Genetic population structure of Epinephelus marginatus (Pisces, Serranidae) revealed by two molecular markers

In this paper, data are presented regarding the population structure of dusky grouper (Epinephelus marginatus) which was sampled in the Mediterranean Sea and Atlantic Ocean using two different molecular markers, ND2 RFLP and cytochrome b (cyt b) sequence analysis. The main objective of the study is to analyse the genetic variability of E. marginatus in the Mediterranean Sea to define how the biological characteristics of the species, such as the dispersal capability of pelagic larvae and the benthonic-sedentary life style, can affect the genetic population structure or maintaining the gene flow or determining genetic differences. Furthermore, we considered an Atlantic sample to establish the presence of genetic differences between the two biogeographical areas under consideration. Analysis of variation based on ND2 RFLP analysis revealed a genetic difference between the Atlantic and Mediterranean samples, whilst cyt b sequence analysis did not. There exists evidence for genetic differentiation for both molecular markers in the Mediterranean region. The majority of the variation was due to the Ustica Island sample and this could be due to differences in fisheries effort since the island is a protected area where recreational and professional fisheries are almost completely forbidden. The pattern of genetic diversity, haplotype networks and mismatch distribution suggest a historical influence on the genetic structure of E. marginatus and recent population expansion. An analysis of the genetic structure of the dusky grouper will be the prerequisite for decisions regarding conservation and fisheries management.