Genetic population structure of polychaeta Neanthes glandicincta (Nereididae) of the Mai Po Inner Deep Bay Ramsar Site, Hong Kong.

Neanthes glandicincta (Nereididae, Polychaeta) is the first numerically dominant benthic infauna in the Mai Po international Ramsar site, Hong Kong and also an economically important species for food source of birds and fishes. In present study, highly conserved nuclear ribosomal DNA (SSU and LSU rDNA) and mitochondrial COI gene were employed to study the population structure of N. glandicincta in the subtropical mudflat. The specimens were collected from five localities in February 2006, February-August 2007 and preserved at -80 °C, methanol or formalin, respectively. DNA extraction efficiency was the highest in fresh materials and lowest in formalin-fixed samples. The 18S (1774 bp), 28S D1 (383 bp) and COI genes were sequenced and analyzed. Both 18S and 28S D1 rDNA were highly conserved and showed no difference among the populations, whereas COI gene exhibited relatively high-level intraspecific polymorphism (2.2 %). The population from onshore and near mangrove station was phylogenetic different from other sites, indicating restricted gene exchange between the region of river mouth and mangrove forest. The mangrove may form a barrier for the dispersal of pelagic/benthic larvae of the population, which indicates that the population genetic difference is related to different habitats.