Systematics Section / ASPT
Brown, Gillian K. , Murphy, Daniel J. , Miller, Joseph T. , Ladiges, Pauline .
Phylogeny of Acacia s.s. and the tropical legume tribe Ingeae (Mimosoideae: Leguminosae).
Recent studies of subfamily Mimosoideae indicate that Acacia sensu stricto (formerly Acacia subg. Phyllodineae) is a distinct evolutionary lineage only distantly related to other genera in tribe Acacieae. These studies suggest that a member of the large group of tropical legumes, the tribe Ingeae, may be the sister group to Acacia s.s. The tribe Ingeae, with almost 1000 species, has a pantropical distribution with two main centres of diversity: one in Central and South America, and another in the Asian-Australian region. At present 36 genera are recognised in the tribe, although very little is known about their phylogenetic relationships, with less than 4% of the taxa included in molecular phylogenetic studies. The phylogeny of the Ingeae is vital to understanding the relationships of the polyphyletic Acacieae, yet the relationships between the Ingeae, and between it and Acacia s.s., remains understudied. This study is the first step in filling this knowledge gap.
We have sequenced two regions of nuclear ribosomal DNA (ITS and ETS) for species of Acacia s.s. and 60 accessions, representing 24 genera, from the tribe Ingeae. Based on parsimony and Bayesian analyses, the monophyletic Acacia s.s. is related to members of the Ingeae from Australia and SE Asia, with Paraserianthes the most likely sister taxon to Acacia s.s. Relationships between genera of the Ingeae are beginning to be discovered, and, even with our limited sampling, not all genera are monophyletic. Additional sampling is needed to further test inter- and intra-generic classifications within Ingeae, and redefine the boundaries of the two tribes Acacieae and Ingeae.
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1 - University of Melbourne, School of Botany, Melbourne, Victoria, 3010, Australia
2 - National Herbarium of Victoria, Royal Botanic Gardens Melbourne, South Yarra, Victoria, 3141, Australia
3 - University of Iowa, Biology Department, 138 Biology Building, Iowa City, Iowa, 52242, USA
Presentation Type: Oral Paper:Papers for Sections
Location: Stevens 3/Hilton
Date: Wednesday, July 11th, 2007
Time: 3:30 PM