Question

Imagine two species of snakes that live in a tropical rain forest of Malaysia do not typically interbreed. In nature, one species is ground-dwelling and feeds mainly on insects and small amphibians near water, whereas the other snake feeds in the lower to mid-canopy of trees and vines rising from the forest floor. However, at a zoo in Singapore where they were kept in the same gallery exhibit, the two species were observed interbreeding and produced viable offspring. Which of the following reproductive barriers is most likely preventing these species from interbreeding in the forest?

• habitat isolation
• gametic isolation
• reduced hybrid viability
• a postzygotic barrier
• mechanical isolation

Answer 1

In the above-mentioned case, habitat isolation is most likely preventing these species from interbreeding in the forest.

Habitat isolation - When the habitat of two different species is different or separated by ecological barriers, the probability of their interbreeding is reduced. In the above-mentioned case, the habitat of the two snake species is different, but their interbreeding is successful in the zoo. For that, it is clear that habitat isolation is playing the main role in preventing their interbreeding.

Gametic isolation - In this case, individuals of two species mate, but the sperm cannot fertilize the egg. In the above case, fertilization can successfully occur, as we see that interbreeding is successful in the zoo. Hence, this can't be the reason in preventing these species from interbreeding in the forest.

Reduced hybrid viability - In this case fertilization between sperm and egg is successful, but the newly formed zygote soon dies before developing into fully grown individuals. In the above case of two species of snakes, mentioned in the question, reduced hybrid viability is not the reason that preventing these snake species from interbreeding in the forest, as the offsprings are viable.

A postzygotic barrier - In this case, individuals born from interbreeding two species are sterile. In the above case of two species of snakes, mentioned in the question, a postzygotic barrier is not the reason that preventing these snake species from interbreeding in the forest, as the offsprings are viable.

Mechanical isolation - In this case, individuals of different species can't mate because of their sex organ incompatibility. In the above case of two species of snakes, mentioned in the question, mechanical isolation is not the reason that preventing these snake species from interbreeding in the forest, as interbreeding is successful in the zoo.