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

Christopher S. Campbell, Martin Wojciechowski, Bruce G. Baldwin, Lawrence A. Alice, Michael J. Donoghue

Research output: Contribution to journalArticle

255 Citations (Scopus)

Abstract

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 plus A. humilis and A. sanguinea of eastern North America form one clade (A), and the remaining eastern North American Amelanchier make up clade B. Five eastern North American taxa are polymorphic at many of the nucleotide sites where clades A and B have diverged and are thought to be of hybrid origin, with A. humilis or A. sanguinea as one parent and various members of clade B as the other parent. Morphological evidence suggests that A. humilis is one of the parents of one of the polymorphic taxa, a microspecies that we refer to informally as A. 'erecta.' Sequences of 21 cloned copies of the ITS1-5.8S gene-ITS2 region from one A. 'erecta' individual are identical to A. humilis sequence or to the clade B consensus sequence, or they are apparent recombinants of A. humilis and clade B ITS repeats. Amelanchier 'erecta' and another polymorphic taxon are suspected to be relatively old because both grow several hundred kilometers beyond the range of one of their parents. ITS sequence polymorphisms have apparently persisted in these two taxa perhaps because of polyploidy and/or agamospermy (asexual seed production), which are prevalent in the genus.

Original languageEnglish (US)
Pages (from-to)81-90
Number of pages10
JournalMolecular Biology and Evolution
Volume14
Issue number1
StatePublished - Jan 1997
Externally publishedYes

Fingerprint

Amelanchier
Rosaceae
DNA sequences
Ribosomal DNA
Polymorphism
ribosomal DNA
internal transcribed spacers
polymorphism
genetic polymorphism
nucleotide sequences
DNA
Nucleotides
Genes
polyploidy
Ribosomal Spacer DNA
seed production
gene flow
nucleotides
Polyploidy
seed productivity

Keywords

  • agamospermy
  • Amelanchier
  • hybridization
  • nuclear rDNA internal transcribed spacer (ITS)
  • phylogeny reconstruction
  • polymorphism

ASJC Scopus subject areas

  • Genetics
  • Biochemistry
  • Genetics(clinical)
  • Biochemistry, Genetics and Molecular Biology(all)
  • Ecology, Evolution, Behavior and Systematics
  • Agricultural and Biological Sciences (miscellaneous)
  • Molecular Biology

Cite this

Persistent nuclear ribosomal DNA sequence polymorphism in the Amelanchier agamic complex (Rosaceae). / Campbell, Christopher S.; Wojciechowski, Martin; Baldwin, Bruce G.; Alice, Lawrence A.; Donoghue, Michael J.

In: Molecular Biology and Evolution, Vol. 14, No. 1, 01.1997, p. 81-90.

Research output: Contribution to journalArticle

Campbell, Christopher S. ; Wojciechowski, Martin ; Baldwin, Bruce G. ; Alice, Lawrence A. ; Donoghue, Michael J. / Persistent nuclear ribosomal DNA sequence polymorphism in the Amelanchier agamic complex (Rosaceae). In: Molecular Biology and Evolution. 1997 ; Vol. 14, No. 1. pp. 81-90.
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