The genetics of phenotypic plasticity. II. Response to selection

Authors

  • Samuel M. Scheiner,

    1. Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois 60115, USA
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  • Richard F. Lyman

    1. Department of Biological Sciences, Northern Illinois University, DeKalb, Illinois 60115, USA
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    • 1

      Present address: Department of Genetics, North Carolina State University, Raleigh, North Carolina 27695, USA


Abstract

We selected on phenotypic plasticity of thorax size in response to temperature in Drosophila melanogaster using a family selection scheme. The results were compared to those of lines selected directly on thorax size. We found that the plasticity of a character does respond to selection and this response is partially independent of the response to selection on the mean of the character. One puzzling result was that a selection limit of zero plasticity was reached in the lines selected for decreased plasticity yet additive genetic variation for plasticity still existed in the lines. We tested the predictions of three models of the genetic basis of phenotypic plasticity: overdominance, pleiotropy, and epistasis. The results mostly support the epistasis model, that the plasticity of a character is determined by separate loci from those determining the mean of the character.

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