Fig. 2.

Crossing schemes to generate reciprocal X chromosome hybrid males and deficiency/balancer hybrid females. (A) Crossing wild-type Drosophila melanogaster females (LH_M, shown in white) to D. simulans males (Lhr, shown in grey) produces hybrid males with a D. melanogaster X chromosome (melX) and hybrid females. (B) Crossing LH_M females with a compound X (C(1)DX LH_M) to Lhr males produces hybrid males with a D. simulans X chromosome (simX). Females of this cross would inherit two D. melanogaster X chromosomes and a D. simulans Y chromosome, but are inviable. (A, B) Note that the background of the reciprocal male hybrids resulting from each cross (melX and simX) is an identical combination of Lhr and LH_M with the exception of the sex chromosomes. (C) Crossing D. melanogaster X chromosome deficiency lines, which have a balancer X chromosome with a dominant visible marker (DVM) and an X chromosome with a large deletion, to Lhr produces deficiency hybrid females, balancer females, balancer males, and deficiency males (*mostly dead due to large deletions on a hemizygous chromosome with some deficiency lines being exceptions).