Watch https://youtu.be/Zsbhvl2nVNE 1.a. In areas of the world where malaria is c

Question

Watch https://youtu.be/Zsbhvl2nVNE

1.a. In areas of the world where malaria is common, sickle-cell alleles appear to be under positive selection. In other words, natural selection appears to have increased the frequencies of sickle-cell alleles. Evolutionarily, how could sickle-cell alleles increase fitness? In other words, what was Dr. Tony Allison’s hypothesis?

1.b.How did researchers test this hypothesis? For full credit, describe at least two distinct tests.

1.c.Dr. Sean Carroll, the narrator of the video, stated: “The sickle cell mutation was not the best genetic solution you might imagine to resist malaria. That’s not how evolution works.” Based on your understanding of evolution and mutation, explain what he meant by this statement.

Explanation / Answer

1a) So the 1st question is how sickle-cell alleles increase fitness / Dr. Tony Allison’s hypothesis,

So the answer comes here, during his studies in Kenya, he saw an interesting co-relation between malaria which was caused by the mosquito, and Sickle Cell Anemia which was a genetic disease. He saw that people with Sickle Cell anemia were being protected against the parasite causing malaria; however, the mechanism of this protection is not very much understood until now. In 1954 he discovered, confirming his preconception, that people with sickle-cell trait are resistant to the deadly falciparum malaria. This is Dr. Tony Allison’s hypothesis.

1b) Researchers in East, Central, and West Africa read his theory and by knowing the necessity for studying children between 6 months and 4 years of age, they repeated his work in several populations. In a well-studied West African population, heterozygous children were found subsequently to have more than 90% protection from severe malaria.

Another test became possible when a method for cultivating malaria parasites in vitro was developed in 1977, an independent assay for the resistance of red blood cells containing HbS to parasite multiplication became available. It was soon reported that P. falciparum infection increased the rate of sickling of erythrocytes containing HbS and that the parasites were killed under these conditions.

1C) Dr. Sean Carroll stated that the sickle cell mutation was not the best genetic solution you might imagine to resist malaria. That’s not how evolution works. By this statement, he wanted to make us better understand that sickle cell mutation could cause a lethal disease, known as sickle cell anemia and as we all know A person who has sickle cell disease can become more likely to get infections because their immune system might become weaker and they could get sick more. So this mutation is not the best solution for treatment of malaria.

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