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Introgression and the fate of domesticated genes in a wild mammal population

Authors

  • Philine G. D. Feulner,

    Corresponding author
    1. Evolutionary Ecology, Max Planck Institute for Evolutionary Biology, Ploen, Germany
    • Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
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    • These authors are joint first authors.
  • Jacob Gratten,

    1. Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
    2. The University of Queensland, Queensland Brain Institute, Brisbane, QLD 4072, Australia
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    • These authors are joint first authors.
  • James W. Kijas,

    1. Livestock Industries, CSIRO 4067, Brisbane, QLD, Australia
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  • Peter M. Visscher,

    1. Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
    2. The University of Queensland Diamantina Institute, Brisbane, QLD 4072, Australia
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  • Josephine M. Pemberton,

    1. Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK
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  • Jon. Slate

    1. Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
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Correspondence: Philine Feulner, Fax: 49 (0) 4522 763-310; E-mail: feulner@evolbio.mpg.de

Abstract

When domesticated species are not reproductively isolated from their wild relatives, the opportunity arises for artificially selected variants to be re-introduced into the wild. However, the evolutionary consequences of introgression of domesticated genes back into the wild are poorly understood. By combining high-throughput genotyping with 25 years of long-term ecological field data, we describe the occurrence and consequences of admixture between a primitive sheep breed, the free-living Soay sheep of St Kilda, and more modern breeds. Utilizing data from a 50 K ovine SNP chip, together with forward simulations of demographic scenarios, we show that admixture occurred between Soay sheep and a more modern breed, consistent with historical accounts, approximately 150 years ago. Haplotype-sharing analyses with other breeds revealed that polymorphisms in coat colour and pattern in Soay sheep arose as a result of introgression of genetic variants favoured by artificial selection. Because the haplotypes carrying the causative mutations are known to be under natural selection in free-living Soay sheep, the admixture event created an opportunity to observe the outcome of a ‘natural laboratory’ experiment where ancestral and domesticated genes competed with each other. The haplotype carrying the domesticated light coat colour allele was favoured by natural selection, while the haplotype associated with the domesticated self coat pattern allele was associated with decreased survival. Therefore, we demonstrate that introgression of domesticated alleles into wild populations can provide a novel source of variation capable of generating rapid evolutionary changes.

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