Kajita, Tadashi , Takayama, Koji , Wakita, Norihisa , Tamura, Mariko , Vatanparast, Mohammad , Yoichi, Tateishi .
Phylogeography of Pantropical Plants with Sea-drifted Seeds.
"Pantropical Plants with Sea-drifted Seeds" are characterized by their vast distribution ranges over littoral areas of the tropics worldwide that may be achieved by dispersal of their sea-drifted seeds. A small number of such plants are known from divergent families. To clarify how the characteristic distribution patterns have been attained, we studied representative species: Hibiscus tiliaceus (Malvaceae), Canavalia rosea (Fabaceae), Rhizophora mangle (Rhizophoraceae), Ipomoea pes-caprae (Convolvulaceae), and so on. To obtain samples for phylogeographic studies, we have conducted field works over 27 countries for seven years. Using more than 1,000 samples obtained for each species, we performed various analyses by molecular markers to investigate genetic structures. Comparing results obtained from these species, several common phylogeographic patterns were revealed. First, analyses of chloroplast DNA sequences showed that a few common haplotypes distributed over very wide range, sometimes over different oceanic regions. Long distance seed dispersal by sea-drifted seeds would actually play an important role to maintain the extremely wide distribution range. Secondly, clear genetic structures were observed between populations over American continents or over East Pacific in several analyses. Both of the continental land mass and wide ocean space would be main barriers to prevent dispersal of sea-drifted seeds. Thirdly, gene flows between closely related species were revealed in several species. Secondary contact between species would be an important process for the speciation of "Pantropical Plants with Sea-drifted Seeds" and its allies.
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1 - Chiba University, Graduate School of Science, Depertment of Biology, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
2 - Chiba University, Graduate School of Science, Depertment of Biology, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan
3 - University of the Ryukyus, Faculty of Education, 1 Senbaru, Nishihara, Okinawa, 903-0129, Japan
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 28th, 2008
Time: 2:00 PM