Phage-host dynamics during spatial expansions modulate the rate of genetic diversity loss.

During expansion of a population into a new habitat, individuals at the front have first access to resources and their offspring are more likely to remain at the front of the expansion. As a result, there is generally a rapid decrease in genetic diversity in the colonized region during range expansion. This effect, however, is attenuated in the case of density-dependent growth or dispersal, such as that which occurs in cooperative growth. Recent work reveals that in viral expansions across a host population, an effective density dependent dispersal emerges as an emergent property due the latent period during which viral particles are trapped in the host before cell lysis occurs.

We show that during viral expansions, this effective density dependent dispersal alters the shape of genetic drift, or random sampling of offspring, and subsequently the rate of loss of genetic diversity. Agent-based simulations and an accompanying perturbation analysis of a continuum model both show that the lysis time has a strong impact on the rate of genetic diversity loss. In addition, this rate can be parameterized as an effective population size of the population front, allowing for comparison to previous generic range expansion models, as well as experimental data in the future.