Genetic drift: effective population size

I've warned you repeatedly that population geneticists approach understanding the world in peculiar ways. If you've started the lab exercise for this week, you've already seen that this thing called "effective population size" doesn't behave as well as we might like it to, but there's a good chance that you don't know what "effective population size" means, even if you've heard the phrase before and even if you know that, in some sense, it's the effective population size that matters for genetic drift.

Well, today is your lucky day. We're going to dive into what effective population size means, and in doing so, you'll learn that there's more than one definition of effective population size. Unlike with the inbreeding coefficient where the different definitions are (almost) equivalent, different definitions of effective population size can be very different. It's important to understand where those differences come from and when you might want to use one rather than the other and what you need to be careful of whenever you use any of them.

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