title: Molecular phylogenetics and character evolution of morphologically diverse groups, Dendrobium section Dendrobium and allies.
abstract: It is always difficult to construct coherent classification systems for plant lineages having diverse morphological characters. The genus Dendrobium, one of the largest genera in the Orchidaceae, includes ∼1100 species, and enormous morphological diversification has hindered the establishment of consistent classification systems covering all major groups of this genus. Given the particular importance of species in Dendrobium section Dendrobium and allied groups as floriculture and crude drug genetic resources, there is an urgent need to establish a stable classification system. To clarify phylogenetic relationships in Dendrobium section Dendrobium and allied groups, we analysed the macromolecular characters of the group. Phylogenetic analyses of 210 taxa of Dendrobium were conducted on DNA sequences of internal transcribed spacer (ITS) regions of 18S-26S nuclear ribosomal DNA and the maturase-coding gene (matK) located in an intron of the plastid gene trnK using maximum parsimony and Bayesian methods. The parsimony and Bayesian analyses revealed 13 distinct clades in the group comprising section Dendrobium and its allied groups. Results also showed paraphyly or polyphyly of sections Amblyanthus, Aporum, Breviflores, Calcarifera, Crumenata, Dendrobium, Densiflora, Distichophyllae, Dolichocentrum, Holochrysa, Oxyglossum and Pedilonum. On the other hand, the monophyly of section Stachyobium was well supported. It was found that many of the morphological characters that have been believed to reflect phylogenetic relationships are, in fact, the result of convergence. As such, many of the sections that have been recognized up to this point were found to not be monophyletic, so recircumscription of sections is required.
authors.affiliation: School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Takamiya
authors.affiliation: Institute of Agriculture and Forestry, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Pheravut
authors.initials: P
authors.lastname: Wongsawad
authors.affiliation: Faculty of Science, Srinakharinwirot University, Bangkok 10110, Thailand.
authors.forename: Apirada
authors.initials: A
authors.lastname: Sathapattayanon
authors.affiliation: Institute of Agriculture and Forestry, University of Tsukuba, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Natsuko
authors.initials: N
authors.lastname: Tajima
authors.affiliation: School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan.
authors.forename: Shunichiro
authors.initials: S
authors.lastname: Suzuki
authors.affiliation: School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan.
authors.forename: Saki
authors.initials: S
authors.lastname: Kitamura
authors.affiliation: School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan.
authors.forename: Nao
authors.initials: N
authors.lastname: Shioda
authors.affiliation: School of Agriculture, Meiji University, Kawasaki, Kanagawa 214-8571, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Handa
authors.affiliation: School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Kitanaka
authors.affiliation: School of Pharmacy, Nihon University, Funabashi, Chiba 274-8555, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Iijima
authors.affiliation: Tsukuba Botanical Garden, National Museum of Nature and Science, Tsukuba, Ibaraki 305-0005, Japan yukawa@kahaku.go.jp.
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Yukawa
keywords: Dendrobium; ITS; Orchidaceae; evolution; matK; phylogeny; systematics; taxonomy.
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