Which isolation mechanism arises when morphological differences prevent successful mating between species?

Which isolation mechanism arises when morphological differences prevent successful mating between species?

• A. Ecological Isolation
• B. Mechanical Isolation
• C. Prezygotic Barrier
• D. Postzygotic Barrier

Answer: (B)

Mechanical isolation happens when physical differences in reproductive structures prevent mating between species. Because the barrier is a matter of anatomy, it stops the act of mating or the transfer of sperm before fertilization can occur, making it a prezygotic barrier. This is different from ecological isolation, which would separate species by habitat, and from postzygotic barriers, which affect offspring after fertilization. The idea here is that morphological mismatches—reproductive organs or mating structures that don’t fit—prevent successful mating, so no gene flow happens between the species.

Mechanical isolation happens when physical differences in reproductive structures prevent mating between species. Because the barrier is a matter of anatomy, it stops the act of mating or the transfer of sperm before fertilization can occur, making it a prezygotic barrier. This is different from ecological isolation, which would separate species by habitat, and from postzygotic barriers, which affect offspring after fertilization. The idea here is that morphological mismatches—reproductive organs or mating structures that don’t fit—prevent successful mating, so no gene flow happens between the species.