Strong divergence in trait means but not in plasticity across hatchery and wild populations of sea-run brown trout Salmo trutta

Authors

  • BJÖRN ROGELL,

    1. Department of Population Biology and Conservation Biology Evolutionary Biology Center, Norbyvägen 18D, 752 36 Uppsala, Sweden
    2. Department of Animal Ecology, Evolutionary Biology Center, Norbyvägen 18D, 752 36 Uppsala, Sweden
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  • JOHAN DANNEWITZ,

    1. Department of Population Biology and Conservation Biology Evolutionary Biology Center, Norbyvägen 18D, 752 36 Uppsala, Sweden
    2. Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, Stångholmsvägen 2, 178 93 Drottningholm, Sweden
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  • STEFAN PALM,

    1. Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, Stångholmsvägen 2, 178 93 Drottningholm, Sweden
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  • ERIK PETERSSON,

    1. Department of Animal Ecology, Evolutionary Biology Center, Norbyvägen 18D, 752 36 Uppsala, Sweden
    2. Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, Stångholmsvägen 2, 178 93 Drottningholm, Sweden
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  • JONAS DAHL,

    1. Kristianstads Vattenrike Biosphere Reserve, Spannmålsgatan 11, Kvarnen, Kristianstads kommun, 291 80 Kristianstad, Sweden
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  • TORE PRESTEGAARD,

    1. Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, Stångholmsvägen 2, 178 93 Drottningholm, Sweden
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  • TORBJÖRN JÄRVI,

    1. Institute of Freshwater Research, Department of Aquatic Resources, Swedish University of Agricultural Sciences, Stångholmsvägen 2, 178 93 Drottningholm, Sweden
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  • ANSSI LAURILA

    1. Department of Population Biology and Conservation Biology Evolutionary Biology Center, Norbyvägen 18D, 752 36 Uppsala, Sweden
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Björn Rogell, Fax: +46 18 471 6484, E-mail: bjorn.rogell@ebc.uu.se

Abstract

There is ample evidence that organisms adapt to their native environment when gene flow is restricted. However, evolution of plastic responses across discrete environments is less well examined. We studied divergence in means and plasticity across wild and hatchery populations of sea-run brown trout (Salmo trutta) in a common garden experiment with two rearing environments (hatchery and a nearly natural experimental stream). Since natural and hatchery environments differ, this arrangement provides an experiment in contemporary adaptation across the two environments. A QST − FST approach was used to investigate local adaptation in survival and growth over the first summer. We found evidence for divergent selection in survival in 1 year and in body length in both years and rearing environments. In general, the hatchery populations had higher survival and larger body size in both environments. QST in body size did not differ between the rearing environments, and constitutive divergence in the means was in all cases stronger than divergence in the plastic responses. These results suggest that in this system, constitutive changes in mean trait values are more important for local adaptation than increased plasticity. In addition, ex situ rearing conditions induce changes in trait means that are adaptive in the hatchery, but potentially harmful in the wild, suggesting that hatchery rearing is likely to be a suboptimal management strategy for trout populations facing selection in the stream environment.

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