Question

The arctic fox has 50 chromosomes (25 per set), and the common red fox has 38 chromosomes (19 per set). These species can interbreed to produce viable but infertile offspring. How many chromosomes would the offspring have? What problems do you think may occur during meiosis that would explain the offspring’s infertility?

Answer 1

The organism is sterile because parts of the chromosomes in the zygote will only have a single set of chromosomes rather than the ideal pair. The arctic fox will produce gamates with 25 chromosomes (a single set) while the red fox will produce gametes with 19 chromosomes (another set). These gametes are supposed to fuse and have their chromosomes paired. However notice that the offspring will have (25 – 19) six (6) unpaired chromosomes. This means that during the formation of gametes in this hybrid offspring, there will be an issue in meiosis I which will result in nonviable gametes.