Genetic bottleneck and the Founder effect (OCR A-level Biology)

This engaging and fully-resourced lesson looks at how genetic drift can arise after a genetic bottleneck or as a result of the Founder effect. The detailed PowerPoint and accompanying resources have been designed to cover the second part of point 6.1.2 (e) of the OCR A-level Biology A specification which states that students should be able to demonstrate and apply an understanding of the factors that affect the evolution of a species.

A wide range of examples are used to show the students how a population that descends from a small number of parents will have a reduction in genetic variation and a change in the frequency of existing alleles. Students are encouraged to discuss new information to consider key points and understanding checks in a range of forms are used to enable them to check their progress and address any misconceptions. Students are provided with three articles on Huntington’s disease in South Africa, the Caribbean lizards and the plains bison to understand how either a sharp reduction in numbers of a new population beginning from a handful of individuals results in a small gene pool. Links to related topics are made throughout the lesson to ensure that a deep understanding is gained.

This lesson has been designed to tie in with another uploaded lesson on types of selection which is part of this specification point