Length And Sequence Variation In Mitochondrial DNA Control Region And Genetic Structure Of Bostrichthy Sinensis

To study the genetic structure of Bostrichthy sinensis, which is a kind of costal warm water fish, 124 individuals fish sampled from eight different geographical sites and one cultured population were sequenced. The complete mitochondrial DNA control region (D-loop) has been acquired, and other 7 species D-loop sequences fish belong to the same family (Gobioidei) has been downloaded from Genebank. Our research results based on analysis of those sequences as follows:1. all the individuals were aligned by Clustal W with seven other species of Gobioidei family from GenBank. According to the alignment, three domains the termination associated sequence domain (TAS), the central conserved domain (CD) and the conserved sequence block domain (CSB), were identified in the mtDNA control region of Eleotridae. A termination associated sequence (TACAT) and its reverse complementary sequence (ATGTA) were found in the three TAS domain (TAS-1, TAS-2,TAS-3). Three conserved blocks (CSB-F, CSB-E, CSB-D) in the CD domain and three conserved sequence blocks (CSB-1, CSB-2, CSB-3) in the CSB domain were also identified. Repeat sequences were found in the 5'ends of the control region. A special stem-loop structure is be found in the TAS domain, the sequences (TATTTAT, ATAAATA) is conserved among different species among Gobioidei family.2. The molecular phylogenetic relationship of eight species of Gobioidei was based on the control region using MEGA software. The results showed that three Eleotridae species get in one cluster; three kinds Gobiidae fish get together in another cluster, the results supports the traditional taxonomy.3. The genetic structure within populations are analyzed, the level of genetic diversity among different populations vary large. The highest level of nucleotide diversity is the ZJ population, and the lowest one is BH population. The haplotype diversity ranged from 1(Y, ZH, and XM)to 0.86(BH). The results also revealed the cultured population has lower level genetic diversity than most of natural population. 4. The genetic structure among different population has also analyzed, the genetic distance ranged from 0.02581(ZJ and ND) to 0.00703 (BH and DX), and the adjacent populations all have high gene flow. The data showed that there has a linear relationship between the geographic distance and the level of genetic differentiation among populations. The haplotypes network indicates that single origin, and multiple population expansion among Y, BH, DX, and ZJ. Three neutrality tests all showed that the XM and ND population had experienced bottleneck effect in the history of evolution, the reason could be the Quaternary Glaciation had changed the earlier habit conditions of Bostrichthy sinensis in Fujian province.