utility of multiscale approaches to disease ecology. Specifically, integrating concepts from community ecology with information about infectious diseases and host-parasite interactions provides insight into the general mechanisms that control the diversity of parasites across space and time.
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  • In Copyright
Advisor
  • Mitchell, Charles
  • Hurlbert, Allen
  • Umbanhowar, James
  • Vilgalys, Rytas
  • White, Peter
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2017
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