The Phenotypic and Fitness Effects of Colicin Resistance in Escherichia coli K-12

Feldgarden, Michael; Riley, Margaret A.

doi:10.2307/2640807

Cited by 61 publications

(33 citation statements)

References 18 publications

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“…The bacterial ancestor was derived from a K-12 strain of E. coli (BZB1011) by selecting for resistance to colicin E2, then colicin D, and then phage T6. Resistance to both colicin E2 and phage T6 is known to be individually costly (44,45). The initiation of the experiment with an unfit strain was intentional (SI Appendix).…”

Section: Resultsmentioning

confidence: 99%

A tortoise–hare pattern seen in adapting structured and unstructured populations suggests a rugged fitness landscape in bacteria

Nahum

Godfrey‐Smith

Harding

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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In the context of Wright's adaptive landscape, genetic epistasis can yield a multipeaked or "rugged" topography. In an unstructured population, a lineage with selective access to multiple peaks is expected to fix rapidly on one, which may not be the highest peak. In a spatially structured population, on the other hand, beneficial mutations take longer to spread. This slowdown allows distant parts of the population to explore the landscape semiindependently. Such a population can simultaneously discover multiple peaks, and the genotype at the highest discovered peak is expected to dominate eventually. Thus, structured populations sacrifice initial speed of adaptation for breadth of search. As in the fable of the tortoise and the hare, the structured population (tortoise) starts relatively slow but eventually surpasses the unstructured population (hare) in average fitness. In contrast, on singlepeak landscapes that lack epistasis, all uphill paths converge. Given such "smooth" topography, breadth of search is devalued and a structured population only lags behind an unstructured population in average fitness (ultimately converging). Thus, the tortoise-hare pattern is an indicator of ruggedness. After verifying these predictions in simulated populations where ruggedness is manipulable, we explore average fitness in metapopulations of Escherichia coli. Consistent with a rugged landscape topography, we find a tortoise-hare pattern. Further, we find that structured populations accumulate more mutations, suggesting that distant peaks are higher. This approach can be used to unveil landscape topography in other systems, and we discuss its application for antibiotic resistance, engineering problems, and elements of Wright's shifting balance process.adaptive landscape | experimental evolution | NK model | landscape topography | spatial structure

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Section: Resultsmentioning

confidence: 99%

A tortoise–hare pattern seen in adapting structured and unstructured populations suggests a rugged fitness landscape in bacteria

Nahum

Godfrey‐Smith

Harding

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Pleiotropy, the effect of one mutation on multiple phenotypes, is one explanation for the lack of a relationship between total resistance and fitness (Lenski, 1988a). For example, E. coli resistance to colicins arises nonindependently, such that bacterial resistance to one colicin type confers resistance to additional colicin types (Feldgarden and Riley, 1999). Similarly, on average, marine Synechococcus gained resistance to eight additional viruses when challenged against a single viral isolate (Stoddard et al, unpublished data).…”

Section: Cor Affected By Compositional Resistancementioning

confidence: 99%

Is there a cost of virus resistance in marine cyanobacteria?

et al. 2007

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Owing to their abundance and diversity, it is generally perceived that viruses are important for structuring microbial communities and regulating biogeochemical cycles. The ecological impact of viruses on microbial food webs, however, may be influenced by evolutionary processes, including the ability of bacteria to evolve resistance to viruses and the theoretical prediction that this resistance should be accompanied by a fitness cost. We conducted experiments using phylogenetically distinct strains of marine Synechococcus (Cyanobacteria) to test for a cost of resistance (COR) to viral isolates collected from Mount Hope Bay, Rhode Island. In addition, we examined whether fitness costs (1) increased proportionally with ‘total resistance’, the number of viruses for which a strain had evolved resistance, or (2) were determined more by ‘compositional resistance’, the identity of the viruses to which it evolved resistance. A COR was only found in half of our experiments, which may be attributed to compensatory mutations or the inability to detect a small COR. When detected, the COR resulted in a ∼20% reduction in relative fitness compared to ancestral strains. The COR was unaffected by total resistance, suggesting a pleiotropic fitness response. Under competitive conditions, however, the COR was dependent on compositional resistance, suggesting that fitness costs were associated with the identity of a few particular viruses. Our study provides the first evidence for a COR in marine bacteria, and suggests that Synechococcus production may be influenced by the composition of co-occurring viruses.

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“…Notably, when more than two strains are examined, coexistence can occur in the absence of spatial heterogeneity. Resistant strains can evolve either from sensitive strains [48] or represent non-producing cheaters [45]. If resistant strains have higher growth rates than producers (because they are not paying the cost of production) and lower growth rates than sensitives (because they are paying a cost of resistance), then resistant strains can out-compete producers, but are out-competed by sensitives in a rock-paper-scissors-like dynamic (RPS).…”

Section: Effects Of Competition On Parasite Diversitymentioning

confidence: 99%

Within-host competitive interactions as a mechanism for the maintenance of parasite diversity

Bashey

2015

Phil. Trans. R. Soc. B

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Variation among parasite strains can affect the progression of disease or the effectiveness of treatment. What maintains parasite diversity? Here I argue that competition among parasites within the host is a major cause of variation among parasites. The competitive environment within the host can vary depending on the parasite genotypes present. For example, parasite strategies that target specific competitors, such as bacteriocins, are dependent on the presence and susceptibility of those competitors for success. Accordingly, which parasite traits are favoured by within-host selection can vary from host to host. Given the fluctuating fitness landscape across hosts, genotype by genotype (G×G) interactions among parasites should be prevalent. Moreover, selection should vary in a frequency-dependent manner, as attacking genotypes select for resistance and genotypes producing public goods select for cheaters. I review competitive coexistence theory with regard to parasites and highlight a few key examples where within-host competition promotes diversity. Finally, I discuss how within-host competition affects host health and our ability to successfully treat infectious diseases.

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The Phenotypic and Fitness Effects of Colicin Resistance in Escherichia coli K-12

Cited by 61 publications

References 18 publications

A tortoise–hare pattern seen in adapting structured and unstructured populations suggests a rugged fitness landscape in bacteria

A tortoise–hare pattern seen in adapting structured and unstructured populations suggests a rugged fitness landscape in bacteria

Is there a cost of virus resistance in marine cyanobacteria?

Within-host competitive interactions as a mechanism for the maintenance of parasite diversity

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