Effects of local versus global competition on reproductive skew and sex differences in social dominance behaviour

Abstract

Social hierarchies are often found in group-living animals. The hierarchy position can influence reproductive success (RS), with a skew towards high-ranking individuals. The amount of aggression in social dominance varies greatly, both between species and between males and females within species. Using game theory we study this variation by taking into account the degree to which reproductive competition in a social group is mainly local to the group, emphasizing within-group relative RS, or global to a larger population, emphasizing an individual’s absolute RS. Our model is similar to recent approaches in that reinforcement learning is used as a behavioural mechanism allowing social-hierarchy formation. We test two hypotheses. The first is that local competition should favour the evolution of mating or foraging interference, and thus of reproductive skew. Second, decreases in reproductive output caused by an individual’s accumulated fighting damage, such as reduced parenting ability, will favour less intense aggression but should have little influence on reproductive skew. From individual-based simulations of the evolution of social dominance and interference, we find support for both hypotheses. We discuss to what extent our results can explain observed sex differences in reproductive skew and social dominance behaviour.

The role of learning in the evolution of status signalling: a modeling approach

“…This is evident in classical situations such as when animals learn to avoid food that makes them sick or use environmental cues to find food. More recent theoretical work has highlighted the potential role that associations can have in social contexts such as hierarchy formation (Leimar 2021; Leimar and Bshary 2022a, 2022b) and cooperation (Leimar and McNamara 2019; Dridi and Akçay 2018). In these examples, models involve individuals who use various sources of reward to make adaptive choices.…”

“…This set of algorithms allows the implementation of biologically realistic problems, capturing the essence of learning processes (Frankenhuis, Panchanathan, and Barto 2018; Quiñones et al 2020). Furthermore, these algorithms can be embedded in evolutionary simulations to generate theoretical predictions of the effect of learning on behavioural evolution (Leimar and McNamara 2019; Leimar and Bshary 2022b).…”

Executive functions and brain morphology of male and female dominant and subordinate cichlid fish

“…Living in social groups poses various social challenges for individuals, such as sharing and defending territories and resources, mate choice, and bookkeeping (remembering partners’ behavior during past social interactions) (De Dreu & Triki, 2022 ; Lukas & Clutton‐Brock, 2018 ). One of the important challenges that group‐living animals face is adjusting behavior to their own position in a social dominance hierarchy (Leimar & Bshary, 2022 ; Strauss et al., 2022 ). In most social species, dominant individuals are older and physically more capable of defending their status and, hence, enjoy more privileges than low‐ranking younger subordinates.…”

“…Despite the interest in social dominance hierarchy (Leimar & Bshary, 2022 ; Strauss et al., 2022 ), to the best of our knowledge, only a few studies have looked either into the brain structure or cognitive abilities of dominant and subordinate individuals but failed to examine the important relationship between brain structure and cognition simultaneously in order to understand individual differences. For instance, the mushroom body calyx, a crucial structure in insect brains that plays a significant role in memory and learning, is more developed in dominant paper wasps than in subordinates (O'Donnell et al., 2007 ).…”

Social control is associated with increased reproductive skew in a wild mammal

“…Traditionally, social control is quantified by determining individual dominance ranks and the resulting dominance hierarchy. Dominance rank generally influences reproduction, with high-ranking individuals often having enhanced access to resources and reproductive success [6,15,16], as seen in some macaques (Macaca spp. [17][18][19]) and spotted hyenas (Crocuta crocuta [20,21]).…”