Dangerous liaisons: the ecology of private interest and common good

Abstract

Many ecological interactions that are called mutualistic are in fact mixtures of antagonistic and mutualistic aspects. For example, plasmids exploit their bacterial hosts but also protect them against external threats. In this study, we analyse the conditions for the evolution of what we call 'dangerous liaisons': interactions combining mutualistic and antagonistic aspects. Starting point of our analysis is a model that was proposed as early as 1934. In this model, partners have to form a complex (either temporary or long lasting) in order to interact. Using this model framework we then set out to define and tease apart private interests of the interacting partners from their common good. This dichotomy provides a unifying perspective to classify ecological interactions. We discuss some examples to illustrate how the outcome of the interaction may depend on densities or on other contextual variables. Finally, we note that having a common good is not a necessary condition for partners to have aligned interests. In a dangerous liaison partners may have interest to cooperate even when this does not bolster the common good. M. 6an Baalen,

Diet–dependent effects of gut bacteria on their insect host: the symbiosis ofErwiniasp. and western flower thrips

“…The interaction between gut symbionts and thrips represents an example of what Van Baalen & Jansen (2001) referred to as a 'dangerous liaison'. It seems likely that the interests of the two interacting species are aligned on a diet of leaves alone, but on a diet of leaves and pollen the interests of the host conflict with those of the gut bacteria.…”

“…It seems likely that the interests of the two interacting species are aligned on a diet of leaves alone, but on a diet of leaves and pollen the interests of the host conflict with those of the gut bacteria. Such variation in interest alignment and conflict are more likely to occur: when vertical transmission is costly, horizontal transmission takes place, within-host competition varies depending on single versus multiple infections, and there are (negative) effects of excessively intensive exploitation of the host (Van Baalen & Sabelis 1995;Genkai-Kato & Yamamura 1999;Van Baalen & Jansen 2001). Clearly, thrips do not transmit the gut bacteria transovarially, nor externally via the egg (De Vries et al 2001b).…”

Red Queen Dynamics of Protein Translation

“…A more complete formulation takes account of parasites interested in vertical transmission, in which case host and parasite share a common good [see van Baalen & Jansen (2001) for detailed discussion]. The population dynamics of this model are well known; the densities show neutrally stable oscillations around the equilibrium.…”

Cooperation for direct fitness benefits

“…Some of the mechanisms that influence the evolution of cooperation also play a role in exploitative manipulation, which has given rise to suggestions that cooperation and exploitation are phenomena that should be looked at jointly (Herre et al 1999;Bronstein 2001;van Baalen & Jansen 2001;Oliver et al 2009). The observation applies both to questions of the evolutionary origin and eventual fate of mutualistic interactions (Bronstein 2001(Bronstein , 2009Edwards & Yu 2007;Kautz et al 2009) and to the study of the coexistence of exploitative and mutualistic interactions (Bronstein 2001;Ferrière et al 2007;Kautz et al 2009;Little & Currie 2009).…”