2000 Fiscal Year Final Research Report Summary
Speciation and phylogeny of the lancelet, Branchiostoma belcheri (Gray) in East Asian waters, as viewed from molecular and morphological analyses
| Project/Area Number |
11640694
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
系統・分類
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| Research Institution | Nagoya University |
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Principal Investigator |
NISHIKAWA Teruaki The Nagoya University Museum, Nagoya University, Professor, 博物館, 教授 (50126885)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIDA Mutsumi Ocean Research Institute, University of Tokyo, Professor, 海洋研究所, 教授 (90136896)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Branchiostoma belcheri / genetic differentiation / C01 / 16SrRNA / mitochondrial genome / Japan / Pacific / Atlantic |
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| Research Abstract |
1. Allozyme analysis for the 3 Japanese local (Enshu-nada Sound, Seto Inland Sea, and Amakusa) populations of Branchiostoma belcheri, revealed statistically significant differences among them at 5 out of 9 polymorphic loci. However, the smallness of the overall value of Fst (0.007) indicates that there should be a certain degree of genetic exchanges among the populations.
2. Molecular phylogenetic studies based on nucleotide sequences of mitochondrial cytochrome C oxidase subunit I (C01) and 16S ribosomal RNA (16S rRNA) genes were performed for B.belcheri from Enshu-nada Sound, Gokasho Bay, Seto Inland Sea, Amakusa, Qingdao (North China), and Jimmnen Island, near Xiamen (South China) ; B.malayanum from Gulf of Thailand and Phuket ; Epigonichthys lucayanus (as an outgroup) from Okinawa, Japan ; E.maldivense (do.) from Taiwan ; and Atlantic B.floridae and B.lanceolatum, both cited from DDBJ.The results are :
(1) No significant differences were detected among all the analysed local populations of B.belcheri. It is unexpected because marked morphological differences have been recognized between Qingdao plus Japanese and Xiamen populations.
(2) In the neighbor-Joining trees among the six species based on the genetic distances in the C01 and 16S rRNA genes, the Pacific pairs (B.belcheri and B.malayanum) and the Atlantic ones (B.lanceolatum and B.floridae) were clustered each into a distinct group, with the branch lengths of the latter from the node of the cluster being much shorter than those of the Pacific.
(3) On the basis of the sequence data of C01 gene, the divergence time between the Atlantic and Pacific species about was measured ca. 110 million years ago and that the Branchiostoma and Epigonichthys species ca. 130 million years. In contrast, the divergence time between B.lanceolatum and B.floridae was estimated zero.
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Research Products
(2 results)
