| Co-Investigator(Kenkyū-buntansha) |
NAKANO Shigeru Hokkaido University, Fac.of Agr.Asoc., Prof., 農学部, 助教授 (50217791)
TAKADA Takenori Hokkaido tokai University, Dep.of Internat.Cult.Relat., Asoc.Prof., 国際文化学部, 助教授 (80206755)
MAEKAWA Koji Hokkaido University, Fac of Agr., Aso.Prof., 農学部, 助教授 (80002301)
NISHIDA Mutsumi Fukui Prefectural University, Fac of Biotechnol., Prof., 生物資源学部, 教授 (90136896)
GOTO Akira Hokkaido University Fac.of Fish., Asoc.Prof., 水産学部, 助教授 (30111165)
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| Research Abstract |
In order to clarify the extinction mechanism of freshwater fishes inhabiting in Japanese archipelago, we conducted ecological survey and genetic analysis. (1) For Dolly Varden (Salvelinus malma), analysis at the full archipelago level indicated a loss of 27.5,67.2,79.6 and 89.6% of the current geographic range, respectively, for a 1,2,3 and 4C increase in mean annal air temperature. The present distribution area of white-spotted char (s.leucomaenis) would likewise reduce by 4.1,20.5,33.8 and 45.6%, respectively. (2) Through the spawning season of landlocked charr living in honshu island, the most dominant males monopolized some mature females. This suggests a reduce of effective number of charr population (Ne). (3) In mitochondorial DNA analysis of ayu fish living in most southern island of Japanese archipelago, the fewer the individual number, the lower the genetic variation. (4) From mitochondorial DNA anlysis for land-locked river sculpin, Cottus nozawae, captured from 5 tributaries, Hokkaido, heterogeneities of allele and haplotype frequencies were significant between some tributary populations, suggesting that genetic differentiation has occurred between them. Thus, the low gentic variation and specified mating system may easily lead to extinction of some populations in these freshwater fishes (some species of landlocked trouts, isolated ayu fish and landlocked freshwater sculpins) following the change of environment.
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