Dutch botanist famous for his contributions to genetics. He rediscovered the results first obtained by Mendel and described genetic changes in his plants. Based on his observations, DeVries argued that individual mutations had wide-ranging effects and could cause speciation in a single step; however, T. H. Morgan later discovered that many mutations seemed to have rather small effects. DeVries, it turns out, had observed changes in chromosome number, not the minor change in base pair sequence that are typical of mutation.
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