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Abstract

Trade-offs among the abilities of organisms to respond to different environmental factors are often assumed to play a major role in the coexistence of species. There has been extensive theoretical study of the role of such trade-offs in ecological communities but it has proven difficult to study such trade-offs experimentally. Microorganisms are ideal model systems with which to experimentally study the causes and consequences of ecological trade-offs. In model communities of E. coli B and T-type bacteriophage, a trade-off in E. coli between resistance to bacteriophage and competitive ability is often observed. This trade-off can allow the coexistence of different ecological types of E. coli. The magnitude of this trade-off affects, in predictable ways, the structure, dynamics and response to environmental change of these communities. Genetic factors, environmental factors, and gene-by-environment interactions determine the magnitude of this trade-off. Environmental control of the magnitude of trade-offs represents one avenue by which environmental change can alter community properties such as invasability, stability and coexistence.

Availability of prey resources drives evolution of predator–prey interaction

“…Our results on evolution of defence and stability are broadly similar to experiments with host-parasitoid systems (Bohannan & Lenski 1999;Bohannan et al 2002;Forde et al 2004Forde et al , 2007 despite the fundamental differences between predator-prey and host-parasitoid interactions. This suggests that rapid resource-driven evolution of antagonistic interactions can be an important and a common factor determining the structure and dynamics of natural food webs.…”

“…growth-related traits) and defensive traits has recently been shown to be an important mechanism driving the interplay between evolutionary and ecological dynamics of antagonistic interactions (Bohannan & Lenski 1999;Bohannan et al 2002;Yoshida et al 2003Yoshida et al , 2004Meyer & Kassen 2007). Besides genetic factors, the magnitude of this trade-off is determined by the quality of the environment, that is, how much there are available resources for the prey or host to allocate between different traits (Bohannan et al 2002;Yoshida et al 2004). Theory and experiments (Mole 1994;Hochberg & van Baalen 1998;Bohannan & Lenski 1999;Abrams 2000;Yoshida et al 2004) suggest that when the allocation to defensive traits is costly, the competitive ability of the prey should decrease, especially in the low-resource environments (large magnitude tradeoffs).…”

A Generalist Protist Predator Enables Coexistence in Multitrophic Predator-Prey Systems Containing a Phage and the Bacterial Predator Bdellovibrio

“…A common trade-off for the development of bacterial defense mechanisms is a reduction in the competitive ability of bacteria, e.g., a decline in growth rate (Bohannan and Lenski, 1999;Bohannan et al, 2002;Meyer and Kassen, 2007). Surprisingly, we observed the exact opposite, namely a significant decrease in the generation time of some of the bacteria (Figure 5).…”

“…Finally, the high grazing pressure exerted by specialist predators should induce the emergence of predationresistant bacteria. Resistance to phages and BALOs is known to induce fitness costs (Bohannan and Lenski, 1999;Bohannan et al, 2002;Meyer and Kassen, 2007;Gallet et al, 2009), and the subsequent appearance of counter-adapted predators might have direct consequences for the coexistence of the community members.…”

Coevolutionary arms races between bacteria and bacteriophage

“…The particular choice of functional forms describing the interactions implies that not every phage can infect every host equally well. In addition, avoiding infection of viruses by bacteria comes with a tradeoff in terms of the host bacteria's uptake of resources (46). Given these core assumptions, the coevolutionary dynamics may lead to stable fixed points, Red Queen cycling, as well as diversification leading to multistrain coexistence.…”