Differences in transcription levels among wild, domesticated, and hybrid Atlantic salmon (Salmo salar) from two environments

Authors

  • PAUL V. DEBES,

    1. Department of Biology, Dalhousie University, LSC, 1355 Oxford Road, Halifax, NS B3H 4J1, Canada
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  • ERIC NORMANDEAU,

    1. Département de Biologie, Université Laval, Pavillon Charles-Eugène-Marchand, 1030 Avenue de la Médecine, Québec City, QC G1V 0A6, Canada
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  • DYLAN J. FRASER,

    1. Department of Biology, Concordia University, 7141 Sherbrooke St. West, Montreal, QC H4B 1R6, Canada
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  • LOUIS BERNATCHEZ,

    1. Département de Biologie, Université Laval, Pavillon Charles-Eugène-Marchand, 1030 Avenue de la Médecine, Québec City, QC G1V 0A6, Canada
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  • JEFFREY A. HUTCHINGS

    1. Department of Biology, Dalhousie University, LSC, 1355 Oxford Road, Halifax, NS B3H 4J1, Canada
    2. Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, P.O. Box 1066 Blindern, NO-0316 Oslo, Norway
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Paul V. Debes, Fax: +19024943736; E-mail: paul.debes@dal.ca

Abstract

Escaped domesticated individuals can introduce disadvantageous traits into wild populations due to both adaptive differences between population ancestors and human-induced changes during domestication. In contrast to their domesticated counterparts, some endangered wild Atlantic salmon populations encounter during their marine stage large amounts of suspended sediments, which may act as a selective agent. We used microarrays to elucidate quantitative transcriptional differences between a domesticated salmon strain, a wild population and their first-generation hybrids during their marine life stage, to describe transcriptional responses to natural suspended sediments, and to test for adaptive genetic variation in plasticity relating to a history of natural exposure or nonexposure to suspended sediments. We identified 67 genes differing in transcription level among salmon groups. Among these genes, processes related to energy metabolism and ion homoeostasis were over-represented, while genes contributing to immunity and actin-/myosin-related processes were also involved in strain differentiation. Domestic–wild hybrids exhibited intermediate transcription patterns relative to their parents for two-thirds of all genes that differed between their parents; however, genes deviating from additivity tended to have similar levels to those expressed by the wild parent. Sediments induced increases in transcription levels of eight genes, some of which are known to contribute to external or intracellular damage mitigation. Although genetic variation in plasticity did not differ significantly between groups after correcting for multiple comparisons, two genes (metallothionein and glutathione reductase) tended to be more plastic in response to suspended sediments in wild and hybrid salmon, and merit further examination as candidate genes under natural selection.

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