Molecular evolution: detecting selection on nucleotide sequences
Nora will be giving the lecture today and Thursday while I'm out of town. If you have questions she's not prepared to answer, she'll keep track of them, and we'll deal with them when I return.
We've seen by now that we can detect the impact of selection in it's "purifying" mode, i.e., when it's eliminating mutations that reduce the fitness of individuals carrying the allele. But we also know that there are cases when selection may favor certain alleles. Rather than asking whether individual nucleotides are selected against most of the time, what if we ask whether particular allelic differences are the result of selection. You've heard of the sickle-cell hemoglobin example, but you probably haven't heard about Adh in Drosophila. Nora will talk about that today and a couple of the ways selection has been studied at that locus. She'll also describe a general approach to detecting balancing or purifying selection (or recent population bottlenecks or expansions).