title: Plasticity, not genetic variation, drives infection success of a fungal parasite.
abstract: Hosts strongly influence parasite fitness. However, it is challenging to disentangle host effects on genetic vs plasticity-driven traits of parasites, since parasites can evolve quickly. It remains especially difficult to determine the causes and magnitude of parasite plasticity. In successive generations, parasites may respond plastically to better infect their current type of host, or hosts may produce generally 'good' or 'bad' quality parasites. Here, we characterized parasite plasticity by taking advantage of a system in which the parasite (the yeast Metschnikowia bicuspidata, which infects Daphnia) has no detectable heritable variation, preventing rapid evolution. In experimental infection assays, we found an effect of rearing host genotype on parasite infectivity, where host genotypes produced overall high or low quality parasite spores. Additionally, these plastically induced differences were gained or lost in just a single host generation. Together, these results demonstrate phenotypic plasticity in infectivity driven by the within-host rearing environment. Such plasticity is rarely investigated in parasites, but could shape epidemiologically important traits.
authors.affiliation: Department of Biological Sciences,Purdue University,West Lafayette,Indiana 47907,USA.
authors.forename: C L
authors.initials: CL
authors.lastname: Searle
authors.affiliation: School of Biology,Georgia Institute of Technology,Atlanta,Georgia 30332,USA.
authors.forename: J H
authors.initials: JH
authors.lastname: Ochs
authors.affiliation: School of Integrative Biology,University of Illinois at Urbana-Champaign,Urbana,Illinois 61801,USA.
authors.forename: C E
authors.initials: CE
authors.lastname: Cáceres
authors.affiliation: Department of Biology,Emory University,Atlanta,Georgia 30322,USA.
authors.forename: S L
authors.initials: SL
authors.lastname: Chiang
authors.affiliation: Department of Biology,Emory University,Atlanta,Georgia 30322,USA.
authors.forename: N M
authors.initials: NM
authors.lastname: Gerardo
authors.affiliation: Department of Biology,Indiana University,Bloomington,Indiana 47405,USA.
authors.forename: S R
authors.initials: SR
authors.lastname: Hall
authors.affiliation: Department of Ecology and Evolutionary Biology,University of Michigan,Ann Arbor,Michigan 48109,USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Duffy
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D003621:Daphnia / Q000382:microbiology*; D014644:Genetic Variation; D054884:Host-Pathogen Interactions; D055163:Metschnikowia / Q000235:genetics* / Q000502:physiology*; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction
keywords: within-host dynamics