title: High sexual reproduction and limited contemporary dispersal in the ectomycorrhizal fungus Tricholoma scalpturatum: new insights from population genetics and spatial autocorrelation analysis.
abstract: Dispersal and establishment are fundamental processes influencing the response of species to environmental changes, and the long-term persistence of populations. A previous study on the symbiotic ectomycorrhizal fungus Tricholoma scalpturatum revealed strong genetic differentiations between populations in Western Europe, suggesting restricted dispersal for this wind-dispersed cosmopolitan fungus. Two distinct genetic groups (genetic groups 1 and 2), co-occurring in some locations, were also identified and could correspond to cryptic species. In the present work, we examine the reproductive strategy and dispersal biology of the two T. scalpturatum's genetic groups. Variable molecular markers (intersimple sequence repeats and intergenic spacer 2-restriction fragment length polymorphisms) and spatial autocorrelation analyses were used to examine fine-scale patterns (< 140 m) of genetic structure, in an effort to determine the physical scale at which genetic structure exists. A total of 473 fruit bodies were mapped and collected over 3 years from two plots located in the south of France, including 219 and 254 samples from group 1 and group 2, respectively. High genetic diversity and the presence of numerous small genets were observed in both groups. Autocorrelation analyses revealed significant positive spatial genetic structures of genets at close distances (up to few metres for both groups). Mantel tests confirmed this isolation-by-distance pattern. These results clearly demonstrate high sexual reproduction and spatial structuring of genets at very small geographical scales in this wind-dispersed ectomycorrhizal fungal species, a pattern consistent with restricted contemporary dispersal of spores.
authors.affiliation: Laboratoire Evolution et Diversité Biologique, UMR 5174 CNRS-UPS-ENFA, Bât. 4R3, Université Paul Sabatier-Toulouse III, 118 route de Narbonne, 31062 Toulouse cedex 9, France. fcarrico@cict.fr
authors.forename: Fabian
authors.initials: F
authors.lastname: Carriconde
authors.forename: Hervé
authors.initials: H
authors.lastname: Gryta
authors.forename: Patricia
authors.initials: P
authors.lastname: Jargeat
authors.forename: Bello
authors.initials: B
authors.lastname: Mouhamadou
authors.forename: Monique
authors.initials: M
authors.lastname: Gardes
mesh_terms: D004271:DNA, Fungal / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D017753:Ecosystem; D005602:France; D048690:Fruiting Bodies, Fungal / Q000145:classification / Q000235:genetics; D005800:Genes, Fungal; D005828:Genetics, Population; D018895:Microsatellite Repeats / Q000235:genetics; D016533:Mycological Typing Techniques; D038821:Mycorrhizae / Q000145:classification / Q000235:genetics*; D012150:Polymorphism, Restriction Fragment Length; D019105:Random Amplified Polymorphic DNA Technique; D012091:Repetitive Sequences, Nucleic Acid; D055439:Tricholoma / Q000145:classification / Q000235:genetics*
chemical_list: D004271:DNA, Fungal; D021903:DNA, Ribosomal Spacer