Fine-scale genetic structure and relatedness in fungi associated with the mountain pine beetle

The mountain pine beetle forms beneficial symbiotic associations with fungi. Here we explored the fine-scale spatial genetic structure of three of those fungi using single nucleotide polymorphism. We found that single mated pairs of beetles not only carry multiple fungal species, but also multiple genotypes of each species into their galleries. We observed genetic diversity at a fine spatial scale. Most of the diversity was found within and among galleries with non-significant diversity among trees. We observed clonal propagation almost exclusively within galleries. Ophiostoma montium possessed larger expected number of multilocus genotypes and lower linkage disequilibrium than Grosmannia clavigera and Leptographium longiclavatum. More than 80% of fungal samples were genetically unrelated, a result that parallels what has been observed in the beetles. The proportion of genetically-related samples within galleries was higher in O. montium (40%) than in G. clavigera (20%) or L. longiclavatum (6%), likely the consequence of within-gallery sexual recombination in O. montium. The underlying genetic diversity reported here and the differences among fungal species could enable the symbiont community to quickly respond to new environmental conditions or changes in the host, enhancing the maintenance of this multipartite relationship and allowing the MPB to colonize new habitats.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author