Genetic Diversity Of Crangon Affinis And Acetes Chinensis From Marginal Seas In The East Of China

Based on mitochondrial DNA?mtDNA?,the genetic diversity of Crangon affinis and Acetes chinensis were studied in this paper.In addition,DNA barcoding was establishing to identify 10 common shrimp?including Sergestidae?from the East China Sea based on the part of mtDNA COI gene.In order to understand the genetic structure and genetic diversity of Crangon affinis from the Yellow Sea,we collected a total of 83 individuals from 4 sampling sites in this sea area,and 515 bp of the mitochondrial 16S rRNA gene was sequenced.Through the analysis of these sequences,a total of 9 haplotypes and 6 polymorphic loci were found.The overall haplotype diversity and nucleotide diversity were low,and their values were 0.6556±0.0403 and 0.0003±0.0005,respectively.The result of the NJ phylogenetic tree was that there was no distinct lineage in this species.The result of AMOVA showed that the significant genetic differentiation was absent among the sampling sites of Crangon affinis from the Yellow Sea,and the analysis of pairwise genetic differentiation index(F_ST)also showed no significant difference between the sample sites,indicating that the population of Crangon affinis in the Yellow Sea should be treated as one fishery management unit.Both of the mismatch distribution analysis and the neutral test?Tajima's D and Fu's Fs?showed that Crangon affinis had experienced historic demographic expansions.The population expansion of this species was 0.366?95%CI:0.234⁰.575?million years ago.The ratio of effective female population sizes after expansion and before the expansion was 7.6 million.Based on the mitochondrial DNA 16S rRNA and COI gene fragments,the population genetic structure and genetic diversity of the Acetes chinensis in the East China Sea were studied.?1?A 528 bp segment of the 5'end of the 16S rRNA was obtained from 75individuals in 4 sampling sites of East China Sea.A total of 4 haplotypes and 6polymorphic loci were found,and the overall haplotype diversity and nucleotide diversity were low,and their values were 0.2800±0.0618 and 0.0020±0.0015,respectively.The NJ phylogenetic tree was constructed and this rooted tree showed that there was no lineage branch of Acetes chinensis in the East China Sea.The results of AMOVA and pairwise genetic differentiation index(F_ST)showed that group B was significantly different from the other three groups.Analysis of mismatch distribution and two neutral tests showed that the population of Acetes chinensis was relatively stable.?2?Six hundred and fifty-eight bp segment of the mitochondrial COI gene was sequenced from 4 sampling sites.A total of 9haplotypes and 32 polymorphic loci were found in these sequences,and their diversities were also lower when compared with the other shrimps,for which the haplotype and nucleotide diversity of lineage A were 0.4175±0.0729 and 0.0729±0.0007,and their values of lineage B were 0.2279±0.1295 and 0.2279±0.0005.The NJ phylogenetic tree showed that there were two distinct branches of Acetes chinensis in the East China Sea.The results of AMOVA and pairwise genetic differentiation index(F_ST)showed that group B was also significantly different from the other three groups.Both of the mismatch distribution analysis and the neutral tests showed that Acetes chinensis had experienced historic demographic expansions.The population expansion of lineage A was 27,800?95%CI:7,600⁵2,600?years ago and its ratio of effective female population sizes after expansion and before the expansion was 4 million.The population expansion of lineage B was152,000?95%CI:19,700¹77,300?years ago and its ratio of effective female population sizes after expansion and before expansion was 1.6 million.The result of the comparison of the two different mitochondrial gene segments supported that COI gene might be more sensitive than 16S rRNA gene,which was more suitable as a molecular marker for the genetic diversity analysis of marine crustaceans.In this paper,the mitochondrial COI gene of common shrimp in the East China Sea was amplified,and their sequences were combined with others downloaded from NCBI to establish a DNA barcoding.The minimum value of the interspecific genetic distance of 10shrimp species was 0.065?between Solenocera koelbeli and Solenocera alticarinata?and the maximum value was 0.361?between Solenocera alticarinata and Exopalaemon annandalei?,which met the requirement of the minimum interspecific genetic distance recommended by Hebert et al.for species identification.In addition,we calculated that the average interspecific genetic distance of shrimp species was 17 times as much as that of the intraspecific average.Based on the results,we believed that a more reasonable and effective DNA barcoding should be established on the basis of a certain number of samples,so as to ensure that one could neither underestimate the differences of intraspecies nor overestimate the differences of interspecies.This study will contribute to the design of specific primers and provide a basis for the rapid identification of species.