The distribution of SNPs within VRs between inbred strains of mice. (A) The distribution of the total number of SNPs identified within the coding region of vomeronasal receptor genes (VRs) compared with the total number of SNPs in the entire accessible genomes. (B) A similar comparison showing the relative distribution of private SNPs (those that are unique to one strain). The distributions of SNPs across entire accessible genomes were calculated from data in . (C) The relative proportions of the VR SNPs in each strain that is private. The data from the 13 laboratory-derived strains (Lab) are pooled. Increasing evolutionary distances from the C57BL/6J, mainly domesticus-derived, reference strain are indicated with increasingly darker shading. (D) A heat map showing whether WSB/EiJ, PWK/PhJ or another laboratory-derived strain matches V1R sequences from 14 wild-caught isolates described in . The V1R genes are arranged vertically in order and the isolates are arranged by hierarchical clustering (indicated top), resulting in two clusters consistent with the subspecific origin of the isolates.