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 increase the frequencies of sickle-cell alleles. Evolutionarily, how could sickle-cell alleles increase fitness? The Evolutionary Advantage of Sickle-Cell Alleles in Malaria-Endemic Areas

The Evolutionary Advantage of Sickle-Cell Alleles in Malaria-Endemic Areas

The sickle-cell allele is an example of how natural selection can lead to positive selection of certain traits. In areas of the world where malaria is common, it has been observed that those with the sickle-cell allele have higher survival rates than those without it. This is because individuals with the allele are less likely to contract malaria or suffer from its effects (Gonçalves et al., 2019; Talaat et al., 2020). This leads to a higher chance of survival, which is an evolutionary advantage. The sickle-cell allele confers resistance to malaria by impairing the ability of the malaria parasite to reproduce within red blood cells (Talaat et al., 2020). It does this by causing the cells to become misshapen, making it harder for the parasite to survive and reproduce. This advantage has been observed in areas where malaria is present, leading to the allele being under positive selection. In addition, the sickle-cell allele also confers resistance to other infectious diseases such as cholera (Gonçalves et al., 2019). This makes the allele advantageous for individuals living in areas where these diseases are common, as it increases their chances of survival and reproduction. Cont…