Final answer:
Reproductive isolation is a process that leads to speciation by preventing populations from breeding due to geographic isolation. Over time, the isolated populations evolve differently and become genetically distinct, resulting in the formation of new species.
Step-by-step explanation:
Reproductive isolation is one of the ways speciation occurs naturally. It can happen through geographic isolation, where populations are separated by physical barriers like a forest fire, preventing them from breeding. Over time, the isolated populations evolve in different directions, eventually becoming so different that they can no longer produce fertile offspring together, resulting in the formation of new species.