Interaction testing. (A) Interaction graph is given by a two-way analysis of variance considering the two QTL as two fixed factors with an interaction between them. The "Q-q" QTL effect at the proximal QTL is more important when the animals have the Q allele at the distal QTL (-4g/+15g with the q/Q allele at the distal QTL respectively). (B) The table gives the resulting p-value for both factors and the interaction. (C) QTL analysis using the "interaction model": the blue curve corresponds to the classical model testing the hypothesis « No QTL versus 1 QTL», the grey curve to the model testing «One QTL versus 2 QTL», the green curve corresponds to the interaction model « No QTL versus 1 QTL in interaction with another one fixed at 168 cM » and the red corresponds to the interaction model after adding the six novel markers. For each case, the significance threshold at the 0.05 level is displayed.
Blum et al. BMC Genomics 2011 12:567 doi:10.1186/1471-2164-12-567