title: Spatial structure, transmission modes and the evolution of viral exploitation strategies.
abstract: Spatial structure and local migration are predicted to promote the evolution of less aggressive host exploitation strategies in horizontally transmitted pathogens. Here we explore the effect of spatial structure on the evolution of pathogens that can use both horizontal and vertical routes of transmission. First, we analyse theoretically how vertical transmission can alter evolutionary trajectories and confirm that space can impede the spread of virulent pathogens. Second, we test this prediction using the latent phage λ which transmits horizontally and vertically in Escherichia coli populations. We show that the latent phage λ wins competition against the virulent mutant λcI857 in spatially structured epidemics, but loses when spatial structure is eroded. The vertical transmission of phage λ immunizes its local host pool against superinfection and prevents the spread of the virulent λcI857. This effect breaks down when mixing facilitates horizontal transmission to uninfected hosts. We thus confirm the importance of spatial structure for the evolutionary maintenance of prudent infection strategies in latent viruses.
authors.affiliation: Phage Technology Center GmbH, Bönen, Germany; Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS-Université de Montpellier-Université Paul-Valéry Montpellier-EPHE. Montpellier, France.
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Berngruber
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS-Université de Montpellier-Université Paul-Valéry Montpellier-EPHE. Montpellier, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Lion
authors.affiliation: Centre d'Ecologie Fonctionnelle et Evolutive (CEFE), UMR 5175, CNRS-Université de Montpellier-Université Paul-Valéry Montpellier-EPHE. Montpellier, France.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Gandon
mesh_terms: D010582:Bacteriophage lambda / Q000472:pathogenicity*; D005075:Biological Evolution; D018562:Disease Transmission, Infectious; D004926:Escherichia coli / Q000821:virology*; D018445:Infectious Disease Transmission, Vertical; D008962:Models, Theoretical