| Summary: | 碩士 === 國立東華大學 === 海洋生物研究所 === 106 === In this study, we used the COI gene of mitochondrial DNA to examine the genetic structure of populations of Macrobrachium japonicum in Taiwan and Okinawa of Japan. A total of 234 individuals were sampled, including 12 Taiwanese populations and 1 Okinawa population. They were grouped by geography site (Northwest, Southwest, east and North).We used the length of 644 base pairs COI gene to analysis. There are 142 haplotypes, Haplotype diversity = 0.988, Nucleotide diversity = 0.00896, Fu's Fs = -234.352*, Tajima's D = -2.14489*. High level of Hd, Low level of Nd and neutral tests were significantly negative, which means that populations had expanded, this result also be supported by Mismatch distribution analysis, in addition, the M falue analysed by MIGRATE v3.6 shows the direction of gene flow is mainly from Taiwan to Okinawa in a single direction. Pairwise FST estimates shows there are a median degree of differentiation between most of Taiwanese and Okinawa population as well as the Da-an River and parts of other populations. The proportion of genetic difference among four groups and among populations within group are very low in AMOVA analysis, the genetic difference is mainly within populations. From the NJ tree we can see that all populations do not form the geographically distinct branches. Minimum spanning network also shows that there is no obvious grouping among haplotypes, except of Okinawa haplotypes, some of them form a special branch. In the Bayesian skyline plot, population expansion rose slowly about 1.25 ten thousand years ago, rapidly expanded in 2500 years ago, and reached a stable population about 1500 years ago.
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