scholarly journals Skew in ovarian activation depends on domicile size in a facultatively social thrips

2016 ◽  
Author(s):  
James DJ Gilbert ◽  
Alice Wells ◽  
Stephen J Simpson
Keyword(s):  
Group Size ◽  
Group Formation ◽  
Group Living ◽  
Reproductive Skew ◽  
Behavioural Ecology ◽  
Costs And Benefits ◽  
Reproductive Competition ◽  
Ovarian Activation ◽  
Per Capita ◽  
Breeding Resources

Costs and benefits of group living are a fundamental topic in behavioural ecology. Resource availability affects individuals' breeding prospects alone and in groups, as well as how reproduction is distributed within groups ("reproductive skew"). Here, we provide correlational evidence in facultatively social thrips that breeding resources are associated with (1) whether solitary or social living is favoured, and (2) the degree of ovarian skew.Dunatothrips aneurae(Thysanoptera, Phlaeothripidae) cooperatively build silk "domiciles" on Australian acacias, feeding exclusively from internal phyllode surfaces. Per capita productivity scaled differently with group size depending on domicile volume - females in small domiciles did better alone than in groups, whereas in large domiciles single and group-nesting females did equally well. Ovarian dissections revealed that in small domiciles some females were nonreproductive, indicating ovarian (i.e. reproductive) skew. Skew increased as domicile size decreased and group size increased. Breeders had smaller oocyte volume in smaller domiciles, especially those containing nonreproductives. These findings suggest group formation and reproductive skew inD. aneuraemay be influenced by reproductive competition for breeding resources. Nonreproductive females in small domiciles may be reproductively suppressed, subfertile, or waiting to reproduce. We speculate they may avoid eviction by contributing as "helpers" to domicile maintenance.

scholarly journals Costs and benefits of multi-male associations in redfronted lemurs ( Eulemur fulvus rufus )

2010 ◽  
Vol 6 (5) ◽  
pp. 620-622 ◽  
Author(s):  
Markus Port ◽  
Rufus A. Johnstone ◽  
Peter M. Kappeler
Keyword(s):  
Driving Force ◽  
Group Living ◽  
Behavioural Ecology ◽  
Costs And Benefits ◽  
Reproductive Competition ◽  
Eulemur Fulvus

The evolution of group-living has fascinated but also puzzled researchers from the inception of behavioural ecology. We use a simple optimality approach to examine some of the costs and benefits of group-living in redfronted lemurs ( Eulemur fulvus rufus ). We show that dominant males profit from accepting subordinates within their groups, as the latter significantly decrease the likelihood that the group is taken over by intruders. This benefit is large enough to outweigh the costs of reproductive competition and may constitute the driving force behind the evolution of multi-male associations in this species.

scholarly journals Costs and benefits of group living in primates: an energetic perspective

2017 ◽  
Vol 372 (1727) ◽  
pp. 20160239 ◽  
Author(s):  
A. Catherine Markham ◽  
Laurence R. Gesquiere
Keyword(s):  
Group Size ◽  
Group Living ◽  
Field Studies ◽  
Adaptive Significance ◽  
Physiological Measures ◽  
Costs And Benefits ◽  
Energetic Stress ◽  
Metabolic States ◽  
Spatial And Temporal Changes ◽  
Energetic Balance

Group size is a fundamental component of sociality, and has important consequences for an individual's fitness as well as the collective and cooperative behaviours of the group as a whole. This review focuses on how the costs and benefits of group living vary in female primates as a function of group size, with a particular emphasis on how competition within and between groups affects an individual's energetic balance. Because the repercussions of chronic energetic stress can lower an animal's fitness, identifying the predictors of energetic stress has important implications for understanding variation in survivorship and reproductive success within and between populations. Notably, we extend previous literature on this topic by discussing three physiological measures of energetic balance—glucocorticoids, c-peptides and thyroid hormones. Because these hormones can provide clear signals of metabolic states and processes, they present an important complement to field studies of spatial and temporal changes in food availability. We anticipate that their further application will play a crucial role in elucidating the adaptive significance of group size in different social and ecological contexts. This article is part of the themed issue ‘Physiological determinants of social behaviour in animals'.

scholarly journals Costs and benefits of group living with disease: a case study of pneumonia in bighorn lambs ( Ovis canadensis )

2014 ◽  
Vol 281 (1797) ◽  
pp. 20142331 ◽  
Author(s):  
Kezia R. Manlove ◽  
E. Frances Cassirer ◽  
Paul C. Cross ◽  
Raina K. Plowright ◽  
Peter J. Hudson
Keyword(s):  
Population Size ◽  
Communicable Disease ◽  
Group Living ◽  
Ovis Canadensis ◽  
Pathogen Transmission ◽  
Costs And Benefits ◽  
Force Of Infection ◽  
Per Capita ◽  
Lamb Survival

Group living facilitates pathogen transmission among social hosts, yet temporally stable host social organizations can actually limit transmission of some pathogens. When there are few between-subpopulation contacts for the duration of a disease event, transmission becomes localized to subpopulations. The number of per capita infectious contacts approaches the subpopulation size as pathogen infectiousness increases. Here, we illustrate that this is the case during epidemics of highly infectious pneumonia in bighorn lambs ( Ovis canadensis ). We classified individually marked bighorn ewes into disjoint seasonal subpopulations, and decomposed the variance in lamb survival to weaning into components associated with individual ewes, subpopulations, populations and years. During epidemics, lamb survival varied substantially more between ewe-subpopulations than across populations or years, suggesting localized pathogen transmission. This pattern of lamb survival was not observed during years when disease was absent. Additionally, group sizes in ewe-subpopulations were independent of population size, but the number of ewe-subpopulations increased with population size. Consequently, although one might reasonably assume that force of infection for this highly communicable disease scales with population size, in fact, host social behaviour modulates transmission such that disease is frequency-dependent within populations, and some groups remain protected during epidemic events.

Costs and benefits of group living in primates: group size effects on behaviour and demography

2008 ◽  
Vol 76 (4) ◽  
pp. 1235-1247 ◽  
Author(s):  
Bonaventura Majolo ◽  
Aurora de Bortoli Vizioli ◽  
Gabriele Schino
Keyword(s):  
Group Size ◽  
Size Effects ◽  
Group Living ◽  
Costs And Benefits

Subjective Fear Dilutes as Group Size Increases

2020 ◽  
Author(s):  
dean mobbs ◽  
Ellen Tedeschi ◽  
Anastasia Buyalskaya ◽  
Brian Silston
Keyword(s):  
Group Size ◽  
Real World ◽  
Survival Benefit ◽  
Group Living ◽  
External Factors ◽  
Threat Perception ◽  
Perception Of Threat ◽  
Threat Level ◽  
Internal States ◽  
Risk Dilution

According to Hamilton’s Selfish Herd Theory, a crucial survival benefit of group living is that it provides a ‘risk dilution’ function against predation. Despite a large literature on group living benefits in animals, few studies have been conducted on how group size alters subjective fear or threat perception in humans, and on what factors drive preferences for being in groups when facing threats. We conducted seven experiments (N=3,838) to test (A) if the presence of others decreases perception of threat under a variety of conditions. In studies 1 to 3, we experimentally manipulated group size in hypothetical and real-world situations, to show that fear responses decreased as group size increased. In studies 4 to 7 we again used a combination of hypothetical, virtual and real-world decisions to test (B) how internal states (e.g. anxiety) and external factors (e.g. threat level, availability of help) affected participants’ preference for groups. Participants consistently chose larger groups when threat and anxiety were high. Overall, our findings show that group size provides a salient signal of protection and safety.

scholarly journals Female fertile phase synchrony, and male mating and reproductive skew, in the crested macaque

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
James P. Higham ◽  
Michael Heistermann ◽  
Muhammad Agil ◽  
Dyah Perwitasari-Farajallah ◽  
Anja Widdig ◽  
...  
Keyword(s):  
Group Living ◽  
Reproductive Skew ◽  
Male Dominance ◽  
Male Mating ◽  
Marked Variation ◽  
Phase Synchrony ◽  
Fertile Phase ◽  
Macaca Nigra ◽  
Primary Determinant ◽  
High Social Status

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.

Optimal Rent-Seeking Group

1992 ◽  
Vol 36 (2) ◽  
pp. 58-60 ◽  
Author(s):  
Sanghack Lee
Keyword(s):  
Group Formation ◽  
Rent Seeking ◽  
Costs And Benefits

This note characterizes rent-seeking competition under the possibility of cooperation between rent seekers. Rational individuals are shown either to form a group to fight for the rent or not, depending upon costs and benefits of group formation. In the normative respect, group formation by rent seekers turns out to reduce social wastes resulting from rent-seeking competition.

scholarly journals Fitness of breeders in social Damaraland mole-rats is independent of group size

2021 ◽  
Author(s):  
Jack Thorley ◽  
Hanna Bensch ◽  
Kyle Finn ◽  
Tim Clutton-Brock ◽  
Markus Zöttl
Keyword(s):  
Reproductive Success ◽  
Group Size ◽  
Survival Rates ◽  
Group Living ◽  
Adult Survival ◽  
High Survival ◽  
Successful Reproduction ◽  
Related Group ◽  
Group Members ◽  
Using Data

Damaraland mole-rats (Fukomys damarensis) are usually viewed as an obligatorily group living eusocial species in which successful reproduction is dependent on reproductive altruism of closely related group members. However, the reproductive ecology of social mole-rats in their natural environment remains poorly understood and it is unclear to what extent successful reproduction is dependent on assistance from other group members. Using data from a 7-year field study of marked individuals, we show that, after dispersal from their natal group, individuals typically settled alone in new burrow systems where they enjoyed high survival rates, and often remained in good body condition for several years before finding a mate. Unlike most other eusocial or singular cooperative breeders, we found that Damaraland mole-rats reproduced successfully in pairs without helpers and experimentally formed pairs had the same reproductive success as larger established groups. Overall there was only a weak increase in reproductive success with increasing group size and no effect of group size on adult survival rates across the population. Juveniles in large groups grew faster early in life but their growth rates declined subsequently so that they eventually plateaued at a lower maximum body mass than juveniles from small groups. Taken together, our data suggest that the fitness benefits of group living to breeders are small and we suggest that extended philopatry in Damaraland mole-rats has evolved because of the high costs and constraints of dispersal rather than because of strong indirect benefits accrued through cooperative behaviour.

scholarly journals Group Size, Coordination, and the Effectiveness of Punishment in the Voluntary Contributions Mechanism: An Experimental Investigation

2021 ◽  
Author(s):  
Bin Xu ◽  
C. Bram Cadsby ◽  
Liangcong Fan ◽  
Fei Song
Keyword(s):  
Group Size ◽  
Group Treatment ◽  
Entire Group ◽  
Voluntary Contributions ◽  
Good Efficiency ◽  
Marginal Group ◽  
Voluntary Contributions Mechanism ◽  
Punishment Mechanism ◽  
Per Capita ◽  
The Individual

We examine the effectiveness of the individual-punishment mechanism in larger groups, comparing groups of four to groups of 40 participants. We find that the individual punishment mechanism is remarkably robust when the marginal per capita return (MPCR), i.e. the return to each participant from each dollar that is contributed, is held constant. Moreover, the efficiency gains from the punishment mechanism are significantly higher in the 40-participant than in the four-participant treatment. This is true despite the coordination problems inherent in an institution relying on decentralized individual punishment decisions in the context of a larger group. It reflects increased per capita expenditures on punishment that offset the greater coordination difficulties in the larger group. However, if the marginal group return (MGR), i.e. the return to the entire group of participants, stays constant, resulting in an MPCR that shrinks with group size, no such offset occurs and punishment loses much but not all of its effectiveness at encouraging voluntary contributions to a public good. Efficiency is not significantly different from the small-group treatment.

Goal Relevance and Desirability of Virtuous Behavior in Satisfying Affiliative and Pathogen Avoidance Needs

2021 ◽  
Author(s):  
Mitch Brown
Keyword(s):  
Group Living ◽  
Self Control ◽  
Evolutionary Perspective ◽  
Costs And Benefits ◽  
Behavioral Repertoire ◽  
Fundamental Nature ◽  
Virtuous Behavior ◽  
Goal Relevance ◽  
Effective Group ◽  
Pathogen Avoidance

Recent findings suggest that behavioral repertoires frequently conceptualized as virtuous possess a fundamental nature that implicates virtues as highly desirable in facilitating group living through factors of caring, self-control, and inquisitiveness. Although much of this desirability has previously demonstrated in mating domains, it could be possible their benefits extend to affiliative and pathogen-avoidant domains. Two studies (N=285) sought to determine the potential costs and benefits of associating with virtuous individuals (Study 1) and how these affordances could shape subsequent interpersonal preferences (Study 2). In Study 1, participants inferred a caring behavioral repertoire as particularly effective at facilitating both affiliative and pathogen-avoidant goals, whereas inquisitiveness was perceived as threatening to pathogen-avoidant goals. Study 2 provides evidence dispositionally heightened affiliative interests heightened preferences for caring, but pathogen-avoidant motives did not influence preferences. I frame results from an evolutionary perspective and synthesize it with recent findings demonstrating how virtue shapes effective group living.

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