Fig. 1: Gene drive element (w^GDe) inheritance and somatic eye phenotype in the progeny of double heterozygote split drive carriers.

a Illustration of gRNA:Cas9 split drive system. The gene drive element ^GDe is inserted into, and disrupts, the white gene which is tightly linked to the sex-determining region (M or m). b Breeding schemes for the four crosses per Cas9 expression variant. The solid boxes indicate the F₁ genotypes that may bias the inheritance of w^GDe in their germline. The upper family tree shows the double heterozygous F₁ with paternally contributed Cas9 and maternally contributed w^GDe, m-linked in both F₁ males and females. The bottom family tree shows the double heterozygous F₁ with paternally contributed w^GDe, M-linked in male and m-linked in female F₁s, and maternally contributed Cas9. c F₁ drives parent germline inheritance bias of w^GDe when combined with a sds3, bgcn or nup50-Cas9 expressing element. The horizontal dotted line indicates the expected Mendelian 50% inheritance. For nup50, individual crosses were performed, and each circle represents the percentage of w^GDe positive progeny from an individual parent. Data are presented as mean values with the Wilson confidence intervals for the binomial proportion calculated for the pooled progeny count, which does not take into account the potential lack of independence due to parent-by-parent batch effects. Stars indicate the p value thresholds from two-sided Fisher’s exact tests to the matched drive sex F₁−Cas9 condition. The p values and number of progeny scored are presented in Supplementary Table S9. Source data are provided as a Source Data file. d The percentage of w^GDe inheriting F₂ progeny, initially of the w⁺/w^GDe genotype, that display a mosaic or total loss of eye pigment phenotype due to disruption of their w⁺ allele. The circle size indicates the number of progeny, and circle colour indicates if the Cas9 carrying F₀ grandparent was male (Blue) or female (Orange). Progeny from F₁ drive females is indicated with ‘Maternal Deposition’. Progeny that inherited both a w^GDe allele and Cas9 element are indicated with ‘Somatic Expression’. White phenotype rates for the F₂ progeny that did not inherit w^GDe are shown in Supplementary Fig S3.