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PLANT BACTERIA. “The experimentally evolved transition of a chimeric Ralstonia solanacearum strain from a plant pathogen into a symbiont that is able to colonize root nodules also required only a single mutation in hrpG, which encodes a protein that regulates the expression of several virulence factors.” https://www.nature.com/articles/nrg3564 View in LinkedIn

TOOLBOX. “When there is genetic diversity in evolving populations for long periods of time, there is the opportunity for selection to operate not only on the immediate effects of mutations or new combinations of alleles but also on how those new genotypes differ in their capability to further evolve (that is, their evolvability).” https://www.nature.com/articles/nrg3564 View in LinkedIn

BACTERIAL SURPRISE. “That key mutation did not revert any of the previous mutations but occurred instead in a previously uncharacterized small RNA.” https://www.nature.com/articles/nrg3564 View in LinkedIn

THE STRESS LEVER. “Stressful environments can sometimes help to separate the more beneficial mutations from the less beneficial mutations.” https://www.nature.com/articles/nrg3564 View in LinkedIn

BACTERIAL EXAMPLE. “For example, whole-genome sequencing of experimentally evolved Myxococcus xanthus strains found that 14 mutations were substituted after 1,000 generations in a liquid medium, while social motility and the capability to form fruiting bodies were lost, but only one mutation was involved in the subsequent restoration of those functions.” https://www.nature.com/articles/nrg3564 View in LinkedIn

MANY PATHWAYS. “Indeed, divergent paths have been described in most evolution experiments with microorganisms, and these dynamics have been reconstructed in certain cases.” https://www.nature.com/articles/nrg3564 View in LinkedIn

LOW RATES IN HIGHER ANIMALS. “Rates of point mutations in multicellular eukaryotes are of the order of 0.05–1.0 per generation across the entire protein-coding portions of these genomes, which is still fairly low given the much longer generation times and the multiple cell divisions in the germ line between generations in these organisms.” https://www.nature.com/articles/nrg3564 View in LinkedIn

LESS STRESS. “When selection is less stringent, more genetic diversity can usually be sustained, which allows more opportunities for populations to optimize by exploring alternative mutational paths.” https://www.nature.com/articles/nrg3564 View in LinkedIn

EXPERIMENTAL STRESS. “An important 'dial' that can be adjusted in experimental evolution studies is the strength of selection, particularly if the goal is to improve some phenotypic property. In one limit, selection may be so strong that it becomes a genetic screen in which only rare mutants with extreme, perhaps innovative, phenotypes can survive the stress (Fig. 2c).” https://www.nature.com/articles/nrg3564 View in LinkedIn

CONFOUNDER. “The earlier potentiating mutations did not confer any immediate advantage with respect to using citrate, but they may have been beneficial with respect to growth on glucose. If so, it is possible that other populations in the LTEE have also become potentiated and might evolve the Cit+ phenotype, although no others have done so even after >50,000 generations.” https://www.nature.com/articles/nrg3564 View in LinkedIn