scholarly journals Reproductive skew, fitness costs, and winner-loser effects in social-dominance evolution

2021 ◽  
Author(s):  
Olof Leimar ◽  
Redouan Bshary

Social hierarchies can increase reproductive skew in group-living animals. Using game theory we investigate how the opportunity for differently ranked individuals to acquire resources influences reproductive skew, costs of hierarchy formation, and winner and loser effects. Individuals adjust their aggressive and submissive behaviour through reinforcement learning. The learning is based on perceived rewards and penalties, which depend on relative fighting ability. From individual-based simulations we determine evolutionary equilibria of traits that control an individual's learning. We examine situations that differ in the extent of monopolisation of contested resources by dominants and in the amounts of uncontested resources that are distributed independently of rank. With costly fighting, we find that stable dominance hierarchies form, such that reproductive skew mirrors the distribution of resources over ranks. Individuals pay substantial costs of interacting, in particular in high-skew situations, with the highest costs paid by intermediately ranked individuals. For cases where dominants monopolise contested resources there are notable winner and loser effects, with winner effects for high ranks and very pronounced loser effects for lower ranks. The effects are instead weak when acquired resources increase linearly with rank. We compare our results on contest costs and winner-loser effects with field and experimental observations.

1999 ◽  
Vol 202 (24) ◽  
pp. 3497-3506 ◽  
Author(s):  
F.A. Issa ◽  
D.J. Adamson ◽  
D.H. Edwards

The formation of social dominance hierarchies was studied in groups of five juvenile crayfish, 1.3-1.8 cm in length. Animals were grouped together in a small, featureless aquarium after having lived in isolation for more than a month. The occurrence of each of four behavior patterns (‘attack’, ‘approach’, ‘retreat’ and ‘escape’) was recorded for each animal, together with the frequency of encounters and the frequency of wins and losses. The frequencies of wins and losses were used to calculate the relative dominance value of each animal in the group. High levels of fighting developed immediately upon grouping the animals, and a positive feedback relationship between attacking and winning enabled one animal in each group to emerge quickly as the superdominant. If that animal was the largest, it remained as the superdominant; otherwise, it was replaced as superdominant within the first few days by the largest animal. This form of dominance hierarchy, with one superdominant and four subordinates, persisted throughout the duration of the grouping. Fighting declined over the first hour and by 24 h had dropped to low levels. After the first day, approaches were used together with attacks, and retreats replaced escapes. Attack and approach were the behavior patterns displayed most frequently by animals with high dominance values, whereas retreat and escape were performed by animals of low dominance. All these trends continued to develop over the next 2 weeks as the number of agonistic encounters declined to a low level.


Author(s):  
John M. McNamara ◽  
Olof Leimar

Game theory in biology seeks to predict social behaviour and other traits that influence how individuals interact. It does this by tentatively assuming that current traits are stable endpoints of evolution by natural selection. The theory is used to model aggressive behaviour, cooperation, negotiation, and signalling, as well as phenotypic attributes like an individual’s sex and mating type. This book covers the basic concepts and the traditional examples of biological game theory. It expands the frontiers of the field, emphasizing the importance of the co-evolution of traits and the implications of variation for reputation, markets, negotiation, and other social phenomena. It also highlights that it can be important to embed game interactions in the environment and an individual’s life. A major new direction developed in the book is that game theory can be extended by incorporating behavioural mechanisms, including mechanisms of reinforcement learning. By doing this the theory can successfully describe important phenomena like social dominance in group-living animals that previously have been difficult to model. By focusing on behavioural mechanisms, game theory can also make closer contact with empirical observation and with current research in fields like animal psychology and neuroscience.


2007 ◽  
Vol 3 (6) ◽  
pp. 614-616 ◽  
Author(s):  
Lee Alan Dugatkin ◽  
Aaron David Dugatkin

We examined the impact of winner and loser effects on dominance hierarchy formation when individuals are capable of estimating their opponent's resource holding power (RHP). The accuracy of such estimates was a variable in our simulations, and we considered cases in which all individuals err within the same bounds, as well as cases in which some individuals consistently overestimate, while others consistently underestimate their opponent's fighting RHP. In all cases, we found a clearly defined linear hierarchy. In most simulations, the vast majority of interactions were ‘attack–retreats’, and the remainder of interactions were almost all ‘fights’. Error rates had no effect on the linearity of the hierarchy or the basic attack–retreat nature of interactions, and consistent over and underestimation did not affect the ultimate position of an individual in a hierarchy.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
James P. Higham ◽  
Michael Heistermann ◽  
Muhammad Agil ◽  
Dyah Perwitasari-Farajallah ◽  
Anja Widdig ◽  
...  

AbstractHigh social status is the primary determinant of reproductive success among group-living male mammals. Primates living in multimale–multifemale groups show the greatest variation in the strength of this link, with marked variation in reproductive skew by male dominance among species, dependent on the degree of female fertile phase synchrony, and the number of competing males. Here, we present data on two groups of wild crested macaques (Macaca nigra), living in the Tangkoko Reserve, Sulawesi, Indonesia. We investigated male monopolization of fertile females in 31 cycles of 19 females, and genetic paternity of 14 offspring conceived during the study period. We show that female fertile phase synchrony was low, that females had few mating partners in their fertile phase, and that dominant males monopolized a high proportion of consortships and matings, resulting in marked and steep mating and reproductive skew. We conclude that female cycle asynchrony provides the opportunity for strong direct male–male competition in crested macaques, resulting in monopolization of females by dominant males, consistent with their marked sexual dimorphism. Our study provides a test of the underlying factors that determine the relative occurrence and strength of different mechanisms of sexual selection, and the phenotypes that evolve as a result.


2004 ◽  
Vol 67 (2) ◽  
pp. 239-247 ◽  
Author(s):  
Elizabeth A Whiteman ◽  
Isabelle M Côté

2015 ◽  
Vol 282 (1814) ◽  
pp. 20151512 ◽  
Author(s):  
Mathias Franz ◽  
Emily McLean ◽  
Jenny Tung ◽  
Jeanne Altmann ◽  
Susan C. Alberts

Linear dominance hierarchies, which are common in social animals, can profoundly influence access to limited resources, reproductive opportunities and health. In spite of their importance, the mechanisms that govern the dynamics of such hierarchies remain unclear. Two hypotheses explain how linear hierarchies might emerge and change over time. The ‘prior attributes hypothesis’ posits that individual differences in fighting ability directly determine dominance ranks. By contrast, the ‘social dynamics hypothesis’ posits that dominance ranks emerge from social self-organization dynamics such as winner and loser effects. While the prior attributes hypothesis is well supported in the literature, current support for the social dynamics hypothesis is limited to experimental studies that artificially eliminate or minimize individual differences in fighting abilities. Here, we present the first evidence supporting the social dynamics hypothesis in a wild population. Specifically, we test for winner and loser effects on male hierarchy dynamics in wild baboons, using a novel statistical approach based on the Elo rating method for cardinal rank assignment, which enables the detection of winner and loser effects in uncontrolled group settings. Our results demonstrate (i) the presence of winner and loser effects, and (ii) that individual susceptibility to such effects may have a genetic basis. Taken together, our results show that both social self-organization dynamics and prior attributes can combine to influence hierarchy dynamics even when agonistic interactions are strongly influenced by differences in individual attributes. We hypothesize that, despite variation in individual attributes, winner and loser effects exist (i) because these effects could be particularly beneficial when fighting abilities in other group members change over time, and (ii) because the coevolution of prior attributes and winner and loser effects maintains a balance of both effects.


eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Stoyo Karamihalev ◽  
Elena Brivio ◽  
Cornelia Flachskamm ◽  
Rainer Stoffel ◽  
Mathias V Schmidt ◽  
...  

Sex differences and social context independently contribute to the development of stress-related disorders. However, less is known about how their interplay might influence behavior and physiology. Here we focused on social hierarchy status, a major component of the social environment in mice, and whether it influences behavioral adaptation to chronic stress in a sex-specific manner. We used a high-throughput automated behavioral monitoring system to assess social dominance in same-sex, group-living mice. We found that position in the social hierarchy at baseline was a significant predictor of multiple behavioral outcomes following exposure to chronic stress. Crucially, this association carried opposite consequences for the two sexes. This work demonstrates the importance of recognizing the interplay between sex and social factors and enhances our understating of how individual differences shape the stress response.


Author(s):  
Elizabeth A. Tibbetts ◽  
Juanita Pardo-Sanchez ◽  
Chloe Weise

Animal groups are often organized hierarchically, with dominant individuals gaining priority access to resources and reproduction over subordinate individuals. Initial dominance hierarchy formation may be influenced by multiple interacting factors, including an animal's individual attributes, conventions and self-organizing social dynamics. After establishment, hierarchies are typically maintained over the long-term because individuals save time, energy and reduce the risk of injury by recognizing and abiding by established dominance relationships. A separate set of behaviours are used to maintain dominance relationships within groups, including behaviours that stabilize ranks (punishment, threats, behavioural asymmetry), as well as signals that provide information about dominance rank (individual identity signals, signals of dominance). In this review, we describe the behaviours used to establish and maintain dominance hierarchies across different taxa and types of societies. We also review opportunities for future research including: testing how self-organizing behavioural dynamics interact with other factors to mediate dominance hierarchy formation, measuring the long-term stability of social hierarchies and the factors that disrupt hierarchy stability, incorporating phenotypic plasticity into our understanding of the behavioural dynamics of hierarchies and considering how cognition coevolves with the behaviours used to establish and maintain hierarchies. This article is part of the theme issue ‘The centennial of the pecking order: current state and future prospects for the study of dominance hierarchies’.


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