Question 19 As humans spread around the world, they often adapted to local conditions, especially local diseases. One example is the evolution of greater resistance to the pathogen that causes malaria. The evolution of greater resistance to malaria has been observed in human populations from three regions (South America, Western Africa, and Southeast Asia). Recent genomic studies of these populations have identified several alleles related to malaria resistance that show evidence of selection based on SNP analysis. SNP is short for What does it mean that these alleles show "evidence of selection", from a genomic perspective?