SNPs for thornback ray Raja clavata, validated from genotyped individuals

We developed a panel of single nucleotide polymorphism (SNP) markers for thornback ray Raja clavata using a RADSeq protocole. Demultiplexed sequences were aligned to the genome of Leucoraja erinacea which was used as reference genome. From an initial set of 389 483 putative SNPs, 7741 SNPs with the largest minor allele frequency were selected for implementation on an Infinium® XT iSelect-96 SNP-array implemented by LABOGENA DNA. For the array, SNPs [T/C] and [T/G] were replaced by those from the complementary strand [A/G] and [A/C] respectively. For some SNPs, a second SNP was found in the 50 nucleotide bases flanking sequence. In these cases, two SNP probes were developed with each of the two alleles of the second SNP. A SNP probe naming convention was adopted to identify these pairs of probes corresponding to the same SNP locus: “MAJ” or “MIN” followed by the corresponding base was included in the probe name. For some of these pairs, only one of the two markers could be developed, resulting in a total set of 9120 SNP probes, including 6360 single SNP probes, 10 MAJ or MIN probes for which a single probe was successfully developed, and 1375 pairs of probes with MAJ and MIN versions. The 9120 SNP genotypes were then scored using the clustering algorithm implemented in the Illumina® GenomeStudio Genotyping Analysis Module v2.0.3 for 7726 individual samples, including duplicates, mostly from the Bay of Biscay but also from the Mediterranean Sea and West Iberia. Overall, 1643 SNPs failed to be genotyped in all individuals, for 319 markers the minor allele was not found and 7158 markers (including 1974 for 987 MIN-MAJ pairs) produced bi-allelic genotypes. The majority of these SNPs had a minor allele frequency between 0.1 and 0.5. The MIN-MAJ probes can be used for quality checking the genotyping results