Two distinct QTL on two linkage groups (LGs) were detected for bone bending stiffness. Both loci show evidence for dominance of the MZ allele, which is consistent with the mean values for each population reported in Figure 2. The LF/LF genotype increases mean stiffness at both loci, although the mean phenotypic values of each genotypic class were lower than what would be expected based on parental averages. This is likely due to our low F₂ sample size, which has also likely inflated the percent variance explained (PVE) by each QTL.