Figure 1. A picture of a real mapping gel showing three polymorphisms between b-+ and b-Pak (markers 1, 2, and 3). The R1 lines have various combinations of these alleles. The first and last lanes are size standard ladders (L). The next four lanes are from b-Pakistan parents (b-Pak) followed by four lanes from b-- parents. The numbered lanes are 32 different representatives from R1 lines. For an explanation of how this leads to a map, attend my workshop this summer.