Geographic information and summary statistics of the sampled populations.

N is the number of individuals sampled, He is the unbiased genetic diversity [41], Na is the number of alleles, AR is the allelic richness based on the smallest sample size (19 diploid individuals), Fis is the departure from random meeting [43] and R is the genotypic diversity ((G−1/N−1, where G is the number of distinct genotypes, [44]). He, Na, AR and Fis have been calculated using FSTAT [42]; values by population are mean ± standard error over loci and values by region are mean ± standard error over populations.
1These sites have already been analyzed in Valero et al. 2011 [35] (Sieck = NB3, Porspoder = NB1 and Porz Mellec = NB4); values might slightly differ because of different sub-sampling in the two analysis.
2These sites have already been analyzed in Couceiro et al. 2013 [36] (Le Conquet = MPA2 and Molène = MPA1); values might slightly differ because of different sub-sampling in the two analysis.