Topic Genetic Basis for Variation: Q) What is reciprocal cross?

It refers to a cross where the same genetic characteristic (e.g. eye colour) is used but the sexes of the parents are reversed. Assuming a red-eyed female fly is crossed with a white-eyed male fly. The reciprocal cross is now the cross between the red-eyed male and the white-eyed female.

This cross is good for testing if the genetic characteristic (or gene) is found on the X chromosome (i.e. X-linked) or not (i.e. autosomal gene). If it is the former, then the phenotypic ratio of the offspring in the two crosses are different. If the gene is autosomal, the phenotypic ratio is the same.