关键词: 中华按蚊, 线粒体DNA细胞色素C氧化酶亚基Ⅰ基因, 多态性, 种群遗传

Abstract: Objective To determine the polymorphism of mitochondrial cytochrome c oxidase subunitⅠ(mtDNA-COⅠ) gene sequence in different geographical strains of Anopheles sinensis population in Guizhou province, China, and to explore the genetic diversity, genetic differentiation, population expansion, and the correlation between genetic distance and geographical distance. Methods From July 2017 to August 2018, adult mosquitoes around the rice fields at 12 sampling sites in the East, West, South, North, and central area of Guizhou province were captured by light trapping method. The DNA sample of a single mosquito was extracted by kit method after the mosquito was confirmed as An. sinensis by morphology, and the mtDNA-COⅠ gene was amplified and sequenced. The sequencing results were spliced by DNAStar 5.0 software, and the molecular identification of mosquito species was carried out by BLAST comparison in National Center for Biotechnology Information. The haplotype diversity and nucleotide diversity of the mtDNA-COⅠ gene sequence of An. sinensis were analyzed by DnaSP 5.1 software, and the differentiation coefficient (Fst) and gene flow size (Nm) among various populations were calculated. The neutrality test was carried out to clarify the differentiation degree and population expansion among various populations. The genetic distance among various populations and within populations was calculated by MEGA 7.1 software to determine the degree of genetic variation among populations. The geographical distance between populations was calculated according to the latitude and longitude of sampling sites, and the correlation with the corresponding genetic distance was analyzed by the correlation test. Results In this study, 551 sequences of mtDNA-COⅠgene were obtained from 12 geographical strains of An. sinensis in Guizhou province, through molecular biological identification, with a length of 709 bp. Among them, the average content of base A+T was 68.57%, and the average content of G+C was 31.43%. Among the 709 base sites, there were 586 conserved sites, 123 variable sites, 189 monomorphic sites, 278 parsimony-informative sites, and no insertion or deletion sites. A total of 329 haplotypes were detected from 551 sequences, with a haplotype diversity index of 0.992 and a nucleotide diversity of more than 0.015 22. The Fstvalue of 12 populations was between 0.000 8 and 0.420 7, and the Nm values ranged from 0.086 1 to 75.239 2. The neutrality test statistic values were all negative values. The genetic distance within populations ranged from 0.007 1 to 0.052 9, and the genetic distance between populations ranged from 0.007 9 to 0.052 2. The genetic distances within Zhijin and Duyun populations were larger than those within other populations. There was no correlation between genetic distance and geographical distance. There might be a certain geographical isolation between different populations, but the genetic distance between populations was not related to the geographical distance. Conclusion There is abundant genetic diversity among different geographical strains of An. sinensis populations in Guizhou province, in which regional population expansion has been experienced in history. There may be some degree of genetic differentiation and geographical isolation, but there is also gene exchange among populations in a certain range, showing a distribution pattern of coexistence of exchange and isolation.

Key words: Anopheles sinensis, Mitochondrial DNA cytochrome c oxidase subunitⅠgene, Polymorphism, Population genetics