Comparing Anaylysis On Genetic Diversity Of Three Different Geographical Silurus Asotus Groups

The research object was three different geographical silurus asotus groups, which were sampled respectively Zhengzhou group in Yellow River(ZZ), Donggang group in Bigyang River(DG) and Harbin group in Songhua River(HEB). Morphological variation, genetic structure, genetic diversity and back muscles nutritional variation of three groups was analyzed by morphology markers, molecular markers and statistical software in the dissertation. The research aimed at providing basic information on resource conservation and utilization. The contents and results are as follows: 1. Morphology comparative of three silurus asotus groupsThe research object in experiment was countable character, metric characters and framework data of morphology. Morphological variation of three silurus asotus groups was compared by four multivariation analysis methods. Chi-square test results for countable characters among in three groups indicated that countable characters had been existed differentiation. One-way ANOVA results showed that metric characters and framework data in three groups had been existed partly differentiation. Coefficients of difference between characters were less than 1.28. The varitation belonged to geographical differences. Cluster analysis results indicated that DG group and HEB group had high similar in morphology, ZZ group had low similar to the other two groups. Discriminant analysis showed that discriminant equation had good effect on identifying the ownership of the three groups. Principal component analysis showed that 11 characters influence on first principal component were mainly concentrated in the head and part of the fish body frame data. The results of four multivariation analysis methods indicated that three groups in morphology had been existed partly differentiation, thus three groups could be identified by multivariation analysis methods. 2. Comparative study on back muscle nutritional of three silurus asotus groupsNational standard method was used for determining back muscles nutritional comparative(general nutritive components, fatty acids, amino acids) of three natural Silurus asotus groups. The results shown that DG existed the clear differentiation comparing with ZZ and HEB in general nutritive components. The result of weight and body length covariance tests indicated that body weight and length influence on general nutritive components not reached significant level. The percentage of fatty acids in three groups was close to the ideal model. Amino acids of three groups are in accordance with the FAO/WTO ideal mode. HEB was the highest score in essential amino acid index(EAAI). Valine and Isoleucine were respectively the first and second limiting amino acids. The differentiation in three groups was mainly reflected on C20:5n-3, C22:5n-3, Glycine, Alanine, TDAA/TAA, ∑n-3/∑n-6, C22:6n-3, crude fat and ∑EPA+DHA. In conclusion, three groups all had high nutritional quality and satisfyed people’s nutritional needs. 3. Comparing analysis on genetic diversity of three Silurus asotus groups based on mitochondrial DNA D-LOOP regionMitochondrial DNA D-loop region was used for analyzing genetic diversity of three different geographical Silurus asotus groups. The content of G+C in three groups was significantly(P<0.05) lower than A+T. The turn of haplotype number, polymorphic site and nucleotide polymorphism from high to low were DG, HEB and ZZ. Three were twenty-one haplotypes in three groups. The same consequence was acquired by neighbor-joining tree of haplotype and median joining network that haplotype 3, 8 and 19 constituted a branch and others haplotypes constituted a branch. The genetic distance between HEB and DG was highest in three groups. Three were nearly relationship between DG and ZZ. The highest and lowest genetic differentiation coefficient was respectively appeared between ZZ and HEB, between ZZ and DG. The average gene flow of three groups was 1.532. The Fu’Fs and Tajima’s D test value of three groups were negative and had no significant(P>0.05) difference. The measured curve of mismatch distribution had no singlet. These findings suggested that three groups all had high genetic diversity; there was no significant(P>0.05) genetic differentiation between groups; the genetic structure within groups remained to be seen by more method to comprehensive analysis; three groups not suffered population expansion in the past and remained steady. 4. Comparing analysis on genetic diversity of three Silurus asotus groups based on AFLP markersAFLP markers were used for analyzing genetic diversity of three different geographical Silurus asotus groups. The result showed that the extraction of DNA template, enzyme-cut and link up, pre-amplification and selective amplification all achieved good effect. 64 primer-combinations were used to study genetic diversity, 3700 bands were amplified by 7 pairs of primers. HEB and ZZ were respectively the highest and lowest in percentage of polymorphic loci and Shannon’s information index of three groups. Source of variation mainly existed within groups. Three groups had high genetic diversity and good environmental adaptability. Molecular variation among groups and within groups had significant difference(p<0.001). The genetic differentiation coefficient between ZZ and DG was 0.118, the gene flow between ZZ and DG was 1.869. Structure analysis, PcoA analysis and UPGMA evolutionary tree obtained consistent results that DG, ZZ constituted a class group and HEB constituted a class group.