Question

While we may find certain species difficult to distinguish, morphologically, they can often recognize one another perfectly well. If they are sufficiently genetically divergent to have reduced hybrid viability, why would it be selectively advantageous for them to maintain behavioral isolation from one another?

Answer 1

Animals always prefer pre-zygotic reproductive isolation than post-zygotic reproductive isolation. In pre-zygotic isolation, energy cost is more because here the organisms have to mate with each other and the female have to give rise to a sterile hybrid baby. The female have to bear the metabolic cost to bear the baby during congestion period. But in case of pre-zygotic isolation, fertilization is not occured and as a result metabolic cost is low. So behavioural isolation is more preferred here than giving rise to sterile offspring. Thus pre-zygotic isolation is selected by nature over post-zygotic reproductive isolation.