Genetic characterization of the scyphozoan jellyfish Aurelia spp. in Chinese coastal waters using mitochondrial markers

Blooms of the moon jellyfish Aurelia spp. have occurred in the harbors and coastal waters around the world. The phylogenetic relationship and genetic characterization of Aurelia spp. was determined along the Chinese coastal waters based on sequences of the mitochondrial cytochrome c oxidase subunit I (COI) gene. The molecular analysis confirmed that all samples collected in Chinese coastal waters were Aurelia sp.1. We also analyzed the phylogenetic and population genetic structure of Aurelia sp.1 using the newly generated sequences supplemented with existing data from previous studies. The phylogenetic analyses of the COI regions did not support geographically restricted groups among the global samples of Aurelia sp.1. Analysis of molecular variance (AMOVA) indicated a complex genetic population structure and pattern of connectivity. Populations of Aurelia sp.1 were highly structured between most sampling sites over distances as small as 100 km (Rizhao and Qingdao) in certain cases. However, non-significant pairwise FST values were also observed between short geographic distances (Yantai, Rongcheng and Qingdao) and relatively distant sampling sites (Caofeidian, Rizhao and Japan). The life-cycle characteristics, together with the prevailing ocean currents in this region and possible anthropogenic introduction, were proposed and discussed as the main factors that determined the genetic patterns of Aurelia sp.1.