Biology subjects

Leeks, A.

Publications and source records attributed to Leeks, A..

3 recordsLinked to original sources

bioRxiv2026

Spatial structure drives the evolution of parasites into host defense systems

Host defense systems in prokaryotes and eukaryotes often appear to be derived from the very parasites they now defend against, yet the evolutionary route for such a transition remains poorly understood. Based on the biology of integrating viruses such as temperate bacteriophages and retroviruses, we develop a multilevel eco-evolutionary framework in which within-host viral replication is treated as a public goods game over a costly, shared replication product. In well-mixed host populations, we predict convergence on a single viral strategy of intermediate replicative investment. However, when we impose spatial structure by restricting host reproduction and virus transmission to local events, the virus population diversifies into two lineages: a horizontally transmitted lineage that parasitises hosts, and a vertically transmitted hyperparasitic lineage that parasitises the horizontally transmitting viruses. The latter "hyperparasite" is a viral cheat that suppresses the replication and propagation of the parasitic virus, thereby acting as a defense system to the hosts. Local interactions concentrate the benefits of this suppression among neighbouring hosts that carry related proviruses, allowing selection on the proviral cheat as a host-level defense. Our results show that evolutionary cheating within parasite populations can drive the evolution of parasites into defense systems in spatially structured host populations.

evolutionary biology↗

bioRxiv2023

Community ecology of phages on a clonal bacterial host

Bacteriophages are the most abundant and diverse biological entities on Earth, yet the ecological mechanisms that sustain this extraordinary diversity remain unclear. Here, we have discovered a general mechanism that allows phage diversity to outstrip the diversity of their bacterial hosts. We assembled and passaged dozens of diverse phage communities on a single, non-coevolving strain of Escherichia coli until the phage communities reached equilibrium. In all cases, we found multiple phage species coexisted stably, despite competition for a single, clonal host population. Coexistence within these communities was supported through host phenotypic heterogeneity, whereby phages specialized on cells adopting different growth phenotypes. Our experiments reveal a rich community ecology of bacteriophages where multiple phage species coexist and interact at the scale of a single bacterial host. One-Sentence SummaryDiverse communities of phages emerge stably and consistently on a clonal bacterial host, enabled by phenotypic heterogeneity.

microbiology↗

bioRxiv2019

The evolution of collective infectious units in viruses

Viruses frequently spread among cells or hosts in groups, with multiple viral genomes inside the same infectious unit. These collective infectious units can consist of multiple viral genomes inside the same virion, or multiple virions inside a larger structure such as a vesicle. Collective infectious units deliver multiple viral genomes to the same cell simultaneously, which can have important implications for viral pathogenesis, antiviral resistance, and social evolution. However, little is known about why some viruses transmit in collective infectious units, whereas others do not. We used a simple evolutionary approach to model the potential costs and benefits of transmitting in a collective infectious unit. We found that collective infectious units could be favoured if cells infected by multiple viral genomes were significantly more productive than cells infected by just one viral genome, and especially if there were also efficiency benefits to packaging multiple viral genomes inside the same infectious unit. We also found that if some viral sequences are defective, then collective infectious units could evolve to become very large, but that if these defective sequences interfered with wild-type virus replication, then collective infectious units were disfavoured.

evolutionary biology↗