Identify the effect(s) of specific population-genetic forces ongenetic variation within and between populations over time. In eachof the table cells, choose one of the options in the drop-down menuthat appears.

	Genetic variation within a population	Genetic variation between multiple populations
Mutation	                          [Select ]                      [\"increases\", \"decreases\",\"can either increase or decrease\", \"stays the same\"]    Â	                          [Select ]                      [\"increases\", \"decreases\",\"can either increase or decrease\", \"stays the same\"]    Â
Migration	                          [Select ]                      [\"increases\", \"decreases\",\"can either increase or decrease\", \"stays the same\"]    Â	                          [Select ]                      [\"increases\", \"decreases\",\"can either increase or decrease\", \"stays the same\"]    Â
Genetic drift	                          [Select ]                      [\"increases\", \"decreases\",\"can either increase or decrease\", \"stays the same\"]    Â	                          [Select ]                      [\"increases\", \"decreases\",\"can either increase or decrease\", \"stays the same\"]    Â
Natural selection	                          [Select ]                      [\"increases\", \"decreases\",\"can either increase or decrease\", \"stays the same\"]    Â	                          [Select ]                      [\"increases\", \"decreases\",\"can either increase or decrease\", \"stays the same\"]    Â

In a large, randomly-mating population, the frequency of theallele (a) for sickle-cell hemoglobin is 0.028. Theresults of studies have shown that people with the followinggenotypes at the beta-chain locus produce the average numbers ofoffspring given. In the table below, indicate the relative fitnessvalues for these three genotypes.

Genotype	Mean offspring	Relative fitness
AA	5	                          [Select ]                      [\"0\", \"1\", \"0.83\"]    Â
Aa	6	                          [Select ]                      [\"0\", \"1\", \"0.83\"]    Â
aa	0	                          [Select ]                      [\"0\", \"1\", \"0.83\"]    Â

What form of selection is acting on the sickle-cellallele?                           [ Select ]                     [\"directional selection against the a allele\", \"directionalselection against the A allele\", \"overdominance\", \"underdominance\"]     

Over time, we should expect genetic variation in this populationto                           [Select ]                      [\"increase\", \"decrease\",\"stay the same\"]         .