Systematics Section / ASPT
Fiaschi, Pedro , Plunkett, Gregory M. , Lowry, Porter P. II .
What do we know about Neotropical Schefflera (Araliaceae)?: a first molecular phylogenetic analysis.
Schefflera is the largest genus in Araliaceae (over 900 spp.), but earlier studies suggest that its current circumscription does not reflect evolutionary relationships. Instead, the genus appears to represent 5 unrelated lineages including Schefflera s. str. (8 spp.), and four geographically-centered clades: Melanesian (ca. 50 spp.), African-Madagascan (ca. 50 spp.), Asian (ca. 200-300 spp.), and Neotropical (as many as 300-400 spp.). The largest (Neotropical) clade, however, was represented by only 7 specimens in these earlier studies. Here, we present a phylogenetic study based on two molecular markers (nuclear ITS and plastid trnL-trnF) using an expanded taxon set of 50 specimens of Neotropical Schefflera to test further the monophyly of this group and explore relationships among its subgroups. Sequences of both markers (analyzed individually and in combination) provided strong support for the monophyly of Neotropical Schefflera. At the same time, subgeneric groups such as “Didymopanax,” “Cephalopanax,” and “Crepinella,” which can be easily recognized based on morphological features, also appear to be monophyletic within Neotropical Schefflera (although sampling at the subgeneric level is still very preliminary). The “Cotylanthes” group, however, was nested within “Sciodaphyllum,” confirming previous evidence for the non-monophyly of the latter. “Sciodaphyllum” has been defined as an “unspecialized” group within Schefflera, and in the Neotropics it comprises at least 200 species in as many as 20 morphological lineages ranging from southern Central America and the Caribbean to Andean South America. Among “Sciodaphyllum” species, this preliminary analysis suggests a close relationship between representatives from the Andean subgroup “Patulae” and the circum-Caribbean “Attenuatae” subgroup. Additional sampling across all five major groups of Neotropical Schefflera, with a special emphasis on the morphological and geographic ranges within “Sciodaphyllum,” are still required to gain a clear understanding of their phylogenetic relationships.
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1 - Virginia Commonwealth University, Department of Biology, P.O. Box 842012, Richmond, Virginia, 23284
2 - Missouri Botanical Garden, P.O. Box 299, St. Louis, Missouri, 63166
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM