Heterozygosity. The heterozygosity track highlights heterozygous regions of the genome, which occur primarily in outbred and wild strains. Similar to SNPs, independent heterozygous calls are represented as a histogram at course scales and individual loci at finer scales. Blocks of heterozygosity are inferred from the individual calls using an HMM, and represent suspected outbred regions. Classical laboratory and wild-derived strains are largely inbred however they may maintain small regions of residual heterozygosity.