Molecular Evidence for Definition of Genera in the Oxylobium Group (Fabaceae: Mirbelieae)

Michael D. Crisp*, Lyn G. Cook

*Corresponding author for this work

    Research output: Contribution to journalArticlepeer-review

    17 Citations (Scopus)

    Abstract

    The circumscription of Oxylobium and related genera has been problematic for nearly 200 years. Traditional definitions of genera in the group have relied on morphological features of the leaves, flower, and fruit that overlap extensively between genera. Therefore sequences of cpDNA (trnL-F intron and spacer) and nrDNA (ITS) were used to estimate the phylogeny of the group in an attempt to redefine the genera as monophyletic groups. Oxylobium sens. str. was found to be a well supported clade in both data sets, with the inclusion of Mirbelia oxylobioides. No other genus in the group was supported by these data, except Gastrolobium sens. lat. Some species groups within Chorizema, Mirbelia, and Podolobium were supported but relationships among these, Oxylobium and Gastrolobium differed significantly between the chloroplast and nuclear data sets. No group supported by the molecular data had a morphological synapomorphy, not even Oxylobium or Gastrolobium. Therefore it may be necessary to adopt a much broader generic concept in this group than has been done previously. Incongruence between the two molecular data sets, and very short internal basal branches in both, suggest a rapid early radiation in this group, possibly combined with hybridization and lineage sorting.

    Original languageEnglish
    Pages (from-to)705-713
    Number of pages9
    JournalSystematic Botany
    Volume28
    Issue number4
    Publication statusPublished - Oct 2003

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