title: Hybrid sterility and inviability in the parasitic fungal species complex Microbotryum.
abstract: Microbotryum violaceum, the anther-smut fungus, forms a complex of sibling species which specialize on different plants. Previous studies have shown the presence of partial ecological isolation and F1 inviability, but did not detect assortative mating apart from a high selfing rate. We investigated other post-mating barriers and show that F1 hybrid sterility, the inability of gametes to mate, increased gradually with the increasing genetic distance between the parents. F2 hybrids showed a reduced ability to infect the plants that was also correlated with the genetic distance. The host on which the F2 hybrids were passaged caused a selection for alleles derived from the pathogen species originally isolated from that host, but this effect was not detectable for the most closely related species. The post-mating barriers thus remain weak among the closest species pairs, suggesting that premating barriers are sufficient to initiate divergence in this system.
authors.affiliation: Ecologie, Systématique et Evolution, Université Paris-Sud, Orsay Cedex, France.
authors.forename: D M
authors.initials: DM
authors.lastname: De Vienne
authors.forename: G
authors.initials: G
authors.lastname: Refrégier
authors.forename: M E
authors.initials: ME
authors.lastname: Hood
authors.forename: A
authors.initials: A
authors.lastname: Guigue
authors.forename: B
authors.initials: B
authors.lastname: Devier
authors.forename: E
authors.initials: E
authors.lastname: Vercken
authors.forename: C
authors.initials: C
authors.lastname: Smadja
authors.forename: A
authors.initials: A
authors.lastname: Deseille
authors.forename: T
authors.initials: T
authors.lastname: Giraud
mesh_terms: D001487:Basidiomycota / Q000235:genetics / Q000502:physiology*; D002678:Chimera / Q000502:physiology*; D020090:Chromosome Segregation / Q000235:genetics; D016681:Genome, Fungal / Q000235:genetics; D005838:Genotype; D005854:Germ Cells / Q000502:physiology; D043563:Receptors, Pheromone / Q000235:genetics
chemical_list: D043563:Receptors, Pheromone