Question: Several traits are affected by the environment, but also have a genetic component. How can we partition the sources of variation? Write a formula for this. If you want to measure the sources of variation, how can this be done experimentally? Write out how you can do this making specific reference to your formula.

Heritability can be defined in two ways. What are these definitions and how are they different?

Not all genetic variation is the same. What is the difference between additive, dominance, and epistatic forms of genetic variation? Define all three, and update your formula. In addition, use a regression plot to schematize additive and dominance variation (ie, box 9.2).

Differential survival and reproduction can be measured empirically, as can quantitative phenotypes of nearly any organism. From these we can calculate selection differentials and selection gradients. What are selection differentials and gradients?

Selection can act on quantitative traits in a variety of ways. Draw a diagram of what directional, stabilizing, and disruptive selection would look like on the distribution of a trait, then describe and explain the differences. Write concise definitions next to each type of selection.

If two populations differ in a trait that has a high heritability, is it valid to conclude that the two populations differ genetically with respect to that trait? Use evidence from section 9.7 to explain why or why not.