The effect of Y chromosome substitution on body weight in F
-+/+ (left column) and F
- Ay/+ (right column) hybrids. The difference between (B6.Cg-Ay × DH-Chr YDH) F1 hybrids and others were analyzed and only the difference between (B6.Cg-Ay × DH-Chr YDH) F1 and (B6.Cg-Ay × DH-Chr YKK) F1 hybrids was statistically significant in both +/+ and Ay/+ backgrounds. F1-+/+ hybrids are sorted in descending order from the top to the bottom.