Mitochondrial DNA reveals two recent diverged lineages in Amphioctopus aegina (Gray, 1849) (Cephalopoda, Octopodidae) across the Leizhou Peninsula: a marine ecoregion barrier

Amphioctopus aegina is an economically important species that has been intensively exploited in the marine areas along the Chinese coast. However, the genetic variation and population genetic structure, which would provide valuable information for their fisheries management, have rarely been investigated. In this study, the genetic variation within and among four A. aegina populations throughout its full distribution range were estimated based on mitochondrial cytochrome b DNA sequences. Our results indicated low (Qinzhou) to high (Dongshan) genetic diversities among the four populations. Analysis of molecular variance (AMOVA), ΦST statistics, phylogenetic tree and haplotype networks revealed two significant ( p < 0.01) divergent lineages with a ΦST value of 0.7116 between them, one from a population in Qinzhou and the other from the remaining three populations of Dongshan, Huizhou and Zhanjiang. However, the low genetic distance (0.0032) and only two fixed substitutions between them suggest their recent divergence is possibly due to the last glacial period barriers to gene flow produced by the Leizhou Peninsula. The observed lineage divergence suggests that populations of A. aegina in China are genetically subdivided and may represent evolutionary lineages that should be managed individually.