A Preliminary Study On The Phylogenetic Geography Of Lastischia And Its Three Generations Of Parasitic Worms On The North And South Slopes Of The Qinling Mountains

There is a typical interspecies relationship named parasitic between Rhynchocypris lagowskii(Cyprinidae:Rhynchocypris)and Gyrodactylus konovalovi(Gyrodactylidae:Gyrodactylus).R.lagowskii,a species of nutrient-rich and economic fishes which distributes widely in Qinling Mountains River-Valley.G.konovalovi is a potential pathogene which may do harm to the parasitifer.Whereas,there are rarely relative researches about the parasitic in China.In the study,we take advantage of molecular methods to assess the genetic diversity and phylogeography of R.lagowskii and G.konovalovi under merits of Qinling Mountains.This essay may provide fundamental theory for the biological protection of R.lagowskii and the prevention of G.konovalovi.The researh took samples from eight geography groups in the field of Qinling Mountains,including QC,SBYK,JWZ,GHJ,YP,ZA,XYB and HDT.This study took measures to the molecular markers of DNA fragments and 55 samples' genes of R.lagowskii were sequenced by primer walking method,so was G.konovalovi.Using a series of biological softwares mainly to carried out the analysis of base compositions of sequences,the evaluation of genetic diversity and differentiation among populations,the construction of phylogenetic trees and Median-Joining network based on haplotype datas,the guess of historical dynamic of populations and so on.The main results were as follows:1.There were 1063 sites in the joint-data set(Cytb+D-loop)of R.lagowskii,including 93 variable sites which created total 18 haplotypes.The haplotype diversity and nucleotide diversity respectively were 0.933,0.0243.There were 1551 sites in the joint-data set(CO I +ND5)of G.konovalovi,including 178 variant sites which created total 31 haplotypes.The haplotype diversity and nucleotide diversity were 0.960 and 0.0226,respectively.Samples distributed in the south and north slope of Qinling Mountains shared some haplotypes,which exist both in the populations of R.lagowskii and G.konovalovi.2.The results of genetic diversity and differentiation among populations in R.lagowskii were inconsistent with G.konovalovi.Among the R.lagowskii populations,the SBYK population distributed downstream of the artifical reservoir had significant genetic distance and high genetic differentiation index compared with the other seven populations.Among the G.konovalovi populations,there were significant genetic distance and high genetic differentiation indexs between HDT population,XYB population compared with other six populations.The small genetic distance and low genetic differentiation indexs were manifested in GHJ population,JWZ population,and YP population of R.lagowskii and G.konovalovi.The average genetic differentiation value of Fst(>0.25)among populations of R.lagowskii and G.konovalovi were significant,which was consistent with low-level gene flow(Nm<1).3.The results showed that the construction of phylogenetic trees and network according to haplotype datas was almost similar.The haplotype clades of R.lagowskii were disorderly and unsystematic,it was irrelevant to geographical distribution.The haplotype topology structure of G.konovalovi was divided into three clades:Cladel represented the southern slope of Qinling Mountains,Clade2 represented the northern slope and Clade3 represented intersection of north and south slope.But this result requested more powerful data for the argument.4.The guess of genetic structure and historical dynamic of populations in R.lagowskii and G.konovalovi was analyzed.According to the value of GST and NST,the more significant genetic differentiation existed in G.konovalovi rather than R.lagowskii,which may provide a clue that the former was preferable to explore the phylogeography structure.There were no enough evidences to suggest that the population of R.lagowskii and G.konovalovi had experienced expansion in the past by predicting the historical dynamic with mismatch distribution and the statistics of Tajima' D inspection value,the value of Fu' s Fs,the parameters of SSD and R2.It needs further evidences to prove that the Clade2 group may expand in G.konovalovi.5.The elementary results concluded that Qinling Mountains did not segregate these two groups seriously.The essay predicts that data of G.konovalovi will possibly reveal the geographical distribution and evolutionary process of R.lagowskii,which is based on this study considering the life habit and diffusivity of species.