Essential Genetics 6th Edition by Daniel Hartl

Exercise 13

Human chromosome 2 resulted from a Robertsonian translocation in which the short arms of two nonhomologous acrocentric chromosomes underwent fusion in a recent primate ancestor. The fused chromosome retains the centromere of one of the ancestral chromosomes in an active form, while the centromere from the other ancestral chromosome was eventually inactivated. Imagine a human ancestor who was heterozygous for this fusion mating with an individual who was homozygous for the unfused, ancestral chromosomes. If the ratio of adjacent-1 : adjacent-2 : alternate segregation were 1 : 1 : 2, what proportion of the zygotes would be viable?