DNA Barcode Identification Of Antarctic Fishery Organisms And Population Genetics Of Euphausia Superba

With the world’s offshore fishery resources seriously declining,it is urgent for human to develop new fishery resources to meet the growing food demand.The vast southern ocean is rich in fishery resources,which have not been fully exploited and utilized.Exploitation of fish and krill resources in the southern ocean is conducive to opening up new space and resources for fishery development.Firstly,the species identification of 97 Antarctic fish samples collected from 48.1,48.2and 48.3 sea areas in the Southern Ocean and 26 krill samples collected from “astronaut”sea areas in the Southern Ocean are carried out by using DNA barcode technology and morphological characteristics analysis.After preliminary morphological identification,97 Antarctic fish samples are divided into 17 groups,and it is preliminarily judged that there are 17 kinds of samples collected this time,of which only 6 groups of samples identified species;Twenty-six krill samples are divided into four groups,all of which could be identified.In order to verify the accuracy of the above results,the genetic distance between two taxonomic units is calculated by using DNA barcode.The results shows that the average level of genetic distance between species and intraspecific of 17 Antarctic fish species DNA barcode sequences is 0.0746 and 0.0032,respectively,and the genetic distance between species is 23 times that of intraspecific.The average level of genetic distance between species and intraspecific of 4 krill species DNA barcode sequences is 0.164 and 0.007,respectively,and the genetic distance between species is 23 times that of intraspecific.In view of this,DNA barcode technology can accurately identify 17 effective species in 97 Antarctic fish samples and 4 effective species in 26 krill samples.Through the comparison of BLAST similarity,the samples can be identified to species accurately,and then the BLAST results are verified by the system tree.All the samples are clustered with the same species,and each family is clustered together,which indicates that DNA barcode can effectively identify Notothenioidei fishes and Southern Ocean Euphausiacea species,and the phylogenetic relationship between Notothenioidei fishes and Southern Ocean Euphausiacea is discussed.Secondly,the population genetics of 120 Euphausia superba collected from 6 stations in Southern Ocean 48.1,48.2,48.3 and “astronaut” sea area is studied by using reducedrepresentation sequencing technology.Based on 2b-RAD sequencing technology,3718 SNP loci are screened,and the genetic structure and genetic diversity of Euphausia superba population are analyzed.According to the results of phylogenetic tree and Structure analysis,there is a small genetic structure between population 1 and population 2,which are far apart;PCA principal component analysis results show that almost all samples are clustered together,and no obvious clustering phenomenon is formed.Therefore,although there is a small genetic structure among Euphausia superba populations,it cannot prove that there is genetic differentiation among Euphausia superba populations with different geographic cluster values in this area,and it is still a random free mating population with high genetic consistency.The Fst value between the six stations ranged from 0 to 0.0121,indicating that the genetic differentiation of the six stations is at a low level.He,Ho,PIC,Ne and Pi of each SNP site in the samples of six stations are counted respectively,and PIC ranged from 0.0362 to 0.0177,indicating that all stations are at low polymorphism level;The average value of Ne is 1.0330,which indicates that the genetic variation of Euphausia superba is less as a whole;The values of Ho and He are between 0-1 and 0-0.5,and Ho is lower than He,which indicates that the heterozygosity of Euphausia superba population is low,that is the genetic diversity is low.Generally speaking,there is no significant genetic structure among different populations of Euphausia superba,and the genetic diversity is low,so it is a random free mating population with high genetic consistency.