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

Journal Article

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.

Full Text

Duke Authors

Cited Authors

  • Hahn, MW; Rausher, MD; Cunningham, CW

Published Date

  • May 2002

Published In

Volume / Issue

  • 161 / 1

Start / End Page

  • 11 - 20

PubMed ID

  • 12019219

International Standard Serial Number (ISSN)

  • 0016-6731

Language

  • eng

Conference Location

  • United States