Analyses of genetic diversity reveal major forces impacting a local population of the gourmet mushroom Cantharellus enelensis

Cantharellus enelensis is a popular edible mushroom in eastern North America. Burnt Hill (BH), a small hill surrounded by water on three sides in the heart of Gros Morne National Park of Canada, has been consistently producing fruiting bodies of C. enelensis since at least the 1960s. In contrast, the surrounding areas are not known to produce any fruiting body of this species. Understanding how such an isolated population persists has significant conservation and economic importance. In this study, we obtained and analyzed the genotypes of 109 fruiting bodies from BH, among which, 81 were collected from six patches separated by more than 100 m from each other and the remaining 28 were randomly collected five days later throughout the hill. Genotyping based on microsatellite markers revealed three, five and two alleles at the three loci respectively, with each local patch dominated by one to two alleles at each locus. The three markers revealed 29 multilocus genotypes (MLGs) among the 109 fruiting bodies. The genotype frequencies at each local patch population and in the total sample were overall consistent with Hardy-Weinberg equilibrium. Among the six local patches, while the total samples showed statistically significant genetic differentiation, no difference was observed among the clone-corrected samples. Comparisons between samples from the two time points separated by five days revealed minor differences in allele and genotype frequencies. In addition, we compared the BH population with those at two other sites in Newfoundland (~200 km and ~600 km away) and one site in Hamilton, Ontario (~2 000 km away) to identify potentially unique alleles and genotypes at BH. Together, our analyses demonstrated that mutation, sexual reproduction, gene flow, selection, and genetic drift have all contributed to the genetic diversity within this local chantarelle population.