title: Joint effects of habitat, zooplankton, host stage structure and diversity on amphibian chytrid.
abstract: Why does the severity of parasite infection differ dramatically across habitats? This question remains challenging to answer because multiple correlated pathways drive disease. Here, we examined habitat-disease links through direct effects on parasites and indirect effects on parasite predators (zooplankton), host diversity and key life stages of hosts. We used a case study of amphibian hosts and the chytrid fungus, Batrachochytrium dendrobatidis, in a set of permanent and ephemeral alpine ponds. A field experiment showed that ultraviolet radiation (UVR) killed the free-living infectious stage of the parasite. Yet, permanent ponds with more UVR exposure had higher infection prevalence. Two habitat-related indirect effects worked together to counteract parasite losses from UVR: (i) UVR reduced the density of parasite predators and (ii) permanent sites fostered multi-season host larvae that fuelled parasite production. Host diversity was unlinked to hydroperiod or UVR but counteracted parasite gains; sites with higher diversity of host species had lower prevalence of infection. Thus, while habitat structure explained considerable variation in infection prevalence through two indirect pathways, it could not account for everything. This study demonstrates the importance of creating mechanistic, food web-based links between multiple habitat dimensions and disease.
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405, USA jlhite@indiana.edu.
authors.forename: Jessica L
authors.identifier: 0000-0003-4955-0794
authors.initials: JL
authors.lastname: Hite
authors.affiliation: Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de Guadarrama, Cta. M-604, Km. 27.6, 28740 Rascafría, Spain.
authors.forename: Jaime
authors.initials: J
authors.lastname: Bosch
authors.affiliation: Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain.
authors.forename: Saioa
authors.initials: S
authors.lastname: Fernández-Beaskoetxea
authors.affiliation: Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Medina
authors.affiliation: Department of Biology, Indiana University, Bloomington, IN 47405, USA.
authors.forename: Spencer R
authors.initials: SR
authors.lastname: Hall
mesh_terms: D000663:Amphibians / Q000382:microbiology*; D000818:Animals; D008411:Chytridiomycota / Q000502:physiology*; D017753:Ecosystem; D014466:Ultraviolet Rays; D015048:Zooplankton
keywords: UV; chytrid; diversity; habitat; stage structure; zooplankton