Figure 3. Edited Rsp alleles show altered sensitivity to meiotic drive.

We tested each subline from the Iso1 (A,B) and Ral309 (C) allelic series for sensitivity to drive with drivers of different strengths and background. Drive strength, or k, is the proportion of SD offspring from heterozygous SD/target male, corrected for viability (by controlling for transmission through a heterozygous SD/target female). R16 is a control—this line has a large deletion of pericentric heterochromatin including the Rsp locus and is completely insensitive to drive²⁶. A. SD-5 is a strong driver (k^Iso1=0.996). The deletion alleles (Iso1ΔC16, Iso1ΔC8, and Iso1ΔC16ΔC20) each show reduced sensitivity to drive with SD5, while R16 is completely insensitive (FET P=0.41). The expansion Iso1ExpC11 allele, like Iso1, remains highly sensitive to this strong driver. B. SD-Mad¹ is an isolate of a weaker drive haplotype (k^Iso1=0.792) that allows us to distinguish between the sensitivity at large copy number alleles. In this background, the deletion alleles (Iso1ΔC16, Iso1ΔC8, and Iso1ΔC16Δ20) show very little sensitivity to drive and R16 is completely insensitive (FET P=0.26), whereas the sensitivity of Iso1ExpC11 is similar to Iso1, but shifted. Drive sensitivity with an intermediate-strength driver and background is in Fig S10. C. We repeated these crosses with a marked version of SD-Mad (SD-Mad-DsRed) and Ral309 and its subline RalΔM17b and see reduced sensitivity to drive in the deletion allele. Taken together, our results indicate that CRISPR editing creates alleles with phenotypic effects on sperm viability.