| Phylogeography research of this article adopted the molecular system method and used molecular system to do mitochondrial COI DNA analysis of snail from Ningbo, Zhoushan,Dongying, Laizhou, Huangdao, Wenzhou, Dalian, Lianyungang, Nantong nine groups from coastal intertidal zone, to clarify the different geographical pattern of the area of snail population system, population genetic structure and the influencing factors of the geographical structure.Research results can accurately divide and judge the snail populations in our country and build foundation to evaluate the invasion of alien species, and provide important genetic basis for reasonable utilization and scientific management of snail,which was beneficial to protect the diversity of marine biological resources which will also fill the blank in the field of domestic related research at the same time.Analysis of 163 DNA mitochondrial COI DNA sequences of Bullacta exarata included:analysis of population genetic diversity,the number and diversity of haploid type,nucleotide diversity,polymorphism loci,the nucleotide difference between two groups; Conditions of genetic differentiation: genetic distance between populations, genetic differentiation index;Using AMOVA to analysis all kinds of parameter of genetic differentiation; Phylogenetic relationships: haploid type network diagram, phylogenetic trees based on all individuals and haploid types, and the factors infuence the population development according to the genetic structure and parameters.The main results were as follows:(1)163 COI fragments of 610 bp which have 80 variation sites accounted for 13% of the total locations. There are 54 kinds of haploid type and 14 kinds of sharing haploid type which was from 70.5% of the sample. 40 kinds of haploid were as the specific haploid populations,but not all groups had a common type of haploid, most of the group has small part of the population was crossed. The overall nucleotide diversity(ND) was 0.016 + /- 0.008, haploid(HD) was 0.925 + /- 0.011. Scope of a single nucleotide diversity from every population was0.001 ~ 0.419, haploid variety range was 0.431 ~ 0.902. The nucleotide diversity of zhoushan,ningbo were lower, the other seven groups had higher haploid type diversity and nucleotide diversity.(2)The result of phylogenetic relationship showed that the clustering of haploid types and geographic distribution of haploid type had no significant correlation.The snail haploid type network diagram showed two great branches, one of the branches countained 63% of the samples with 103 individuals which is from nine geographic populations with 25 kinds ofhaploid type, the other branch contained 37% of total samples with 60 individuals from seven geographic populations with 29 kinds of haploid type, topological structure of haploid type and the compositions in internal haploid type were similar to the phylogenetic tree the geographical distribution of haploid type did not show significant correlation. NJ tree based on the construction of individual was divided into two large branches, the individual of geographic populations cross each other, the distribution of individuals in the phylogenetic tree was inconsistent with the geographical distribution of individual. In conclusion,the snail had no significant geographical structure system.(3)According to the AMOVA, nine geographic populations of this research were merged into a large group, or according to the province divided into four groups, the result of population variation which were accounted for 78.48% and 79.58% respectively in total variance. The above results showed that significant genetic differentiation among snail populations, a certain degree of genetic differentiation showed within population and the differentiation among populations was much more than the population differentiation. |
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