Question

The reproductive barrier that maintains the species boundary between horses and donkeys is ______.

Options

• mechanical isolation

• gametic isolation

• hybrid inviability

• hybrid sterility

Answer 1

The reproductive barrier that maintains the species boundary between horses and donkeys is hybrid sterility.

Explanation:

Horses and donkeys can mate and produce a hybrid offspring called a mule; however, mules are almost always sterile and cannot produce offspring. This sterility of the hybrid offspring acts as a postzygotic reproductive barrier that maintains the species boundary between horses and donkeys. It prevents gene flow between the two species despite successful mating and fertilization.