Plant Systematics and Evolution

, Volume 217, Issue 1, pp 119–135

Phylogenetic utility of the nuclear rDNA ITS region in subfamilyIxoroideae (Rubiaceae): Comparisons with cpDNArbcL sequence data

  • K. Andreasen
  • B. G. Baldwin
  • B. Bremer
Article

DOI: 10.1007/BF00984925

Cite this article as:
Andreasen, K., Baldwin, B.G. & Bremer, B. Pl Syst Evol (1999) 217: 119. doi:10.1007/BF00984925

Abstract

ITS of the nrDNA were sequenced for 21 taxa inIxoroideae and outgroups (Rubiaceae) and compared with sequences of the cp-generbcL. Separate and combined analyses were performed. ITS-variation was extensive and, because of alignment ambiguities, some sites were excluded from the analyses. Several topologies from therbcL analysis that conflicted with earlier classifications are corroborated by the ITS data: 1)Posoqueria should be excluded fromGardenieae. 2) The disputed genusBertiera, previously inGardenieae, is basal in an extendedCoffeeae, includingTricalysia. 3)Ixora should be excluded fromPavetteae. 4)Vangueria, (Antirheoideae), belongs toIxoroideae. This affiliation ofAntirheoideae tribes withIxoroideae is also shown by new ITS andrbcL data forAlberta. Incongruities found between the two data sets may be caused by density of taxon sampling, different evolutionary rates, phylogenetic sorting, homoplasy caused by functional constraints, or sampling of non-orthologous ITS types.

Key words

Rubiaceae Ixoroideae cpDNA nrDNA rbcITS DNA sequences phylogeny incongruence combined analysis 

Copyright information

© Springer-Verlag 1999

Authors and Affiliations

  • K. Andreasen
    • 2
  • B. G. Baldwin
    • 3
  • B. Bremer
    • 2
  1. 1.Jepson Herbarium & Department of Integrative BiologyUniversity of California, BerkeleyBerkeleyUSA
  2. 2.Department of Systematic BotanyUppsala UniversityUppsalaSweden
  3. 3.Jepson Herbarium & Department of Integrative BiologyUniversity of CaliforniaBerkeleyUSA