Phylogenetics and conservation of the Genus Vanda (Orchidaceae)

• Main Author: Gardiner, Laura Maria
• Published: University of East Anglia 2007
• Subjects: 635.9344
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.446457

The most comprehensive molecular study of the genus Vanda Jones ex R. Br and closely affiliated taxa to date is presented here, greatly contributing to the understanding of this diverse genus, horticulturally important, yet threatened in the wild. Using sequence data from three chloroplast regions, it is shown that Vanda s. l. forms a monophyletic Glade containing approximately 70 species, including the genera Ascocentrum, Euanthe, Christensonia, Neofinetia, and Trudelia, and the species Aerides flabellata. Resolution of the relationships between these groups of species within Vanda s. I. is low and Ascocentrum and Neofinetia, with their distinctive morphological character sets, may form separate monophyletic and basal sister genera to the rest of the genus. Existing morphological classification systems for the genus Vanda are partially incongruent to the phylogenies produced, and some novel species relationships are revealed. A potential 'out of Asia' colonisation route for the genus and affiliated genera is inferred from the phylogeny and geographic distributions of taxa. A single morphologically diverse species from the genus, V. tricolor, is found to exhibit genetic and geographic structure across its range in Java and Bali, and is assessed in the context of a reintroduction programme taking place in Java. A hypothesised historical route of dispersal is inferred from the data, with the most recent common ancestor as being from the Philippines/Sulawesi region and estimated at having diverged into Java and Bali in the early Pleistocene era. A novel study of the relationship between genetic and geographic distances between species in selected orchid genera shows that a degree of phylogenetic signal is carried by present day distribution data. Very simple, non-specific data sources and basic methods are used to reveal this signal and future research in this area could provide a useful conservation tool for rapid assessment of phylogenetic relatedness of taxa