Persistent nuclear ribosomal DNA sequence polymorphism in the Amelanchier agamic complex (Rosaceae).

  title={Persistent nuclear ribosomal DNA sequence polymorphism in the Amelanchier agamic complex (Rosaceae).},
  author={Christopher S. Campbell and Martin F. Wojciechowski and Bruce G. Baldwin and Lawrence A. Alice and Michael J. Donoghue},
  journal={Molecular biology and evolution},
  volume={14 1},
Individual plants of several Amelanchier taxa contain many polymorphic nucleotide sites in the internal transcribed spacers (ITS) of nuclear ribosomal DNA (nrDNA). This polymorphism is unusual because it is not recent in origin and thus has resisted homogenization by concerted evolution. Amelanchier ITS sequence polymorphism is hypothesized to be the result of gene flow between two major North American clades resolved by phylogenetic analysis of ITS sequences. Western North American species… 

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