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Systematics Section / ASPT

Wen, Jun [2], Lee, Chunghee [1], Plunkett, Gregory [3], Lowry II, Porter [4].

Evolution of Araliaceae in Asia: inference from the ITS, ndhF, trnL-F, and morphological data.

Araliaceae in Asia consist of about 25 genera, representing 50% of the generic diversity and over 35% of the known species diversity of the family. We sampled over 70 species of Araliaceae, especially the Asian taxa with three molecular markers: the nuclear ribosomal ITS, and the chloroplast ndhF and trnL-F regions (4014 aligned nucleotide positions). Our three-marker analysis supports the monophyly of each of the three major clades within the family: the Aralia Panax clade, the Asian core clade, and the Pseudopanax Polyscias clade. The first two of the three major clades are largely distributed in Asia, although the more basally branching members of the family are in Australasia. The Asian core clade consists of 20 genera with a wide distribution throughout the continent ranging from the tropics to the cold temperate zone. Little resolution was detected at the deep nodes of the Asian clade in all analysis: (1) the ITS sequences alone, (2) the cpDNA sequences alone, and (3) the combined data. The lack of resolution was due to the lack of characters, suggesting a rapid radiation in the early history of the clade. Fossil and molecular estimates suggest that the radiation dates back to 60 million years ago at the Cretaceous/Paleocene boundary. Asia possesses many ancient genera, although many of these old genera have young species, e.g., in Brassaiopsis, Eleutherococcus, and Oplopanax. Morphologically the Asian clade is highly diverse and there are no obvious synapomorphies for the group. The radiation was perhaps facilitated by the broad ecological diversity of taxa of the clade in Asia. The key adaptation of an earlier radiation in Araliaceae is herein hypothesized to be the berries, which are easily dispersible via long or short distance. Berries perhaps facilitated the successful colonization/radiation of Araliaceae into diverse geographic areas and habitats in Asia.

1 - University of California, Botany and Plant Sciences, Riverside, California, 92521
2 - Field Museum, Botany Department, 1400 S. Lake Shore Dr., Chicago, Illinois, 60605-2496, USA
3 - Virginia Commonwealth University, Department of Biology, P.O. Box 842012, Richmond, Virginia, 23284-2012, USA
4 - Missouri Botanical Garden, PO Box 299, St. Louis, Missouri, 63166-0299, USA

evolutionary radiation
key adaptation.

Presentation Type: Paper
Session: 28-14
Location: Cottonwood A (Snowbird Center)
Date: Tuesday, August 3rd, 2004
Time: 11:30 AM
Abstract ID:868

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