2001 Fiscal Year Final Research Report Summary
Variation and evolution of sexual and asexual races in Mexican Stevia
| Project/Area Number |
12575010
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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 | 海外学術 |
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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 Tetsukazu Faculty of Science, Department of Biology, Kyushu University, Professor, 理学研究院, 教授 (90158048)
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| Co-Investigator(Kenkyū-buntansha) |
KAWAHARA Takayuki Institute of Forestry and Forest Product, Hokkaido Branch, Head Investigator, 北海道支所, 研究室長 (90221902)
AKIKO Soejima Osaka Prefecture University, College of Integrated Arts and Sciences, Assistant Professor, 総合科学部, 助手 (00244674)
WATANABE Kuniaki Kobe University, Faculty of Science, Professor, 理学部, 教授 (80031376)
MISHIMA Misako Kyushu University, Faculty of Science, Research Fellow of Japan Society for Promotion of Science, 理学部, 学術振興会特別研究員 (30346770)
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| Project Period (FY) |
2000 – 2001
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| Keywords | Sexual reproduction / Asexual reproduction / Sepciation / Evolutionary rate / ITS / Polyploidy |
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| Research Abstract |
Mexica Stevia is represented by 99 species among which asexual races are found in 42 species. Among them, sexual races are mostly restricted to small area. However, S. origanoides is an interesting exception in which sexual and asexual races are widely distributed. We carried out transect studies in six area where sexual and asexual races of S. origanoides are found. As a result, we found that sexual populations in three area include cryptic species that are differentiated in morphological traits and habitat preferences. To examine whether these cryptic species differentiated in each area or in defferent area, we sequenced ITS for various samples of S. oritanoides. The results obtained seem to support the differentiation in each area, but resolution of the tree was not sufficient to be conclusive. Now, AFLP analysis is on going. The ITS tree showed that most of asexual triploids clustered together, indicating their monophyly. On the other hand, sexual populations of S. origanoides are differentiated to at least six cryptic species. These findings suggest that sexual reproduction is advantageous when populations are rapidly differentiating under spatially heterogeneous environments.
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