Article

Coevolutionary alternation in antagonistic interactions

Department of Ecology & Evolutionary Biology, University of California, Santa Cruz, Santa Cruz, California, United States
Evolution (Impact Factor: 4.61). 12/2006; 60(11):2207-17. DOI: 10.1111/j.0014-3820.2006.tb01858.x
Source: PubMed

ABSTRACT

Coevolution between parasites and hosts or predators and prey often involves multiple species with similar kinds of defenses and counter-defenses. Classic examples include the interactions between phytophagous insects and their host plants, thick-shelled invertebrates and their shell-crushing predators, and ungulates and their predators. There are three major hypotheses for the nonequilibrium coevolutionary dynamics of these multispecific trophic interactions: escalation in traits, cycles in traits leading to fluctuating polymorphisms, and coevolutionary alternation. The conditions under which cycles and escalation are likely to occur have been well developed theoretically. In contrast, the conditions favoring coevolutionary alternation-evolutionary fluctuations in predator or prey preference driven by evolutionary shifts in relative levels of prey defense and vice versa-have yet to be identified. Using a set of quantitative coevolutionary models, we demonstrate that coevolutionary alternation can occur across a wide range of biologically plausible conditions. The result is often repeated, and potentially rapid, evolutionary shifts in patterns of specialization within networks of interacting species.

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    • "In the case of no correlation (independent predator effects), the combined effect of multiple predators may result in divergent selection for specialist defence strategies, where different sub-populations adapt to different interacting species (Futuyma and Moreno, 1988; Davies and Brooke, 1989; Nuismer and Thompson, 2006; Edeline et al., 2008). If defence correlations are negative, selection by one predator could reduce the selection imposed by another predator owing to trade-offs in morphology or physiology (Davies and Brooke, 1989; Stinchcombe and Rausher, 2001; Thompson and Cunningham, 2002; Nuismer and Thompson, 2006; Berenbaum and Zangerl, 2006; Friman and Buckling, 2013). It is also possible that defence against one predator correlates positively with the defence against other predator (for example, owing to functional similarity between different enemies). "
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    • "Although coevolutionary alternation with escalation was defined as enemies shifting from one victim species to another (Thompson 2005), the same underlying process could occur with shifts between different populations of victims. In the model of coevolutionary alternation (without escalation; Nuismer and Thompson 2006), the predator or parasite specializes on one victim species at a time so that defenses decline in past victim species. This would presumably arise because trade-offs favor specialization on only one or a few victim species at a time. "
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    • "However, it remains unclear to what extent defence to one enemy directly reduced defence to the other. The evolution of specialised resistance is crucial to the maintenance of pairwise coevolutionary interactions at the community level (Nuismer & Thompson 2006). But why did bacteria diversify in their resistance strategies rather than evolving generalised defence? "
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