Systematics Section / ASPT
Tronchet, Frédéric , Plunkett, GM , Jérémie, Joël , Lowry II, Porter P. .
Phylogeny of Meryta (Araliaceae) based on nuclear ribosomal ITS and ETS sequence data..
The genus Meryta J.R.Forst. & G.Forst. is characterized by simple leaves and a dioecious sexual system, a unique combination in Araliaceae. Recent phylogenetic analyses have placed Meryta in one of the three major clades recognized in the family, the Polyscias-Pseudopanax group, and more specifically in the Pacific Schefflera subclade. Meryta comprises ca. 30 arborescent species, all endemic to one or a few islands in the Pacific, with its center of diversity in New Caledonia (11 endemic spp.). Previous studies based on several molecular markers (ITS, trnL-trnF, matK, rbcL) have included only a very limited number of exemplars from Meryta. With an expanded sample representing nearly the entire genus, we present the results of analyses using sequence data from two nuclear ribosomal rDNA spacers (ITS and ETS). In Meryta, ETS evolves on average 1.45 times faster than ITS and provides good resolution at the species level. Separate and combined analyses of the ITS and ETS data confirm the monophyly of Meryta and strongly support its placement in the Pacific Schefflera subgroup. They also reveal several pairs or groups of closely related species within the genus (correlated with vegetative and reproductive morphology and geography). Our results further indicate that three segregate genera, Botryomeryta R.Vig., Schizomeryta R.Vig. et Strobilopanax R.Vig., are included within the Meryta clade. While it is not yet possible to identify the likely center of origin of Meryta, our findings suggest that colonization of the Pacific islands proceeded primarily through long-distance dispersal eastward from New Caledonia.
1 - Muséum National d'Histoire Naturelle, Systématique et Evolution, USM 0602 Taxonomie et Collections, 16, rue Buffon, Paris, 75005, France
2 - Virginia Commonwealth University, Department of Biology, P.O. Box 842012, Richmond, Virginia, 23284-2012, USA
3 - Missouri Botanical Garden, PO Box 299, St. Louis, Missouri, 63166-0299, USA
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 11:45 AM