Phylogeny of Polemoniaceae Based on Nuclear Ribosomal Internal Transcribed Spacer DNA Sequences

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Aliso, Vol: 15, Issue: 1, Page: 57-77

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Porter, J. Mark
Claremont Colleges Library
DNA sequences; Gilia; Polemoniaceae; phylogeny; Botany
article description
Nuclear ribosomal internal transcribed spacer (ITS) DNA sequences are used to estimate the phylogeny of 53 members of Polemoniaceae, representing all but two genera of the family. Fitch parsimony analysis of equal-weighted nucleotide sites result in 1080 minimal-length trees. However, when alignment-ambiguous positions are removed and an II: 10 transition to transversion weighting is imposed only eight trees are found. These data are used to address two issues: I) patterns of diversification in Polemoniaceae, and 2) the circumscription and monophyly of the genus Gilia. Although the monophyly of Polemoniaceae is well supported, relationships inferred among the earliest diverging lineages are altered by character weighting, treatment of indels, and taxon inclusion. In spite of the lack of reliable resolution at the basal nodes, ITS data provide evidence that Gilia, as currently interpreted, is polyphyletic and comprises at least five independent lineages.