Genetic Diversity Of Gymnocyprinus Przewalskii Based On COI Gene And D-loop Control Region Sequences

Gymnocypris przewalskii,belonging to Cyprinidaes,Cyprinidae,Schizothoracine and Gymnocypris,is a unique species in China,and is only distributed in the Qinghai Lake and its surrounding tributaries.From July 2019 to July 2020,82 and 79 were collected in Buha estuary and yilangjian,respectively.81,80,80,81 and 83 samples of G.przewalskii fin were collected from the five main tributaries,Buha River,Heima River,Quanji River,Shaliu River and Haergai River,respectively.A total of 566 samples of G.przewalski fin were collected in Qinghai Lake.The genetic diversity of G.przewalskii was studied by using mitochondrial cytochrome oxidase subunit I gene and mitochondrial control area.The results were analyzed.The main results are as follows:(1)The COI gene sequence of 566 individuals in G.przewalskii was analyzed.15 heterotopia points,17 haplotypes,0.50243-0.67184 haplotypes and 0.00079-0.00118 were detected in 7 regions.Among them,the genetic diversity of G.przewalskii was the highest in the Quanji River population(Hd = 0.67184,pi = 0.00118),and that of yilangjian was the lowest(HD = 0.50243,pi = 0.00079).Based on the Kimura two parameter model,the genetic distance between seven populations is 0.000806-0.001091,and the difference of the overall genetic distance is small.AMOVA molecular variation analysis showed that the Fst values were all less than 0.05,and G.przewalskii had no genetic differentiation,and the genetic relationship was close.(2)The D-loop control region sequence(693bp)of 566 individuals in G.przewalskii was analyzed.55 heterotopia points,66 haplotypes,0.91790-0.94620 haplotypes and0.00509-0.00632 were detected in 7 populations.The haplotype diversity of the Heima River group was the highest(Hd = 0.94620),the lowest in the Buha River group(Hd = 0.91790),the highest in the nucleotide diversity in Yilangjian group(pi = 0.00632),and the lowest in the Heima River group(pi = 0.00509).Based on the Kimura two parameter model,the genetic distance between 7 populations was 0.005228-0.006332,and the overall genetic distance was also small.AMOVA molecular variation analysis,Fst values are all less than 0.05,G.przewalskii has no genetic differentiation and close genetic relationship,which is consistent with the study based on COI gene.(3)Based on two labeling methods,NJ evolutionary tree of corresponding haplotype is established respectively.The evolutionary tree of COI haplotype is simpler and the branch is clear,while the branch of haplotype in D-loop control area is more refined.The two marker methods were exclusive haplotypes and shared haplotypes,and the genetic differentiation G.przewalskii was not high.(4)Based on the analysis of Tajima′s D and Fu′ s FS values,the population of G.przewalskii is in a stable state and has experienced population expansion in history.(5)The results showed that the proportion of heterotopic point of COI gene(2.07%)was significantly less than that of D-loop control area(7.94%),indicating that the D-loop control area of G.przewalskii had faster evolution rate than COI gene,and it was more suitable for the study of genetic variation with close genetic relationships.