Question

Which one of the following is a "post-zygotic" isolating mechanism of speciation?

• A. {Behavioral isolation}
• B. {Fertilization failure}
• C. {Hybrid sterility}
• D. {Seasonal isolation}

Hint:

Post-zygotic isolating mechanisms prevent hybrid offspring from reproducing, with hybrid sterility being a key example. Mules, which are sterile hybrids, demonstrate this concept.

Answer 1

The Correct Option is C

Post-zygotic isolation mechanisms occur after fertilization and prevent successful reproduction. Hybrid sterility is an example of a post-zygotic barrier, where the hybrid offspring are sterile and unable to reproduce. The most well-known example of this is the mule, which is a hybrid between a horse and a donkey. Although mules are typically healthy, they are sterile and cannot produce offspring.
On the other hand, behavioral isolation and seasonal isolation are pre-zygotic mechanisms, meaning they prevent fertilization from happening in the first place. Fertilization failure could be considered a pre-zygotic barrier as well, as it prevents the egg from being fertilized. Therefore, the correct answer is Hybrid sterility, which is a classic example of post-zygotic isolation.