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Article
Molecular Phylogenetics of Vandeae (Orchidaceae) and the Evolution of Leaflessness
American Journal of Botany (2006)
  • Barbara S. Carlsward, Eastern Illinois University
  • W. Mark Whitten, University of Florida
  • Norris H. Williams, Florida Museum of Natural History
  • Benny Bytebier
Abstract
Members of tribe Vandeae (Orchidaceae) form a large, antropical clade of horticulturally important epiphytes. Monopodial leafless members of Vandeae have undergone extreme eduction in habit and represent a novel adaptation to the canopy environment in tropical Africa, Asia, and America. To study the evolution of monopodial leaflessness, molecular and structural evidence was used to generate phylogenetic hypotheses for Vandeae. Molecular analyses used sequence data from ITS nrDNA, trnL-F plastid DNA, and matK plastid DNA. Maximum parsimony analyses of these three DNA regions each supported two subtribes within monopodial Vandeae: Aeridinae and a combined Angraecinae þ Aerangidinae. Adding structural characters to sequence data resulted in trees with more homoplasy, but gave fewer trees each with more well-supported clades than either data set alone. Two techniques for examining character evolution were compared: (1) mapping vegetative characters onto a molecular topology and (2) tracing vegetative characters onto a combined structural and molecular topology. In both cases, structural synapomorphies supporting monopodial Vandeae were nearly identical. A change in leaf morphology (usually reduced to a nonphotosynthetic scale), monopodial growth habit, and aeration complexes for gas exchange in photosynthetic roots seem to be the most important characters in making the evolutionary transition to leaflessness.
Keywords
  • Vandeae,
  • Orchidaceae,
  • Leaflessness
Disciplines
Publication Date
2006
Publisher Statement
This article was originally published in the American Journal of Botany and is available here: http://www.amjbot.org/content/93/5/770.full.pdf+html
Citation Information
Barbara S. Carlsward, W. Mark Whitten, Norris H. Williams and Benny Bytebier. "Molecular Phylogenetics of Vandeae (Orchidaceae) and the Evolution of Leaflessness" American Journal of Botany Vol. 93 Iss. 5 (2006)
Available at: http://works.bepress.com/barbara_carlsward/2/