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Final OD at 420 nm (a-c) and time to stationary phase (d-f) of clones isolated from the Cit + clade at the various generations indicated, when grown in M9 medium supplemented with 30.5 mg l −1 succinate, 39.5 mg l −1 fumarate, or 45.7 mg l −1 malate. Open and filled circles show clones with Cit − and Cit + phenotypes, respectively. If the bacteria did not reach a density consistent with depleting the available resource within 24 h, then the time to stationary phase is shown as 24 h. Error bars are 95 % confidence intervals.
Source publication
The evolution of a novel trait can profoundly change an organism's effects on its environment, which can in turn affect the further evolution of that organism and any coexisting organisms. We examine these effects and feedbacks following the evolution of a novel function in the Long-Term Evolution Experiment (LTEE) with Escherichia coli. A characte...
Contexts in source publication
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... clones isolated from the clade that later gave rise to the Cit + trait showed negligible growth on C 4 -dicarboxylates through 32 000 generations (Figs 4 and S3). By contrast, Cit + clones from 33 000 generations onward showed significantly improved growth on succinate, fumarate, and malate as sole carbon sources (Fig. 4a-c). The 32 000-generation clone has a weak Cit + phenotype, but it did not grow on succinate, fumarate, or malate, indicating that the ability to use these carbon sources was not simply a pleiotropic effect of the mutations that allowed growth on citrate. In contrast to the clones from the Cit − clade, we did not observe consistent ...
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... allowed growth on citrate. In contrast to the clones from the Cit − clade, we did not observe consistent improvement in growth on succinate by the Cit + clones across the generations. For example, the Cit + clones from generations 35 000 and 38 000 had lower final densities than other Cit + clones, and they did not reach stationary phase by 24 h (Fig. 4d). The Cit + clones showed similar variability on fumarate and malate (Fig. 4e, f), but the particular clones with slower growth or lower final densities differed across the three ...
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... did not observe consistent improvement in growth on succinate by the Cit + clones across the generations. For example, the Cit + clones from generations 35 000 and 38 000 had lower final densities than other Cit + clones, and they did not reach stationary phase by 24 h (Fig. 4d). The Cit + clones showed similar variability on fumarate and malate (Fig. 4e, f), but the particular clones with slower growth or lower final densities differed across the three ...
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... Cit + lineage also evolved improved growth on C 4 -dicarboxylates, although its gains were more sporadic than the improvement in the Cit − lineage (Fig. 4). The earliest clone able to grow on citrate, from generation 32 000, did not show detectable growth on C 4 -dicarboxylates, indicating that improved growth on these compounds was not simply a pleiotropic effect of the ability to consume citrate. The greater variability of growth on C 4 -dicarboxylates among clones from the Cit + ...
Citations
Microbial evolution within polymicrobial communities is a complex process. Here we report within-species diversification within multi-species microbial communities during experimental evolution with the nematode Caenorhabditis elegans. We describe morphological diversity in the target species Chryseobacterium gleum, which developed a novel colony morphotype in a small number of replicate communities. Alternate morphotypes co-existed with original morphotypes in communities, as well as in single-species experiments using evolved isolates. We found that the original and alternate morphotypes differed in motility and in spatial expansion in the presence of C. elegans. This study provides insight into the emergence and maintenance of intra-species diversity in the context of microbial communities.
