Systematics/Phytogeography / Taxonomie/ Section
Ye, Tun Tun , Javadi, Firouzeh , Yamaguchi, Hirofumi .
Phylogenetic relationships and biogeography within the subgenus Ceratotropis (Leguminosae) based on the four plastid non-coding region sequences.
The subgenus Ceratotropis is the most economically important group in the genus Vigna (Leguminosae) which distributes a wide area in South Asia, the Himalayan highlands, South East Asia, and East Asia. Its 21 species inhabit coastal sandy soil, limestone hills, forest margins, and open fields. East Asian and South East Asian species of subgenus Ceratotropis (i.e., V. angluaris, V. nakashimae, and V. tenuicaulis) occur in temperate and subtropical regions, while Indian subcontinental species (V. mungo, V. radiata, and V. grandiflora) are mainly confined to the tropical region. Yet despite this pattern, the phylogenetic and geographical relationships of the taxa within the subgenus were poorly understood, owing to low levels of sequence variation detected in previous studies, coupled with relatively limited species sampling from different geographical regions. This study represents phylogenetic analysis of the subgenus inferred from the four plastid (psbD-trnT, trnT-trnL, trnT-trnE, and petA-psbJ) DNA intergenic spacer regions using parsimony and Bayesian methods. In the absence of any fossil data for calibration, absolute rate of nucleotide substitution of cpDNA was used to estimate divergence time. Our results clearly indicate geographical and ecological relationships within subgenus Ceratotropis and that the 18 Vigna species fall into the two geographical groups (Indian subcontinent and East Asia-South East Asia group) and three eco-geographical subgroups (tropical subgroup, subtropical subgroup, and temperate subgroup). The estimated divergence time between Indian subcontinent and East Asia-South East Asia group (4.2 mya) was younger than that of Tibetan uplift (8 mya or 15 mya), suggesting the diversification within the subgenus Ceratotropis might be associated with climatic changes during the glacial ages after the collision of Indian subcontinent and Asian plate. The evolution of seedling germination type and other taxonomic diagnostic trait will be discussed in the phylogenetic framework.
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1 - Osaka Prefetcure University, Graduate School of Life and Environmental Sciences, Sakai, Osaka, 599-8531, Japan
2 - Osaka Prefecture University, Graduate School of Life and Environmental Sciences, Sakai, Osaka, 599-8531, Japan
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM