Posterior lobes are smaller in size when only the D. mauritiana allele of Sox21b is working (IL108/DsimSox21b1.1 and IL108/DsimSox21b1.2) (n > 22). The lower schematic illustrates the generation of reciprocal hemizygotes, containing either a D. simulans working allele or D. mauritiana working allele of Sox21b. The lightning bolt represents the disrupted Sox21b locus, the shaded rectangle represents the D. mauritiana introgressed region (3L: 12,277,961–15,075,323).
