To solve this problem we first need to find the amount of gametes a fruit fly produces in a meiotic division. For this we will use the formula , where n represents the number of gene pairs. In our case then,
= 2.2.2.2 = 16
So a fly produces 16 different combinations of gametes. If this fly crosses another one, we have a universe of possibilities of combinations given by the multiplication of the male and female gametes. In the case, then, it would be 16 x 16.
16 x 16 = 256