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北海道のヒグマ (Ursus arctos yesoensis) の遺伝的変異に関する研究

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Title: 北海道のヒグマ (Ursus arctos yesoensis) の遺伝的変異に関する研究
Other Titles: A study on the genetic variability of Hokkaido brown bears (Ursus arctos yesoensis)
Authors: 釣賀, 一二三1 Browse this author
Authors(alt): Tsuruga, Hifumi1
Issue Date: 24-Mar-1995
Abstract: there was no difference in the condition of immobilized bears between the two combinations. ln use of tiletamine-zolazepam, there was no difference in the volume and induction time between sexes. The tiletamine-zolazepam was found to be more effective for the immobilization of Hokkaido brown bears. 2. Allozyme analysis of genetic differentiation A total of 21 biochemical loci were analyzed electrophoretically in 10 bears from 3 subpopulations in Hokkaido in order to estimate genetic variability of the brown bear population. No polymorp hic locus was observed and the genetic variability of Hokkaido brown bears are thought to be as low as other land mammals inhabiting in Japan. 3. Application of DNA fingerprinting in bears. DNA fingerprinting employing a minisatellite Myo probe, which is known to be valuable in forensic study, was applied for individual identification and paternity determination of 47 captive bears. Moreover, it was applied for the estimation of genetic variability within and between subpopulations using 6 captive bears with known origins and 26 free-ranging bears captured in the southwestern Oshima peninsula (n=13) and the Shiretoko peninsula (n=13). Two restriction enzymes, HinfI and HaeIII were used to make DNA fingerprints and the band patterns obtained from 45 (HinfI) and 33 (HaeIII) pairs of randomly selected bears were compared with each other. The obtained values of the probability x that a fragment in an individual is also present in the other were 0.69 for HinfI and 0.83 for HaeIII and the mean probability of all fragments was calculated to be 2.5×10-2 for HinfI and 1.3×10-1 for HaeIII. The value of x for HinfI (0.69) was similar to that obtained from other species, such as domestic animals. Thus, the results suggest that DNA fingerprinting can be used for individual identification. On the other hand, DNA fingerprinting is effective for paternity determination only in the case suspected males are limited, owing to the insufficient number of paternal fragments. The estimates of the average heterozygosity (gene div ersity) were 0.302 and 0.241 for the populations on the southwestern part of the Oshima peninsula and the Shiretoko peninsula, respectively. These values suggest that the local populations sampled in this study have low genetic variability compared with those of other animal species. The degree of genetic differentiation between the populations, measured by the coefficient of gene diversity, was 7.9 percent for both captive and free-ranging bears and 19.5 percent for free-ranging bears only. These results indicate a low degree of genetic differentiation between the local populations. 4. Restriction analysis of mitochondrial DNA The restriction fragment length polymorphisms of mitochondrial DNA in 24 bear samples collected from 4 subpopulations (Oshima, Syakotan-Eniwa, Hidaka-Yubari and east Hokkaido-Soya) were examined using 10 restriction enzymes. The restriction patterns of 9 enzymes showed polymorphisms, and mitochondrial DNAs of the sample bears were separated into 9 haplotypes by means of the combination of restriction patterns. There were some shared haplotypes between Hidaka-Yubari and east Hokkaido-Soya subpopulation, although there was no shared haplotype between Oshima and other populations. The haplotype frequency in the east Hokkaido-Soya and the Hidaka-Yubari subpopulations was lower than that of the Oshima subpopulation. The minimum genetic distance between east Hokkaido-Soya and Hidaka-Yubari subpopulation was very small, so that these subpopulations are presumed to begen etically close. In the conclusion, the low genetic variability of Hokkaido brown bears were revealed by allozyme analysis and DNA fingerprinting. East Hokkaido-Soya and Hidaka-Yubari subpopulation are thought to be genetically close by restriction analysis of mitochondrial DNA.
Conffering University: 北海道大学
Degree Report Number: 甲第3679号
Degree Level: 博士
Degree Discipline: 獣医学
Type: theses (doctoral)
Appears in Collections:学位論文 (Theses) > 博士 (獣医学)

Submitter: 釣賀 一二三

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