Question

The blue people of Troublesome Creek Kentucky were genetically isolated from the rest of the world for generations. A rare recessive allele that causes people to have a blue tone to their skin, methemoglobinemia, became disproportionately common within this population by way of their genetic isolation. In the last few decades new roads opened leading to the end of this communities isolation. To the surprise of many, the methemoglobinemia phenotype disappeared along with their genetic isolation. Which of the following may best explain the apparent disappearance of this once common trait?
a. Methemoglobinemia did not confer any physical advantage so that the trait was selected against.
b. Methemoglobinemia was probably lethal and all those that carried this trait died and did not have a chance to pass on this trait to future generations.
c. Those that had the traits simply did not have descendents.
d. With the end of genetic isolation gene flow took place.

Answer 1

Answer:

The correct answer would be - d. With the end of genetic isolation gene flow took place

Explanation:

It is given that people of Troublesome Creek Kentucky were isolated and have a rare recessive allele that results in a blue tone to their skin. However, later these isolated people connected with the people from outside, and due which allow them to intermate. Intermating among populations from isolated and people from outside leads to gene flow.

Methemoglobinemia was present in the isolated population as they had both recessive alleles in their genotype and other hand people from outside might have heterozygous or both dominant allele genotypes that make them free from this disorder.

Due to the intermating and gene flow, the number of heterozygous conditions rises and after many generations slowly methemoglobinemia could have disappeared due to the masked recessive allele.