Practise AP Biology 6.7.C questions by explaining how mutations, horizontal gene transfer and viral recombination create variation subject to natural selection.
The EPAS1 gene in human populations encodes a transcription factor activated in low-oxygen conditions, such as those found in high altitude (mountainous) regions. Researchers collected DNA from several populations of modern humans, including Han, Yoruban, Luhya, and Tibetan. They also collected DNA from the fossils of Denisovans, a prehistoric population. The researchers sequenced the most common EPAS1 allele in each population and determined the specific pattern of variations, called single nucleotide polymorphisms (SNPs), at six positions in each population (Table 1).
The EPAS1 gene shows strong indications of positive selection in Tibetans, a population located in a mountainous region in Asia. Describe how the specific EPAS1 gene SNP pattern shown above became common in the Tibetan population.
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Figure 1. Effect of increasing concentrations of atovaquone on the growth of P. falciparum