Phylogenetic analysis of Australian Acacia (Leguminosae: Mimosoideae) by using sequence variations of an intron and two intergenic spacers of chloroplast DNA

Abstract

Three regions of chloroplast DNA are assessed for their utility for phylogenetic analysis of Acacia subgenus Phyllodineae: psbA–trnH intergenic spacer, the trnL intron and the trnL–trnF intergenic spacer. There are large differences in the lengths of the psbA–trnH spacer (155–440 bp) and trnL–trnF intergenic spacer (101–422 bp) regions, and large multi-residue indels were coded as multistate characters. Overall information content in these regions is relatively low, but the total evidence tree has 12 nodes resolved, five with jackknife support. By using Parkia timoriana as the outgroup, Acacia subgenus Acacia (A. farnesiana) is basal and Acacia subgenus Aculeiferum (A. senegal) is the sister taxon to subgenus Phyllodineae. Although based on a small sample size, within subgenus Phyllodineae, the results of this study have shown that section Alatae is not monophyletic, section Lycopodiifoliae is monophyletic and Botrycephalae is related to members of section Phyllodineae with racemose inflorescences.