Question

M. domesticus M. musculus M. musculus M. domesticus (LEWES, WSB) Chi Ch2 Ch3xx (PWK, CZECH) (PWK, CZECH) (LEWES, WSB) Ch1 Ch2 Ch3 XY Ch сhа скз XX Cht Ch2 Ch3 X X REE

Figure 1 The crossing scheme used to generate interspecific hybrids. Dark boxes show chromosomes from M. domesticus, light boxes show chromosomes from M. musculus.

Question 3. In birds, sex determination is the reverse of that in mammals: females are XY, and males are XX. Suppose that most interactions that result in hybrid inviability arise from interactions between an X-linked gene of one species and an autosomal gene of the other species, and that the inviability of the X-linked genes tends to be recessive. All other things being equal, which sex would expect to be more adversely affected in interspecific F₁ hybrid crosses?

Answer 1

In birds, females have XY chromosome and males have XX chromosome. Hybrid inviability arise from interactions between X linked genes of one species and autosomal gene of the other species. The inviability of the X linked genes follows recessive more of inheritance. Here, females are more commonly affected than males because females have only one X chromosome whereas males contain two X chromosome. Females get affected even when one of their X chromosome is affected.