The Pingelapese people of the East Caroline Islands are descended from 20 survivors of a typhoon and subsequent famine in 1775.
Among the survivors was an individual heterozygous for a recessive mutation that causes achromatopsia, a condition that causes color-blindness, extreme sensitivity to light, and poor visual acuity. Although this condition is usually very rare, affecting about 1 person in 20,000, about 20% of today’s 3000 Pingelapese are achromats. The most likely explanation for the plight of the Pingelapese is:________. a. bottleneck effect.
b. directional selection.
c. founder effect.
d. a high rate of mutation for the achromatopsia allele.
e. non-random mating.
A bottleneck effect occurs when some adverse environmental conditions such as typhoons and famine reduce the population size considerably. The allele frequencies of the population are changed. As the population grows again, the gene pool has different allele frequencies than the original population. During population growth, some harmful alleles may become more abundant resulting in a rare disease such as achromatopsia. Therefore, the given population represents the bottleneck effect.
