title: Phylogenetic evidence of host-specific cryptic species in the anther smut fungus.
abstract: Cryptic structure of species complexes confounds an accurate accounting of biological diversity in natural systems. Also, cryptic sibling species often become specialized to different ecological conditions, for instance, with host specialization by cryptic parasite species. The fungus Microbotryum violaceum causes anther smut disease in plants of Caryophyllaceae, and the degree of specialization and gene flow between strains on different hosts have been controversial in the literature. We conducted molecular phylogenetic analyses on M. violaceum from 23 host species and different geographic origins using three single-copy nuclear genes (beta-tub, gamma-tub, and Ef1alpha). Congruence between the phylogenies identified several lineages that evolved independently for a long time. The lineages had overlapping geographic ranges but were highly specialized on different hosts. These results thus suggest that M. violaceum is a complex of highly specialized sibling species. Two incongruencies between the individual gene phylogenies and one intragene recombination event were detected at basal nodes, suggesting ancient introgression events or speciation events via hybridizations. However, incongruencies and recombination were not detected among terminal branches, indicating that the potentials for cross-infection and experimental hybridization are often not sufficient to suggest that introgressions would likely persist in nature.
authors.affiliation: Ecologie, Systématique et Evolution, UMR 8079 CNRS-UPS-ENGREF, Bâtiment 360, Université Paris-Sud, F-91405 Orsay, France. legac@zoology.ubc.ca
authors.forename: Mickael
authors.initials: M
authors.lastname: Le Gac
authors.forename: Michael E
authors.initials: ME
authors.lastname: Hood
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Fournier
authors.forename: Tatiana
authors.initials: T
authors.lastname: Giraud
mesh_terms: D000220:Adaptation, Biological / Q000235:genetics*; D001483:Base Sequence; D001487:Basidiomycota / Q000145:classification* / Q000235:genetics*; D001499:Bayes Theorem; D029748:Caryophyllaceae / Q000382:microbiology*; D016000:Cluster Analysis; D017931:DNA Primers; D051456:Gene Flow / Q000235:genetics; D049810:Genetic Speciation; D005843:Geography; D008957:Models, Genetic; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000235:genetics; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D013045:Species Specificity; D013559:Symbiosis; D014404:Tubulin / Q000235:genetics
chemical_list: D017931:DNA Primers; D020648:Peptide Elongation Factor 1; D014404:Tubulin