title: Taxonomic similarity, more than contact opportunity, explains novel plant-pathogen associations between native and alien taxa.
abstract: Novel associations between plants and pathogens can have serious impacts on managed and natural ecosystems world-wide. The introduction of alien plants increases the potential for biogeographically novel plant-pathogen associations to arise when pathogens are transmitted from native to alien plant species and vice versa. We quantified biogeographically novel associations recorded in New Zealand over the last 150 yr between plant pathogens (fungi, oomycetes and plasmodiophorids) and vascular plants. We examined the extent to which taxonomic similarity, pathogen traits, contact opportunity and sampling effort could explain the number of novel associates for host and pathogen species. Novel associations were common; approximately one-third of surveyed plants and pathogens were recorded with at least one biogeographically novel associate. Native plants had more alien pathogens than vice versa. Taxonomic similarity between the native and alien flora and the total number of recorded associations (a measure of sampling effort) best explained the number of novel associates among species. The frequency of novel associations and the importance of sampling effort as an explanatory variable emphasize the need for effective monitoring and risk assessment tools to mitigate the potential environmental and economic impact of novel pathogen associations.
authors.affiliation: Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln, 7647, New Zealand. jennifer.bufford@lincoln.ac.nz.
authors.forename: Jennifer L
authors.identifier: http://orcid.org/0000-0003-3320-6024
authors.initials: JL
authors.lastname: Bufford
authors.affiliation: Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln, 7647, New Zealand.
authors.forename: Philip E
authors.initials: PE
authors.lastname: Hulme
authors.affiliation: Department of Ecology and Evolutionary Biology and Kansas Biological Survey, University of Kansas, 2101 Constant Ave, Lawrence, KS, 66047, USA.
authors.forename: Benjamin A
authors.initials: BA
authors.lastname: Sikes
authors.affiliation: Landcare Research, PO Box 69040, Lincoln, 7640, New Zealand.
authors.forename: Jerry A
authors.initials: JA
authors.lastname: Cooper
authors.affiliation: Landcare Research, Private Bag 92170, Auckland, 1142, New Zealand.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Johnston
authors.affiliation: Bio-Protection Research Centre, Lincoln University, PO Box 85084, Lincoln, 7647, New Zealand.|Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia.
authors.forename: Richard P
authors.initials: RP
authors.lastname: Duncan
mesh_terms: D016001:Confidence Intervals; D054884:Host-Pathogen Interactions / Q000502:physiology*; D010802:Phylogeny; D058974:Phylogeography; D010944:Plants / Q000145:classification* / Q000382:microbiology; D013045:Species Specificity
keywords: 
  Phytophthora
  ; biosecurity; emerging diseases; epidemiology; exotic; invasion; nonnative; novel interactions