Discuss how crossing-over leads to greater variability of phenotypes. Give an example.

Crossing over shuffles alleles between chromosomes, resulting in greater change in the subsequent meiotic chromosomal separation. Say you have two homologous chromosomes, one from your father and one from your mother. Instead of passing these chromosomes down as they are, crossing over will take some parts from the mothers chromosome and put them onto the father's chromosome, and vice versa for the exact same parts. So you now have a chromosome made from parts of both your mother and father's chromosome, which means more variance than if you just passed down, say, you father's chromosome in its entirety. More variance in the chromosomes means more possibilities of getting more different genotypes and therefore different phenotypes.