Antagonistic coevolution between a bacterium and a bacteriophage

Abstract

Antagonistic coevolution between hosts and parasites is believed to play a pivotal role in host and parasite population dynamics, the evolutionary maintenance of sex and the evolution of parasite virulence. Furthermore, antagonistic coevolution is believed to be responsible for rapid differentiation of both hosts and parasites between geographically structured populations. Yet empirical evidence for host-parasite antagonistic coevolution, and its impact on between-population genetic divergence, is limited. Here we demonstrate a long-term arms race between the infectivity of a viral parasite (bacteriophage; phage) and the resistance of its bacterial host. Coevolution was largely driven by directional selection, with hosts becoming resistant to a wider range of parasite genotypes and parasites infective to a wider range of host genotypes. Coevolution followed divergent trajectories between replicate communities despite establishment with isogenic bacteria and phage, and resulted in bacteria adapted to their own, compared with other, phage populations.

Rapid evolution of generalized resistance mechanisms can constrain the efficacy of phage–antibiotic treatments

“…After 24 hr of incubation at 37°C, phage resistance was measured in terms of optical density (OD 600 nm ) where higher growth of evolved bacteria in the presence of phage relative to density of bacteria grown without phage denotes the evolution of phage resistance (growth data shown in Supporting information Figure S4). Phage resistance was also measured every second time point throughout the experiment using streak assay (Buckling & Rainey, 2002) as a part of time‐shift assay (see below).…”

“…A time‐shift assay approach (Buckling & Rainey, 2002; Nee, 1989) was used to determine whether bacteria and phages evolved adaptations and counteradaptations during the selection experiment. To this end, bacteria and phages were isolated from different sampling points during the experiment (transfers 1, 3 and 5).…”

“…A similar method was used for bacteria isolated from transfers 3 and 5. A colony was defined as resistant if there was no inhibition of growth, otherwise it was defined as sensitive (Brockhurst, Morgan, Rainey, & Buckling, 2003; Buckling & Rainey, 2002). …”

Bacterial competition and quorum‐sensing signalling shape the eco‐evolutionary outcomes of model in vitro phage therapy

“…A streak assay methodology was used to estimate the evolution of bacterial resistance and phage infectivity (Buckling & Rainey, 2002). A total of 12 randomly chosen colonies per each P. aeruginosa population were isolated at the end of the experiment and grown in 96‐well microplates at 37°C in 150 μl of NB media.…”

Availability of prey resources drives evolution of predator–prey interaction

“…It is also possible that predators or parasitoids evolve in response to adaptations in prey species (Abrams 2000;Buckling & Rainey 2002;Brockhurst et al 2003), which can, for example, lead to a sustained coevolutionary arms race (Dawkins & Krebs 1979). The theoretical predictions on the dynamics and outcome of evolution, however, differ depending on model assumptions (Abrams 2000).…”