| Project/Area Number |
09041164
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Field Research |
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| Research Field |
系統・分類
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
YAHARA Tatsukazu Kyushu University, Faculty of Science, Professor, 理学部, 教授 (90158048)
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| Co-Investigator(Kenkyū-buntansha) |
OOI Kazuyuki Kyoto Univ., Ctr.of Ecol.Res., COE Researcher, 生態学研究センター, COE研究員
OYAMA Ken UNAM,Mexico, Centro de Ecologia, Assoc.Prof., 準教授
SOEJIMA Akiko Osaka Prefectur Univ., Synthet.Sci., Res.Assoc., 総合科学部, 助手 (00244674)
WATANABE Kuniaki Kobe University, Faculty of Science, Professor, 理学部, 教授 (80031376)
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| Project Period (FY) |
1997
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| Project Status |
Completed (Fiscal Year 1997)
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| Budget Amount *help |
¥4,900,000 (Direct Cost: ¥4,900,000)
Fiscal Year 1997: ¥4,900,000 (Direct Cost: ¥4,900,000)
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| Keywords | Sexual reproduction / Agamospermy / Stevia / Mexico / Annual / ITS / Evolutionary rate |
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| Research Abstract |
Stevia (Asteraceae) is much diversified in Mexico where 88 species have been reported. These include annuals, perenials, and shrubs, reproducing by outcrossing, selfing or agamospermy. Our ultimate goal is to estimate phylogeny of these species using DNA sequence data and elucidate correlated evolutionary changes of life form and reproductive systems through the evolutionary history of Mexican Stevia. The purpose of the project in 1997 is to collect materials for molecular and ecological studies through field trips in Mexico. We already had some field trips in Mexico in 1995 and 1996 and collected 56 species. Primary results of field surveys in 1997 are as follows.
(1) We collected additional 13 species including 6 new species.
(2) In five speacies which had been known as exclusively asexual, we discovered sexual populations.
(3) Using materials collected, we carried out molecular phylogenetic studies using sequence data set of ITS and obtained the following results.
*Sequence divergence between sexual and asexual races of the same species is always quite low, suggesting very recent origin of asexual races.
*Evolutionary rate is approximately 10 times larger in annuals than in perenials and shurubs.
*Annuals are polyphyletic.
*Asexual reproduction was evolved repeatedly in perenial lineages, but was not evolved in annual and shurb lineages.
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