Final answer:
Mechanical isolation is a prezygotic barrier where morphological differences in reproductive anatomy prevent species from successfully mating, an essential factor in the speciation process.
Step-by-step explanation:
The type of isolation where morphological differences prevent mating is known as mechanical isolation, a form of prezygotic barrier. Mechanical isolation occurs when differences in the structure of reproductive organs between species prevent successful mating. An example of this is seen in damselflies, where the males of different species have differently shaped reproductive organs, and thus cannot successfully mate with females of another species.
This form of reproductive isolation is crucial for the process of speciation, as it prevents the gene flow between species that could otherwise interbreed. Over time, mechanical isolation can lead to increased differences between the species as they evolve independently of each other.