Skip to main content
bioRxiv
  • Home
  • About
  • Submit
  • ALERTS / RSS
Advanced Search
New Results

Replaying Evolution to Test the Cause of Extinction of One Ecotype in an Experimentally Evolved Population

Caroline B. Turner, Zachary D. Blount, Richard E. Lenski
doi: https://doi.org/10.1101/022798
Caroline B. Turner
1Ecology, Evolutionary Biology and Behavior Program, Michigan State University, East Lansing, MI, United States of America
2Department of Integrative Biology, Michigan State University, East Lansing, MI, United States of America
3BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, United States of America
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Zachary D. Blount
3BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, United States of America
4Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States of America
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
Richard E. Lenski
1Ecology, Evolutionary Biology and Behavior Program, Michigan State University, East Lansing, MI, United States of America
2Department of Integrative Biology, Michigan State University, East Lansing, MI, United States of America
3BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, United States of America
4Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, United States of America
  • Find this author on Google Scholar
  • Find this author on PubMed
  • Search for this author on this site
  • For correspondence: lenski@msu.edu
  • Abstract
  • Full Text
  • Info/History
  • Metrics
  • Preview PDF
Loading

Abstract

In a long-term evolution experiment with Escherichia coli, bacteria in one of twelve populations evolved the ability to consume citrate, a previously unexploited resource in a glucose-limited medium. This innovation led to the frequency-dependent coexistence of citrate-consuming (Cit+) and non-consuming (Cit−) ecotypes, with Cit− bacteria persisting on the exogenously supplied glucose as well as other carbon molecules released by the Cit+ bacteria. After more than 10,000 generations of coexistence, however, the Cit− lineage went extinct; cells with the Cit− phenotype dropped to levels below detection, and the Cit− clade could not be detected by molecular assays based on its unique genotype. We hypothesized that this extinction event was a deterministic outcome of evolutionary change within the population, specifically the appearance of a more-fit Cit+ ecotype that competitively excluded the Cit− ecotype. We tested this hypothesis by re-evolving the population from one frozen sample taken just prior to the extinction and from another sample taken several thousand generations earlier, in each case for 500 generations and with 20-fold replication. To our surprise, the Cit− type did not go extinct in any of these replays, and Cit− cells also persisted in a single replicate that was propagated for 3,000 generations. Even more unexpectedly, we showed that the Cit− ecotype could reinvade the Cit+ population after its extinction. Taken together, these results indicate that the extinction of the Cit− ecotype was not a deterministic outcome driven by competitive exclusion by the Cit+ ecotype. The extinction also cannot be explained by demographic stochasticity, as the population size of the Cit− ecotype should have been many thousands of cells even during the daily transfer events. Instead, we infer that the extinction must have been caused by a rare chance event in which some aspect of the experimental conditions was inadvertently perturbed.

Copyright 
The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY-NC-ND 4.0 International license.
Back to top
PreviousNext
Posted July 19, 2015.
Download PDF
Email

Thank you for your interest in spreading the word about bioRxiv.

NOTE: Your email address is requested solely to identify you as the sender of this article.

Enter multiple addresses on separate lines or separate them with commas.
Replaying Evolution to Test the Cause of Extinction of One Ecotype in an Experimentally Evolved Population
(Your Name) has forwarded a page to you from bioRxiv
(Your Name) thought you would like to see this page from the bioRxiv website.
CAPTCHA
This question is for testing whether or not you are a human visitor and to prevent automated spam submissions.
Share
Replaying Evolution to Test the Cause of Extinction of One Ecotype in an Experimentally Evolved Population
Caroline B. Turner, Zachary D. Blount, Richard E. Lenski
bioRxiv 022798; doi: https://doi.org/10.1101/022798
Reddit logo Twitter logo Facebook logo LinkedIn logo Mendeley logo
Citation Tools
Replaying Evolution to Test the Cause of Extinction of One Ecotype in an Experimentally Evolved Population
Caroline B. Turner, Zachary D. Blount, Richard E. Lenski
bioRxiv 022798; doi: https://doi.org/10.1101/022798

Citation Manager Formats

  • BibTeX
  • Bookends
  • EasyBib
  • EndNote (tagged)
  • EndNote 8 (xml)
  • Medlars
  • Mendeley
  • Papers
  • RefWorks Tagged
  • Ref Manager
  • RIS
  • Zotero
  • Tweet Widget
  • Facebook Like
  • Google Plus One

Subject Area

  • Evolutionary Biology
Subject Areas
All Articles
  • Animal Behavior and Cognition (4222)
  • Biochemistry (9095)
  • Bioengineering (6733)
  • Bioinformatics (23916)
  • Biophysics (12066)
  • Cancer Biology (9484)
  • Cell Biology (13720)
  • Clinical Trials (138)
  • Developmental Biology (7614)
  • Ecology (11644)
  • Epidemiology (2066)
  • Evolutionary Biology (15459)
  • Genetics (10610)
  • Genomics (14281)
  • Immunology (9447)
  • Microbiology (22749)
  • Molecular Biology (9056)
  • Neuroscience (48811)
  • Paleontology (354)
  • Pathology (1478)
  • Pharmacology and Toxicology (2558)
  • Physiology (3817)
  • Plant Biology (8299)
  • Scientific Communication and Education (1466)
  • Synthetic Biology (2285)
  • Systems Biology (6163)
  • Zoology (1295)