Question

A donkey and a horse are able to mate and produce an offspring known as a mule. The resultant mule possesses 63 chromosomes in its cells due to the donkey parent having 62 chromosomes and the horse parent having 64. The mule is unable to mate with other mules to produce its own offspring.
Which of the following reproductive isolating mechanisms is operating in this situation?

• A. Hybrid inviability
• B. Hybrid mortality
• C. Behavioral isolation
• D. Hybrid sterility
• E. Temporal isolation

Answer 1

Answer: (D)

Hybrid sterility

A. Hybrid inviability is a type of post zygotic barrier due to which the hybrid is unable to mature into a healthy adult.

B. Hybrid mortality is a type of post zygotic barrier in which the zygote formed inside the hybrid's body aborts during its early development.

C. In behavioural isolation, individuals choose members of their own species and reject other species as mates.

D. Hybrid sterility is the inability of a hybrid to form functional gametes due to abnormality in meiosis.

E. In temporal isolation, different species mate at different times of the day or year.

Hence, mule is a sterile hybrid as it can't produce functional gametes.

So, the correct answer is 'Hybrid sterility'.