Table 6 

Parameter coefficients (i.e., M matrix; [Lynch and Walsh 1998]) for each of the models. 

Line 
μ_{0} 
α 
δ 
α^{2} 
δ^{2} 
αδ 



P1 
CTS 
1 
1 
1 
1 
1 
1 
P2 
BTS 
1 
1 
1 
1 
1 
1 
F1 
(P1 × P2) & (P2 × P1) 
1 
0 
1 
0 
1 
0 
F2 
(P1 × P2) × (P1 × P2) 
1 
0 
0 
0 
0 
0 
B1 
[P1 × (P1 × P2)] & [(P1 × P2) × P1] = bcCTS 
1 
0.5 
0 
0.25 
0 
0 
B2 
[P2 × (P1 × P2)] & [(P1 × P2) × P2] = bcBTS 
1 
0.5 
0 
0.25 
0 
0 


The purely additive model (α) holds that F1 and F2 trait values should fall at the midpoint of the values for P1 and P2, with values for B1 and B2 crosses falling at the midpoint of the F1 and P1 or P2, respectively. 

Johnson et al. BMC Evolutionary Biology 2010 10:147 doi:10.1186/1471214810147 