Abstract Detail

Ecological Section

Yamamoto, Takashi [1], Takayama, Koji [2], Nagashima, Reiko [1], Tateishi, Yoichi [3], Kajita, Tadashi [1].

Refugia might affect the genetic structure of a sea-dispersal plants: Vigna marina.

“Pantropical plants with sea-drifted seeds” are groups of littoral plants that  have extremely wide distribution ranges in tropics and subtropics of the world, and the distribution ranges are attributed to long distance seed dispersal by ocean currents. According to some recent studies using genetic markers, presence of genetic structures were revealed within the wide distribution range, and they were shaped by land masses, for example, Malay Peninsula, across which seed dispersal by ocean currents might have prevented. However, population differentiation within an oceanic region where no apparent land barriers were also suggested for some species. To clarify the factor that shaped the genetic structure of sea-dispersal plants within a oceanic region, we performed a phylogeographic study on one of “Pantropical plants with sea-drifted seeds”, Vigna marina (Burm.) Merr., which is a legume plant distributed across the Indo-West Pacific region. Previous study on this plant suggested genetic differentiation between populations of South East Asia and those from the South Pacific where no apparent land barriers were reported. To obtain detail pattern of haplotype distribution in this region, we used more than 100 individuals of V. marina from 17 populations collected over 10 countries, especially focusing on the South East Asia and South Pacific. We reconstructed phylogenetic trees based on the sequence data of two cpDNA inter-genic spacer regions, trnT-trnL and psbB-psbH, in total of 1262 bp. The distribution map of six haplotype groups recognized based on the tree confirmed the presence of genetic structure within the oceanic region. In addition, one major haplotype group dominated in the north-western populations of the study area, and the other one dominated in the south-eastern populations, and mixed populations of the two haplotype groups were observed among them. This pattern of haplotype distribution may suggest the range expansion from the two isolated populations which were fixed into different haplotypes as were reported in phylogeographic studies in tree species. Considering the oceanic region from South East Asia to South Pacific, there were a big land mass connecting Australia and New Guinea about the last glacial maxima. The land mass might isolated two populations (refugia) which might be fixed one of the two different haplotype groups, then after the glacial period, they might have expanded their distribution by sea-dispersal, and formed mixed population. This study suggests that the glacial refugia might have played important role to shape the genetic structure even in a sea-dispersal plants. 

1 - Graduate School of Science, Chiba University, Department of Biology, Yayoi-cho 1-33, Inage-ku, Chiba-shi, Chiba, 263-8522, Japan
2 - The University of Tokyo, The University Museum, Hongo 7-3-1, Bunkyo-ku, Tokyo, 113-0033, Japan
3 - University of the Ryukyus, Faculty of Education, 1 Senbaru, Nishihara, Okinawa, 903-0129, Japan

Keywords:
Vigna marina
phylogeography
long-distance seed dispersal
coastal plant
land barrier
refugia.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PEC025
Abstract ID:621
Candidate for Awards:Ecological Section Best Graduate Student Poster