Analysis Of Phylogenetic Evolution Of Culture Fishes In Percoidei And Genetic Diversity Of Jade Perch

The jade perch?Scortum barcoo?is an economic fish species in the Scortum genus of Terapontidae family,which is an important sport fish distributed in Australian rivers.The jade perch?S.barcoo?were introduced into China in the 1990s,and both have been cultured in ponds and indoor intensive culturing in China.In this study,mitochondrial genome was used to analyze the phylogenetic status of jade perch,and the genetic diversification and genetic differentiation of gemstones were studied by using SSR and mtDNA D-loop analysis techniques.The followings are the main contents of this study:1.The complete mtDNA of sooty grunter?Hephaestus fuliginosus?and phylogenetic analysis of 19 species in the suborder PercoideiTo analyze the phylogenetic relationships between sooty grunter and major freshwater fishes in Percoidei,this study analyzed the whole sooty grunter mitochondrial genome and obtained the mitochondrial genome of 19 fishes from the Terapontidae,Serranidae,and Centrarchidae families in Percoidei from GenBank.The mitochondrial genome of sooty grunter was 16 770 bp,encoding 37 genes?includes 13proteins,two rRNAs,22 tRNAs?and a non-encoded control region?D-loop?.The sequence and distribution of mitochondrial-encoded genes were similar to those of most vertebrates.Phylogenetic analyses were conduct using the complete mitochondrial genome and six genes,including CO I?cytochrome oxidase I?,Cyt b?cytochrome B?,12S rRNA,ND2,ND4,and ND5,and the results of these analyses were consistent.In these phylogenetic trees,fishes in Terapontidae and Centrarchidae formed monophyletic clades,while fishes in Serranidae were divided into two.For the three kind of freshwater fish in Terapontidae,the sooty grunter showed more closely relationship to jade perch.The results also suggested that freshwater Terapontidae fishes originate from marine fishes.In addition,Micropterus salmoides salmoides and Micropterus salmoides floridanus in Centrarchidae should be designated as two independent species,and Siniperca in Serranidae should be an independent family.The results would benefit the study of sooty grunter germplasm resources,and could provide molecular basis for cross-breeding of the cultured species of Percoid.2.Analysis of genetic diversity of jade perch farming populationsThe mtDNA D-loop sequence was amplified from 96 individuals of 4 groups and was 598 bp in length.The sequencing results showed that there were 14 polymorphic sites in the D-loop sequence,and a total of 8 haplotypes were defined.The haplotype Hap1 is a shared haplotype of the three populations of ZS,FS1 and FS2,and Hap3 is a shared haplotype of three populations of PY,FS1 and FS2.The H_d?Haplotype diversity?and P_i?Nucleotide diversity?of the D-loop sequences in the 4 populations were 0.0000-0.5435 and 0.00000-0.00176,respectively,indicating that the genetic diversity of the 4populations was lower.The genetic differentiation(F_ST)and AMOVA analysis among populations showed that the genetic differentiation among populations was at a high level(F_ST=0.40345>0.2),and 59.66%of the genetic variation was from within the population.Using fluorescently labeled SSR primers for PCR amplification and typing of 96 samples,the results showed that in addition to L2052 in 11 microsatellite loci detected,all other sites had more than a moderate polymorphism,PIC?Polymorphism information content?was 0.261-0.609>0.25,and each population had low to medium-level genetic diversity[desired heterozygosity?He?=0.396-0.516],indicating that the genetic diversity of each population was at a medium to low level.Genetic differentiation index(F_ST)and AMOVA analysis showed that the genetic differentiation among the groups was low(F_ST=0.0445<0.05),and 60.72%of the genetic variation was from within the population.Genetic distance analysis showed that the genetic relationship among the four groups was very close.The genetic distance between the Panyu?PY?and Zhongshan?ZS?populations was the nearest?0.013?,while the Panyu population?PY?and the Foshan population 2nd?FS 2?with the longest genetic distance were only 0.047.According to the UPGMA phylogenetic tree constructed based on the genetic distance,the two populations of PY and ZS were clustered into one clade,and two of the two groups?FS1,FS2?in Foshan were clustered into another clade of the two.The results obtained by the two methods in this study were slightly different,but all showed that the genetic diversity of the 4 breeding populations in Guangdong analyzed was relatively low,and the genetic relationship between them was relatively close.Therefore,it is necessary to introduce more individuals of jade perch to the original species to enrich the genetic diversity of domestic breeding populations.