Answer:
Mechanical isolation
Explanation:
Mechanical mechanism of reproductive isolation operates as one of the prezygotic mechanisms. In this process, the incompatibility of the structure of the reproductive organs between populations does not allow them to interbreed.
In the given example, two species of genus Ipomea can not interbreed irrespective of their presence in the same habitat and same reproductive behavior. These two species produce flowers which are not compatible with each other and do not allow these two species to interbreed. Since structural incompatibility is operative here, it is a mechanical mechanism of prezygotic isolation.
