Fig. 1. Ecological and Coevolutionary Dynamics of Host-Parasite Interactions.
(A) We tracked the population dynamics of hosts (solid lines) and parasites (dashed lines) for high (yellow), medium (blue) and low (black) diversity populations alongside the parasite free control (grey). All plotted points show the mean +/- standard error population density. Bacterial populations challenged with phage rapidly recovered their density. We did not observe cyclical oscillations in host and parasite densities. (B and C) To directly test for co-evolution, we used 13,500 time shift assays to measure changes in phage infectivity and bacterial resistance to phage. Lower levels or parasite infectivity (B) and higher levels of host resistance (C) evolve with increasing parasite diversity (F2,85 =9.7, P < 0.001). Furthermore, hosts are more susceptible to parasites from their future than their contemporary parasites and they are most resistant to parasites from their past. Likewise future parasite are more infective than past or contemporary parasites (F2,13044 =1766.21, P < 0.0001). Error bars show 1 standard error.