In the cross shown here, involving two linked genes, ebony (e) and claret (ca), in Drosoph...

In the cross shown here, involving two linked genes, ebony (e) and claret (ca), in Drosophila, where crossing over does not occur in males, offspring were produced in a 2 + : 1 ca : 1 e phenotypic ratio:

These genes are 30 units apart on chromosome III. What did crossing over in the female contribute to these phenotypes?