Phylogeography and genetic structure of the edible sea urchin Paracentrotus lividus (Echinodermata: Echinoidea) inferred from the mitochondrial cytochrome b gene

Phylogeographical analysis of Paracentrotus lividus was carried out by means of sequencing the mitochondrial cytochrome b gene (1143 bp) of 260 individuals collected at 22 Mediterranean and four Atlantic localities. Against a background of high haplotype diversity and shallow genetic structuring, we observed significant genetic divergence between the Adriatic Sea and the rest of the Mediterranean, as well as between the Mediterranean and the Atlantic sample groups. Furthermore, on the largest spatial scale, isolation by distance was detected. Three main haplogroups were identified by network and Bayesian assignment analyses. The relative proportions of haplogroups were different in the four regions considered, with the exception of Western and Eastern Mediterranean that showed a similar pattern. This result together with the outcome of S-nn statistics, analysis of molecular variance and network analyses allowed to identify three weakly differentiated populations corresponding to the Atlantic, Western + Eastern Mediterranean, and Adriatic seas. Analyses of mismatch distribution and neutrality tests were consistent with the presence of genetic structuring and past demographic expansion(s). From a fisheries perspective, the results obtained in the present study are consistent with genetic sustainability of current exploitation; local depleted stocks are recurrently replenished by recruits that may have originated from nonharvested areas. (C) 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 910-923.