Why is group size correlated with the size of the host sea anemone in the false clown anemonefish?

2005 ◽  
Vol 83 (2) ◽  
pp. 372-376 ◽  
Author(s):  
Jeremy S Mitchell ◽  
Lawrence M Dill
Keyword(s):  
Group Size ◽  
Patch Size ◽  
Resource Limitation ◽  
Direct Consequence ◽  
Sea Anemone ◽  
Dominant Group ◽  
Subordinate Group ◽  
Indirect Consequence ◽  
Group Members ◽  
Group Member

When social groups monopolize discrete habitat patches, group size may be positively correlated with patch size. The correlation can be a direct consequence of limited resources. Alternatively, it can be an indirect consequence of patch-size effects on a dominant group member. We asked which of these two mechanisms was responsible for a positive correlation between the group size of false clown anemonefish (Amphiprion ocellaris Cuvier in Cuvier and Valenciennes, 1830) and that of the host sea anemone Stichodactyla gigantea (Forskål, 1775). We argue that some false clown anemonefish groups may have reached the carrying capacities of their hosts, but that the group size : patch size correlation in the population as a whole is best interpreted as an indirect consequence of a positive relationship between anemone size and the length of the dominant group member. The dominant's length in turn limits group size because dominant group members inhibit the growth of their subordinates. Thus, a correlation between group size and patch size need not imply resource limitation of subordinate group members.

Beyond prejudice: Relational inequality, collective action, and social change revisited

2012 ◽  
Vol 35 (6) ◽  
pp. 451-466 ◽  
Author(s):  
John Dixon ◽  
Mark Levine ◽  
Steve Reicher ◽  
Kevin Durrheim
Keyword(s):  
Social Change ◽  
Collective Action ◽  
Intergroup Relations ◽  
Prejudice Reduction ◽  
Dominant Group ◽  
Negative Attitudes ◽  
Main Target ◽  
Subordinate Group ◽  
Group Members ◽  
Intergroup Inequality

AbstractThis response clarifies, qualifies, and develops our critique of the limits of intergroup liking as a means of challenging intergroup inequality. It does not dispute that dominant groups may espouse negative attitudes towards subordinate groups. Nor does it dispute that prejudice reduction can be an effective way of tackling resulting forms of intergroup hostility. What it does dispute is the assumption that getting dominant group members and subordinate group members to like each other more is the best way of improving intergroup relations that are characterized by relatively stable, institutionally embedded, relations of inequality. In other words, the main target of our critique is the model of change that underlies prejudice reduction interventions and the mainstream concept of “prejudice” on which they are based.

scholarly journals Prey synchronize their vigilant behaviour with other group members

2007 ◽  
Vol 274 (1615) ◽  
pp. 1287-1291 ◽  
Author(s):  
Olivier Pays ◽  
Pierre-Cyril Renaud ◽  
Patrice Loisel ◽  
Maud Petit ◽  
Jean-François Gerard ◽  
...  
Keyword(s):  
Predation Risk ◽  
Group Size ◽  
Prey Species ◽  
Group Members ◽  
The Individual ◽  
The Cost ◽  
Group Member

It is generally assumed that an individual of a prey species can benefit from an increase in the number of its group's members by reducing its own investment in vigilance. But what behaviour should group members adopt in relation to both the risk of being preyed upon and the individual investment in vigilance? Most models assume that individuals scan independently of one another. It is generally argued that it is more profitable for each group member owing to the cost that coordination of individual scans in non-overlapping bouts of vigilance would require. We studied the relationships between both individual and collective vigilance and group size in Defassa waterbuck, Kobus ellipsiprymnus defassa , in a population living under a predation risk. Our results confirmed that the proportion of time an individual spent in vigilance decreased with group size. However, the time during which at least one individual in the group scanned the environment (collective vigilance) increased. Analyses showed that individuals neither coordinated their scanning in an asynchronous way nor scanned independently of one another. On the contrary, scanning and non-scanning bouts were synchronized between group members, producing waves of collective vigilance. We claim that these waves are triggered by allelomimetic effects i.e. they are a phenomenon produced by an individual copying its neighbour's behaviour.

scholarly journals Behavioral and physiological evidence that increasing group size ameliorates the impacts of social disturbance

2020 ◽  
Vol 223 (14) ◽  
pp. jeb217075
Author(s):  
Hannah M. Anderson ◽  
Alexander G. Little ◽  
David N. Fisher ◽  
Brendan L. McEwen ◽  
Brett M. Culbert ◽  
...  
Keyword(s):  
Group Size ◽  
Dominant Group ◽  
Social Instability ◽  
Group Stability ◽  
Physiological Evidence ◽  
The Social ◽  
The Face ◽  
Large Groups ◽  
Group Member

ABSTRACTIntra-group social stability is important for the long-term productivity and health of social organisms. We evaluated the effect of group size on group stability in the face of repeated social perturbations using a cooperatively breeding fish, Neolamprologus pulcher. In a laboratory study, we compared both the social and physiological responses of individuals from small versus large groups to the repeated removal and replacement of the most dominant group member (the breeder male), either with a new male (treatment condition) or with the same male (control condition). Individuals living in large groups were overall more resistant to instability but were seemingly slower to recover from perturbation. Members of small groups were more vulnerable to instability but recovered faster. Breeder females in smaller groups also showed greater physiological preparedness for instability following social perturbations. In sum, we discover both behavioral and physiological evidence that living in larger groups helps to dampen the impacts of social instability in this system.

Empathy by dominant versus minority group members in intergroup interaction: Do dominant group members always come out on top?

2016 ◽  
Vol 21 (4) ◽  
pp. 549-567 ◽  
Author(s):  
Jacquie D. Vorauer ◽  
Matthew S. Quesnel
Keyword(s):  
Minority Group ◽  
Power Dynamics ◽  
Minority Group Member ◽  
Dominant Group ◽  
Intergroup Interaction ◽  
Face To Face ◽  
General Power ◽  
Group Members ◽  
Status Differences ◽  
Group Member

What power dynamics are instantiated when a minority group member empathizes with a dominant group member during social interaction? How do these dynamics compare to those instantiated when the dominant group member instead does the empathizing? According to a general power script account, because empathy is generally directed “down” toward disadvantaged targets needing support, the empathizer should come out “on top” with respect to power-relevant outcomes no matter who it is. According to a meta-stereotype account, because adopting an empathic stance in intergroup contexts leads individuals to think about how their own group is viewed (including with respect to power-relevant characteristics), the dominant group member might come out on top no matter which person empathizes. Two studies involving face-to-face intergroup exchanges yielded results that overall were consistent with the meta-stereotype account: Regardless of who does it, empathy in intergroup contexts seems more apt to exacerbate than mitigate group-based status differences.

scholarly journals Male monkeys remember which group members have given alarm calls

2005 ◽  
Vol 273 (1587) ◽  
pp. 735-740 ◽  
Author(s):  
Serge A Wich ◽  
Han de Vries
Keyword(s):  
Group Size ◽  
Alarm Call ◽  
Alarm Calls ◽  
Unanswered Question ◽  
Alarm Calling ◽  
Group Members ◽  
Presbytis Thomasi ◽  
Group Member

Primates give alarm calls in response to the presence of predators. In some species, such as the Thomas langur ( Presbytis thomasi ), males only emit alarm calls if there is an audience. An unanswered question is whether the audience's behaviour influences how long the male will continue his alarm calling. We tested three hypotheses that might explain the alarm calling duration of male Thomas langurs: the fatigue , group size and group member behaviour hypotheses. Fatigue and group size did not influence male alarm calling duration. We found that males only ceased calling shortly after all individuals in his group had given at least one alarm call. This shows that males keep track of and thus remember which group members have called.

Does crossing the road in a group influence pedestrians’ gaze behavior?

2020 ◽  
Vol 64 (1) ◽  
pp. 1938-1942
Author(s):  
Mirjam Lanzer ◽  
Martin Baumann
Keyword(s):  
Group Size ◽  
Situational Factors ◽  
Gaze Behavior ◽  
The Road ◽  
Road Users ◽  
Gender Influence ◽  
Vulnerable Road Users ◽  
Group Members ◽  
And Gender ◽  
Group Characteristics

So far, research on pedestrians’ gaze behavior while crossing roads has mainly focused on individual pedestrians rather than groups. However, pedestrians often travel in groups especially in downtown areas. This observational study investigated how group characteristics (group size and movement of the group), situational factors (presence of traffic), and demographic variables (age and gender) influence pedestrians’ gaze behavior towards traffic during road crossing. A total of N = 197 pedestrians were observed of whom n = 24 traveled alone, n = 128 traveled in groups of two or three, and n = 45 traveled in groups of four or more. Results indicated that with increasing group size, the odds to observe traffic decreased. Diffusion of responsibility among group members might explain this effect. Finally, pedestrians’ group characteristics should be considered when developing automated vehicles that interact with vulnerable road users.

scholarly journals The Effects of Group Size and Time on the Formation of Online Communities: Evidence From Reddit

2018 ◽  
Vol 4 (4) ◽  
pp. 205630511881590 ◽  
Author(s):  
Elliot Panek ◽  
Connor Hollenbach ◽  
Jinjie Yang ◽  
Tyler Rhodes
Keyword(s):  
Multilevel Analysis ◽  
Group Size ◽  
Online Communities ◽  
Cohort Effect ◽  
Active Member ◽  
Group Discussions ◽  
Large Group ◽  
Group Member

These studies examine the influence of group size and the passage of time on two characteristics of online communities: dispersion of participation in group discussions and active member turnover from month to month. We used multilevel analysis to examine the dynamics of user contributions to discussions on Reddit, a popular website that hosts large-group discussions, across 30 groups over 6 years. As groups grow in size, participation becomes more highly concentrated among fewer members while turnover decreases. As time passes, participation becomes more widely dispersed while group member turnover increases. An increase in group member turnover appears to be the result of both a maturation effect (as each group ages, turnover increases) as well as a cohort effect (groups formed at a later date have higher turnover than groups formed earlier). We can conclude from these results that as time progresses and groups become larger, they become less community-like, but in different ways.

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