In a study of genetic variation of the Graceland gene, a researcher finds that there are two alleles in a population. In a large sample (500 individuals), the frequency of heterozygotes is 0.63. Is the population in Hardy-Weinberg equilibrium. You come back after 500 generations have past and observe that the frequency of heterozygotes is still 0.63. You conclude that the population is experiencing selection. Which type of selection is the population most likely experiencing?
