Temporal patterns of genetic variation in a salmon population undergoing rapid change in migration timing

Authors

  • Ryan P. Kovach,

    Corresponding author
    1. Biology and Wildlife Department, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
    • Correspondence

      Biology and Wildlife Department, University of Montana, Flathead Biological Station, 32111 BioStation Ln, Polson, MT 59860, USA.

      Tel.: 406-982-3301 extn. 245;

      Fax: 406-982-3201

      e-mail: rpkovach@alaska.edu

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  • Anthony J. Gharrett,

    1. School of Fisheries and Oceanic Sciences, University of Alaska Fairbanks, Juneau, AK, USA
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  • David A. Tallmon

    1. Biology and Wildlife Department, Institute of Arctic Biology, University of Alaska Fairbanks, Fairbanks, AK, USA
    2. School of Fisheries and Oceanic Sciences, University of Alaska Fairbanks, Juneau, AK, USA
    3. Biology and Marine Biology Program, University of Alaska Southeast, Juneau, AK, USA
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Abstract

Though genetic diversity is necessary for population persistence in rapidly changing environments, little is known about how climate-warming influences patterns of intra-population genetic variation. For a pink salmon population experiencing increasing temperatures, we used temporal genetic data (microsatellite = 1993, 2001, 2009; allozyme = 1979, 1981, 1983) to quantify the genetic effective population size (Ne) and genetic divergence due to differences in migration timing and to estimate whether these quantities have changed over time. We predicted that temporal trends toward earlier migration timing and a corresponding loss of phenotypic variation would decrease genetic divergence based on migration timing and Ne. We observed significant genetic divergence based on migration timing and genetic heterogeneity between early- and late-migrating fish. There was also some evidence for divergent selection between early- and late-migrating fish at circadian rhythm genes, but results varied over time. Estimates of Ne from multiple methods were large (>1200) and Ne/Nc generally exceeded 0.2. Despite shifts in migration timing and loss of phenotypic variation, there was no evidence for changes in within-population genetic divergence or Ne over the course of this study. These results suggest that in instances of population stability, genetic diversity may be resistant to climate-induced changes in migration timing.

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