Which mechanism is NOT a part of reproductive isolation?

The mechanism that is not part of reproductive isolation is genetic mutation. Reproductive isolation refers to evolutionary mechanisms that prevent different species or populations from interbreeding, thereby maintaining distinct species. The primary types of reproductive isolation include temporal isolation, which occurs when species breed at different times; behavioral isolation, where differences in mating rituals or behaviors prevent interbreeding; and geographical isolation, which occurs when physical barriers, like mountains or rivers, separate populations.

Genetic mutation, while essential in the process of evolution and the generation of genetic diversity within a population, does not directly inhibit the reproductive capabilities between species. Instead, mutations can lead to new traits that may eventually contribute to speciation over time but are not a mechanism that actively prevents reproduction. Thus, it does not fit the definition of reproductive isolation.