Hierarchies in a Troop of Captive Squirrel Monkeys
An observation investigation into whether or not dominance hierarchies exist in a troop of Captive Squirrel monkeys
Introduction
Darwin (1859, as cited in Darwin, 1909) proposed the idea that species of animals have evolved through survival of the fittest and in doing this form a social group in order to increase their chances of survival against predation.
Drews (1993) defined dominance hierarchies as the pattern of repeated, agonistic interaction between two individuals, characterised by a consistent outcome in favour of the same dominant member and a default submissive response of its opponent rather than escalation, further developed by Cole (1981) who suggested that dominance hierarchies are characterised by routine displays of dominance, avoidance behaviours, and even fighting. A social hierarchy arises when members of a social group interact, often aggressively in order to create a ranking system. Within this ranking, individuals compete against each other for limited resources and the chances to mate. Alonso et al. (2012) proposed that during the reproductive season, some species establish a social dominance hierarchy which determines their access to resources and reproduction for individuals of the highest rank. Alonso et al also observed that, particularly in males, that ranking of dominance is relative to the size of the individual, and that in females, aggressiveness and reproductive ability determine the rank of an individual.
The dominance hierarchies displayed in primate groups suggest that higher-ranking males have the highest reproductive success due to increased female attention and availability. Female primates at a higher level benefit and are able to produce more surviving offspring, (Huntingford and Turner, 1987). In relation to Darwin’s sexual selection theory, Huntingford and Turner’s theory suggests that the advantageous genes of higher level females are able to be passed on, and will therefore benefit the next generation of the
Introduction
Darwin (1859, as cited in Darwin, 1909) proposed the idea that species of animals have evolved through survival of the fittest and in doing this form a social group in order to increase their chances of survival against predation.
Drews (1993) defined dominance hierarchies as the pattern of repeated, agonistic interaction between two individuals, characterised by a consistent outcome in favour of the same dominant member and a default submissive response of its opponent rather than escalation, further developed by Cole (1981) who suggested that dominance hierarchies are characterised by routine displays of dominance, avoidance behaviours, and even fighting. A social hierarchy arises when members of a social group interact, often aggressively in order to create a ranking system. Within this ranking, individuals compete against each other for limited resources and the chances to mate. Alonso et al. (2012) proposed that during the reproductive season, some species establish a social dominance hierarchy which determines their access to resources and reproduction for individuals of the highest rank. Alonso et al also observed that, particularly in males, that ranking of dominance is relative to the size of the individual, and that in females, aggressiveness and reproductive ability determine the rank of an individual.
The dominance hierarchies displayed in primate groups suggest that higher-ranking males have the highest reproductive success due to increased female attention and availability. Female primates at a higher level benefit and are able to produce more surviving offspring, (Huntingford and Turner, 1987). In relation to Darwin’s sexual selection theory, Huntingford and Turner’s theory suggests that the advantageous genes of higher level females are able to be passed on, and will therefore benefit the next generation of the
References: Alonso, F., Honji, R.M., Moreira, R.G. and Pandolfi, M. (2012) Dominance hierarchies and social status ascent opportunity: Anticipatory behavioral and physiological Andersson, M. and Simmons, L.W. (2006). Sexual selection and mate choice. Trends in Ecology & Evolution, Vol 21: 296–302 Cole, B.J. (1981). Dominance Hierarchies in Leptothorax Ants. Science Magazine, Vol 212: 83-84 Darwin, C. (1909) On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life Filby, A.L., Paull, G.C., Bartlett, E.J. Van Look, K.J.W and Tyler, C.R. (2010) Physiological and health consequences of social status in zebrafish (Danio rerio) Pusey, A.E., and C. Packer. (1997). The ecology of relationships. In Behavioural Ecology: An Evolutionary Approach, edited by J Samuels, A., Silk, J.B. and Rodman, P. (1984) Changes in the dominance rank and reproductive behavior of male bonnet macaques (Macaca radiate)