• Open Access

Adaptation, migration or extirpation: climate change outcomes for tree populations

Authors

  • Sally N. Aitken,

    1.  Centre for Forest Conservation Genetics and Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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  • Sam Yeaman,

    1.  Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
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  • Jason A. Holliday,

    1.  Centre for Forest Conservation Genetics and Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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  • Tongli Wang,

    1.  Centre for Forest Conservation Genetics and Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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  • Sierra Curtis-McLane

    1.  Centre for Forest Conservation Genetics and Department of Forest Sciences, University of British Columbia, Vancouver, British Columbia, Canada
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Sally N. Aitken, Centre for Forest Conservation Genetics and Department of Forest Sciences, University of British Columbia, 3041-2424 Main Mall, Vancouver, BC V6T 1Z4 Canada. Tel.: 1-604-822-6020; fax 1-604-822-9102; e-mail: sally.aitken@ubc.ca

Abstract

Species distribution models predict a wholesale redistribution of trees in the next century, yet migratory responses necessary to spatially track climates far exceed maximum post-glacial rates. The extent to which populations will adapt will depend upon phenotypic variation, strength of selection, fecundity, interspecific competition, and biotic interactions. Populations of temperate and boreal trees show moderate to strong clines in phenology and growth along temperature gradients, indicating substantial local adaptation. Traits involved in local adaptation appear to be the product of small effects of many genes, and the resulting genotypic redundancy combined with high fecundity may facilitate rapid local adaptation despite high gene flow. Gene flow with preadapted alleles from warmer climates may promote adaptation and migration at the leading edge, while populations at the rear will likely face extirpation. Widespread species with large populations and high fecundity are likely to persist and adapt, but will likely suffer adaptational lag for a few generations. As all tree species will be suffering lags, interspecific competition may weaken, facilitating persistence under suboptimal conditions. Species with small populations, fragmented ranges, low fecundity, or suffering declines due to introduced insects or diseases should be candidates for facilitated migration.

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