Distinguishing between selection and population expansion in an experimental lineage of bacteriophage T7

Experimental evolution of short-lived organisms offers the opportunity to study the dynamics of polymorphism over time in a controlled environment. Here, we characterize DNA polymorphism data over time for four genes in bacteriophage T7. Our experiment ran for 2500 generations and populations were s...

Full description

Saved in:
Bibliographic Details
Published in:Genetics (Austin) 2002-05, Vol.161 (1), p.11-20
Main Authors: Hahn, Matthew W, Rausher, Mark D, Cunningham, Clifford W
Format: Article
Language:English
Subjects:
Bacteriophage T7 - genetics
Bacteriophage T7 - growth & development
Deoxyribonucleic acid
Directed Molecular Evolution
DNA
DNA, Viral
Genes
Molecular Sequence Data
Mutation
Phage T7
Polymorphism, Genetic
Recombination, Genetic
Selection, Genetic
Statistics as Topic
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Experimental evolution of short-lived organisms offers the opportunity to study the dynamics of polymorphism over time in a controlled environment. Here, we characterize DNA polymorphism data over time for four genes in bacteriophage T7. Our experiment ran for 2500 generations and populations were sampled after 500, 2000, and 2500 generations. We detect positive selection, purifying ("negative") selection, and population expansion in our experiment. We also present a statistical test that is able to distinguish demographic from selective events, processes that are hard to identify individually because both often produce an excess of rare mutations. Our "heterogeneity test" modifies common statistics measuring the frequency spectrum of polymorphism (e.g., Fu and Li's D) by looking for processes producing different patterns on nonsynonymous and synonymous mutations. Test results agree with the known conditions of the experiment, and we are therefore confident that this test offers a tool to evaluate natural populations. Our results suggest that instances of segregating deleterious mutations may be common, but as yet undetected, in nature.
ISSN:0016-6731
1943-2631
1943-2631
DOI:10.1093/genetics/161.1.11