(A) Image of a young adult C. elegans and schematic depicting the twelve pairs of sensory neurons in the anterior amphid individuals carrying a virus with k deleterious mutations at its endemic equilibrium. class carrying the fewest number of deleterious mutations is defined as mutation class k = 0. Inset: variation in the basic reproductive rate of infected individuals (gray histogram) and variation in the net reproductive rate R of infected individuals (brown histogram) resulting from variation in the number of deleterious mutations carried by circulating viruses.

Listed are, for each triplet of cell types, the probabilities of the four topologies for prior odds $\frac{p\left({\beta}_{i}=1\right)}{p\left({\beta}_{i}=0\right)}=0.05$; the number of topologies that reach probability $p\left(T\text{}|\text{}\left\{{g}_{i}^{A,B,C}\right\}\right)>0.6$ for some value of $\frac{p\left({\beta}_{i}=1\right)}{p\left({\beta}_{i}=0\right)}$ between 10^{−6} and 10^{2}; the non-null topology that has the highest probability $p\left(T\text{}|\text{}\left\{{g}_{i}^{A,B,C}\right\}\right)$ over the range of prior odds (if the null topology is the most likely topology for the entire range of prior odds, the topology is marked ‘null’); and the value of highest probability $p\left(T\text{}|\text{}\left\{{g}_{i}^{A,B,C}\right\}\right)$ over the range of prior odds; the correct topology and triplet length in the traditional model; and the correct topology and triplet length in the Adolfsson model.

(**A**) Doxycycline-inducible *gam-gfp* fusion construct in the *E. coli* chromosome. Constitutively produced TetR protein represses the P_{N25tetO} promoter, which produces GamGFP upon doxycycline induction. *oriC*, origin of replication; *ter*, replication terminus; arrows, directions of transcription. (**B**) Phage λ assay for end-blocking activity by Mu Gam and GamGFP. Rolling-circle replication of phage λ*red gam* is inhibited by *E. coli* RecBCD, which causes small plaques of λ*red gam* on wild-type *E. coli* (Smith, 1983). Mu Gam protein binds and protects DNA ends from RecBCD exonuclease activity (Akroyd and Symonds, 1986) and so is expected to allow rolling-circle replication of λ*red gam* and therefore allow formation of large plaques. (**C**) λ*red gam* plaques are small on *recB*^{+} (WT) and large on *recB*-deficient cells (*recB*^{-}). Plaques produced on WT cells carrying *gam* and *gam-gfp* are small when Gam and GamGFP proteins are not produced (Uninduced). (**D**) λ*red gam* produce large plaques on WT cells if Gam or GamGFP are produced (Induced). (**E**) UV sensitivity of *E**. coli recB*-null mutant compared with *recB*^{+}(WT), and uninduced *gam* and *gam-gfp* carrying cells. WT (), *recB*^{−} (), WT GamGFP, (); WT Gam, (). (**F**) Induction of Gam or GamGFP with 200 ng/ml doxycycline causes UV sensitivity similar to that of *recB-*null mutant cells, indicating that Gam or GamGFP block RecBCD action on double-stranded DNA ends. WT, SMR14327; *recB*, SMR8350; WT GamGFP, SMR14334; WT Gam, SMR14333. Representative experiment performed three times with comparable results.