Abstract:

Gonionemus vertens is widely distributed throughout the Atlantic and Pacific Oceans and is one of venomous jellyfish species in China. To investigate the population genetic structure of G. vertens, we sequenced the mtDNA COI gene in 104 individuals collected from four geographic locations along the coast of the Yellow Sea and the Bohai Sea, and the homologous sequences of other 182 individuals which were obtained from GenBank were also analyzed. A total of 52 polymorphic nucleotide sites were detected among the 286 individuals, which defined 14 haplotypes. The overall haplotype diversity and nucleotide diversity were 0.743 ± 0.012 and 1.046% ± 0.097%, respectively. Compared with several other giant jellyfish species, the genetic diversity of G. vertens was at the higher level. AMOVA analysis indicated that extremely significant difference existed among the groups, within populations and among the populations within groups, with 60.17% molecular variation among the groups, 13.37% molecular variation within populations, and 26.46% molecular variation among the populations within groups. Pairwise fixation index (F_st) values showed that significant population structure existed between the G. vertens population collected in Xiamen waters with other populations collected from Laoting, Dongying, Yantai, and Dalian waters, and the population structure throughout Dalian with Dongying, or with Yantai were also significant. Phylogeographic analysis of the COI region revealed two lineages. The results indicated that the complex life cycle characteristics, dispersal ability, geographic isolation, together with the prevailing ocean currents in this region, may be important factors influencing the genetic structure of G. vertens.

Key words: Gonionemus vertens, mtDNA, DNA barcode, population genetic structure, genetic differentiation