A shared QTL is found close to ppw-1. The RNAi treatment is indicated in the grey box at the top of each individual panel. The significance (y-axis) of the marker explaining the variation in the FCs is plotted against the marker position (x-axis). Significance is shown as -log10 of the p-value per marker. Chromosome borders are indicated by the grey vertical lines. The positions of the RNAi targeted genes are indicated by the blue triangle on the x-axis. The vertical orange dotted line indicates the position of ppw-1, a gene polymorphic between N2 and CB, known to be involved in germline RNAi sensitivity . The genome-wide threshold (0.05 after 1000 permutations) is indicated by the horizontal dashed red line. The part of the QTL profile below the threshold was plotted on a grey background. For both the QTL calculations and threshold determination see methods. Critically, a shared QTL close to the ppw-1 locus is observed between mel-26(RNAi), pos-1(RNAi), par-1(RNAi), smo-1(RNAi), par-6(RNAi), gld-1(RNAi) and let-502(RNAi).