Portion of fox chromosome 12 (VVU12) demonstrating SNP distribution and informativeness. The region of VVU12 that is homogous to canine chromosome 35 is graphed to indicate the position and zygosity of SNPs detected by transcriptome analysis of one tame and one aggressive fox. The top row/lines indicates the alignment of CFA35 with this part of VVU12; the next row (Fox map cM) provides fox meiotic map distances; and the bottom row indicates estimated position in megabases, based on extrapolation from the canine genome sequence assembly. On the four central tracks, each SNP is represented by a single tick mark (+) for each individual (Aggressive or Tame), on either the heterozygous or homozygous track for that individual. Similar data is presented for all fox autosomes in Supplementary Figure 3. The grey box highlights a region that has previously been shown  to harbor a quantitative trait locus (QTL) associated with specific components of fox behavior with an association peak at 23 cM. The aggressive and tame individuals are homozygous for opposite SNP alleles in this interval. The outlined box on the Tame Het row indicates how the region of homozygosity is extended in the tame individual.