Epistatic interactions among QTL.

1The test is either ‘QTL-QTL,’ which identifies epistatic interactions between main-effect QTLs (Figure 1, unboxed numbers; Table 1), or ‘QTL-other,’ which identifies epistatic interactions between QTLs and non-QTL regions of the genome (Figure 1, boxed numbers). Note that there were no significant epistatic effects detected when the phenotype was scored only by sperm presence vs. absence.2QTL #8 is located at 17 cM on chromosome 3.3QTL #9 is located at 197 cM on chromosome 3.4The additive effect is half of the difference between the two homozygous classes.5%VP is the proportion of the phenotypic variance accounted for by the epistatic interaction.