Data from: Genetic relationships between Atlantic and Pacific populations of the notothenioid fish Eleginops maclovinus: the footprints of Quaternary glaciations in Patagonia

The genetic relationships between the Pacific and the Atlantic populations of marine costal biota in Southern South America have been analyzed in few studies, most of them relying on a single mitochondrial locus. We analyzed ten polymorphic microsatellite loci, isolated from a dinucleotide-enriched E. maclovinus genomic library, in a total of 240 individuals (48 from each of five sampled sites: two Atlantic, two Pacific and one in Beagle Channel). The results were contrasted against a previous work on the same species with mtDNA. Observed heterozygosity within localities ranged from 0.85 to 0.88 and the highest overall number of alleles was observed at the northernmost locality on the Pacific side (Concepción) but no clear geographic pattern arose from the data. On the other hand, the number of private alleles was negatively correlated with latitude (Spearman's rs test, p = 0.017). Among-population variance was low but significant (1.35 %; p < 0.0001, AMOVA) and low genetic differentiation between populations was observed (pairwise FST values ranged from 0 to 0.021). A Mantel test reveled a significant correlation between geographic distances and FST (r = 0.56, p = 0.047). This could be partially accounted for the Atlantic vs Pacific population differentiation detected in three different analyses (Structure, SAMOVA and a population phylogeny). The observed pattern is compatible with a history of separation into two glacial refugia, which was better captured by the multilocus microsatellite data than by the mtDNA analysis