Systematics Section / ASPT
Kim, Seung-Chul , Lee, Namsook .
Generic delimitation and biogeography of Maianthemum and Smilacina (Convallariaceae): preliminary results based on chloroplast noncoding sequences.
THE relationship between Maianthemum and Smilacina has long been controversial as regards generic delimitation. Smilacina is comprised of 25 species of perennial herbs distributed in eastern Asia, North America, and Central America. They display the typical tri-merous flowers of the Liliaceae. Maianthemum, in contrast, consists of three species with di-merous flowers occurring in eastern Asia, northern Europe, and North America. Several attempts to combine the two genera have been made since the 1800's. Recently, LaFrankie (1986) acknowledged no entirely unique feature, other than the number of floral parts, in each genus and consequently combined them. Subsequent molecular phylogenetic studies were conducted to test this circumscription, but were based on very limited and inadequate sampling, including the absence of several critical species that are morphologically intermediate between the two genera. To test LaFrankie’s generic delimitation and to broaden understanding of the biogeographic patterns of these groups, we sequenced the partial 3’ matK gene and trnK 3' intron of chloroplast DNA for 38 accessions, representing three species of Maianthemum, seven species of Smilacina, and four outgroup taxa. Maximum parsimony and neighbor-joining trees show reciprocal monophyly of the two genera. Within each genus, relationships among species were poorly resolved and showed low bootstrap values. Despite the low resolution, this study demonstrates that east Asian species of Smilacina and Maianthemum are generally more closely related to taxa in eastern, not western, North America. The divergence of Maianthemum sensu lato from Polygonatum is estimated to have occurred in the late Oligocene, while the intercontinental spread of taxa is estimated to have been during the late Miocene and approximately 650,000 years ago.
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1 - University of California Riverside, Department of Botany & Plant Sciences, Riverside, California, 92521-0124, USA
2 - Ewha Womans Univesrsity, Division of Molecular and Life Sciences, 11-1 Daehyun-dong, Seodaemun-gu, Seoul, 120-750, Korea
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 9:45 AM