Final answer:
A mule, the offspring of a male donkey and female horse, is an interspecific hybrid that is sterile due to hybrid sterility, a type of postzygotic barrier which prevents it from reproducing.
Step-by-step explanation:
An example of an interspecific hybrid that does not produce fertile offspring is the mule, which is the offspring of a male donkey (jack) and a female horse (mare). This hybrid is an example of hybrid sterility, where the resulting offspring is unable to reproduce. Mules have 63 chromosomes, which is a mix of the horse's 64 and the donkey's 62 chromosomes. This uneven number prevents the chromosomes from pairing up properly to produce gametes during meiosis, resulting in sterility.
In biology, this phenomenon is a type of postzygotic barrier, which prevents the hybrid from contributing genetically to future generations. This serves as a mechanism to maintain reproductive isolation between the two parent species, ensuring they remain separate in the biological sense.
An example of an interspecific hybrid that does not produce fertile offspring is when two species of insects produce infertile offspring. This is an example of a postzygotic barrier, specifically hybrid sterility. When fertilization occurs between the two insect species, the resulting hybrid offspring are unable to reproduce and produce offspring of their own.