Systematics Section / ASPT
Motley, Timothy J. , Raz, Lauren .
Origins, Evolution, and Systematics of Hawaiian and Pacific Chamaesyce (Euphorbiaceae).
The genus Chamaesyce consists of approximately 250 species with a cosmopolitan distribution. The genus is best represented in the New World (ca. 80% of the species) and exhibits the highest amount of species diversity in Mexico. There are 22 species of Chamaesyce in the Hawaiian Islands. Fifteen species are endemic to the archipelago and seven are thought have been introduced and have become naturalized. The Hawaiian endemics are semi-woody to arborescent taxa that were reputed derived from a single ancestor of the Pacific C. fosbergii complex. Molecular analysis of nucleotide sequence data from the nrITS regions were used to examine relationships among Hawaiian and Pacific species. Species sampled in this study included 14 of the endemic Hawaiian species, multiple accessions of C. fosbergii (= C. atoto), Marquesas, Austral, and Galapagos Island species, and various taxa from the southwestern United States, Mexico, and the Caribbean. Based on the species included in this study: (1) the Hawaiian taxa represent a monophyletic lineage resulting from a single colonization event, most likely from the New World; (2) there have been at least two additional introductions from the New World to account for the endemic French Polynesian taxa; (3) woodiness has evolved several times in island taxa; and (4) the character (lack of the glandular appendages) which traditionally separated the subsection Gymnadeniae (Hawaiian taxa) from the rest of section Sclerophyllae is no longer a synapomorphy defining the Hawaiian taxa or the subsection.
1 - New York Botanical Garden, Cullman Program for Molecular Systematics Studies, 200th St. & Southern Blvd., Bronx, New York, 10458-5126, USA
Presentation Type: Paper
Location: Cottonwood A (Snowbird Center)
Date: Wednesday, August 4th, 2004
Time: 10:15 AM