Reproductive separation of two populations can result in the accumulation of genetic differences in their gene pools
When two populations stop interbreeding, their alleles change independently over time. Mutations and natural selection build up separately in each group, making the two gene pools increasingly different.
Real World
Approximately 5 million years ago, the Grand Canyon separated squirrel populations; the Kaibab squirrel on the north rim and the Abert's squirrel on the south rim have since accumulated distinct fur colours and body sizes through independent mutation and selection.
Exam Focus
State that gene flow stops first, then explain how mutation, selection, and drift act independently — sequence matters for full marks.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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