Sustained fitness gains and variability in fitness trajectories in the long-term evolution experiment with Escherichia coli.

Autor:	Lenski RE; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA Department of Integrative Biology, Michigan State University, East Lansing, MI, USA Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, USA lenski@msu.edu., Wiser MJ; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Integrative Biology, Michigan State University, East Lansing, MI, USA., Ribeck N; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA., Blount ZD; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA., Nahum JR; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA., Morris JJ; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Biology, University of Alabama at Birmingham, Birmingham, AL, USA., Zaman L; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Biology, University of Washington, Seattle, WA, USA., Turner CB; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Integrative Biology, Michigan State University, East Lansing, MI, USA Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA., Wade BD; Department of Plant, Soil and Microbial Sciences, Michigan State University, East Lansing, MI, USA., Maddamsetti R; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Integrative Biology, Michigan State University, East Lansing, MI, USA., Burmeister AR; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA., Baird EJ; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA., Bundy J; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Integrative Biology, Michigan State University, East Lansing, MI, USA., Grant NA; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA., Card KJ; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA., Rowles M; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA., Weatherspoon K; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA., Papoulis SE; BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI, USA Department of Microbiology, University of Tennessee, Knoxville, TN, USA., Sullivan R; Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA., Clark C; Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA., Mulka JS; Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA., Hajela N; Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA.
Jazyk:	angličtina
Zdroj:	Proceedings. Biological sciences [Proc Biol Sci] 2015 Dec 22; Vol. 282 (1821), pp. 20152292.
DOI:	10.1098/rspb.2015.2292
Abstrakt:	Many populations live in environments subject to frequent biotic and abiotic changes. Nonetheless, it is interesting to ask whether an evolving population's mean fitness can increase indefinitely, and potentially without any limit, even in a constant environment. A recent study showed that fitness trajectories of Escherichia coli populations over 50 000 generations were better described by a power-law model than by a hyperbolic model. According to the power-law model, the rate of fitness gain declines over time but fitness has no upper limit, whereas the hyperbolic model implies a hard limit. Here, we examine whether the previously estimated power-law model predicts the fitness trajectory for an additional 10 000 generations. To that end, we conducted more than 1100 new competitive fitness assays. Consistent with the previous study, the power-law model fits the new data better than the hyperbolic model. We also analysed the variability in fitness among populations, finding subtle, but significant, heterogeneity in mean fitness. Some, but not all, of this variation reflects differences in mutation rate that evolved over time. Taken together, our results imply that both adaptation and divergence can continue indefinitely--or at least for a long time--even in a constant environment. (© 2015 The Authors.)
Databáze:	MEDLINE
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