The Benefits of Dear Enemy Recognition in Three-Contender Convict Cichlid (Cichlasoma Nigrofasciatum) Contests

Abstract

We staged eight types of contests using adult male convict cichlids (Cichlasoma nigrofasciatum) to study the effects of dear enemy recognition on the defensive decisions of territorial residents when confronted by two opponents. Our observations supported the hypothesis that residents faced with two intruders simultaneously would divide the overall response shown to a single intruder between the two intruders with respect to their relative threats (i.e. sizes). Consequently, in comparison to a single-intruder circumstance, the residents' attacks against any given intruder were reduced. The relative threat of competitors was dramatically altered when one of the residents' opponents was a dear enemy neighbour. When faced with a dear enemy neighbour and an unfamiliar intruder simultaneously, residents preferentially confronted the unfamiliar opponent. That is, the establishment of dear enemy recognition between a resident and a neighbour allowed the resident to direct his aggression to the greater competitive threat, i.e. the intruder. In this case, the amount of aggression residents exhibited toward the intruder was similar to the amount of aggression against a single nonterritorial intruder. Therefore, having a dear enemy neighbour freed a resident to defend its territory against an intruder with similar efficiency compared to when the intruder had been the resident's only opponent.

Tit for Tat in the Dear Enemy Relationship Between Territorial Females of a Cichlid Fish

“…This reduction in aggression is known as the dear enemy relationship, and is exhibited by a variety of vertebrates (e.g., Fisher, 1954;Getty, 1989;Temeles, 1994;Ydenberg et al, 1998;Frostman and Sherman, 2004;Briefer et al, 2008). The dear enemy effect is beneficial for participant territory owners because it allows them to reduce territorial defense costs and to spend their energies on other activities that may increase their fitness (e.g., Temeles, 1994;Leiser and Itzkowitz, 1999;Leiser, 2003;Carazo et al, 2007;Briefer et al, 2008). Explanations for the evolution of this relationship have invoked reciprocal altruism based on the tit for tat (TFT) strategy in an iterated Prisoner's Dilemma (Trivers, 1971(Trivers, , 1985Axelrod and Hamilton, 1981;Getty, 1987), and we do not know alternative mechanical hypotheses for this phenomenon.…”

Intra-male variability of its communication signal in the weakly electric fish, Marcusenius macrolepidotus (South African form), and possible functions

“…This effect is called the 'dear enemy' phenomenon (Fisher, 1954; for reviews of neighbour-stranger discrimination see Ydenberg et al, 1988;Temeles, 1994). The 'dear enemy' phenomenon was observed in many different species, including cichlid fish (Peeke et al, 1971;Leiser & Itzkowitz, 1999), trout (Johnsson, 1997;Höjesjö et al, 1998), swordtails (Morris et al, 1995, and the gymnotiform Gymnotus carapo (McGregor & Westby, 1992).…”

The gall of subordination: changes in gall bladder function associated with social stress

“…Cichlid fishes are useful models for laboratory studies on social subordination because they quickly establish dominance relationships for access to and in defence of mating territories (Oliveira & Almada 1998;Leiser & Itzkowitz 1999). Subordinates incur substantial fitness costs, including the loss of reproductive and/or foraging opportunities (Grand & Grant 1994;Wisenden 1995), and chronic subordination constitutes a behaviourally relevant stressor in these fishes (Fox et al 1997).…”