The magnitude of local adaptation under genotype-dependent dispersal

Authors

  • Daniel I. Bolnick,

    Corresponding author
    1. Howard Hughes Medical Institute, Department of Integrative Biology, University of Texas at Austin, Austin, Texas, USA
    • Correspondence

      Daniel I. Bolnick, Howard Hughes Medical Institute, Department of Integrative Biology, One University Station C0990, University of Texas at Austin, Austin TX 78712.

      Tel: (512) 471-2824; Fax: (512) 471-3878;

      E-mail: danbolnick@austin.utexas.edu

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  • Sarah P. Otto

    1. Department of Zoology, University of British Columbia, Vancouver, BC, Canada
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  • Data Archiving: Mathematica code for the proofs and figures will be archived in Dryad. Raw data to recreate Figure  will be archived in Dryad.

Abstract

Dispersal moves individuals from patches where their immediate ancestors were successful to sites where their genotypes are untested. As a result, dispersal generally reduces fitness, a phenomenon known as “migration load.” The strength of migration load depends on the pattern of dispersal and can be dramatically lessened or reversed when individuals move preferentially toward patches conferring higher fitness. Evolutionary ecologists have long modeled nonrandom dispersal, focusing primarily on its effects on population density over space, the maintenance of genetic variation, and reproductive isolation. Here, we build upon previous work by calculating how the extent of local adaptation and the migration load are affected when individuals differ in their dispersal rate in a genotype-dependent manner that alters their match to their environment. Examining a one-locus, two-patch model, we show that local adaptation occurs through a combination of natural selection and adaptive dispersal. For a substantial portion of parameter space, adaptive dispersal can be the predominant force generating local adaptation. Furthermore, genetic load may be largely averted with adaptive dispersal whenever individuals move before selective deaths occur. Thus, to understand the mechanisms driving local adaptation, biologists must account for the extent and nature of nonrandom, genotype-dependent dispersal, and the potential for adaptation via spatial sorting of genotypes.

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