Miryeganeh, Matin , Kajita, Tadashi .
Population genetic study of a pantropical plant with sea-drifted seeds: Ipomoea pes-caprae using single copy nuclear genes.
"Pantropical Plants with Sea-drift Seed" (PPSS) are plants that exhibit remarkably wide distribution range in the tropical and subtropical areas in the world. One of the representative species of PPSS is Ipomea pes-caprae (L.) R. Br. (Convolvulaceae). It has extremely wide distribution range that spread over the littoral areas of tropics of the five continents. According to the work of Sir St. John, two subspecies are included in the species: ssp. pes-caprae that is distributed in the northern part of Indian Ocean (Arabia to Indonesia), and ssp. brasiliensis (L.) Ooststr. in the remaining parts. The wide distribution range of the species is thought to be accomplished by its seeds that can float on sea-water and transferred by the ocean current. Although the fact that the seeds of this species are conveyed by sea currents is apparent, the history of migration between populations has not well understood. Wakita, et al. (unpublished), revealed phylogeographic structure of this species using AFLP analysis. He detected 3major barriers to gene flow in distribution range of Ipomea pes-caprae. But, the AFLP data did not allow the reconstruction of genealogies and estimate historical relationships among populations. By using single copy nuclear markers, it is expected that we can elucidate more precise geographic structure of the species, and hopefully,the history of population expansion over the globe. We used samples collected from the four geographic regions as were same as the previous AFLP study: East pacific, West Pacific, Atlantic Ocean and Indian Ocean. By now we conducted sequencing of 8 nuclear genes (ca. 5,000 bp, namely Waxy, HSP-90, TPI and Cam; PCR products of which were around 500 bp; and Chs,UF3GT and beta amylase with PCR products of around 700 bp; and an EST marker which amplifies around 400 bp. 272 samples were collected from 34 populations that almost cover the entire distribution range. The haplotype distribution of these markers revealed the presence of two distinct haplotypes in Indo-west Pacific and Atlantic- Pacific regions. This result suggests gene flow over different oceanic regions by long distance dispersal of sea-drifted seeds by oceanic currents. Moreover, our results suggests clear genetic differentiation of the two subspecies. We also didn't find any genetic structure over the Isthmus of Panama which was detected as biggest barrier byAFLP. We will apply an Isolation with Migration (IM) model to test the significance of genealogical history between populations
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1 - Chiba University, Department of Biology, Graduate School of Science, 1-31 Yayoi-Cho, 283-8522, Japan
long distance dispersal
Single/low copy nuclear genes.
Presentation Type: Poster:Posters for Topics
Location: Battelle South/Convention Center
Date: Monday, July 9th, 2012
Time: 5:30 PM