Genetic Diversity And Phylogeography Of Different Populations Of Mastacembelus Armatus In Southern China And Its Adjacent Areas

Mastacembelus armatus is a very important economic fish belonging to genus Mastacembelus,family Mastacembelidae,and order Symbranchiformes.In this study,we developed the nuclear gene sequence markers using the EST sequence of closely related species of M.armatus.The genetic diversity,genetic structure and genetic relationship of M.armatus in Southern China and its adjacent areas were discussion by using nuclear gene sequence markers combined with mitochondrial sequence markers,provide basic data for germplasm conservation of M.armatus,and the phylogenetic relationship of the genus Mastacembelus is also discussed.The results of the study were as follows:1.Compared EST sequence of Monopterus albus with Reference genome,screened EPICs primers that can be used for M.armatus populations analysis.A total of 52 pairs of EPICs primers were screened,of which 26 pairs of stable primers were amplified,There were 7 pairs of primers can be used to study populations of M.armatus.The average genetic distance between of 7 pairs of primers was between 0.250~1.222 and the average number of nucleotide differences was between 0.222~1.222.The primer development method in this study can quickly identify the nuclear gene sequence marker suitable for population research,and it was a simple and quick development method.2.The analysis genetic diversity,genetic structure and phylogeography of different populations were based on mitochondrial COI.9 populations of the M.armatus showed higher genetic diversity in Southern China and its adjacent areas that Hd=0.768 Pi=0.00578.Renhua and Enping populations had high haplotype diversity and nucleotide diversity.Longyan,Zengcheng and Honghe populations has high haplotype diversity,but the nucleotide diversity was low.The haplotype diversity and nucleotide diversity of Wuhua,Chaozhou and Baise populations were low.Longyan,Wuhua,Chaozhou and Zengcheng populations were highly differentiated from other populations,possibly reason is the special geographical location of the Hanjiang River system.3.In this study,two pairs of EPICs and a pair of intron LWS nuclear gene sequence markers were used for population genetics,phylogenetic analysis and phylogenetic analysis of the M.armatus populations.The maximum likelihood tree constructed by the joint sequence(mtDNA and nDNA),can be divided into three clusters.Among them,Longyan,Wuhua,Chaozhou and Zengcheng populations as a cluster,Renhua,Enping and Honghe populations as a cluster,Tunchang population as a cluster.AIS analysis based on genetic distance found obvious genetic differentiation between the East and west parts.The Nandujiang population and other populations in genetic structure,belonging to the continental-island model,gene flow was mainly the land to the island.It is speculated that the Red River population may be the center of diffusion,on the one hand,it spreads eastward along the Pearl River system,and on the other hand spreads from the coastal zone of the Beibu Gulf to the Dandu River.The correlation analysis of environmental factors shows that the observed heterozygosity was significantly correlated with the maximum annual precipitation and the average annual precipitation.4.The amplification efficiency of EPICs primers in closely related species was explored.It was found that the amplification efficiency in 4 species was higher than 50%.Using nuclear gene(S7)to explore the phylogenetic relationship of the genus Mastacembelus,it is found that it was clearly divided into 4 clusters.The relationship between M.armatus and M.favus was close.