@misc{oai:niigata-u.repo.nii.ac.jp:00005323, author = {Sakai, Masato}, month = {Sep}, note = {In the Part I, I used two sequencing methods, namely long polymerase chain reaction (PCR) and primer walking to determine the complete mitochondrial DNA (mtDNA) sequence of Dugesia japonica and most of the mtDNA sequence of Dugesia ryukyuensis. The genome of D. japonica contained 36 genes including 12 of the 13 protein-coding genes characteristic of metazoan mitochondrial genomes, two ribosomal RNA genes, and 22 transfer RNA genes. The genome of D. ryukyuensis contained 33 genes including 12 protein-coding genes, two ribosomal RNA genes, and 19 transfer RNA genes. The gene order of the mitochondrial genome from the Dugesia species showed no clear homology with either the Neodermata or other free-living Rhabditophora. This indicates that the platyhelminths exhibit a great variability in mitochondrial gene order. This is the first complete sequence analysis of the mitochondrial genome of a free-living Rhabditophora, which will facilitate further studies on the population genetics and genomic evolution of the Platyhelminthes. In the Part II, I surveyed detailed genetic population structure in wild populations of Dugesia species in the Japanese Islands by using molecular phylogenetic analysis based on 18S rRNA type II haplotype and coI mitotype sequences. BI and ML tree of 18S rRNA type I and type II allocated haplotypes of D. ryukyuensis into one, and D. japonica into six genetic lineages. The divergence time based on 18S rRNA type II between D. ryukyuensis and D. japonica is estimated at 24.7-36 million years ago. NJ tree of coI allocated mitotypes of D. ryukyuensis into two (a1 and a2), and D. japonica into 17 genetic lineages (b-q). Since comparison of 18S rRNA type II genotypes and coI mitotypes among individuals demonstrated particular combinations of genotypes, I defined seven new genetic groups (R; D.ryukyuensis, J-I, -II, -III, -IV, -V and -IV; D. japonica). Furthermore, the particular combinations of genotypes were also demonstrated in the populations where were observed two or more genotypes. This suggested that there is genetic isolation among J -I, -II, -III, -IV, -V and -VI, and existence of six sibling species in D. japonica., 学位の種類: 博士(理学). 報告番号: 甲第3701号. 学位記番号: 新大院博(理)甲第359号. 学位授与年月日: 平成24年9月20日, 新大院博(理)甲第359号}, title = {Genetic Diversity Dugesia Planarians in Japan}, year = {2012} }