| Project/Area Number |
09839044
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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 |
自然史科学
|
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| Research Institution | National Institute of Genetics |
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Principal Investigator |
HATTA Masayuki National Institute of Genetics, Developmental Genetics, Assistant Professor, 個体遺伝研究系, 助手 (00249947)
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| Project Period (FY) |
1997 – 1999
|
| Project Status |
Completed (Fiscal Year 1999)
|
| Budget Amount *help |
¥2,900,000 (Direct Cost: ¥2,900,000)
Fiscal Year 1999: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1998: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 1997: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | Acropora coral / mass-spawning / hybridization / gene introgression / speciation |
|---|
| Research Abstract |
Crossing experiments were carried out systematically using mass-spawning corals of the genus Acropora in Okinawa, Japan. Interspecific fertilization was observed in specific combinations of species, even between species that have very different morphologies. The correlation of fertilization specificity and morphological types suggests that the hybridized species cannot be regarded as morphological variants within a shingle species. The Mendelian transmission of the mini-collagen alleles revealed that the offspring produced in experimental crosses are really hybrids. Molecular phylogenetic analysis of the mini-collagen gene, rDNA and histone gene clusters suggested the species were divided to three related groups. Within the groups, the genetic relationships of the species are intermixed and hybridization was observed. These characteristics are explained by interspecific gene introgression via the hybrids produced by mass spawning, and are consistent with the concept of a species complex under the processes of the fusion of multiple species.
Surveyrance of alternative reproductive behaviors and genetic relationships suggested sympatric speciation by shifting spawning timing from mass-spawning as an alternative mechanism of speciation in sympatric Acropora corals.
PhyIogeny of the coral family Acroporidae based on mitochondria genes suggested that divergence of extant species in each genus is recent events after extinction during palaeoclimatic changes. And mass-spawning appeared the ancestral reproductive behavior.
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