An alternative expression for $V_a$

There's another way to write the expression for $V_a$ when there are only two alleles at a locus. I show it here because it comes in handy some times.

$$\begin{eqnarray*} V_a &=& p^2(2\alpha_1)^2 + 2pq(\alpha_1+\alpha_2)^2 + q^2(2\a... ... \\ &=& 2pq[\alpha_1 - \alpha_2]^2 \\ &=& 2pq\alpha^2 \\ \end{eqnarray*}$$