| Project/Area Number |
16380125
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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 |
General fisheries
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| Research Institution | Hokkaido University |
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Principal Investigator |
MUNEHARA Hiroyuki Hokkaido University, Field Science Center for Northern Biosphere, Associate Professor, 北方生物圏フィールド科学センター, 助教授 (80212249)
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| Co-Investigator(Kenkyū-buntansha) |
YABE Mamoru Hokkaido University, Faculty of Fisheries Sciences, Professor, 大学院水産科学研究院, 教授 (80174572)
IMAMURA Hisashi Hokkaido University, The Hokkaido University Museum, Associate Professor, 総合博物館, 助教授 (00312421)
HAYAKAWA Youichi International Christian University, Division of Natural Sciences, Researcher, 教養学部, 研究員 (50384011)
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| Project Period (FY) |
2004 – 2006
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| Project Status |
Completed (Fiscal Year 2006)
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| Budget Amount *help |
¥15,600,000 (Direct Cost: ¥15,600,000)
Fiscal Year 2006: ¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 2005: ¥5,600,000 (Direct Cost: ¥5,600,000)
Fiscal Year 2004: ¥6,800,000 (Direct Cost: ¥6,800,000)
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| Keywords | substrate preference / habitat isolation / mtDNA markers / hexagramidae / artificial construction / crossbreeding / breeding territory / gene introgression / 産卵基質 / ミトコンドリアDNA / 分布 / 生殖的隔離 / 卵保護 |
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| Research Abstract |
In hexagramids, one boreal species (Hexagrammos octogrammus) and two temperate species (H.otakii and H.agrammus) are distributed in the coast of Japan, and crossbreeding among the three species is known to occur. This study was conducted to clarify what ecological factors involve in the crossbreeding.
1.The preference of spawning substratum differed among the three species. In natural habitats, H.otakii occurred deeper than the other two species which preferred to seaweed. On the other hand, the three species established concurrently their breeding territory in the artificial area.
2.H.octogrammus females were observed in the spawning area of H.otakii on breaker zone, and hybrids were often observed near the artificial fish reefs. It was possible to discriminate visually the eggs of H.otakii from the other two species because of difference of egg-coloration. Several egg masses of H.octogrammus or H.agrammus were often deposited in the H.otakii terrirories.
3.Polymorphism of mtDNA enables to discriminate what species deposited the egg masses in the territory of H.otakii. 40% of the egg masses deposited in H.otakii territories was crossbreeding, and mother of all of them was H.octogrammus. 1.9% of the egg masses in H.agrammus territories were deposited by H.octogrammus. No eggs of H.otakii were observed in the other species territory. This uni-direction hybridization showed that gene introgression from H.octogrammus into H.otakii is proceeding through crossbreeding.
4.80 individuals of hybrid and backcross were collected during this study. Sex of all the fishes was female. To clarify this sexual bias FISH method and survival experiments of embryos were conducted. FISH method denied a possible of gynogenesis of hybrid, and there was no significant difference the survival rates of between purebred embryos and crossbred ones. These results suggested that genetic males exist at least just after hatching.
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