XVI International Botanical Congess

Partial sequences of the A-alpha locus of the mushroom S. commune were generated for strains which all share the same mating specificity at this locus. Although overall sequence diversity was low, phylogenetic analyses revealed geographic patterns within a single A-alpha allelic lineage which are largely congruent with patterns attributed to genetic drift observed at other nuclear loci. Thus the phylogeny of A-alpha demonstrates that drift can affect neutral genetic variation that is absolutely linked to a locus under strong balancing selection. Results from Monte-Carlo simulations suggest that loci held in such a highly polymorphic state are unlikely to exert an effect on levels of population genetic substructure at closely linked loci.