LEE, CHUNGHEE* and JUN WEN. Department of Botany, Field Museum of Natural History, 1400 S. Lake Shore Dr., Chicago, IL 60605. - Phylogeny and biogeography of the Asian clade of the core Araliaceae: insights from the nuclear ribosomal and chloroplast DNA data.
The Asian clade of the core Araliaceae consists of 20 genera with a
wide distribution in eastern and South Asia and the Himalayan region.
The phylogeny of the clade was constructed with sequences of the
nuclear ribosomal ITS regions and the chloroplast ndhF gene. The
sampling scheme of the study included all genera, 75-100% of species
in smaller genera (those with 1-10 species), and broad representatives
to cover the morphological diversity of larger genera (those with more
than 10 species). The ITS and ndhF phylogenies produced congruent
topologies. With few exceptions, most genera of the Asian clade were
supported to be monophyletic. Strong support was observed for several
clades of closely related genera, e.g., the Brassaiopsis-Trevesia
clade, the Macropanax-Metapanax clade, and the Chengiopanax-Gamblea
clade. However, the two molecular markers showed little resolution for
the deeper nodes, which had relatively short branch lengths. The
phylogenetic pattern observed in the Asian clade of the core Ariaceae
suggests rapid evolution in the early diversification of the Asian
clade. The highly diverse ecological habitats and a wide geographic
region occupied by taxa of this Asian clade may have driven the rapid
evolution of major lineages within this clade.
Key words: Araliaceae, Asia, ITS, ndhF, rapid evolution