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. 2008 Jul 23;3(7):e2763.
doi: 10.1371/journal.pone.0002763.

Cheating on the edge

Lee Alan Dugatkin  1 , Aaron D Dugatkin, Ronald M Atlas, Michael H Perlin
Affiliations

Cheating on the edge

Lee Alan Dugatkin et al. PLoS One. .

Abstract

We present the results of an individual agent-based model of antibiotic resistance in bacteria. Our model examines antibiotic resistance when two strategies exist: "producers"--who secrete a substance that breaks down antibiotics--and nonproducers ("cheats") who do not secrete, or carry the machinery associated with secretion. The model allows for populations of up to 10,000, in which bacteria are affected by their nearest neighbors, and we assume cheaters die when there are no producers in their neighborhood. Each of 10,000 slots on our grid (a torus) could be occupied by a producer or a nonproducer, or could (temporarily) be unoccupied. The most surprising and dramatic result we uncovered is that when producers and nonproducers coexist at equilibrium, nonproducers are almost always found on the edges of clusters of producers.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1
Figure 1. Two-dimensional snapshots of the 10,000 slot torus.
B/C = 0.62, help = 0.14 (this “help” value was chosen, in part, as the result of unpublished experimental work on β–lactamase secretion in producer cells). a) Generation 1, b) Generation 10, c) Generation 20, d) Generation 40, e) Generation 300 and f) Generation 1000. Note that for generations 1–999, any yellow (nonproducers) cells surrounded by only yellow or by only yellow and white cells would die and be replaced the next generation.
Figure 2
Figure 2. Two-dimensional snapshots of the 10,000 slot torus.
B/C = 0.56, help = 0.19. a) Generation 1, b) Generation 10, c) Generation 20, d) Generation 40, e) Generation 300 and f) Generation 1000. Note that for generations 1–999, any yellow (nonproducers) cells surrounded by only yellow or by only yellow and white cells would die and be replaced the next generation.
Figure 3
Figure 3. Zoomed-in version of upper left hand section of a snapshot at generation 1000.
B/C = 0.62, help = 0.09. Red lines outline some cases in which nonproducers exist at the boundary between empty space and clusters of altruists. In all figures, yellow = nonproducers, green = producer, white = empty slot.
See this image and copyright information in PMC

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