Problem
In Africa, two related species of fleas feed on two different species of mammals: one species feeds on antelopes, and the other on buffalo. Since antelopes and buffaloes live side by side in the same spaces, both flea species can mate and produce hybrids. Hybrids grow more slowly and have a lower survival rate, suggesting the presence of a type of post-zygotic barrier.
1. Describe, conceptually, what you should demonstrate in order to infer that ecological speciation is the mechanism that generates this reproductive barrier.
2. Describe, concretely, how this could be tested experimentally.