Heterozygosity data for the C32 and SJD strains. Marker positions derived from Knapik et al. (1998) and Shimoda et al. (1999). Centromere positions are from those determined by Johnson et al. (1996), with markers genotyped on both panels. The relationship of markers on LG 4 to its centromere has not been determined. The left forward hatched rectangles indicate homozygous regions in the C32 strain and the right backward hatched regions indicate homozygous regions in the SJD strains. Centromeres are depicted as solid black rectangles. The heterozygous regions in both strains are shown in gray. The extent of these regions is given as a midpoint between a heterozygous marker and the next adjacent tested maker that was not polymorphic. Markers that did not amplify an SJD allele, but amplify in the C32 strain are designated by #. If a C32 allele was equal in size to the SJD allele, the marker is denoted by an asterisk (*). Sizes of bands were estimated from acrylamide and agarose gels (see Table 1).