| Project/Area Number |
08304041
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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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 | KYOTO UNIVERSITY |
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Principal Investigator |
HORI Michio Department of Zoology, Kyoto University, Professor, 大学院・理学研究科, 教授 (40112552)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Satoshi Department of Mathematics, Osaka University, Associate Professor, 理学部, 助教授 (70226835)
MATSUDA Hiroyuki Marine Research Institute, University of Tokyo, Associate Professor, 海洋研究所, 助教授 (70190478)
KOHDA Masanori Department of Biology, Osaka City University, Professor, 理学部, 教授 (70192052)
YUMA Masahide Center of Ecological Research, Associate Professor, 生態学研究センター, 助教授 (80240828)
YAMAOKA Kosaku Usa Marine Biological Institute, Kochi University, Professor, 海洋生物教育研究センター, 教授 (20200587)
西田 睦 福井県立大学, 生物資源学部, 教授 (90136896)
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| Project Period (FY) |
1996 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1998: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 1997: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | laterality / Lake Biwa / frequency-dependent selection / fish community / polimorphism / prey-predator relationship / Lake Tanganyika / species interaction / カンガニイカ湖 |
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| Research Abstract |
1. The examination on samples from Lake Biwa has turned out as follows. In most species the ratio of laterality (the ratio of sinistral individuals in population) changed yearly suggesting a oscillation with an amplitude 0.3 to 0.7 and a period of about 5 years. The oscillation seemingly synchronizes among species of same or similar feeding habit. These results coincide with that from Lake Tanganyika, In the native predator, the piscivorous chub, and its main prey, Ayu fish, the ratio of laterality oscillate in a characteristic way for 4-year survey period, suggesting that the dynamics of laterality were driven by prey-predator interaction in the community.
These results suggest that the oscillations are also caused through the interspecific relationship among fish species in a community. Especially, prey predator relationship may be the most responsible to the incidence of the oscillation, because frequency dependent vigilance of prey fish against predators and the resultant minority a
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dvantage among predators are one of the most reliable and probable mechanisms to maintaining the polymorphism in animal populations.
2. The genetic system of the laterality was examined in laboratory rearing using a lizard goby. The result strongly suggests that the laterality in determined by a Mendelian one locus - two alleles system, in which dextrality is dominant over sinistrality, but the homozygote of dextrality seems to be lethal.
3. The results from the investigation using mathematical models are as follows. If two competing species have the lateral asymmetry polymorphisms, with their frequencies not oscillating, the polymorphisms will be lost as a consequence of random genetic drift. If the frequencies of lateral asymmetry polymorphisms are oscillating, it diminishes the difference of the sinistral frequencies of both of species, and maintains the lateral asymmetry polymorphisms in species.
The oscillation of the lateral asymmetry polymorphisms contributes to the coexistence or the exclusion of competing species, if their growth periods are different. When the difference is small, the species with longer growth period will extinct. When the difference is large, the oscillation makes both species coexist. Less
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