The frequency of interactions, the regularity of outcomes and the linearity of hierarchies all vary widely between and within species. In some species, there are well-defined dominance hierarchies in both sexes and subordinate individuals seldom win encounters with competitors of higher rank, as in baboons or spotted hyenas (Silk, 1993; East & Hofer, 2010). In others, an individual’s rank depends on location: for example, in red deer, the relative dominance of females is affected by whether or not they are within their usual range (Thouless & Guinness, 1986). Finally, in a few species, there is no regular pattern in the

outcome of aggressive interactions between adult female group members. For example, selleckchem lionesses commonly threaten pride-mates

feeding on the same kill, but individuals are seldom displaced from their feeding sites and there are no marked differences in the frequency with which individuals give and receive threats (Packer, Pusey & Eberly, 2001). Similarly, in Kalahari meerkats, foraging females usually respect each other’s access to feeding sites and seldom contest access to feeding sites, though the most dominant female in each group occasionally displaces subordinates (Kutsukake & Clutton-Brock, 2006a). The reasons for variation in the consistency of dominance relationships between females are uncertain. Contrasts in the regularity and stability of hierarchies have been most extensively studied in primates (Rowell, 1974; Bernstein, 1981) where Erlotinib in vivo it has been suggested that the presence of strong linear hierarchies in females is associated with reliance on foods that are distributed in patches of high value and with intense direct competition between group members for resources (Wrangham, 1980; Sterck, Watts & van Schaik, 1997). Some intraspecific comparisons support this suggestion. For example, in one population of savannah baboons

where resources were concentrated, competitive interactions were common, dominance relationships were well developed and affected rates of food intake of while, in a second population where resources were widely dispersed, competitive interactions were less frequent and dominance relations were inconsistent and coalitions did not occur (Barton & Whiten, 1993; Barton, Byrne & Whiten, 1996). However, the quantitative comparisons of hierarchies across samples of populations, which would be needed to test this prediction, are not yet available (Clutton-Brock & Janson, 2012). It is also unclear whether there is any consistent association between food distribution and hierarchical behaviour at the species level (Clutton-Brock & Janson, 2012).