The Study Of Genetic Diversity And Molecular Phylogenetic Of Acheilognathinae

In this study, ISSR (Inter Simple Sequence Repeat) and mitochondrion DNA Cytochrome b gene is applied to investigate the genetic diversity and Molecular phylogenetic relationship of three populations of R.sinensis,R.ocellatus and A.taenianalis. Genetic diversity and Phylogenetic trees are constructed with Popgene software and NJ,MP,ME method of MEGA4.0 software. The main results are as follows:(1)ISSR molecular marker is used to detect the genetic diversities of three wild intra-population and inter-population of R.sinensis,R.ocellatus and A.taenianalis. 10 ISSR primers are screened to amplify 150 individuals belonging to three populations. A total of 90 reproducible DNA fragments ranging from 200 to 2000bp are amplified, 51 fragments are polymorphic, and the percentage of polymorphic loci is 56.67%.The genetic diversity parameters are estimated by POPGENE software. The percentages of polymorphic loci (PPB) in three populations of Rhodeus range from 51.14% to 53.93%.The observed numbers of alleles (Na) are from 1.3229 to 1.4375. The effective numbers of alleles (Ne) varied from 1.1877 to 1.2446. The Nei's gene diversities (h) 0.1081 to 0.1435.The Shannon's information indices (I) varied from 0.2163 to 0.1616. The genetic distances range from 0.0652 to 0.0923.The results show that there is a current level of genetic diversity in wild populations and the level of genetic diversity in the three populations arrange in a decent order is A.taenianalis> R.ocellatus> R.sinensis.The analysis of Nei's gene diversity demonstrated the oefficient of genetic differentiation (Gst) among-population of Rhodeus is 0.3519, that it reveal that the variance of inter-population component accounted for 35.19%, while the intra-populations component account for 64.81%. The gene flow (Nm) of genetic differentiation is 0.9209 within-population, and the level of gene flow is low. The Nei's unbiased genetic distances between three populations of Rhodeus are from 0.1332 to 0.1860. The nearest occur between R.sinensis and R.ocellatus populations, the farthest genetic distance occur between R.ocellatus and A.taenianalis populations. NJ cluster analysis based on Nei's genetic distances show that R.sinensis and R.ocellatus populations assemble one group firstly, the indicated the gene distance of they are closely, and then did A.taenianalis population.(2) The complete cytochrome b gene sequences(1141bp) of R.sinensis and R.ocellatus and four sparid cytochrome b gene sequences(1140bp) belonging to Acheilognathus, Acheilognathinae are downloaded from the molecular biology database NCBI of the 1140bp consensus sequences obtain by alignment. The analyzed for the nucleotide compositions and the nucleotide pair frequencies in which no gap is detected. The contents of T,C,A,G are 30.1%,26.7%,28.2% and 15.0%, respectively, and A+T content (58.3%) is higher than G+C content(41.7%) in the cyt b gene sequences of R.sinensis and R.ocellatus, the results show G relatively absence.The first codon positions show no bias to any of the four nucleotides as a whole while the second and third positions are rich in T(41.2%),A(39.9%) and G(only 5.9%)respectively. The ratio of transitional to transversional substitution is 2.5, in which transitional is obvious higher than transversional.The result show that the mutation of these sequences do not reach up to saturation.The topology structure of Molecular phylogenetic trees which are built by three clustering analysis methods are similar. Those results collectively indicate that A.macropterus and A.barbatulus may be clustered with A.tonkinensis first, then with R.sinensis and R.ocellatus, A.chankaensis is an independent one.The relationship and genetic distance between R.sinensis and R.ocellatus is close. The results support the opinion of Lin renduan that R.sinensis is R.ocellatus.