Fitness dynamics within a poplar hybrid zone: II. Impact of exotic sex on native poplars in an urban jungle

Authors

  • Amanda D. Roe,

    Corresponding author
    1. Natural Resources Canada, Canadian Forest Service, Québec, Québec, Canada
    2. Natural Resources Canada, Canadian Forest Service, Sault Ste. Marie, Ontario, Canada
    • Correspondence

      Amanda D. Roe, Natural Resources Canada, Canadian Forest Service, Sault Ste. Marie, 112 Denwood Dr. Sault Ste. Marie, Ontario, Canada P6A 6T3. Tel: +1-705-256-1013; E-mail: amandaroe5@gmail.com

      Nathalie Isabel, Natural Resources Canada, Canadian Forest Service, 1055 rue du P.E.P.S., C.P. 10380 succ. Saint-Foy, Québec, Québec, Canada G1V 4C7. Tel: +1-418-648-7137; Fax: +1-418-648-5849; E-mail: nathalie.isabel@rncan-nrcan.gc.ca

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  • Chris J.K. MacQuarrie,

    1. Natural Resources Canada, Canadian Forest Service, Sault Ste. Marie, Ontario, Canada
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  • Marie-Claude Gros-Louis,

    1. Natural Resources Canada, Canadian Forest Service, Québec, Québec, Canada
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  • J. Dale Simpson,

    1. Natural Resources Canada, Canadian Forest Service, Fredericton, New-Brunswick, Canada
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  • Josyanne Lamarche,

    1. Natural Resources Canada, Canadian Forest Service, Sault Ste. Marie, Ontario, Canada
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  • Tannis Beardmore,

    1. Natural Resources Canada, Canadian Forest Service, Fredericton, New-Brunswick, Canada
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  • Stacey L. Thompson,

    1. Natural Resources Canada, Canadian Forest Service, Québec, Québec, Canada
    2. Umeå University, Department of Ecology and Environmental Science, Umeå Plant Science Centre, Umeå, Sweden
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  • Philippe Tanguay,

    1. Natural Resources Canada, Canadian Forest Service, Québec, Québec, Canada
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  • Nathalie Isabel

    Corresponding author
    1. Natural Resources Canada, Canadian Forest Service, Québec, Québec, Canada
    • Correspondence

      Amanda D. Roe, Natural Resources Canada, Canadian Forest Service, Sault Ste. Marie, 112 Denwood Dr. Sault Ste. Marie, Ontario, Canada P6A 6T3. Tel: +1-705-256-1013; E-mail: amandaroe5@gmail.com

      Nathalie Isabel, Natural Resources Canada, Canadian Forest Service, 1055 rue du P.E.P.S., C.P. 10380 succ. Saint-Foy, Québec, Québec, Canada G1V 4C7. Tel: +1-418-648-7137; Fax: +1-418-648-5849; E-mail: nathalie.isabel@rncan-nrcan.gc.ca

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Abstract

Trees bearing novel or exotic gene components are poised to contribute to the bioeconomy for a variety of purposes such as bioenergy production, phytoremediation, and carbon sequestration within the forestry sector, but sustainable release of trees with novel traits in large-scale plantations requires the quantification of risks posed to native tree populations. Over the last century, exotic hybrid poplars produced through artificial crosses were planted throughout eastern Canada as ornamentals or windbreaks and these exotics provide a proxy by which to examine the fitness of exotic poplar traits within the natural environment to assess risk of exotic gene escape, establishment, and spread into native gene pools. We assessed postzygotic fitness traits of native and exotic poplars within a naturally regenerated stand in eastern Canada (Quebec City, QC). Pure natives (P. balsamifera and P. deltoides spp. deltoides), native hybrids (P. deltoides × P. balsamifera), and exotic hybrids (trees bearing Populus nigra and P. maximowiczii genetic components) were screened for reproductive biomass, yield, seed germination, and fungal disease susceptibility. Exotic hybrids expressed fitness traits intermediate to pure species and were not significantly different from native hybrids. They formed fully viable seed and backcrossed predominantly with P. balsamifera. These data show that exotic hybrids were not unfit and were capable of establishing and competing within the native stand. Future research will seek to examine the impact of exotic gene regions on associated biotic communities to fully quantify the risk exotic poplars pose to native poplar forests.

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