What mechanism prevents gamete transfer between species due to anatomical differences?

The mechanism that prevents gamete transfer between species due to anatomical differences is mechanical isolation. This occurs when species have reproductive structures that are incompatible, making it difficult or impossible for them to successfully mate. For example, the size and shape of reproductive organs may vary between species, preventing them from aligning properly for fertilization to occur.

In the case of mechanical isolation, even if two species are in the same location and may potentially interact, the anatomical discrepancies ensure that mating cannot take place, thereby preventing the exchange of gametes. This is a critical factor in maintaining the distinctiveness of species and reducing the likelihood of hybridization.

The other mechanisms listed do not pertain directly to anatomical differences. Temporal isolation refers to species that breed at different times, behavioral isolation involves distinct mating behaviors or rituals that differ among species, and geographical isolation describes physical barriers that separate populations of species. Each of these mechanisms reduces the chances of mating but does not specifically address the anatomical incompatibilities that are highlighted by mechanical isolation.