title: Population structure of mountain pine beetle symbiont Leptographium longiclavatum and the implication on the multipartite beetle-fungi relationships.
abstract: Over 18 million ha of forests have been destroyed in the past decade in Canada by the mountain pine beetle (MPB) and its fungal symbionts. Understanding their population dynamics is critical to improving modeling of beetle epidemics and providing potential clues to predict population expansion. Leptographium longiclavatum and Grosmannia clavigera are fungal symbionts of MPB that aid the beetle to colonize and kill their pine hosts. We investigated the genetic structure and demographic expansion of L. longiclavatum in populations established within the historic distribution range and in the newly colonized regions. We identified three genetic clusters/populations that coincide with independent geographic locations. The genetic profiles of the recently established populations in northern British Columbia (BC) and Alberta suggest that they originated from central and southern BC. Approximate Bayesian Computation supports the scenario that this recent expansion represents an admixture of individuals originating from BC and the Rocky Mountains. Highly significant correlations were found among genetic distance matrices of L. longiclavatum, G. clavigera, and MPB. This highlights the concordance of demographic processes in these interacting organisms sharing a highly specialized niche and supports the hypothesis of long-term multipartite beetle-fungus co-evolutionary history and mutualistic relationships.
authors.affiliation: Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Clement Kin-Ming
authors.initials: CK
authors.lastname: Tsui
authors.affiliation: Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Lina
authors.initials: L
authors.lastname: Farfan
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Amanda D
authors.initials: AD
authors.lastname: Roe
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Adrianne V
authors.initials: AV
authors.lastname: Rice
authors.affiliation: Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Janice E K
authors.initials: JE
authors.lastname: Cooke
authors.affiliation: Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
authors.forename: Yousry A
authors.initials: YA
authors.lastname: El-Kassaby
authors.affiliation: Department of Forest and Conservation Sciences, University of British Columbia, Vancouver, British Columbia, Canada; Natural Resources Canada, Canadian Forest Services, Laurentian Forestry Centre, Québec City, Québec, Canada.
authors.forename: Richard C
authors.initials: RC
authors.lastname: Hamelin
mesh_terms: D000416:Alberta; D000818:Animals; D005075:Biological Evolution; D001517:Coleoptera / Q000235:genetics*; D065928:Forests; D055155:Ophiostomatales / Q000235:genetics*; D011157:Population Dynamics; D013559:Symbiosis / Q000235:genetics*