The mode and tempo of adaptation in natural populations of Drosophila
Abstract/Contents
- Abstract
- Evolutionary adaptation is a process in which beneficial mutations increase in frequency in response to selective pressures. If these mutations were previously rare or absent from the population, adaptation should generate a characteristic signature in the genetic diversity around the adaptive locus, known as a selective sweep. Such selective sweeps can be distinguished into hard selective sweeps, where only a single adaptive mutation rises in frequency, or soft selective sweeps, where multiple adaptive mutations at the same locus sweep through the population simultaneously. In my second chapter, I propose two new statistics, H12 and H2/H1, which can identify and differentiate hard and soft sweeps in population genomic data. I apply this method to a Drosophila melanogaster population genomic dataset consisting of 145 sequenced strains collected in North Carolina and find that selective sweeps were abundant in the recent history of this population. Interestingly, I also find that practically all of the strongest and most recent sweeps show patterns that are more consistent with soft rather than hard sweeps. In my third chapter, I demonstrate an inverse relationship between H12 and H2/H1 and develop an upper bound for H2/H1 as a function of H12. This upper bound can be used to normalize H2/H1, which can facilitate the interpretation of the application of H12 and H2/H1 to heterogenous data. Finally, in my fourth chapter, I find that the patterns of abundant soft selective sweeps are not unique to the North Carolina data set and are present in a population sample of 200 individuals from Zambia. These results together suggest that adaptation can be rapid in multiple populations of D. melanogaster.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2015 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Garud, Nandita Raghuram |
|---|---|
| Associated with | Stanford University, Department of Genetics. |
| Primary advisor | Petrov, Dmitri Alex, 1969- |
| Thesis advisor | Petrov, Dmitri Alex, 1969- |
| Thesis advisor | Bustamante, Carlos |
| Thesis advisor | Rosenberg, Noah |
| Thesis advisor | Sherlock, Gavin |
| Thesis advisor | Tang, Hua |
| Advisor | Bustamante, Carlos |
| Advisor | Rosenberg, Noah |
| Advisor | Sherlock, Gavin |
| Advisor | Tang, Hua |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Nandita Raghuram Garud. |
|---|---|
| Note | Submitted to the Department of Genetics. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2015. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2015 by Nandita Raghuram Garud
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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