Comparative analysis of genetic diversity of Dosidicus gigas from eastern Pacific Ocean based on molecular markers of mitochondrial DNA

The worldwide climate and marine environmental changes have significant impacts on the distributions and fishery resources abundance fluctuations of Dosidicus gigas in the East Pacific Ocean. It is important to investigate genetic variance and population genetic structure of D. gigas in order to exploit and manage this squid scientifically. In this study,the genetic diversity and the genetic differentiation betw een tw o geographical populations of D. gigas w ere analyzed based on tw o mitochondrial DNA molecular markers. The results show ed that the number of haplotype,haplotype diversities,nucleotide diversities and average nucleotide differences w ere 7,( 0. 397 ± 0. 079),( 0. 001 09 ± 0. 000 96) and 0. 600 respectively in all Cytb sequences of tw o geographical populations,and haplotype diversity in population off the coast of Peru w as only( 0. 282 ± 0. 101) w hich w as significantly low er than that of equatorial w aters. On the other hand,the number of haplotype,haplotype diversities,nucleotide diversities and average nucleotide differences in all COⅠ sequences w ere 17,( 0. 787 ± 0. 051),( 0. 002 90 ± 0. 001 38) and 1. 802 respectively. The pairw ise fixation index F st and median netw ork revealed lack of genetic structure betw een populations of equatorial w aters and off the coast of Peru( Cytb: F st= 0. 055 23,P 0. 05; CO Ⅰ: F st= 0. 005 91,P 0. 05),and this might be caused by equational oceanographic current. The minimum spanning netw ork tree,mismatch distribution analysis and neutrality tests suggested that D. gigas experienced a recent population expansion,possibly 138 900 to 167 900 years ago.