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Retinitis pigmentosa (RP) is an autosomal recessive trait that results in progressive blindness in humans - VCE - SSCE Biology - Question 21 - 2012 - Paper 1
Question 21
Retinitis pigmentosa (RP) is an autosomal recessive trait that results in progressive blindness in humans. On the island of Tristan da Cunha in the Atlantic Ocean, ... show full transcript
Worked Solution & Example Answer:Retinitis pigmentosa (RP) is an autosomal recessive trait that results in progressive blindness in humans - VCE - SSCE Biology - Question 21 - 2012 - Paper 1
Step 1
What is the process that is most likely responsible for this observation related to allele frequency?
Answer
The phenomenon observed on Tristan da Cunha, where the frequency of the allele causing retinitis pigmentosa (RP) is significantly higher than in the original British population, is best explained by the concept of the founder effect. This occurs when a small group of individuals colonizes a new area, leading to a limited genetic diversity that can amplify certain alleles in the population.
In this case, as the island was colonized in the early 1800s by a small number of individuals from the British population, the alleles present in this small founder population would be overrepresented, resulting in the observed higher frequency of the RP allele. Since no natural disasters have impacted the population, the allele frequency has remained high due to this initial genetic makeup.