A population of squirrels lived together in a forest. An event occurred that caused the population to diverge into two different species over a long period of time. Which of these is most likely the event that occurred?

A natural disaster could split the squirrel population into groups that can no longer regularly mate with each other. Over many generations, the separated groups may adapt to different conditions and accumulate genetic differences until they become separate species. This is geographic isolation; more predators, cold winters, or disease could affect the population without separating it.

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