Alliances as a means of competition in primates: Evolutionary, developmental, and cognitive aspects

Abstract

Nonhuman primates commonly compete for mates, physical resources and dominance status. Competition is manifest in one-to-one contests or in more complex, multipartite aggressive interactions involving the formation of alliances. In this paper, five aspects of competitive alliances are reviewed: 1) the evolutionary and ecological conditions favoring the occurrence of alliances among females, among males, and between males and females, 2) the dynamics of the three main categories of competitive alliances, called bridging, revolutionary, and conservative, 3) the developmental processes that may account for the initial formation of alliances, 4) the cognitive abilities involved in two major aspects of alliances, the recognition of one's allies and of the allies of other individuals, and 5) the value of functional explanations of alliance behavior, namely kin selection, reciprocal altruism and mutualism. o 1995 Wiley-Liss, Inc.For more than a year male 415 had been the undisputed highest-ranking animal in a free-ranging group of 100 rhesus monkeys. Unlike the other males that had transfered to other groups (as is the rule in the majority of primate species), 415 had stayed in his natal group and achieved, as a young adult, the top position in the male dominance order comprising 15 non-natal animals. Interestingly, male 415 was the offspring of the highest-ranking female of his group. His life took on a dramatic turn the day he was severely wounded in a fight with another group. He contracted tetanus, became disabled and disappeared. A few days later however, he was back, following the group from a distance, walking stiffly and showing incipient signs of recovery. From that time on, 415 initiated frequent grooming interactions with adult females, in marked contrast with his past behavior. At the same time and although he was physically severely impaired, 415 undertook to threaten systematically several high-ranking males that had come to outrank him since his disability, provoking them when they were passing by. In these situations he was systematically supported by his relatives (mother, sister, nieces, cousin and younger brother, who formed the most dominant matriline) and by other highranking females. These animals vigorously chased and could even bite 415's targets. In a matter of weeks, 415 regained his position at the top of the male hierarchy (Chapais, 1983a).Male 415's story illustrates the use of alliances in aggressive competition, hereafter competitive alliances, and exemplifies how crucial and efficient these can be in settling long-term dominance relationships. Competitive alliances are manifest whenever the outcome of interindividual conflicts over resources or dominance status is affected by third-parties making use of, or threatening to use, aggression. This definition excludes interactions that affect the outcome of competition in the 0 1995 Wiley-Liss, Inc

Coalitions in theory and reality: a review of pertinent variables and processes

“…Three configurations of within-group coalitions formed by two partners against a single target have been recognized (cf., Chapais, 1995;van Schaik et al, 2006;see Chapais, 1995 for various examples in primates):…”

“…As we will see below, coalitions can serve different functions (van Schaik et al, 2006); they can be observed among different sex and age classes (reviewed in Chapais, 1995); they can involve kin (e.g., Riss & Goodall, 1977;Chagnon & Bugos, 1979;Wahaj et al, 2004), non-kin (e.g., Vigilant et al, 2001;Langergraber et al, 2007;Schülke et al, 2010), and friends or acquaintances (Hruschka & Henrich, 2006;Hruschka, 2010). As this brief review makes clear, coalitionary patterns are varied, and understanding this diversity would be greatly enhanced by formal modelling that would allow us to identify the general conditions under which coalition formation is expected to evolve, characterize the degree of variability expected, and predict when coalitions should, and should not, occur.…”

“…Preventing revolutionary coalitions is particularly important for the highest-ranking individuals if their positions allow them to secure large proportions of the resources within the group (Berman et al, 2007). As such, conservative coalitions may potentially bring important delayed benefits to their members (de Waal, 1982;Chapais, 1986Chapais, , 1995van Schaik et al, 2006). Animals also engage in conservative coalitions after a successful dominance reversal.…”

“…A strong bias towards female philopatry (Smuts, 1987), however, limits the occurrence of male-male nepotistic coalitions in primates. As a result, increasing one's inclusive fitness is not expected to be a major benefit of coalitions among primate males (Chapais, 1995;van Schaik et al, 2006), with rare exceptions (Langergraber et al, 2007).…”

A comparative network analysis of social style in macaques

“…At the group level, affiliative relationships underpin various patterns of social life such as coalitions, collective movements or information transmission (Chepko- Sade & Sade 1979;Silk et al 2004;Sueur & Petit 2008;Voelkl & Noë 2008). Coalitions allow individuals to win in social competition or to gain support in collective decisions by recruiting mates and kin (Chapais 1995); moreover, some key individuals can favour the spread of information or disease by their central position in social networks (Sueur et al 2011).…”