I returned from my trip to Dublin1 Friday evening. Over the past day and a half, I’ve revised notes for this week’s lectures and put together Project #5. We’ll start on Tuesday by answering any questions left over from Nora’s lectures last week on detecting selection on molecular sequences and on evolution in multigene families. You’ll want to be sure that you understand Tajima’s D, and it will be obvious why I say that when you see Project #5.
Once we’ve finished dealing with questions, we’ll move onto discussing how to use molecular data, and especially nucleotide sequence data, to provide insights into the history and demography of populations. The first approach we’ll examine extends Wright’s F-statistics to nucleotide sequence data. If we have time, I’ll introduce some very sophisticated approaches to phylogeography, and we’ll discuss them in detail on Thursday.
I’ve posted notes for next week’s lectures about detecting selection on nucleotide sequences (which will introduce you to Tajima’s D) and on evolution in multigene families (which will introduce you to orthology, paralogy, and concerted evolution). Remember that Nora will be presenting these lectures, since I’ll be in Dublin at the annual meetings of the Deans and Directors of Graduate Studies (DDoGS) for universities in Universitas 21 (http://universitas21.com/event/details/269/re-cluster-workshop-and-meetings). Nora knows population genetics very well, and it’s likely she’ll be able to answer any question you have. If for some reason she can’t, keep track of it. We’ll spend time dealing with any of those questions on the Tuesday when I return.
In catching up on my reading today, I noticed that Sònia Casillas and Antonio Barbadilla have a review article in the March 2017 issue of Genetics on the history of molecular population genetics. I haven’t had a chance to read it carefully, but I did look it over quickly, and it appears to give a very nice overview of developments from the era of protein electrophoresis to the present day and population genomics. I’m pasting the abstract below, but I encourage you to follow the link and read the whole thing.
Casillas, S., and A. Barbabadilla. 2017. Molecular population genetics. Genetics 205:1003-1035. doi:
Molecular population genetics aims to explain genetic variation and molecular evolution from population genetics principles. The field was born 50 years ago with the first measures of genetic variation in allozyme loci, continued with the nucleotide sequencing era, and is currently in the era of population genomics. During this period, molecular population genetics has been revolutionized by progress in data acquisition and theoretical developments. The conceptual elegance of the neutral theory of molecular evolution or the footprint carved by natural selection on the patterns of genetic variation are two examples of the vast number of inspiring findings of population genetics research. Since the inception of the field, Drosophila has been the prominent model species: molecular variation in populations was first described in Drosophila and most of the population genetics hypotheses were tested in Drosophila species. In this review, we describe the main concepts, methods, and landmarks of molecular population genetics, using the Drosophila model as a reference. We describe the different genetic data sets made available by advances in molecular technologies, and the theoretical developments fostered by these data. Finally, we review the results and new insights provided by the population genomics approach, and conclude by enumerating challenges and new lines of inquiry posed by increasingly large population scale sequence data.
Just in case you want to get an early start on Project #4, I’ve posted a link to it on the lecture detail page for tomorrow’s lecture. It’s not due until the Tuesday after spring break, but Nora will be in Texas getting experiments for her postdoc started during spring break, and I’ll be (mostly) unavailable during spring break, so I encourage you to get started on it soon.
We shift gears on Tuesday and start our survey of molecular evolution. We’ll start with a review of the kinds of molecular variation that population geneticists have studied over the last 50 years, then we’ll discuss the neutral theory and some of the ways it’s been modified to fit our increasingly sophisticated understanding of molecular variation. After spring break Nora will talk about some of the ways we can detect selection on nucleotide sequences and about the evolution of multigene families. When I get back we’ll talk about how to use data from molecular markers to make inferences about the recent evolutionary history of individuals and populations, and we’ll finish with a very brief discussion of how the explosion of data that is coming with high-throughput sequencing is changing our approach to understanding evolutionary processes in populations.
I made some last-minute changes to the notes for tomorrow’s lecture, a short section on “genetic draft.” You read that right. It’s not a typo. Genetic draft is a thing – and we’ll discuss it briefly tomorrow. There’s still a permission problem with the notes, so follow the link with the PDF label on the lecture detail page, or click here.
I’ve posted notes for Tuesday (drift and selection) and Thursday (the coalescent). Something strange is happening with the permissions on my server. For some reason I can’t get the regular link from the detail page to the PDF notes for Tuesday to work. Use this link instead. I’ve also posted the link on the lecture detail page for Tuesday. I think I know where the permission problem is, but I may not have time to fix it until next weekend.
I’ve posted the notes for Thursday’s discussion of mutation, migration, and genetic drift. Notes on effective population size are included in the notes from last Thursday on genetic drift. Of course, the notes are always available from the lecture detail page.
If you visit the lecture detail page for Tuesday’s lecture, you’ll also find a link to Project #3. Nora will go over it in lab on Tuesday, but I encourage you to take a look at it ahead of time so that you have questions ready.
I’ve posted notes for this week’s lectures. Since snow prevented us from meeting in person last Thursday, we’ll devote the first part of Tuesday’s lecture to discussing any questions that arose from the practice exercise. (You did take my advice, and try it, didn’t you?) We’ll take as much time as we need to discuss any questions you have before moving on to discuss how to estimate viabilities from data. If there’s time, we’ll close by discussing how the dynamics of viability selection with multiple alleles differ from those with only two alleles present and how fertility selection differs from viability selection.
I hope that you had a chance to look at the Practice Exercise I posted on Thursday. I’ve now posted answers to the questions in the exercise. In addition to following the posted answers link in this post, you can also find links to the exercise and answers on the lecture detail page for last Thursday.
I expect to have notes for this week (estimating viabilities, an introduction to genetic drift) posted by this evening. Enjoy the snow!