| Perca fluviatilis is one of the endemic fishes which are only distributed in Eerqisi River and Ulungur River in China. Currently, the germplasm resources of natural Perca fluviatilis have been degraded, and the number of them also gradually reduces.In this paper, a comparison and analysis was made between the three natural populations(Beitun, Wulungu Lake, Bosten Lake) and two cultivated populations(North Lake, Wujiaqu) in the phenotypic differences and the genetic diversity by a simple morphological measurements and mitochondrial DNA control region sequences and partial cytochrome b gene as the markers. And this provides theoretical reference for the rejuvenation and sustainable exploitation of natural populations of Perca fluviatilis and the cultivation of excellent farmed germplasm groups. The results were as follows:First, complete control region(CR) of Xinjiang Perca fluviatilus mitochondrial genome was determined based on some identified conservative sequence in Europe. And furthermore the blocks of central domain(CSB-F,CSB-E,CSB-C,CSB-B) were identified. Thus the termination associated sequence domain(TAS), the central conserved domain(CD) and the conserved sequence block domain(CSB) in the mt DNA of Perca fluviatilus were divided. By comparing the structure of the basic groups in the control region of Perca flavescens and Perca fluviatilus from Xinjiang and European from both natural and cultivated populations, it is found that the main repeats of the termination sequence region of Xinjiang Perca fluviatilus, European Perca fluviatilus and Perca flavescens are four, three and four respectively. And there are also differences in the other regions in the control region. Compared with the European Perca fluviatilus, part of the bases are missing in Perca. flavescens and Xinjiang Perca fluviatilus. The variation type of the repeated base in natural populations in Xinjiang is greater than cultivated populations. The molecular p Hylogenetic trees were constructed based on neighbour-joining methods,which reveal that the control region can be used for the p Hylogenetic analysis of Perca. And Perca fluviatilus from Xinjiang and European formed two groups obviously, but natural populations and cultured populations of Xinjiang does not appear groups for that the Xinjiang Perca fluviatilus wild populations had a close relationship with cultivated populations.Second, the results showed mt DNA D-loop markers detected 26 variable nucleotide sites and 16 haplotypes in 100 individuals. Among them, 18 variable sites and 13 haplotypes were found in 3 natural populations of 60 individuals, and 8 sites and 5 haplotypes were found in 2 cultivated populations of 40 individuals. The average haplotype and nucleotide of natural populations(Hd =0.688±0.056, Pi =0.0023±0.0011) were more diverous than those of cultivated populations(Hd =0.612±0.078, Pi =0.0015±0.00075). The pairwise fixation index(FST) revealed significant differentiation among all Perca fluviatilis populations(FST>0.25), except that between the Beitun-Wulungu populations and Beitun-Wujiaqu populations which are moderately differentiated(FST>0.15). Neighbor-joining p Hylogenetic tree and haplotype network analysis indicated that perch among haplotypes had close relationship. Various groups were in the early differentiation and didn’t accumulate enough genetic variation.Third, in the sequence fragments of cytochrome b gene in mt DNA whose length is 421 bp, 10 nucleotide sites and 7 haplotypes are detected in 100 individuals. Among them, 9 nucleotide sites and 6 haplotypes were found in 3 natural populations of 60 individuals. 8 nucleotide sites and 4 haplotypes were found in 2 cultivated populations of 40 individuals. The average haplotype diversity and nucleotide diversity of cultivated populations(Hd=0.416±0.127, Pi=0.00123±0.00113) were more diverse than those of wild population(Hd=0.496±0.121, Pi=0.00253±0.00154). AMOVA analysis demonstrated that large part of the variance occurred within populations(98.74%). It implied that genetic variance mainly existed among individuals. The pairwise fixation index(FST) revealed a low degree of genetic differentiation between the natural and cultivated populations(0.05<FST<0.15). Neighbor-joining tree and Median-joining network of Perca fluviatilis also showed that wild populations and cultured population has closed relations in haplotypes, and there was no significant differentiation between them.Fourth, the simple morphological study found that there were relatively obvious differences in body length and weight in the natural populations and cultivated populations which were mainly 2 years old. Among the breeding populations, North Lake and wujiaqu have a significant difference. And among the wild populations, Bosten groups are significantly different from other groups.Fifth,by the Tajima’s D, Fu’s Fs test and Mismatch analysis of the sequence of the control region of mt DNA of Xinjiang Perca fluviatilis in cultivated populations, it showed that all the cultivated Perca fluviatilis experienced the popuation expansion event.The observed value of the age expansion parameter(τ) was 1.886 and the time since population expansion was estimated to be 0.072-0.018 million years ago.Sixth, according to section Cytb gene and gene sequences control region of Xinjiang Perca fluviatilis, the study concluded that there were a certain degree of differentiation between wild populations and cultivated population, but the differentiation is on the early stage. At the same time, both wild populations and cultivated populations have low genetic diversity.Germplasm of all groups are in poor condition, especially the wild populations of Bosten group which has the lowest diversity index, poor germplasm resources and needs urgent protection. |
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