Which, if any, of the following observations are consistent…
Which, if any, of the following observations are consistent with the effect of purifying selection, and which, if any, are consistent with the effect of positive selection? A) Human populations that are accustomed to high-starch diets have higher copy numbers of the α-amylase gene (amalyse is an enzyme that breaks down starch) than human populations with a low starch diet. . [A] B) Telomere DNA sequences in all vertebrates have tandem TTAGGG repeats. [B] C) Humans show very high levels of heterozygosity at the classical HLA loci. [C] D) Human calmodulin and an ortholog in Drosophila each have 149 amino acids and differ at just four amino acid positions. [D]
Read Details