2006 Fiscal Year Final Research Report Summary
The origin and evolution of deep-sea animals : phylogenetic analysis of deep-sea mussels
| Project/Area Number |
16570186
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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 |
Evolutionary biology
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| Research Institution | University of Yamanashi (2005-2006)
University of Tsukuba (2004) |
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Principal Investigator |
MIYAZAKI Jun-ichi University of Yamanashi, Faculty of Education and Human Sciences, Associate Professor, 教育人間科学部, 助教授 (80229830)
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| Co-Investigator(Kenkyū-buntansha) |
FUJIWARA Yoshihiro Japan Agency for Marine-Earth Science and Technology, Research Program for Marine Biology and Ecology, Research Scientist, 海洋生態環境研究部, 研究員 (20344294)
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| Project Period (FY) |
2004 – 2006
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| Keywords | chemosynthesis-based community / whale-fall community / hydrothermal vent / cold-water seep / speciation / dispersion / vicariance / symbiotic bacteria |
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| Research Abstract |
Bathymodiolus mussels are one of the major macroorganisms in the chemosynthesis-based community of deep-sea hydrothermal vents and cold-water seeps. We aimed in this study to gain insights into 1) the adaptability and dispersal ability of Bathymodiolus mussels and factors to promote and inhibit their speciation, 2) the origin and adaptation to deep sea of Bathymodiolus mussels, 3) coevolution of Bathymodiolus mussels and their symbiotic bacteria.
Our study revealed, based on nucleotide sequences of mitochondrial genes, that most of mytilid mussels obtained from whale carcasses and sunken wood constituted an outgroup to Bathymodiolus mussels, and were more closely related to Bathymodiolus mussels than to shallow water mytilid mussels, supporting the evolutionary stepping-stone theory that proposes Bathymodiolus mussels evolved from the shallow water ancestor through whale carcasses and sunken wood mediators.
Our study also revealed that populations of B. platifrons did not genetically dif
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fer between hydrothermal vents and cold-water seeps, indicating the high adaptability of Bathymodiolus mussels to differentiated deep-sea environments. Two species, B. septendierum and B. brevior, did not differ genetically, although their habitats are about 5,000 km apart. These two Pacific species did not strikingly differ in DNA sequences from B. marisindicus of the Indian Ocean, although habitats of the latter are about 10,000 km apart from those of the two former species. This indicates the high dispersal ability of Bathymodiolus mussels.
Sequencing of the bacterial rRNA gene revealed that grouping of symbionts was roughly consistent with that of their hosts, suggesting coevolution of endosymbionts and Bathymodiolus mussels. Electron microscopy revealed that two species of mytilid mussels from whale carcasses had different types of symbiosis. Adipicola crypta harbored intracellular symbionts as in Bathymodiolus mussels and A. pacifica, extracellular symbionts. This indicates the acquisition of symbiosis and transition of symbiotic types on the whale carcasses during adaptation to deep sea. Less
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Research Products
(4 results)
