scholarly journals Cooperative and aggressive behaviours vary between ranks in anemonefish social hierarchies

2021 ◽  
Author(s):  
T Rueger ◽  
SJ Heatwole ◽  
MY Wong

AbstractMany animal groups consist of individuals organised in dominance hierarchies, based on age, size or fighting ability. Lower ranked individuals often do not reproduce themselves but perform cooperative behaviours to help the reproductive output of dominant individuals or the group as a whole. Theoretical models suggest that individuals of higher rank should show increased amounts of aggressive behaviours, such as aggressions towards other group members, but should decrease the amount of cooperative behaviours, such as brood care or territory maintenance. Most empirical tests of these models focus on insect or mammalian systems where kin selection plays a large role, rather than animals that live in groups of unrelated individuals. Here we use two anemonefish species to test hypotheses of variation in cooperation and aggression with respect to social rank and species, for social systems where group members are unrelated. We assessed the behaviours of each rank in 20 groups of Amphiprion percula and 12 groups of A. perideraion in Kimbe Bay, Papua New Guinea. We also performed a removal experiment to test if cooperative and aggressive behaviours are likely adaptive, i.e., if they change as an individual ascends in rank. Our results show differences between the two species, with A. percula showing more cooperative behaviours and A. perideraion showing more aggressive behaviours, despite them being closely related and sharing a very similar ecology. With respect to both cooperation and aggression we found consistent differences between ranks in both species, with higher ranks performing more aggressive as well as more cooperative behaviours. When we experimentally provided lower ranked individuals (rank 4) an opportunity to ascend in the hierarchy, they showed more aggression and more cooperation in line with our observations for rank 3 individuals. Thus, we show that rank specific behavioural patterns are likely adaptive in anemonefishes and that some model predictions do not hold in systems where kin selection benefits are absent. Rather, future fitness benefits through territory inheritance and group augmentation likely motivate cooperative and aggressive behaviours by subordinates in groups of unrelated vertebrates.

Ranking ◽  
2019 ◽  
pp. 42-64
Author(s):  
Péter Érdi

This chapter studies how social ranking in humans emerged as the result of an evolutionary process. It starts with the story of the discovery of pecking order among chickens by a Norwegian boy. Both animals and humans need a healthy balance between cooperation and competition to ensure evolutionarily efficient strategies. The biological machinery behind social ranking is discussed. There are two distinct mechanisms for navigating the social ladder: dominance and prestige. Dominance, an evolutionarily older strategy, is based on the ability to intimidate other members in the group by physical size and strength. The group members don’t accept dominance-based social rank freely, only by coercion. Members of a colony fight, and the winners of these fights will be accepted as “dominants” and the losers as “subordinates.” The naturally formed hierarchy serves as a way to prevent superfluous fighting and injuries within a colony. Prestige, as a strategy, is evolutionarily younger and is based on skills and knowledge as appraised by the community. Prestige hierarchies are maintained by the consent of the community, without pressure being applied by particular members. The mechanisms of forming and maintaining social hierarchies are described. Social structures, both hierarchies and network organizations, are reviewed. Discussion of these structures is carried over to social and political history and the tension between democracy and authoritarianism.


Behaviour ◽  
2016 ◽  
Vol 153 (12) ◽  
pp. 1365-1385 ◽  
Author(s):  
Jacob R. Withee ◽  
Sandra M. Rehan

Dominance hierarchies represent some of nature’s most rudimentary social structures, and aggression is key to their establishment in many animal species. Previous studies have focused on the relative influences of prior experience and physiological traits of individuals in determining social rank through aggression. Here we examine the behavioural potential for dominance hierarchy formation in the subsocial small carpenter bee, Ceratina calcarata. Both physiological traits and social experience were found to play partial roles in predicting future interactive behaviour in this species. Our results suggest that individual size is associated with dominance in initial encounters, while prior experience plays a larger role in predicting dominance in subsequent encounters. Social systems in the early stages of social evolution may well have followed these same predictive factors and these factors are key targets for future studies of social evolution and the behavioural origins of dominance hierarchies.


2019 ◽  
Vol 286 (1906) ◽  
pp. 20190536 ◽  
Author(s):  
Matthew J. Silk ◽  
Michael A. Cant ◽  
Simona Cafazzo ◽  
Eugenia Natoli ◽  
Robbie A. McDonald

Dominance hierarchies are widespread in animal societies and reduce the costs of within-group conflict over resources and reproduction. Variation in stability across a social hierarchy may result in asymmetries in the benefits obtained from hierarchy formation. However, variation in the stability and behavioural costs of dominance interactions with rank remain poorly understood. Previous theoretical models have predicted that the intensity of dominance interactions and aggression should increase with rank, but these models typically assume high reproductive skew, and so their generality remains untested. Here we show in a pack of free-living dogs with a sex–age-graded hierarchy that the central region of the hierarchy was dominated by more unstable social relationships and associated with elevated aggression. Our results reveal unavoidable costs of ascending a dominance hierarchy, run contrary to theoretical predictions for the relationship between aggression and social rank in high-skew societies, and widen our understanding of how heterogeneous benefits of hierarchy formation arise in animal societies.


Author(s):  
Tian Chen Zeng ◽  
Joey T. Cheng ◽  
Joseph Henrich

Dominance captures behavioural patterns found in social hierarchies that arise from agonistic interactions in which some individuals coercively exploit their control over costs and benefits to extract deference from others, often through aggression, threats and/or intimidation. Accumulating evidence points to its importance in humans and its separation from prestige—an alternate avenue to high status in which status arises from information (e.g. knowledge, skill, etc.) or other non-rival goods. In this review, we provide an overview of the theoretical underpinnings of dominance as a concept within evolutionary biology, discuss the challenges of applying it to humans and consider alternative theoretical accounts which assert that dominance is relevant to understanding status in humans. We then review empirical evidence for its continued importance in human groups, including the effects of dominance—independently of prestige—on measurable outcomes such as social influence and reproductive fitness, evidence for specialized dominance psychology, and evidence for gender-specific effects. Finally, because human-specific factors such as norms and coalitions may place bounds on purely coercive status-attainment strategies, we end by considering key situations and contexts that increase the likelihood for dominance status to coexist alongside prestige status within the same individual, including how: (i) institutional power and authority tend to elicit dominance; (ii) dominance-enhancing traits can at times generate benefits for others (prestige); and (iii) certain dominance cues and ethology may lead to mis-attributions of prestige. 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’.


2020 ◽  
Vol 101 (2) ◽  
pp. 526-534 ◽  
Author(s):  
Heng Liu ◽  
Xin Zhao ◽  
Yuze Wang ◽  
Ying Liu ◽  
Jiang Feng ◽  
...  

Abstract Social animals may cooperate to gain resources such as food and territory. However, unavoidable conflicts over limited resources frequently occur between group members. Social rank may effectively decrease conflicts within animal social groups, thereby reducing energy consumption and maintaining group stability. In this study, we tested the two factors most often proposed to influence winning a conflict: body size and prior residence. Our results showed that female Asian particolored bats (Vespertilio sinensis) formed near-linear dominance hierarchies. Forearm length was significantly positively correlated with dominance rank in three replicate experiments. In addition, prior residents had significantly higher dominance ranks than intruders of similar body size. These results suggested that both body size and prior residence might affect dominance ranks in female Asian particolored bats.


2021 ◽  
Author(s):  
Bailly Tiphaine ◽  
Philip Kohlmeier ◽  
Rampal Etienne ◽  
Bregje Wertheim ◽  
Jean-Christophe Billeter

Being part of a group facilitates cooperation between group members, but also creates competition for limited resources. This conundrum is problematic for gravid females who benefit from being in a group, but whose future offspring may struggle for access to nutrition in larger groups. Females should thus modulate their reproductive output depending on their social context. Although social-context dependent modulation of reproduction is documented in a broad range of species, its underlying mechanisms and functions are poorly understood. In the fruit fly Drosophila melanogaster, females actively attract conspecifics to lay eggs on the same resources, generating groups in which individuals may cooperate or compete. The tractability of the genetics of this species allows dissecting the mechanisms underlying physiological adaptation to their social context. Here, we show that females produce eggs increasingly faster as group size increases. By laying eggs faster in group than alone, females appear to reduce competition between offspring and increase their likelihood of survival. In addition, females in a group lay their eggs during the light phase of the day, while isolated females lay them during the night. We show that responses to the presence of others are determined by vision through the motion detection pathway and that flies from any sex, mating status or species can trigger these responses. The mechanisms of this modulation of egg-laying by group is connected to a lifting of the inhibition of light on oogenesis and egg-laying by stimulating hormonal pathways involving juvenile hormone. Because modulation of reproduction by social context is a hallmark of animals with higher levels of sociality, our findings represent a protosocial mechanism in a species considered solitary that may have been the target of selection for the evolution of more complex social systems.


2018 ◽  
Vol 41 ◽  
pp. 13-18
Author(s):  
Olav Hogstad ◽  
Tore Slagsvold

The Willow Tit Poecile montanus is highly sedentary and breeding pairs remain in their exclusive areas throughout the year. During the winter, these areas are defended by small, non-kin flocks, formed as the roaming yearlings become sedentary and join adults during late summer and autumn. Once established, stable social hierarchies are maintained in these flocks during the winter. The winter flocks consist normally of the socially dominant adult mated pair and two mated juvenile pairs, one higher-ranked and one lower-ranked. Individually colour-ringed juvenile Willow Tits were followed over years in subalpine forest in Norway from ringing in the autumn till they disappeared. None of the lower ranked birds survived their first winter, whereas only 4 of 71 higher-ranked juvenile pairs disappeared during this time. Half of the 71 pairs survived their first winter, about 25 % survived two winters, 8.5% survived three winters, and 5.6% survived four winters. Survival was similar for males and females. Alpha pairs remained mated and defended their common territory across years. Maximum age as revealed by ringing showed one female became six years old and two males ringed as adults were at least nine years old when last observed. The main factor associated with survival was early flock establishment that led to a high rank position among the juvenile flock members. Body size seemed insignificant. Birds that survived their first winter either succeeded to establish as territory owners or they were forced into the role as floaters and probably perished.


Author(s):  
Mykhailo Mozhaiev ◽  
Pavlo Buslov

The results of the development of an information model for the personality’s social portrait formation are presented. The modelling has been carried out using OSINT technology that is the technology of legal obtaining and using open source information. In the result of the analysis, it has been found out that the social portrait is a heterogeneous semantic network consisting of personalized data. It has been defined that people organize formal and official communities of various orientations and the number of such communities associated with a particular person is practically unlimited. When formalizing the decision-making process, the concept of a group social portrait (GSP) has been introduced, which takes into account the community’s social tendencies united by certain common properties, group members' interpersonal interactions and their behavioural patterns. The obtained information models of personal and group social portraits let to take into account all the main properties of the objects under study, their tonality and significance, as well as to conduct an analysis of the implicit dependencies determination. The next step is to move on to considering the diversity of the digital social environment elements.


2021 ◽  
Author(s):  
Taylor Lynne Rystrom ◽  
Romy C. Prawitt ◽  
S. Helene Richter ◽  
Norbert Sachser ◽  
Sylvia Kaiser

Social interactions among group members often lead to the formation of stable dominance hierarchies. Glucocorticoids (i.e. cortisol) have been proposed as an endocrine mechanism underlying social behavior, and previous studies have linked baseline as well as challenge glucocorticoid concentrations to dominance rank. Since the importance of rank on fitness differs between males and females, selection pressures acting on the underlying endocrine mechanisms may differ between the sexes. In male guinea pigs, for example, it is known that cortisol responsiveness mediates social behavior and that dominance rank and cortisol responsiveness are stable within individuals over time. It is unclear whether this is also the case for female guinea pigs. Thus the aim of this study was to investigate whether cortisol concentrations are repeatable in female guinea pigs and whether female rank is correlated to baseline cortisol concentrations or cortisol responsiveness. We show that cortisol responsiveness and dominance rank were significantly repeatable but not correlated in female guinea pigs. Furthermore, baseline cortisol was not repeatable and also did not correlate to dominance rank. Our results demonstrate that baseline cortisol and cortisol responsiveness represent different biological processes; cortisol responsiveness reflects a stable trait while baseline cortisol likely fluctuates with current state. Furthermore, cortisol responsiveness as a mediator of aggressive behavior and dominance acquisition might not be important for maintaining dominance hierarchies in stable groups of females displaying minimal aggression. Overall, this study reveals the remarkable stability of cortisol responsiveness and dominance rank in an adult female rodent and lays the groundwork for future investigations into the causes and consequences of this individual variation.


2020 ◽  
Vol 16 (8) ◽  
pp. 20200468
Author(s):  
Steven J. Portugal ◽  
James R. Usherwood ◽  
Craig R. White ◽  
Daniel W. E. Sankey ◽  
Alan M. Wilson

Dominance hierarchies confer benefits to group members by decreasing the incidences of physical conflict, but may result in certain lower ranked individuals consistently missing out on access to resources. Here, we report a linear dominance hierarchy remaining stable over time in a closed population of birds. We show that this stability can be disrupted, however, by the artificial mass loading of birds that typically comprise the bottom 50% of the hierarchy. Mass loading causes these low-ranked birds to immediately become more aggressive and rise-up the dominance hierarchy; however, this effect was only evident in males and was absent in females. Removal of the artificial mass causes the hierarchy to return to its previous structure. This interruption of a stable hierarchy implies a strong direct link between body mass and social behaviour and suggests that an individual's personality can be altered by the artificial manipulation of body mass.


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