Studies On The Conversition Genetics Of Silurus Lanzhouensis

Silurus Lanzhouensis,presently distribute in the narrow regions in the upper reaches of the Yellow River,also known as theYellow Catfish,is the unique large-scale commercial fish in the upper reaches of the Yellow River.In recent decades,because of the dramatic decline of population size and severe population fragmentation,attracted a lot of attentions of the community, conservation seientists and other conservative organizations in the world.In order to design effective conservation strategies,we did comprehensively research on conservation genetics of Silurus Lanzhouensis by using mitochondrial control-region,mitochondrial Cytb,and microsatellite as genetic markers,used Silurus Lanzhouensis,which sampled from Bai Yin,Zhong Wei,Yin Chuan, and other species of Siluriformes(Silurus asotus,Silurus meriaionalis,Clarias fuscus) as the study objects.The major results are as follows:1.Analysis of genetic diversity of four groups, mitochondrial D-loop and Cytb sequences were consistent with the results show that:the genetic diversity of the current Silurus Lanzhouensis population are relatively high,and genetic diversity between the four groups in the order:YCZ>YCQ> ZW>BY.2.Analysis of genetic differentiation of four groups based on mitochondrial D-loop and Cytb sequence received different results.Based on mitochondrial D-loop gene sequence,the results indicated that genetic differentiation are significant(p<0.05).However,Based on mitochondrial Cytb gene sequence,the results indicated that genetic differentiation are no significant(0.05<P<0.1).3.There are 33 haplotypes in the four groups of Silurus Lanzhouensis base on analysis of mitochondrial D-loop,while we received 36 haplotypes base on analysis of mitochondrial Cytb.The phylogenetic tree was constructed using neighbor-joining method of the haplotypes,which suggests that the results are same on two genetic markers,these haplotypes be considered as two clades.This means that the Silurus Lanzhouensis have two maternal lineages.4.Twelve microsatellite markers from Silurus meriaionalis were selected to analyze the application on four closely-related species of siluriformes including S.lanzhouensis, S.asotus and C.fuscus. The result indicated that:among the twelve microsatellite markers,eight microsatellite locis have high versatility,except DQ223147 and DQ223160 have no specific amplification bands,DQ223149 and DQ223159 have no polymorphism.The average value of observed heterezygosity (Ho) was 0.7571;the average of expected heterezygosity (He) was 0.6870;and the polymorphism information content (PIC) was 0.6441,those results indicated the eight locis are highly polymorphic.This means that the eight microsatellite loci are suitable for siluriformes genetic research.5.Nineteen microsatellite markers of Silurus meriaionalis were selected to analyze the genetic structure of Silurus lanzhouensis between wild and artificial breeding populations.The results indicated that genetic diversity of the artificial breeding population was declined,however,the genetic diversity of two populations was rich,and the relationship between them was closely,and the genetic differentiation was relatively low.6.The mitochondrial Cytb sequence has been submitted to GenBank,and the access number is HQ890503.By contrast with mitochondrial Cytb of other species of Siluriformes,the result show that homology between Silurus Lanzhouensis and Silurus asotus is the highest,nucleotide is 91.12%,and amino acid is 95.52%.7.According to the principles of conservation genetics,we identified two evolutionarily significant units among four groups of Silurus lanzhouensis,namely,unit I:Bai Yin groups,which are identified as evolutionaryily significant units;and unit II:Zhong Wei-Yin Chuan groups.