Genetic Diversity Evaluation Of Wild Perca Fluviatilis And Sander Lucioperca Populations In China

Perca fluviatilis and Sander lucioperca are two cold water fishes in the basins of Europe and northern Asia.They grow fast and have high nutritional value.In China,they are mainly distributed in the Irtysh River and Wulungu River basins of Xinjiang in Northwest China.After artificial introduction or spread,they are also distributed in lake basins in Northeast China as well as Tengger lake and Bosten Lake.In order to strengthen the monitoring of wild germplasm and to understand the genetic status,it is of great significance for their conservation and rational utilization.Information on the genetic background of wild populations of Perca fluviatilis and Sander lucioperca is still limited.In this study,microsatellite and mitochondrial gene sequences were used to analyze the genetic diversity of four wild Perca fluviatilis populations and five wild Sander lucioperca populations in Xinjiang.The main results were as follows:A total of 268 Perca fluviatilis samples from Wulungu Lake（WL）,Jili Lake（JL）,Wulungu River（WR）,and Kalaeerqisi River（KR）were studied.Genetic diversity was analyzed by microsatellite markers.According to the genomic data,98425 pairs of microsatellite primers were screened and designed.Dinucleotide microsatellites were the most abundant（78.17%）,followed by trinucleotide（10.66%）,tetranucleotide（8.9%）and pentanucleotide repeat microsatellites（2.27%）.200 pairs of tetranucleotide repeat microsatellite primers were synthesized,of which 152 pairs of primers amplified clear bands.29 polymorphic markers were selected to analyze the genetic diversity of Xinjiang Perca fluviatilis.The results showed that the polymorphism information content（PIC）of29 microsatellite markers ranged from 0.225 to 0.901,with an average of 0.680.Among them,23 markers were highly polymorphic（PIC≥0.5）.The results of population diversity showed that the values of N_a（11.172）and N_e（5.018）of WL population were the highest.The values of N_a（4.621）and N_e（2.563）in KR population were the lowest.The JL population H_o（0.716）and H_e（0.749）were the largest.The values of H_o（0.510）and H_e（0.518）in KR population were the lowest.WL,JL and WR populations had high polymorphism（PIC≥0.5）,while KR population had moderate polymorphism（0.25≤PIC<0.5）.The genetic differentiation coefficient(F_st)among the four populations was 0.074,indicating that there was a moderate degree of genetic differentiation among the populations in Xinjiang.The analysis of molecular variance（AMOVA）showed that6.75%of the genetic variation occurred among populations.The analysis of genetic distance and genetic components based on cluster tree showed that the Perca fluviatilis in the four regions were obviously divided into three branches.Wulungu Lake and Jili Lake belonged to one,Wulungu River was one,and Kalaeerqisi River was one.The genetic diversity of four Perca fluviatilis populations was analyzed by mitochondrial CO I,Cyt b and D-loop sequences,and compared with European population.The results showed that the CO I,Cyt b and D-loop of four populations in Xinjiang had 3,10 and 10 variation sites（accounting for 0.49%,0.90%and 1.92%of the total sequence length）,and 4,11 and 11 haplotypes were defined.The haplotype diversity was 0.065±0.022,0.276±0.049 and 0.186±0.046,respectively.Nucleotide diversity was 0.00011±0.00004,0.00033±0.00007 and 0.00084±0.00013,showing a low level of genetic diversity.There was no shared haplotype between Chinese Xinjiang and European population.The haplotype cluster tree and network diagram also showed obvious separation,and they were different genetic pedigrees.Based on Cyt b and D-loop,the variation of WL,JL and WR in Wulungu River basin was estimated to be-0.005%and 0.44%,respectively.The genetic differentiation coefficient(F_st)was-0.00045 and0.00436,which was in a low degree of differentiation(F_st<0.05).The degree of genetic differentiation between two populations was low(F_st=-0.01158～0.01803),which was the same genetic pedigree.In particular,there were shared haplotypes between the two lakes,and F_st was negative,which means that there was no genetic differentiation.The CO I gene of four populations in Kalaeerqisi River（KR）and Wulungu river basin was estimated to be 1.57%and F_st was 0.01568.However,KR and WL populations were in moderate genetic differentiation(F_st=0.06614>0.05).KR and WR populations were in high genetic differentiation(F_st=0.24627>0.15).Five populations of 242 Sander lucioperca samples from Ulungu Lake（UL）,Tengger Lake（TL）,Heilongjiang River（HR）,Wusuli River（WR）and Khanka Lake（KL）were studied.A total of 92162 pairs of microsatellite primers were designed by microsatellite analysis of population genetic diversity.Dinucleotide repeat was the most abundant microsatellite（81.47%）,followed by trinucleotide（8.21%）,tetranucleotide（7.59%）and pentanucleotide repeat microsatellites（2.73%）.Among the 200 pairs of primers synthesized,122 pairs showed obvious polymorphism.30 polymorphic markers were selected to analyze five Sander lucioperca populations collected from China.The results showed that N_a in each population ranged from 2.333（WR）to 7.800（UL）and N_efrom 1.787（KL）to 4.435（UL）.PIC from 0.304（KL）to 0.715（UL）.UL,TL and HR populations had high polymorphism（PIC≥0.5）,WR and KL populations had moderate polymorphism（0.25≤PIC<0.5）.The F_st estimated by AMOVA was 0.207,indicating that the populations were at a moderate level of genetic differentiation.UPGMA cluster tree and structure analysis showed that the five populations were basically divided into two genetic units.UL,TL and HR belonged to a group,KL and WR belonged to a group.UL,TL and HR populations were highly differentiated from KL and WR populations.The genetic diversity of five populations of Sander lucioperca was analyzed by the full length of mitochondrial Cyt b gene and compared with that of European population.The results showed that 3 variation sites（accounting for 0.26%of the total sequence length）were detected,and 3 haplotypes were defined.Haplotype Hap1 is identical to European haplotype Hap A,which is a shared haplotype of five populations.The haplotype diversity ranged from 0 to 0.516±0.024.Nucleotide diversity ranged from 0to 0.00136±0.00006.The genetic diversity of TL,HR and UL populations was high.The haplotype diversity and nucleotide diversity of WR and KL were 0,and the genetic diversity was very low.AMOVA analysis showed that the variation among the five populations was 24.84%(F_st=0.24843),indicating that the five populations were in moderate genetic differentiation.However,the F_st between the three populations（UL,TL and HR）and the two populations（WR and KL）is large(F_st>0.25),which is highly genetically differentiated.Genetic distance and genetic similarity also showed the same differentiation status.