| Project/Area Number |
12440215
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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 |
生態
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| Research Institution | Tohoku University |
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Principal Investigator |
KAWATA Masakado Graduate School of Life Science, Professor, 大学院・生命科学研究科, 教授 (90204734)
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| Co-Investigator(Kenkyū-buntansha) |
SHIMADA Masakazu University of Tokyo, Graduate School of System Sciences, Assistant Professor, 大学院・総合文化研究科, 助教授 (40178950)
YOKOYAMA Jun Graduate School of Life Sciences, Assistant Professor, 大学院・生命科学研究科, 助手 (80272011)
CHIBA Satoshi Graduate School of Life Sciences, Assistant Professor, 大学院・生命科学研究科, 助教授 (10236812)
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| Project Period (FY) |
2000 – 2002
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| Project Status |
Completed (Fiscal Year 2002)
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| Budget Amount *help |
¥15,300,000 (Direct Cost: ¥15,300,000)
Fiscal Year 2002: ¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 2001: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2000: ¥8,600,000 (Direct Cost: ¥8,600,000)
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| Keywords | density dependence / habitat structure / population fluctuation / freshwater snails / 密度依存的性質 / 遺伝的構造 / 淡水産巻貝 |
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| Research Abstract |
We examined the growth and reproductive rates of freshwater snails, Physa acuta, in two habitat types. In the Asabata habitat, snails lived in isolated water pools, which occasionally joined to form a single large pool ; in the Kakegawa habitat, they lived in a slow-running water way. Genetic structure assessments using three microsatellite loci supports the idea that a stable panmictic population occupies the Kakegawa habitat ; whereas alternate mixing populations, with individuals interacting and reproducing within patches, but occasionally mixing within a large global population, occupy the Asabata habitat. Laboratory experiments, using snails collected from the two habitats, showed that juvenile snails grew faster, laid more eggs, and laid them earlier in the Asabata habitat than in the Kakegawa habitat. Growth rates were lower at high density than at low density in the Kakegawa habitat ; the inverse was true in the Asabata habitat. Density-dependent response of individual snail reproduction was the same for the two habitats. The results support the hypothesis that spatial structure affects the evolution of density-dependent growth rates and of timing for reproduction.
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