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Systematics Section / ASPT

Jarrell, David C. [1], Janelsins, Brian M. [1], Hamed, Hossein H. [1].

A chloroplast phylogeny of Phalaenopsis (Orchidaceae) based on multiple sequences.

Phalaenopsis is a well known member of the Orchidaceae tribe Vandeae subtribe Aeridinae. A recent circumscription of the genus divides the roughly 63 described species into five subgenera with two of these further divided into four sections each. These divisions are based largely on various aspects of the labellum and the column, the highly modified petal and reproductive structure, respectively, of the orchid family. Like many organisms, Phalaenopsis are difficult to classify into a “natural” system that represents evolutionary relationships. This is presumed to be largely an effect of convergent evolution brought about by chance (genetic drift) or pollinator selection. Given that pollinators are directly engaged with exactly the structures used in classification, an independent source of information is needed to develop a robust phylogeny and, potentially, a more evolutionarily accurate classification. Our first step in this process is to develop a chloroplast phylogeny based on several rapidly evolving regions. The sequences of matK, the accD-psaI spacer and the rps16 intron have been sequenced from more than half of all species including representatives from all subgenera and sections. Preliminary analysis based on single regions supports the conclusion of a recent monograph that the genera Doritis and Kingidium be moved to synonymy with Phalaenopsis. Of the most well sampled subgenera, only subgenus Polychilos appears monophyletic while its sections are not. The subgenus Phalaenopsis is not monophyletic while certain of it sections including those whose species have been most commonly used in hybridizing do form a monophyletic group. Phylogenetic analyses of single and combined region data using both nucleotide substitutions and length polymorphisms will be presented. In addition, morphological characters will be discussed in light of the molecular phylogenies.


1 - Mary Washington College, Biological Sciences, Jepson Science Center, 1301 College Av., Fredericksburg, Virginia, 22401, USA

Keywords:
chloroplast DNA sequence
matK
Orchidaceae
Phalaenopsis
phylogeny
rps16 intron
accD-psaI spacer.

Presentation Type: Paper
Session: 2-13
Location: Cottonwood A (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 11:15 AM
Abstract ID:848


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