Genetic drift: mutation and migration
We'll start on Tuesday by reviewing the idea of effective population size and making sure that everyone understands what it is and why it's important. I'll then quickly remind you of how the effective population size depends on the sex ratio, and I'll tell you how the effective population size is related to the average population size when the population size varies over time and how it is related to the variance in reproductive success. With that we will have concluded our review of pure drift.
We'll then move on to talk about the interaction of mutation, migration, and drift. We'll start with a much oversimplified model to develop some intuition. Then I'll share results from more exact models (that are still oversimplified). We'll learn how to determine when a population is "large" and when it is "small", and we'll realize that those words are a lot less meaningful than they seem.