Genetic structure of Amphioctopus fangsiao (Mollusca, Cephalopoda) in Chinese waters inferred from variation in three mtDNA genes (ATPase 6, ND2, and ND5)

Abstract

Amphioctopus fangsiao is an economically important resource found in Chinese coastal waters. Three mitochondrial DNA genes were used to assess the genetic structure among nine populations spanning the northern to southern regions of the Chinese coast. Fragments of 575, 639, and 640 bp in length representing three genes (ATPase 6, ND2, and ND5) were amplified from 183, 170, and 167 individuals, respectively. Overall, ATPase 6, ND2, and ND5 showed high haplotype diversity and low nucleotide diversity (HD: 0.683–0.896; −π: 0.021–0.033). All three mtDNA genes revealed high molecular variance among populations and low variance within populations. ΦST values obtained for ATPase 6 (ΦST = 0.000 to 0.997), ND2 (ΦST = 0.000 to 0.997), and ND5 (ΦST = 0.125 to 0.983) showed differentiation among the populations. The constructed phylogeographic tree and haplotype network separated the nine populations into two clades representing the northern and southern populations. Low salinity in the Changjiang River estuary may act as a barrier to promote the differentiation between the two clades. These results enhance our understanding of the genetic structure of A. fangsiao and can promote the management of its genetic resources.