Mitochondrial Genome Evolution Of Pampus Fishes And Genetic Diversity Of Pampus Argenteus Populations

P. argenteus belongs to Perciformes, Stromateidae and Pampus, which widely distributes along the coast of Bohai Sea, Yellow Sea, East China Sea and South China Sea. But as increasing of catches year by year, the rapid growth of consumer demand and the worsening of environment pollution, the amount of P. argenteus wild resource is significantly decreasing. In this study, we measured and analyzed the genome of P. argenteus, and of five pampus fishes. Then we developed 26 polymorphic microsatellite locis and selected 15 polymorphic microsatellite locis to analyze genetic diversity of eight P. argenteus populations along the coast of China. Through analyzing the structure of mitochondrial genome and population genetic diversity of P. argenteus, we can better understand the evolution potential of P. argenteus populations. It is good for the protection and reasonable development of P. argenteus.1. Analysis of the structrue of the mitochondrial genome of Pampus argenteusThe mitogenome is 17,098 bp long, which contains 2 non-coding regions: origin of light-strand replication(OL) and control region(D-loop), 2 r RNA genes, 13 protein-coding genes, and23 t RNA genes. The base composition of P. argenteus mt DNA is A 30.35%, C 25.55%, G 15.28%, and T 28.82%, with an A+T content of 59.17%, which indicates an obvious anti-G bias. ND6 gene and eight t RNA genes were encoded on the light strand, and all other mitochondrial genes were encoded on the heavy strand. Most of protein-coding genes started with ATG, while the COXI, ND4 and ND6 began with GTG. Most are detected in open reading frames of P. argenteus mt DNA with three types of complete stop codons TAA, TAG, and AGA. Three genes(COXII, ND5 and ND4) had a stop codon: T. In recent years the capture production of P. argenteus has been declining due to over?shing and other factors. The mitochondrial genome of P. argenteus may be helpful to the studies on conservation genetics and stock evaluation of P. argenteus resource.2. Analysis the of mitochondrial genome of five Pampus fishesThis study based on the mitochondrial genome of five pampus fishes to research their phylogenetic relationships. The length of mitochondrial genome of five pampus fishes is between 16535 and 18062. They all contain 13 protein-coding genes and two r RNA genes(16S r RNA and 12 S r RNA). P. cinereus, P. punctatissimus and P. chinensis contain 22 t RNA genes respectively. Howerer P. argenteus and P. minor contain 23 t RNA genes respectively. P. argenteus, P. cinereus, P. punctatissimus and P. chinensis contain one D-loop region, and P. minor contains two D-loop regions. The analysis of structure finds that P. minor has ND1 rearrangement in the region of the 16 S r RNA-t RNAIle, and has the extra t RNAPro and D-loop region. Based on the mitochondrial genome sequences, two r RNA genes(16S r RNA and 12 S r RNA) and thirteen protein-coding genes, we use Mega5.0 to build NJ evolutionary tree. According to the NJ phylogenetic trees: P. cinereus and P. punctatissimus form a clade, and is a pair of sister species. P. chinensis forms a clade alone, and closes to P. cinereus and P. punctatissimus. P. argenteus and P. minor form a clade, and is a pair of sister species.3. Development of twenty-six novel microsatellite markers of Pampus argenteus and cross-species amplificationIn this study, we isolated 26 novel polymorphic microsatellites of P. argenteus. We detected 349 alleles. The size of alleles is range from 60 bp to 366 bp. Observed heterozygosity per locus range from 0.267 to 1.000, and expected heterozygosity per locus is from 0.633 to 0.929. Twenty-six novel polymorphic microsatellite locis of P. argenteus could effectively amplify the closely related species, P. minor. And it will be benefit for the studies on population genetics of P. minor.4. Analysis of genetic diversity of eight Pampus argenteus populations based on microsatellite locisBased on 13 polymorphism microsatellite markers, the genetic diversity of eight P. argenteus populations are analyzed. 1706 alleles are determined among eight P. argenteus populations. The highest average allele is LS population(Na=15.200), and the lowest is HK population(Na=13.000). The average observed heterozygosity(Ho) of eight P. argenteus populations is less than the average expected heterozygosity(He). This results show that it is lack of heterozygote within populations. The average polymorphism information content of eight populations ranges 0.854 to 0.879, and Hardy-Weinberg equilibrium P value is low. The average inbreeding coefficient(Fis) was from 0.290 to 0.426. AMOVA analysis showed that 95.66% genetic variation is from within populations, and only 4.34% genetic variation come from among populations. Population genetic bottlenecks significance tests found that SD population and DT population experienced bottlenecks in history.