Toward a more trait‐centered approach to diffuse (co)evolution

Abstract

Summary• How species evolve depends on the communities in which they are embedded. Here, we briefly review the ideas underlying concepts of diffuse coevolution, evolution, and selection.• We discuss criteria to identify when evolution will be diffuse. We advocate a more explicitly trait-oriented approach to diffuse (co)evolution, and discuss how considering effects of interacting species on fitness alone tells us little about evolution. We endorse the view that diffuse evolution occurs whenever the response to selection by one interacting species on a given trait is altered by the presence of a second interacting species.• Building on the work of others, we clarify and expand the criteria for diffuse evolution and present a simple experimental design that will allow the detection of diffuse selection.• We argue that a greater focus on selection on specific traits and the evolutionary response to that selection will improve our conceptual understanding of how communities affect the evolution of species embedded within them.New Phytologist (2005) 165 : 81-90 © New Phytologist (2004

Macroevolution and the biological diversity of plants and herbivores

“…In this scenario, individual species of herbivores are each abundant and damaging enough to impose significant selection and do not strongly interact over evolutionary time. Alternatively, coevolution would be ''diffuse'' if defense against various enemies were positively genetically correlated (51,52); then selection for defense could stem from the collective impact of many herbivores, some of which might be uncommon (34), and the evolution of new defenses would be impelled not by the identity of herbivores as much as by their collective impact. Probably the question of the incidence of pairwise versus diffuse defense evolution will vary with factors such as plant organ (e.g., fruit vs. leaf), defense type, and herbivore diet breadth.…”

“…They include population-level processes of reciprocal adaptation of interacting species, which may be relatively specific or pairwise (two species, each adapting to a characteristic of the other) or more diffuse (multispecific), in which a species adapts to the properties of a set of interactors, and so has genetically correlated responses to several species (51,52). At a macroevolutionary level, diversity in adaptations of plants to herbivores and vice versa could range from ongoing interactions between antagonist lineages, with relatively short time lags between reciprocal evolutionary changes, to the decoupled, sequential bursts of adaptation and diversification portrayed in Ehrlich and Raven's ''escape-andradiate'' scenario (4).…”

Specificity in the symbiotic association between fungus-growing ants and protective Pseudonocardia bacteria

“…These species-specificity factors likely evolved through reciprocal selection (i.e. coevolution) and are predicted to result in codiversification between partners [6,7]. However, symbiont switches between related hosts are typically frequent enough to prevent cospeciation, without disrupting functional integration between partners, and potentially result in patterns of diffuse coevolution in which groups of related hosts associate with groups of related symbionts (codiversification) [8].…”

Relative importance of evolutionary dynamics depends on the composition of microbial predator–prey community

“…If competition between different predators is more symmetrical, both predators are likely to exert selection on prey but these effects are likely to be weaker compared with the effects predators would be exerting on prey in the absence of competition. Second, trait correlations between defence mechanisms against different predators could affect the evolutionary dynamics in multi-predator communities (Iwao and Rausher, 1997;Strauss and Irwin, 2004;Strauss et al, 2005;. 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).…”