Solution
= Solution
The displayed analysis of variance compares Model 2 with the unrestricted three-mean Model 1. It tests
$$
H_0:\mu_{Aa}=\mu_{AA},
$$
which is precisely full dominance: once an $A$ allele is present, a second copy has no further effect. Under $H_0$,
$$
F=\frac{(54.148-48.487)/1}{48.487/57}=6.6551
\sim F_{1,57}.
$$
The p-value $0.01249$ rejects full dominance at the $5\%$ level, providing evidence that the heterozygote and $AA$ means differ.