DIVERSITY AND LOCAL-DISTRIBUTION OF MATING ALLELES IN MARASMIELLUS-PRAEACUTUS AND COLLYBIA-SUBNUDA (BASIDIOMYCETES, AGARICALES)

The diversity and distribution of mating alleles in local populations of two litter decomposing mushroom species were investigated. The resu lts from mating crosses between single-spore isolates were used to ded uce mating genotypes among closely adjacent individuals. Collybia subn uda has a high mating allele diversity that is comparable to the diver sity of other bipolar species. Adjacent individuals of C. subnuda did not share mating alleles, which suggests that outcrossing usually occu rs in this fungus. The estimate of mating allele diversity in C. subnu da is 45, with a 95% confidence interval of 19-187. A simplified appro ach for designing and analyzing intercollection mating crosses for tet rapolar fungi was tested with Marasmiellus praeacutus and found useful . An unexpectedly low mating allele diversity was found in M. praeacut us, with adjacent individuals frequently sharing more than one mating allele. The pattern of shared alleles in M. praeacutus suggests the oc currence of di-mon crossing (the Buller phenomenon). We suggest that t he observed low level of mating allele diversity in M. praeacutus is a consequence of limited spare dispersal, and we discuss the implicatio ns of these conclusions for population sampling in the higher fungi.