1997 Fiscal Year Final Research Report Summary
Long-term dynamics of dimorphism in salmonid fishes in changing environment
| Project/Area Number |
08454246
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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 | HOKKAIDO UNIVERSITY |
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Principal Investigator |
MAEKAWA Koji Hokkaido University, Fac of Agr.Aso.Prof., 農学部・附属演習林, 助教授 (80002301)
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| Co-Investigator(Kenkyū-buntansha) |
NAKANO Shigeru Hokkaido University, Fac.of Agr.Asoc.Prof., 農学部・附属演習林, 助教授 (50217791)
GOTO Akira Hokkaido University, Fac.of Fish., Asoc.Prof., 水産学部, 助教授 (30111165)
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| Project Period (FY) |
1996 – 1997
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| Keywords | slmonid fishes / mature male parr / body size / sexual selection / finger printing DNA / reproductive success / changing environment |
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| Research Abstract |
1.The factors that affect reproductive behavior and success of precocious male parr in masu salmon, Oncorhynchus masou, were examinsd under experimental conditions.
2.Unlike other salmonid fishes, masu salmon parr were rarely attacked by dominant migratory males. Parr engaged in interactions among themselves to get close to the nest. As a result, the difference in the proximity to the nest resulted in the difference in average sneaking success at a nest.
3.The multivariate regression analyzes revealed selection favoring larger body size for gaining more proximate positions to the nest. A possible consideration is that an optimal body size exists for parr through natural and sexual selection within parr and between parr and migratory males.
No selection on the other morphological characters was detected. Since migratory males having longer snout and larger hump can acquire higher reproductive success, the evolutionary demands on parr might be different from that on migratory males.
4.In miyabe charr, fertilization success of mature male parr was measured by using finger printing DNA.The more numerous the number of mature male parrs, the higher the total fertilization success, but fertilization success per individual decrease. This suggest that existence of refuge around spawning ground plays an important role for life time reproductive success of mature male parr.
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