Long-term commitment promotes honest status signalling

Although there are many examples of status signalling in nature, the mechanisms that maintain the stability of these systems are still poorly understood. Here I show in terms of a simple game of aggressive communication that commitment to the need to defend a given resource repeatedly in the long term greatly increases the conditions under which signalling of strength by means of conventional badges can be honest and evolutionarily stable. Such commitment can efficiently prevent the invasion of potentially weak cheaters pretending to be strong at a very low cost of harassment suffered by such weak individuals. Moreover, as long as such commitment is present, this cost is not a function of the contested resource; thus the value of the resource can be orders of magnitude higher than the potential cost imposed on cheaters, yet the system remains honest and evolutionarily stable. While liar-strong strategies (i.e. Trojans) can invade under some conditions, in most cases there is a broad region of honesty and this honest region is always open ended towards large resource values. In this region of honesty, no other costs, either production costs or handicaps, are necessary to maintain the evolutionary stability of the system. (C) 2011 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.