There are several mechanisms through which reproductive isolation occurs. Which situation is an example of behavioral isolation?

A.

Mules, the offspring of a male donkey and a female horse, are unable to reproduce because they are sterile.

B.

Red and purple sea urchins cannot reproduce with one another because the sperm and egg cannot fuse.

C.

The reproductive organs of snails only properly align when the male and female belong to the same species.

D.

Males of different, closely related species of fireflies signal for mates by flashing different light sequences.

Reproductive isolation is a system of barrier that does not allow different species or even similar species to mate. The example of behavioral isolation is shown by fireflies in which males flash light in different sequences to attract females. So the answer is 'D'.

Explanation:

Species have trouble in mating with each other so easily. Certain reproductive barriers are placed by the nature which do not allow them to mate. These barriers are classified as prezygotic and postzygotic.

In prezygotic, the process of mating does not occur and in case of postzygotic the organism formed is incapable of surviving. Behavioral isolation is a type of prezygotic barrier. In this the behavior of individuals like mating rituals and signals are very specific for organisms to reproduce. For example in case of some birds, dancing is a way to attract females but all males dance differently. In case of fireflies, the males emit different pattern of light sequences and females select the best pattern they like.