Emergence of linkage between donation and discrimination loci.

Abstract

<p><b>A: Selection of discrimination and donor ability.</b> The change in frequency of D⁺ (red) and M⁻ (blue) alleles after antibiotic selection is computed from simulations. The populations are analogous to structured populations <i>s</i> (<a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1002478#pbio.1002478.g003" target="_blank">Fig 3</a>), but here we vary the strength of population structure (<i>x</i>-axis), expressed as the initial difference in D⁺ cell frequency between the two subpopulations. Initially, 2.5% of cells bear the antibiotic plasmid conferring antibiotic resistance. <b>B: Linkage between donation and discrimination alleles.</b> The linkage between D⁺ and M^- alleles is shown at the end of competition as a function of D⁺ population structure, calculated as before, in the absence (dashed line) and presence (bold line) of antibiotic selection that allows only plasmid-bearing cells to grow. <b>C: Plasmid transfer bias.</b> The proportion of each genotype among plasmid-bearing cells, at the end of competition is shown as a function of D⁺ population structure. With increasing population structuring, plasmids are progressively enriched in D⁺ M⁻ cells (red line). Data are available from FigShare at <a href="http://dx.doi.org/10.6084/m9.figshare.3199252" target="_blank">http://dx.doi.org/10.6084/m9.figshare.3199252</a>.</p