List two species that are clear examples of genetic drift and speciation events.

Cougar and cheetah

Explanation:

The cougar and the cheetah are a nice example of genetic drift and speciation. These two felids have a common ancestor that lived in North America. As the environment was changing, some individuals of the species started to occupy the forests, especially in the mountainous regions, while other individuals moved into the open grasslands where there was an open niche in the food chain. The cougar emerged from the ones that lived in the mountainous forests, remaining typically cat like, with lot of muscle tone, relatively short legs, and being an ambush predator. The cheetah emerged from the ones that started living in the grasslands. Unlike their cousins, these individuals experienced lot of changes, developing long legs, larger heart and lung capacity, losing their retractable claws, and becoming sprinters. As the conditions changed, the cheetah migrated, eventually reaching Eurasia and Africa, while the cougar spread across most of North America and South America.