The determinants of dominance relationships among subordinate females in the cooperatively breeding meerkat

Abstract

In cooperatively breeding species with high reproductive skew, a single breeding female is dominant to all other group members, but it is not yet known if there are consistent dominance relationships among subordinates. In this study on meerkats (Suricata suricatta), we used naturally observed dominance assertions and submissive interactions within dyads of subordinate females to investigate: (i) whether or not a dominance structure exists among them and what factors influence dominance relationships; and (ii) how dominance may influence the future reproductive success of subordinate females. Our study indicates that superiority in age and weight provide a competitive advantage during conflicts among subordinate females and that females who consistently dominate in these contests are subsequently more likely to attain a dominant breeding position. This provides a starting point for further investigations into dominance structure among subordinates in meerkat societies and other cooperative breeders.

The importance of being beta: female succession in a cooperative breeder

“…However, we also find that an individual's weight relative to other subordinates is an important proximate factor in determining acquisition of dominance, a result only previously reported in a captive study of house mice (Rusu & Krackow, 2004). Whilst this can be partially explained by weight differences resolving dominance competitions between same aged competitors (Thavarajah et al, 2014), our results also indicate that younger subordinates with a weight advantage are sometimes able to outcompete older subordinates. This raises two possibilities, either weight is playing a more important role in determining the subordinate hierarchical rank than expected or dominance vacancies are not queued for but instead actively competed over when they arise.…”

“…The dominance status of females was determined from the frequency and direction of aggressive and submissive interactions directed at other females within their group as well as from the relative frequency of anal marking, which is substantially higher in dominants than subordinates ( Thavarajah, Fenkes, & Clutton-Brock, 2014). The dominant female was dominant to all other females in the group and, in most cases, to all males, too.…”

“…Previous work has identified age as the main determinant of the outcome of antagonistic interactions among subordinates, with weight dictating outcomes between individuals of the same age (Thavarajah, Fenkes, & Clutton-Brock, 2014). Therefore, we defined a beta individual as the eldest subordinate in the group each month and where several individuals from the same litter were present in the top age rank, we assumed that the heaviest individual in the litter was the beta.…”

“…In this study we describe the relative frequency with which females acquire dominant breeding status, the breeding tenure and success of individuals that acquire dominance in different ways and the traits that affect the ability of females to acquire dominant status. The oldest subordinate female, the beta, is usually dominant to other subordinate females (Thavarajah, Fenkes, & Clutton-Brock, 2014) and is more likely to acquire the dominant position after the death of an existing dominant female in her group than other group members (Clutton-Brock et al, 2006;Hodge et al, 2008). The eldest subordinate is commonly the heaviest subordinate and also at the highest risk of eviction by the dominant (Clutton-Brock, Hodge, Flower, Spong, & Young, 2010).…”

Olfactory attractants and parity affect prenatal androgens and territoriality of coyote breeding pairs

“…Phenotypic consequences of environmental and temporal variation become considerably more far-reaching when considering breeding individuals and their overall influence on group or population dynamics. Breeding individuals undergo significant hormonal and behavioral changes in preparation for parenting [49,50] that can affect both breeders and even non-breeding individuals in socially complex groups such as cooperative breeding systems [51][52][53]. Moreover, phenotypic changes during gestation may affect developing neonates epigenetically [54,55].…”