2.    Distinguish between directional, disruptive and stabilizing selection on multi-locus traits. Include in your answer, 1) how does the mean and variance of the distribution change as a result of an episode of each kind of selection; 2) at what phenotype(s) is mean fitness highest in the population; 3) how is the maintenance of genetic variability influenced by each of these types of multi-locus natural selection. Using graphs to illustrate your answers is a very good idea here.