Question

Pingelap is a small island in Micronesia. About 200 years ago, a large storm killed most of the population, leaving only 20 people alive on the island. One of these survivors carried a faulty allele for a genetic disease that causes complete colour blindness. There are approximately 3000 people living on Pingelap today and nearly all of them are descended from the 20 survivors. Complete colour blindness occurs at a higher frequency on Pingelap than in the USA. Explain why.

Answer 1

The high frequency of complete color blindness on Pingelap is due to the founder effect and genetic drift following a population bottleneck caused by a storm 200 years ago.

Step-by-step explanation:

Explanation for High Frequency of Complete Color Blindness on Pingelap

The high frequency of complete color blindness among the population of Pingelap compared to that in the USA can be attributed to a genetic phenomenon known as founder effect, which is a type of genetic drift. After the storm that left only 20 survivors on the island 200 years ago, one of these survivors carried a gene for complete color blindness. Because of the small initial population and the fact that nearly all of the current inhabitants are descended from these 20 individuals, the allele for color blindness spread through the population more rapidly than it would in a larger population with more genetic variation.

In more technical terms, the phenomenon can be explained by the genetic bottleneck that occurred when the population was greatly reduced by the storm. This bottleneck led to a reduction in genetic diversity and an increase in the frequency of certain alleles, including the allele for achromatopsia, the genetic disease causing complete color blindness. The limited gene pool and the continued interbreeding among the isolated population exacerbated this effect, leading to the high prevalence of the condition in present-day Pingelapese people.