Figure 1

Mapping design and crosses performed. Cross scheme used to generate recombinants between two P-elements. The second chromosome, marked with nt is not shown. Females from 2P line 32-33 (see True et al. 1996a for P-element nomenclature) were crossed to simB males and recombinants were selected by eye color. Recombinants carrying P33 had eye color very similar to non-recombinants, which made the selection difficult. Thus, we decided to select only recombinants carrying P32 for the fertility tests. The D. mauritiana introgression did not cause sterility when heterozygous; so the recombinant lines were crossed to 1P line 45.6, whose introgression covers the region where the location of factor 1 was predicted. Ten males carrying P32 and P45.6 from each cross, i.e. homozygotes for the introgression, were selected by eye color and individually crossed to 3 females w; e. Fertility was assayed by counting the offspring from each cross up to the 20^th day.