Gene genealogies reveal cryptic species and host preferences for the pine fungal pathogen Grosmannia clavigera

Sepideh M. Alamouti, Vincent Wang, Scott Diguistini, Diana L. Six, Jörg Bohlmann, Richard C. Hamelin, Nicolas Feau, Colette Breuil

    Research output: Contribution to journalArticlepeer-review

    Abstract

    Grosmannia clavigera is a fungal pathogen of pine forests in western North America and a symbiotic associate of two sister bark beetles: Dendroctonus ponderosae and D. jeffreyi. This fungus and its beetle associate D. ponderosae are expanding in large epidemics in western North America. Using the fungal genome sequence and gene annotations, we assessed whether fungal isolates from the two beetles inhabiting different species of pine in epidemic regions of western Canada and the USA, as well as in localized populations outside of the current epidemic, represent different genetic lineages. We characterized nucleotide variations in 67 genomic regions and selected 15 for the phylogenetic analysis. Using concordance of gene genealogies and distinct ecological characteristics, we identified two sibling phylogenetic species: Gc and Gs. Where the closely related Pinus ponderosa and P. jeffreyi are infested by localized populations of their respective beetles, Gc is present. In contrast, Gs is an exclusive associate of D. ponderosae mainly present on its primary host-tree P. contorta; however, in the current epidemic areas, it is also found in other pine species. These results suggest that the host-tree species and the beetle population dynamics may be important factors associated with the genetic divergence and diversity of fungal partners in the beetle-tree ecosystems. Gc represents the original G. clavigera holotype, and Gs should be described as a new species.

    Original languageEnglish
    Pages (from-to)2581-2602
    Number of pages22
    JournalMolecular Ecology
    Volume20
    Issue number12
    DOIs
    StatePublished - Jun 2011

    Keywords

    • cryptic species
    • fungal pathogen
    • Grosmannia clavigera
    • host adaptation
    • mountain pine beetle
    • pine tree

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