The SNP calling rate threshold per locus was set at 90%. A MAF ranging from 0.037 to 0.45 was used to filter the raw genotype data set. The minimal MAF was set according to the formula [number of chromosomes/(number of individuals)], as proposed by Aulchenko et al. (2007). The minimal success rate of genotyping per accession was fixed to 90%. All SNPs and accessions that did not respect these criteria were removed using the –maf option implemented in Plink!