Rxivist logo

A Comparison of Methods to Measure Fitness in Escherichia coli

By Michael J. Wiser, Richard E. Lenski

Posted 06 Mar 2015
bioRxiv DOI: 10.1101/016121 (published DOI: 10.1371/journal.pone.0126210)

In order to characterize the dynamics of adaptation, it is important to be able to quantify how a population's mean fitness changes over time. Such measurements are especially important in experimental studies of evolution using microbes. The Long-Term Evolution Experiment (LTEE) with Escherichia coli provides one such system in which mean fitness has been measured by competing derived and ancestral populations. The traditional method used to measure fitness in the LTEE and many similar experiments, though, is subject to a potential limitation. As the relative fitness of the two competitors diverges, the measurement error increases because the less-fit population becomes increasingly small and cannot be enumerated as precisely. Here, we present and employ two alternatives to the traditional method. One is based on reducing the fitness differential between the competitors by using a common reference competitor from an intermediate generation that has intermediate fitness; the other alternative increases the initial population size of the less-fit, ancestral competitor. We performed a total of 480 competitions to compare the statistical properties of estimates obtained using these alternative methods with those obtained using the traditional method for samples taken over 50,000 generations from one of the LTEE populations. On balance, neither alternative method yielded measurements that were more precise than the traditional method.

Download data

  • Downloaded 490 times
  • Download rankings, all-time:
    • Site-wide: 31,993 out of 89,147
    • In evolutionary biology: 2,164 out of 5,449
  • Year to date:
    • Site-wide: 81,016 out of 89,147
  • Since beginning of last month:
    • Site-wide: 50,801 out of 89,147

Altmetric data


Downloads over time

Distribution of downloads per paper, site-wide


PanLingua

Sign up for the Rxivist weekly newsletter! (Click here for more details.)


News