Human migration and population structure 1

Published on March 18, 2015   25 min

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Other Talks in the Series: Human Population Genetics II

Welcome. This is Human Migration and Population Structure, a lecture for a course in Human Population Genetics. My name is John Novembre from the Department of Human Genetics at the University of Chicago.
The objectives for this lecture are going to be that we are going to introduce theoretical models of population structure. We're going to talk about how migration drift and selection impact genetic variation in these structured populations. Then, we are going to be introducing tools for understanding local population structure. And finally, we'll finish with a survey of spatial patterns of genetic variation in humans. A major theme throughout the lecture is going to be the relationship that genes and geography have to one another in complex models of population structure.
Some of the key ideas that we're going to cover are the genetic consequences of population structures being a balance of mutation and genetic drift. These are two forces that allow populations to differentiate. Genetic drift is the random change in allele frequencies due to finite population size. And we'll see how those random changes in allele frequencies will lead to allele frequencies in one population perhaps increasing, in another population perhaps decreasing. And over time, that leading to differentiation. Gene flow, which is the exchange of genes between populations due to individuals migrating between those populations, is going to work as a homogenizing force, pulling those allele frequencies that are differentiating from one another back towards some common mean allele frequency. Less often, we think that there are areas in the genome where natural selection is acting and differentiation can be impacted by that natural selection. So we'll also be talking about adaptive evolution.