Figure 1

A generalized scheme of the crossing procedure used by Ortiz-Barrientos et al. [12] to analyze mating discrimination against D. persimilis by D. pseudoobscura females in sympatric populations. Sympatric and allopatric populations of D. pseudoobscura, differing in their levels of mating discrimination against D. persimilis, were crossed to produce F1 hybrids, which were then backcrossed to the same allopatric population to produce BC1 flies with segregating variation in mating-discrimination traits. BC1 females were tested in mating trials with D. persimilis to assess the degree of mating discrimination. Females were then genotyped at 70 markers distributed throughout the genome in order to map sympatric mating-discrimination loci.