Reproduction Within a Hierarchical Society from a Female’s Perspective

Abstract

The reproductive biology of many female mammals is affected by their social environment and their interactions with conspecifics. In mammalian societies structured by linear dominance hierarchies, such as that of the spotted hyena (Crocuta crocuta), a female’s social rank can have profound effects on both her reproductive success and her longevity. In this species social rank determines priority of access to food, which is the resource limiting reproduction. Due largely to rank-related variation in access to food, reproduction from the perspective of a female spotted hyena can only be understood in the context of her position in the social hierarchy. In this review, we examine the effects of rank on the various phases of reproduction, from mating to weaning. Summed over many individual reproductive lifespans, the effect of rank at these different reproductive phases leads to dramatic rank-related variation in fitness among females and their lineages. Finally, we ask why females reproduce socially despite these apparent costs of group living to low-ranking females. Gregariousness enhances the fitness of females regardless of their positions in the social hierarchy, and females attempting to survive and reproduce without clanmates lose all their offspring. The positive effects of gregariousness appear to result from having female allies, both kin and non-kin, who cooperate to advertise and defend a shared territory, acquire and defend food resources, maintain the status quo, and occasionally also to rise in social rank.

Group size, temperature and body size modulate the effects of social hierarchy on basal cortisol levels in fishes

“…Socially dominant individuals gain advantages that can increase their fitness, for instance they have access to more food (Hahn and Bauer, 2008) or have lower risks of predation (Teichroeb et al, 2015). Dominants also secure access to territory and partners for reproduction (Holekamp and Strauss, 2020) and have enhanced access to helpers in species with cooperative breeding (Dawson and Mannan, 1991). This apparently ideal situation also, however, comes with some costs, especially because access to this specific rank involves stressful situations, such as fights for dominance.…”

The value of individual identification in studies of free-living hyenas and aardwolves

“…Long-term (1979 to present, Holekamp and Strauss 2020 ; 1987 to present, Hofer and East 1993 ) and shorter term (Henschel and Skinner 1990 ) studies of spotted hyenas demand that observers be able to recognize each hyena individually based on its unique spot patterns, ear damage, and other permanent markings (e.g., missing tail, significant scars). Fortunately, except after mud-bathing, individuals are recognizable, as they have unique, permanent spot patterns that vary among individuals (Fig.…”

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Fig. 10 Representation among adult female spotted hyenas of the Talek clan at decade-long intervals (Holekamp and Strauss 2020 ) of descendants of the original 19 adult females studied by Frank ( 1983 ). Reproduced from Holekamp and Strauss ( 2020 ) with permission from Integrative and Comparative Biology

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“… Representation among adult female spotted hyenas of the Talek clan at decade-long intervals (Holekamp and Strauss 2020 ) of descendants of the original 19 adult females studied by Frank ( 1983 ). …”

“… Reproduced from Holekamp and Strauss ( 2020 ) with permission from Integrative and Comparative Biology …”