title: Refugia and connectivity sustain amphibian metapopulations afflicted by disease.
abstract: Metapopulation persistence in fragmented landscapes depends on habitat patches that can support resilient local populations and sufficient connectivity between patches. Yet epidemiological theory for metapopulations has largely overlooked the capacity of particular patches to act as refuges from disease, and has suggested that connectivity can undermine persistence. Here, we show that relatively warm and saline wetlands are environmental refuges from chytridiomycosis for an endangered Australian frog, and act jointly with connectivity to sustain frog metapopulations. We coupled models of microclimate and infection probability to map chytrid prevalence, and demonstrate a strong negative relationship between chytrid prevalence and the persistence of frog populations. Simulations confirm that frog metapopulations are likely to go extinct when they lack environmental refuges from disease and lose connectivity between patches. This study demonstrates that environmental heterogeneity can mediate host-pathogen interactions in fragmented landscapes, and provides evidence that connectivity principally supports host metapopulations afflicted by facultative pathogens.
authors.affiliation: School of BioSciences, University of Melbourne, Parkville, Vic., 3010, Australia.|Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
authors.forename: Geoffrey W
authors.initials: GW
authors.lastname: Heard
authors.affiliation: Department of Biology, University of York, Wentworth Way, York, YO10 5DD, UK.
authors.forename: Chris D
authors.initials: CD
authors.lastname: Thomas
authors.affiliation: Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, L69 7ZB, UK.
authors.forename: Jenny A
authors.initials: JA
authors.lastname: Hodgson
authors.affiliation: Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, P.O. Box 137, Heidelberg, Vic., 3084, Australia.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Scroggie
authors.affiliation: Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, P.O. Box 137, Heidelberg, Vic., 3084, Australia.
authors.forename: David S L
authors.initials: DSL
authors.lastname: Ramsey
authors.affiliation: Department of Environment, Land, Water and Planning, Arthur Rylah Institute for Environmental Research, P.O. Box 137, Heidelberg, Vic., 3084, Australia.
authors.forename: Nick
authors.initials: N
authors.lastname: Clemann
mesh_terms: D000818:Animals; D001001:Anura / Q000382:microbiology*; D001315:Australia; D008411:Chytridiomycota / Q000472:pathogenicity*; D056727:Endangered Species; D053476:Extinction, Biological; D054884:Host-Pathogen Interactions; D008834:Microclimate; D008954:Models, Biological; D015233:Models, Statistical; D009181:Mycoses / Q000635:transmission / Q000662:veterinary; D011157:Population Dynamics; D054712:Salinity; D013312:Stress, Physiological; D013696:Temperature; D053833:Wetlands
keywords: Amphibian; Litoria raniformis; chytrid; colonisation; conservation; extinction; microclimate; pathogen; reservoir host