1997 Fiscal Year Final Research Report Summary
Population-genetic researches on the speciation and extinction of the freshwater prawn Macrobrachium.
| Project/Area Number |
07640850
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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 |
生態
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| Research Institution | Teikyo University |
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Principal Investigator |
MASHIKO Kazuo Teikyo University, Department of Literature, Associate Professor, 文学部, 助教授 (00082321)
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| Project Period (FY) |
1995 – 1997
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| Keywords | Macrobrachium / Speciation / Allozyme analysis / Gene flow / Freshwater prawn / Population-genetics / Parallel evolution / Egg size |
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| Research Abstract |
In 28 local populations of palaemonid prawn Macrobrachium nipponense with different-sized eggs, allozyme and morphometry investigations were undertaken in order to elucidate the process of differentiation. The two groups of populations with large eggs, which occur specifically in the separate limnetic systems of central and northern mainland Japan, were distinctly different in their rostrum spine counts and allozyme gene frequencies, implying that they have originated independently form ancestral estuarine populations with small eggs. Similar situations were recognized for some populations with medium-sized eggs. Geological background suggests that the evolutionary changes of egg size took place very recently in the Holocene. Estuarine small-egg populations are considered to maintain genetic circulation over a wide geographic range through the sea current (Kuroshio) -mediated larval dispersal. The genetic diversity of population (average heterozygosity) remarkably declined in the medium and large-egg populations in isolated limnetic systems.
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