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Spatial genetic structure of the mountain pine beetle (Dendroctonus ponderosae) outbreak in western Canada: historical patterns and contemporary dispersal

Authors

  • G. D. N. GAYATHRI SAMARASEKERA,

    1. Natural Resources and Environmental Studies Institute, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia, Canada V2N 4Z9
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  • NICHOLAS V. BARTELL,

    1. Natural Resources and Environmental Studies Institute, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia, Canada V2N 4Z9
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  • B. STAFFAN LINDGREN,

    1. Natural Resources and Environmental Studies Institute, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia, Canada V2N 4Z9
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  • JANICE E. K. COOKE,

    1. Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Centre, Edmonton, Alberta, Canada T6G 2E9
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  • COREY S. DAVIS,

    1. Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Centre, Edmonton, Alberta, Canada T6G 2E9
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  • PATRICK M. A. JAMES,

    1. Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Centre, Edmonton, Alberta, Canada T6G 2E9
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  • DAVID W. COLTMAN,

    1. Department of Biological Sciences, University of Alberta, CW 405 Biological Sciences Centre, Edmonton, Alberta, Canada T6G 2E9
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  • KAREN E. MOCK,

    1. Department of Wildland Resources, Utah State University, 5230 Old Main Hill, Logan, UT 84322, USA
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  • BRENT W. MURRAY

    1. Natural Resources and Environmental Studies Institute, University of Northern British Columbia, 3333 University Way, Prince George, British Columbia, Canada V2N 4Z9
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Brent W Murray, Fax: (250) 960 5538; E-mail: murrayb@unbc.ca

Abstract

Environmental change has a wide range of ecological consequences, including species extinction and range expansion. Many studies have shown that insect species respond rapidly to climatic change. A mountain pine beetle epidemic of record size in North America has led to unprecedented mortality of lodgepole pine, and a significant range expansion to the northeast of its historic range. Our goal was to determine the spatial genetic variation found among outbreak population from which genetic structure, and dispersal patterns may be inferred. Beetles from 49 sampling locations throughout the outbreak area in western Canada were analysed at 13 microsatellite loci. We found significant north-south population structure as evidenced by: (i) Bayesian-based analyses, (ii) north-south genetic relationships and diversity gradients; and (iii) a lack of isolation-by-distance in the northernmost cluster. The north-south structure is proposed to have arisen from the processes of postglacial colonization as well as recent climate-driven changes in population dynamics. Our data support the hypothesis of multiple sources of origin for the outbreak and point to the need for population specific information to improve our understanding and management of outbreaks. The recent range expansion across the Rocky Mountains into the jack/lodgepole hybrid and pure jack pine zones of northern Alberta is consistent with a northern British Columbia origin. We detected no loss of genetic variability in these populations, indicating that the evolutionary potential of mountain pine beetle to adapt has not been reduced by founder events. This study illustrates a rapid range-wide response to the removal of climatic constraints, and the potential for range expansion of a regional population.

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