2006 Fiscal Year Final Research Report Summary
Studies on gene flow and inbreeding depression in Magnolia stellata for its conservation
| Project/Area Number |
16380100
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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 |
林学・森林工学
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| Research Institution | Nagoya University |
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Principal Investigator |
TOMARU Nobuhiro Nagoya University, Bioagricultural Sciences, Professor (50241774)
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| Co-Investigator(Kenkyū-buntansha) |
ISHIDA Kiyoshi Forestry and Forest Products Research Institute, Kansai Research Center, Forest Ecology Group, Forest Ecology Group Leader(Researcher) (10343790)
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| Project Period (FY) |
2004 – 2006
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| Keywords | endangered species / gene flow / inbreeding depression / genetic structure / flowering phenology / pollen limitation / inbreeding / conservation |
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| Research Abstract |
The objective of this research project was to elucidate gene flow via pollen and inbreeding depression to establish a baseline for conservation of a threatened species, Magnolia stellata, using the methods with microsatellite markers in molecular ecological genetics. The findings are as follows :
1. Genets that are large and located in well-lit sites tend to have many flowers, and blossom both earlier and longer. Large numbers of flowers increase the attractiveness of genets for pollinators and then female reproductive success, and this outweighs the negative effects of geitonogamy.
2. Genets, which apparently produced new ramets through clonal growth (sprouting and layering), were generally composed of several large ramets and many small ramets. Small genets showed within-population genetic structure, suggesting spatially limited seed dispersal. The excess homozygotes in the small genets may be due to genetic substructuring and/or inbreeding, and the reduction in homozygote frequency from the small to large genets may be due to loss of genetic structure and/or inbreeding depression.
3. The level of genetic differentiation among populations within a metapopulation for nuclear DNA was less than half that for chloroplast DNA, suggesting that pollen flow, as well as seed dispersal, has significantly reduced genetic differentiation among populations. Paternity analysis of seeds showed that contemporary pollen flow was greatly restricted by the distance between parents. Although most pollen flow occurred within the study population, pollen flow from outside the population occurred with a low frequency, indicating that the populations were linked by gene flow.
4. Seed production in the study small population is strictly limited by elevated pollen shortage, selfing, and genetic deterioration through genetic drift and inbreeding, which accelerate the risk of extinction.
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Research Products
(16 results)
