Genetic diversity and population structure of Sepiella japonica(Mollusca: Cephalopoda: Decapoda) inferred by mitochondrial DNA (COI) variations

• 96 individuals were collected from five populations of the coast of China Sea.
• There are 22 haplotypes in all 96 individuals after analysis of mtDNA-COI gene.
• All haloptypes had shaped two major branches which come from five populations each.

In order to describe the genetic diversity of five geographical populations of cuttlefish (Sepiella japonica) along with Chinese coast and determined their phylogenetic relationship, partial mitochondrial COI gene (681bp in length) was amplified from 96 individuals collected from these populations and sequenced. The 5 populations of cuttlefish inhabit Yellow Sea, East China Sea and South China Sea. Out of 22 polymorphic nucleotides identified, 8 were represented by a single sequence, 12 were parsimony informative, which defined 22 haplotypes. Haplotype and nucleotide diversity were low among populations. Of 22 haplotypes, 15 appeared only in a single population, 6 appeared in 2 or 3 populations and 1 was shared by all populations. The COI gene was monomorphic in Qingdao population. The haplotypes identified clustered into 2 clades, each covered individuals from 5 populations each. Pairwise FST were not proportional to the geographical distances. Among the 5 populations, relatively high level of genetic diversity was found in Ningde population which was recommended to be the best choice of germplasm resources for artificial releasing project.