The Genetic Diversity Of Schizopygopsis Pylzovi In Different Geographical Populations

Schizopygopsis pylzovi,a member of the genus Schizopygopsis,is a species of river dwelling fish endemic to China.Schizopygopsis pylzovi is a Qinghai Tibetan Plateau endemic fresh water fish species which is dominantly distributed in the waters of the Yellow River upstream,and it is an important commercial fish in plateau area.We take the Schizopygopsis pylzovi from different water area in the Yellow River basin in western China as research objects.In this thesis,by PCR amplification,direct sequencing method,we analyzed the cytochrome(Cyt b)and the D-loop sequences composition and characteristic of the samples which are from seven different geographical populations,aiming at exploring the genetic diversity and phylogenetic relationship.We analyzed 143 Cytb sequences(128 Cytb sequences we extracted,15 sequences we downloaded from NCBI).After sequence alignment,we obtained 1137 bp sequences.The variable sites were 335,29.5% of all sites,and the parsimony informative sites were 304,85.6% of the variable sites.The average composition of T,A,C and G were 30.9%,25.5%,26.6%,17.0%.We used Kimura-based dual method to calculate the genetic distance within geographical populations,and found that the populations DL has the largest genetic distance(0.143).143 Cytb sequences define 55 Haplotypes.The populations of DTH and the populationsof GTH appear to have experienced recent demographic expansion,as indicated by the results of mismatch distribution,the diversity parameters,and the neutral test value and the mismatch distribution figure.The analysis of molecular variance(AMOVA)indicates that 12.08% of variance is among population and 87.92% of variance is within populations.The haplotype network analysis of the 55 haplotypes suggested significant geographical differences,then we use the Cytb sequences to constructed BI phylogenetic tree,which also suggested the geographical differences.We analyzed 118 D-loop sequences which were extracted from the samples of seven different geographical populations.After sequence alignment,we obtained 896 bp sequences.The variable sites were 88,9.8% of all sites.The parsimony informative sites were 52,59.0% of the variable sites,and the average composition of T,A,C and G were 31.6%,31.5%,22.1%,14.8%.We used Kimura-based dual method to calculate the genetic distance within geographical populations,and found that the populations GEM has the largest genetic distance(0.017).118 D-loop sequences define 66 Haplotypes.All the populations appear not to have experienced recent demographic expansion,as indicated by the results of mismatch distribution,the diversity parameters,and the neutral test value and the mismatch distribution figure.The analysis of molecular variance(AMOVA)indicates thatonly 5.42% of variance is among population and 94.58% of variance is within populations.The haplotype network analysis of the 66 haplotypes suggested significantly geographical differences,then we use the D-loop sequences to constructed BI phylogenetic tree,which also suggested some geographical differences.