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de Waal, F. B. M. (2005). A century of getting to know the chimpanzee. Nature, 437(7055), 56–59.
Abstract: A century of research on chimpanzees, both in their natural habitat and in captivity, has brought these apes socially, emotionally and mentally much closer to us. Parallels and homologues between chimpanzee and human behaviour range from tool-technology and cultural learning to power politics and intercommunity warfare. Few behavioural domains have remained untouched by this increased knowledge, which has dramatically challenged the way we view ourselves. The sequencing of the chimpanzee genome will no doubt bring more surprises and insights. Humans do occupy a special place among the primates, but this place increasingly has to be defined against a backdrop of substantial similarity.
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Noë, R., de Waal, F. B., & van Hooff, J. A. (1980). Types of dominance in a chimpanzee colony. Folia Primatol (Basel), 34(1-2), 90–110.
Abstract: This study examines to what extent the concept of dominance can be used to describe the social structure of a group of semi-free-living chimpanzees. 15 behavioural variables, based on agonistic, competitive and affinitive behaviour patterns, have been compared with respect to the interindividual directions in which they occurred. In this analysis use was made of indices that reflect the position an individual occupies in the relationship structure. These indices were calculated per individual for all variables and subjected to factor analysis and cluster analysis. As a result, 13 of the variables could be grouped in three categories which have been labelled: (1) agonistic dominance; (2) bluff dominance, and (3) competitive dominance. Whereas the top positions in the hierarchies based on the first two closely related types of dominance were occupied by the adult males, the hierarchy based on the third type was headed by several adult females.
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de Waal, F. B. (1977). The organization of agonistic relations within two captive groups of Java-monkeys (Macaca fascicularis). Z. Tierpsychol., 44(3), 225–282.
Abstract: The paper offers a detailed quantitative descripition of the distribution of agonistic activities over the members of two groups of Java-monkeys (Macaca fascicularis). These groups lived in captivity and were well-established: i.e. they had an extensive network of genealogical relationships. The study pays special attention to agonistic interactions with three or more participants. Its main purpose is an analysis of the way dyadic agonistic relations (e.g. dominance relations) are affected by third group members and the relations among these. The paper presents data on the ontogeny of 'dependent dominance', the 'control role' of the alpha-male, and the functions of different types of alliances.
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Hemelrijk, C. K., & Wantia, J. (2005). Individual variation by self-organisation. Neurosci Biobehav Rev, 29(1), 125–136.
Abstract: In this paper, we show that differences in dominance and spatial centrality of individuals in a group may arise through self-organisation. Our instrument is a model, called DomWorld, that represents two traits that are often found in animals, namely grouping and competing. In this model individual differences grow under the following conditions: (1) when the intensity of aggression increases and grouping becomes denser, (2) when the degree of sexual dimorphism in fighting power increases. In this case the differences among females compared to males grow too, (3) when, upon encountering another individual, the tendency to attack is 'obligate' and not conditional, namely 'sensitive to risks'. Results resemble phenomena described for societies of primates, mice, birds and pigs.
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Scheffer, M., & van Nes, E. H. (2006). Self-organized similarity, the evolutionary emergence of groups of similar species. Proc. Natl. Acad. Sci. U.S.A., 103(16), 6230–6235.
Abstract: Ecologists have long been puzzled by the fact that there are so many similar species in nature. Here we show that self-organized clusters of look-a-likes may emerge spontaneously from coevolution of competitors. The explanation is that there are two alternative ways to survive together: being sufficiently different or being sufficiently similar. Using a model based on classical competition theory, we demonstrate a tendency for evolutionary emergence of regularly spaced lumps of similar species along a niche axis. Indeed, such lumpy patterns are commonly observed in size distributions of organisms ranging from algae, zooplankton, and beetles to birds and mammals, and could not be well explained by earlier theory. Our results suggest that these patterns may represent self-constructed niches emerging from competitive interactions. A corollary of our findings is that, whereas in species-poor communities sympatric speciation and invasion of open niches is possible, species-saturated communities may be characterized by convergent evolution and invasion by look-a-likes.
Keywords: Animals; *Competitive Behavior; *Ecosystem; *Evolution; *Models, Biological
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Craig, J. V. (1986). Measuring social behavior: social dominance. J. Anim Sci., 62(4), 1120–1129.
Abstract: Social dominance develops more slowly when young animals are kept in intact peer groups where they need not compete for resources. Learned generalizations may cause smaller and weaker animals to accept subordinate status readily when confronted with strangers that would be formidable opponents. Sexual hormones and sensitivity to them can influence the onset of aggression and status attained. After dominance orders are established, they tend to be stable in female groups but are less so in male groups. Psychological influences can affect dominance relationships when strangers meet and social alliances within groups may affect relative status of individuals. Whether status associated with agonistic behavior is correlated with control of space and scarce resources needs to be determined for each species and each kind of resource. When such correlations exists, competitive tests and agonistic behavior associated with gaining access to scarce resources can be useful to the observer in learning about dominance relationships rapidly. Examples are given to illustrate how estimates of social dominance can be readily attained and some strengths and weaknesses of the various methods.
Keywords: Aggression; Agonistic Behavior; Animals; *Behavior, Animal; Cattle; Chickens; Competitive Behavior; Female; Horses; Male; *Social Dominance; Swine
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Hirsch, B. T. (2007). Costs and benefits of within-group spatial position: a feeding competition model. Q Rev Biol, 82(1), 9–27.
Abstract: An animal's within-group spatial position has several important fitness consequences. Risk of predation, time spent engaging in antipredatory behavior and feeding competition can all vary with respect to spatial position. Previous research has found evidence that feeding rates are higher at the group edge in many species, but these studies have not represented the entire breadth of dietary diversity and ecological situations faced by many animals. In particular the presence of concentrated, defendable food patches can lead to increased feeding rates by dominants in the center of the group that are able to monopolize or defend these areas. To fully understand the tradeoffs of within-group spatial position in relation to a variety of factors, it is important to be able to predict where individuals should preferably position themselves in relation to feeding rates and food competition. A qualitative model is presented here to predict how food depletion time, abundance of food patches within a group, and the presence of prior knowledge of feeding sites affect the payoffs of different within-group spatial positions for dominant and subordinate animals. In general, when feeding on small abundant food items, individuals at the front edge of the group should have higher foraging success. When feeding on slowly depleted, rare food items, dominants will often have the highest feeding rates in the center of the group. Between these two extreme points of a continuum, an individual's optimal spatial position is predicted to be influenced by an additional combination of factors, such as group size, group spread, satiation rates, and the presence of producer-scrounger tactics.
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Li, F. - H., Zhong, W. - Q., Wang, Z., & Wang, D. - H. (2007). Rank in a food competition test and humoral immune functions in male Brandt's voles (Lasiopodomys brandtii). Physiol. Behav., 90(2-3), 490–495.
Abstract: Social status can influence an animal's immune and reproductive functions, eventually leading to alterations in immunocompetence and reproductive success. Here, we report that rank assessed in a food competition test, considered as an index of social status, has significant influences on humoral immune functions in male Brandt's voles (Lasiopodomys brandtii) living in a group. Our data reveal a negative correlation of the spleen mass and serum antibody levels with social status, as well as a positive correlation of serum cortisol levels with social status. Males winning in food competition had a smaller spleen, a lower level of serum antibodies, and a higher level of serum cortisol than did their conspecific counterparts. These data indicate interactions between social status and humoral immune functions and might illustrate a trade-off between infection risks and reproductive success in male Brandt's voles.
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Harkins, J. D., Kamerling, S. G., & Church, G. (1992). Effect of competition on performance of thoroughbred racehorses. J Appl Physiol, 72(3), 836–841.
Abstract: The effect of competition and the influence of age and sex on performance were examined in a study of 18 Thoroughbred racehorses. The horses performed two solo and two competitive runs at 1,200 and 1,600 m for a total of eight runs. No group ran faster during competition, which may have been a reflection of the quality of horses used for this study and their susceptibility to stress-induced impairment of performance. Males showed no significant difference between competitive and solo run times, whereas females were consistently slower during competition. Males ran significantly faster than females in all runs. There was no difference in run times due to age, which may have been due to the high mean age (5.9 yr) of the group. The slower competitive run times may have occurred because of an earlier onset of fatigue when compared with solo runs. Plasma lactate was significantly greater for the 1,200-m competitive than for the solo runs.
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Hrdy, S. B. (1974). Male-male competition and infanticide among the langurs (Presbytis entellus) of Abu, Rajasthan. Folia Primatol (Basel), 22(1), 19–58.
Keywords: Aggression; Animals; Animals, Newborn; Coitus; *Competitive Behavior; Estrus; Feeding Behavior; Female; *Haplorhini; Homing Behavior; Humans; India; Infanticide; Leadership; Male; Maternal Behavior; Population Density; Pregnancy; Rain; Seasons; Sex Factors; Sexual Behavior, Animal; Social Behavior; Temperature; Vocalization, Animal
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