Question

Horses and donkeys can breed and produce offspring known as mules. yet horses and donkeys remain separate species. this is because of the __________ of mules.

a. prezygotic sterility
b. inviability
c. postzygotic inviability
d. sterility
e. hybrid breakdown

Answer 1

The answer is D. This ensures that the mule cannot have offsprings hence can't continue its generation. Sterility of the mule is due to mismatch of homologous chromosomes between the horse and the donkey leaving an extra lone horse chromosome on the mule (since a horse has 64 chromosomes and a donkey has 62).