Mitochondrial DNA sequence variation of Japanese anchovy <Emphasis Type="Italic">Engraulis japonicus</Emphasis> from the Yellow Sea and East China Sea

Sequence variation of a fragment of the mitochondrial cytochrome b (cyt b) and cytochrome c oxidase subunit I (COI) gene was examined using polymerase chain reaction and direct sequencing among three populations of Japanese anchovy Engraulis japonicus from the Yellow Sea and East China Sea. A total of 24 and 47 nucleotide sites were detected variable defining 29 and 32 haplotypes in cyt b and COI data, respectively. All variable sites except one in COI were silent in the two sets of sequences. The Ewens-Watterson test indicated that the observed allelic configurations in both data sets were in full agreement with neutral expectations. The variation level was high, with h=0.957±0.018, π=0.644±0.387 (%) in cyt b data set and h=0.958±0.021, π=0.640±0.386 (%) in COI data set, respectively. However, at the population level, Fst values between pairs of populations were not significantly different from zero (P>0.05) in both data sets. The analysis of haplotype frequency distribution showed no significant differences among populations. Similarly, the analysis of the partitioning of molecular variance indicated that all or almost all of the genetic variation was distributed within populations. Based on the data from this study, the existence of separate genetic stocks in this area were not detected. Mixing of stocks to some extent in migration cycle and dispersal capacity of anchovy’s planktonic larvae could be the reasons for genetic homogeneity in this species in the Yellow Sea and East China Sea.