Systematics Section / ASPT
Wenk, Rebecca C. , Daniel, Thomas F. .
Molecular Phylogeny and Biogeography of Elytraria (Acanthaceae: Nelsonioideae).
Elytraria is a genus of about 20 species of perennial herbs, found worldwide in tropical and subtropical regions. Their distributions range from the Indian subcontinent, Madagascar, and tropical Africa in the Old World, to the southeastern United States, Greater Antilles, Mexico/ Central America, and South America in the New World. Most species have narrow distributions that are restricted to just one of the areas listed above. We used molecular sequence data from two genomes (nuclear ribosomal ITS and chloroplast trnS-G) to reconstruct a phylogenetic tree of the genus. Both Bayesian posterior probabilities and parsimony bootstrap values strongly support the monophyly of Elytraria. Within the genus, there is support for five monophyletic clades: East African + Malagasy taxa, West African taxa, West Indian taxa, E. macrophylla (Mexico) + E. caroliniensis (southeast U.S.), and E. imbricata (Central/South America) + E. mexicana (Mexico). Previously published phylogenies show that the origin of other lineages of Acanthaceae (Acantheae, Isoglossinae, Justicieae) is in the Old World. A maximum likelihood analysis of the combined dataset suggests an East African origin for Elytraria and strongly supports monophyly of all New World species. Earlier work in the genus suggested that the two Malagasy taxa formed a subgenus basal to the rest of Elytraria, based on the presence of four (vs. two) fertile stamens. Our work suggests that the increase in stamen number arose within the East African + Malagasy clade, with two fertile stamens being ancestral for the genus. The relationship of Elytraria to the six other genera in the Nelsonioideae remains unresolved due to poor support in the lower branches of the tree.
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1 - California Academy of Sciences, Department of Botany, 875 Howard Street, San Francisco, California, 94103-3009, USA
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM