title: Host jumps shaped the diversity of extant rust fungi (Pucciniales).
abstract: The aim of this study was to determine the evolutionary time line for rust fungi and date key speciation events using a molecular clock. Evidence is provided that supports a contemporary view for a recent origin of rust fungi, with a common ancestor on a flowering plant. Divergence times for > 20 genera of rust fungi were studied with Bayesian evolutionary analyses. A relaxed molecular clock was applied to ribosomal and mitochondrial genes, calibrated against estimated divergence times for the hosts of rust fungi, such as Acacia (Fabaceae), angiosperms and the cupressophytes. Results showed that rust fungi shared a most recent common ancestor with a mean age between 113 and 115 million yr. This dates rust fungi to the Cretaceous period, which is much younger than previous estimations. Host jumps, whether taxonomically large or between host genera in the same family, most probably shaped the diversity of rust genera. Likewise, species diversified by host shifts (through coevolution) or via subsequent host jumps. This is in contrast to strict coevolution with their hosts. Puccinia psidii was recovered in Sphaerophragmiaceae, a family distinct from Raveneliaceae, which were regarded as confamilial in previous studies.
authors.affiliation: Department of Microbiology and Plant Pathology, Tree Protection Co-operative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private Bag X20, Pretoria, 0028, South Africa.
authors.forename: Alistair R
authors.initials: AR
authors.lastname: McTaggart
authors.affiliation: Department of Agriculture and Forestry, Queensland Plant Pathology Herbarium, GPO Box 267, Brisbane, Qld, 4001, Australia.
authors.forename: Roger G
authors.initials: RG
authors.lastname: Shivas
authors.affiliation: Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private bag X20, Pretoria, 0028, South Africa.
authors.forename: Magriet A
authors.initials: MA
authors.lastname: van der Nest
authors.affiliation: Department of Plant Sciences, Tree Protection Co-operative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private Bag X20, Pretoria, 0028, South Africa.
authors.forename: Jolanda
authors.initials: J
authors.lastname: Roux
authors.affiliation: Department of Genetics, Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private bag X20, Pretoria, 0028, South Africa.
authors.forename: Brenda D
authors.initials: BD
authors.lastname: Wingfield
authors.affiliation: Department of Microbiology and Plant Pathology, Tree Protection Co-operative Programme (TPCP), Forestry and Agricultural Biotechnology Institute (FABI), University of Pretoria, Private Bag X20, Pretoria, 0028, South Africa.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Wingfield
mesh_terms: D001487:Basidiomycota / Q000502:physiology*; D005075:Biological Evolution; D002138:Calibration; D054884:Host-Pathogen Interactions; D016013:Likelihood Functions; D010802:Phylogeny
keywords: Mikronegeriaceae; Pucciniales; Uredinales; calibration; host jumps; host-parasite evolution; molecular dating