| Project/Area Number |
06640911
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
系統・分類
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| Research Institution | KANAGAWA UNIVERSITY |
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Principal Investigator |
HINO Akiya DEPERTMENT OF BIOLOGICAL SCIENCES,SCHOOL OF SCIENCE,KANAGAWA UNIVERSITY ASSOCIATE PROFESSOR, 理学部, 助教授 (00144113)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 1994: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Genetic Variability / mitochondrial DNA / Ascidians / Halocynthia / Genetic Distance / Species / Sympatric Speciation / Reproductive Isolation / 原索動物 / mtDNA / 種内変異 / 種間変異 / 地理的隔離 / 種分化 |
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| Research Abstract |
Halocynthia roretzi is classified into three types on account of their reproductive behavior ; spawning season and daily spawning time. Experimentally, the cross fertilization among these three types was succeeded and the resulting embryos gave rise to normal young adults, but F2 embryo has not been developed. There is a possibility that these three types of Halocynthia roretzi show an example of sympatric speciation. To estimate the genetic divergence of these types, 25 individuals of each type were examined by restriction-fragment pattern and by restriction site analysis of mtDNA.The degree of genetic differentiation was estimated by the proportion of shared restriction fragment and restriction site (Nei & Li '79). According to these estimates, the genetic divergence (d) within three types of Mutsu Bay was 4.4-6.2*10^<-4>, and these standard deviations at each diverging point were over lapped among three types. Interestingly, the equal genetic differentiation as Halocynthia roretzi was estimated in same analysis of Halocynthia aurantium. In this study, the genetic distance (d) between the four species in genus Halocynthia was also investigated. The (d) value between H.roretzi and H.aurantium was 6.5 * 10^<-2> and that of between H.hilgendorfi and H.hispada was 4.5 * 10^<-2> and these cluster was jointed at 9.0 *10^<-2>.
According these results, it seems that the genetic differentiation among these types is not significant. In the genus Halocynthia, above-mentioned species might be divided into four the range 6 to 3 million years ago. The relation between the geographic isolation or the reproductive isolation and the genetic differentiation were still under investigation.
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