2003 Fiscal Year Final Research Report Summary
Studies on the evolution of characters in the cephalochordates, based on molecular trees of many living species over the world
| Project/Area Number |
13440253
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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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 Nagoya University, The Nagoya University Museum, Professor, 博物館, 教授 (50126885)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIDA Mutsumi University of Tokyo, Ocean Research Institute, Professor, 海洋研究所, 教授 (90136896)
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| Project Period (FY) |
2001 – 2003
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| Keywords | Cephalochordata / Branchiostoma / Epigonichthys / mitochondrial DNA / cryptic species / phylogeny / evolution / characters |
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| Research Abstract |
We have analyzed the whole mitochondrial genomes of far more than the half of the samples gained during the present project (24 populations of 15 species over the world) and got many important results as follows :
(1) The uniqueness of Epigonichthys lucayanus has been revealed.
(2) Paraphyly of the genus Epigonichthys has been proved, with the deepest branching between E.lucayanus (and its cryptic species, see below) and the remaining (consisting of its congeners and the species of the other recognized genus Branchiostoma) ; thus the Cephalochordata has proved to be divided into the three (instead of the two in the present system) genera.
(3) E.lucayanus has been found to contain two species, which are indistinguishable morphologically from each other.
(4) Molecular data of the European lancelet, Branchiostoma lanceolatum registered in the data bank of molecular information has been revealed quite different from our analyses of the same species from Helgoland and Napoli, instead similar to that of B.floridae from Florida ; this discrepancy is attributable to mis-identification of the data in the bank.
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