Systematics/Phytogeography / Taxonomie/ Section
Kim, Young-Dong , Kim, Sung-Hee , Lim, Yongseok , Hyun, Chang-Woo , Oh, Sang-Hun , Shin, Hyunchur .
Molecular evidence for diploid hybrid origin of Aster chusanensis, an endemic species of Ulleung Island, Korea.
Aster chusanensis is an endemic species of Ulleung Island, a small volcanic island that lies between Korea and Japan. Ulleung Island presents many examples of autochthonous evolution of insular taxa such as A. chusanensis, but speciation and diversification of the endemic plants of the island is poorly understood. Based on the morphology of head and involucre, A. chusanensis has been postulated as a hybrid between sympatric species, A. oharae (2n=18) and A. pseudoglehnii (2n=18), both of which are also endemic to the island. We have sequenced the ITS regions and three regions of chloroplast DNA (trnL-F, rbcL-accD, and psbA-trnH) from A. chusanensis (8 individuals), A. oharae (34 individuals), A. pseudoglehnii (31 individuals), and closely related species distributed in Korea and Japan. ITS sequences from A. chusanensis, obtained via two replications of PCR and cloning procedures producing 20 clones per individual, displayed an extraordinarily high level of intragenomic polymorphisms, whereas those from the parental species showed no or little variation within and among individuals. Of the 160 ITS clones, 50% of the sequences was identical to one of four ITS types of A. oharae, 20% was identical to the single type of A. pseudoglehnii, and 30% was apparent recombinants of the parental sequences. The retention of both parental ITS types in the genomes of the hybrid individuals suggest the hybridization has occurred recently in the island. Chromosome counts revealed that A. chusanensis has 2n=18, suggesting that it is of diploid hybrid origin. The chloroplast DNA data indicate that most of the hybrid individuals inherit the plastid from A. pseudoglehnii except for one plant with the plastid of A. oharae, implying multiple but biased hybridization events between the parental taxa. Results of this study suggest that hybridization is an important process in the evolution of indigenous plants in an island.
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1 - Hallym University, Department of Life Science, Chuncheon, Gangwon, 200-702, S. Korea
2 - Hallym University, Institute of Natural Sciences, Chuncheon, Gangwon, 200-702, S. Korea
3 - Soonchunhyang University, Department of Biology, Asan, Chungnam, 336-745, S. Korea
4 - Cornell University, L.H. Bailey Hortorium, Department of Plant Biology, Ithaca, New York, 14853, USA
Presentation Type: Poster:Posters for Sections
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM