title: Less pollen-mediated gene flow for more signatures of glacial lineages: congruent evidence from balsam fir cpDNA and mtDNA for multiple refugia in eastern and central North America.
abstract: The phylogeographic structure and postglacial history of balsam fir (Abies balsamea), a transcontinental North American boreal conifer, was inferred using mitochondrial DNA (mtDNA) and chloroplast DNA (cpDNA) markers. Genetic structure among 107 populations (mtDNA data) and 75 populations (cpDNA data) was analyzed using Bayesian and genetic distance approaches. Population differentiation was high for mtDNA (dispersed by seeds only), but also for cpDNA (dispersed by seeds and pollen), indicating that pollen gene flow is more restricted in balsam fir than in other boreal conifers. Low cpDNA gene flow in balsam fir may relate to low pollen production due to the inherent biology of the species and populations being decimated by recurrent spruce budworm epidemics, and/or to low dispersal of pollen grains due to their peculiar structural properties. Accordingly, a phylogeographic structure was detected using both mtDNA and cpDNA markers and population structure analyses supported the existence of at least five genetically distinct glacial lineages in central and eastern North America. Four of these would originate from glacial refugia located south of the Laurentide ice sheet, while the last one would have persisted in the northern Labrador region. As expected due to reduced pollen-mediated gene flow, congruence between the geographic distribution of mtDNA and cpDNA lineages was higher than in other North American conifers. However, concordance was not complete, reflecting that restricted but nonetheless detectable cpDNA gene flow among glacial lineages occurred during the Holocene. As a result, new cpDNA and mtDNA genome combinations indicative of cytoplasmic genome capture were observed.
authors: Canada Research Chair in Forest and Environmental Genomics, Centre for Forest Research and Institute for Systems and Integrative Biology, Wood and Forest Sciences, Laval University, Québec, Québec, Canada.
authors: Benjamin
authors: B
authors: Cinget
authors: Canada Research Chair in Forest and Environmental Genomics, Centre for Forest Research and Institute for Systems and Integrative Biology, Wood and Forest Sciences, Laval University, Québec, Québec, Canada.
authors: Sébastien
authors: S
authors: Gérardi
authors: Canada Research Chair in Forest and Environmental Genomics, Centre for Forest Research and Institute for Systems and Integrative Biology, Wood and Forest Sciences, Laval University, Québec, Québec, Canada; Natural Resources Canada, Canadian Wood Fibre Centre, Canadian Wood Fibre Centre, Natural Resources Canada, Québec, Québec, Canada.
authors: Jean
authors: J
authors: Beaulieu
authors: Canada Research Chair in Forest and Environmental Genomics, Centre for Forest Research and Institute for Systems and Integrative Biology, Wood and Forest Sciences, Laval University, Québec, Québec, Canada.
authors: Jean
authors: J
authors: Bousquet
mesh_terms: D028202:Abies / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D002489:Central America; D018742:DNA, Chloroplast / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D051456:Gene Flow; D008969:Molecular Sequence Data; D010641:Phenotype; D058974:Phylogeography; D063148:Plant Dispersal; D011058:Pollen / Q000378:metabolism*; D011110:Polymorphism, Genetic; D000068236:Refugium
chemical_list: D018742:DNA, Chloroplast; D004272:DNA, Mitochondrial