scholarly journals No division of labour, and subfertile foundresses, in a phyllode-gluing Acacia thrips

2019 ◽  
Author(s):  
James D. J. Gilbert
Keyword(s):  
Group Size ◽  
Division Of Labour ◽  
Poor Quality ◽  
Limited Ability ◽  
Indirect Benefits ◽  
Genetic Benefits ◽  
Female Quality ◽  
Colony Productivity ◽  
Animal Societies

ABSTRACTBehavioural variation is a hallmark of animal societies, which commonly contain breeders and nonbreeders, and helpers and nonhelpers. In some cases labour is divided with nonbreeders “helping” – gaining indirectly, via genetic benefits, or directly, e.g. by augmenting group size. Conversely, they may benefit by not helping, conserving energy for breeding later. However, subordinate behaviour after inheriting a breeding position is rarely evaluated.In the Australian interior, Acacia thrips Dunatothrips aneurae (Thysanoptera) glue Acacia phyllodes together into “domiciles”. Foundresses, usually sisters, build domiciles singly or communally. Some co-foundresses are nonreproductive, and their role is currently unknown. I experimentally rejected the idea that they substantially “help” by contributing to domicile repair. Nonreproductives were less likely to repair damage than reproductives. Alternatively, they may be waiting to inherit the domicile, or simply of too poor quality to reproduce or help. To test these alternatives, in the field, I allowed repairer or nonrepairer females to “inherit” a domicile by removing their nestmate(s). Thus isolated, “nonrepairer” females took much longer to repair domiciles than “repairers”, control singletons or pairs. Although ovarian condition was equivalent across groups, after 21 days nonrepairers actually laid fewer eggs compared to other groups.Thus, labour was not divided: instead reproduction and helping covaried, probably depending on female quality and the outcome of intra-domicile competition. Nonreproductive nonhelpers were not waiting to breed. Their role, and their net effect on colony productivity, remains to be shown. They are likely subfertile, and may make the “best of a bad job” by gaining indirect benefits to the best of their limited ability.

scholarly journals Copulation rate declines with mating group size in dusky dolphins (Lagenorhynchus obscurus)

2015 ◽  
Vol 93 (6) ◽  
pp. 503-507 ◽  
Author(s):  
D.N. Orbach ◽  
G.G. Rosenthal ◽  
B. Würsig
Keyword(s):  
New Zealand ◽  
Group Size ◽  
Energy Costs ◽  
Indirect Benefits ◽  
Lagenorhynchus Obscurus ◽  
Mating Group ◽  
Copulation Rate ◽  
Mating Opportunities ◽  
Dusky Dolphins ◽  
Time And Energy

Males in polygamous species often engage in intrasexual competition for mates. If females actively evade mating attempts, it may benefit males to cooperate to restrict female movement, as has been found in some mammals. We tested if male dusky dolphins (Lagenorhynchus obscurus (Gray, 1828)) cooperate or compete during group mating chases. If they cooperate, then the per-male probability of copulating should increase with group size; if they compete, then the probability should decrease. We followed mating groups by boat during the breeding season (October 2013 – January 2014) off Kaikoura, New Zealand. The copulation rate per male decreased with increasing group size and with the number of noncopulating males in proximity to a copulating female. Male dusky dolphins have multiple mates and appear to use sperm and exploitative scramble competition. Males may remain in mating groups despite competition because there are alliances within the groups, they are unable to exclude rivals from joining a group, the time and energy costs of searching for unescorted females exceed the costs of reduced mating opportunities in a group, they receive other direct or indirect benefits that offset the costs of reduced mating opportunities, or they are in the group largely for social learning rather than procreation.

scholarly journals Skills, division of labour and economies of scale among Amazonian hunters and South Indian honey collectors

2015 ◽  
Vol 370 (1683) ◽  
pp. 20150008 ◽  
Author(s):  
Paul L. Hooper ◽  
Kathryn Demps ◽  
Michael Gurven ◽  
Drew Gerkey ◽  
Hillard S. Kaplan
Keyword(s):  
Group Size ◽  
Economies Of Scale ◽  
Returns To Scale ◽  
Division Of Labour ◽  
Social Constraints ◽  
Cooperative Groups ◽  
Self Organized ◽  
South Indian ◽  
Group Members ◽  
Group Success

In foraging and other productive activities, individuals make choices regarding whether and with whom to cooperate, and in what capacities. The size and composition of cooperative groups can be understood as a self-organized outcome of these choices, which are made under local ecological and social constraints. This article describes a theoretical framework for explaining the size and composition of foraging groups based on three principles: (i) the sexual division of labour; (ii) the intergenerational division of labour; and (iii) economies of scale in production. We test predictions from the theory with data from two field contexts: Tsimane' game hunters of lowland Bolivia, and Jenu Kuruba honey collectors of South India. In each case, we estimate the impacts of group size and individual group members' effort on group success. We characterize differences in the skill requirements of different foraging activities and show that individuals participate more frequently in activities in which they are more efficient. We evaluate returns to scale across different resource types and observe higher returns at larger group sizes in foraging activities (such as hunting large game) that benefit from coordinated and complementary roles. These results inform us that the foraging group size and composition are guided by the motivated choice of individuals on the basis of relative efficiency, benefits of cooperation, opportunity costs and other social considerations.

scholarly journals Self-assembly, self-organization and division of labour

1999 ◽  
Vol 354 (1388) ◽  
pp. 1395-1405 ◽  
Author(s):  
Ana B. Sendova-Franks ◽  
Nigel R. Franks
Keyword(s):  
Self Assembly ◽  
Division Of Labour ◽  
Self Organization ◽  
Ecological Communities ◽  
Social Resilience ◽  
Biological Organization ◽  
Ant Colonies ◽  
The Social ◽  
Biological Hierarchy ◽  
Animal Societies

The prospect of generic principles of biological organization being uncovered through the increasingly broad use of the concepts of ‘self–assembly’ and ‘self–organization’ in biology will only be fulfilled if students of different levels of biological organization use the same terms with the same meanings. We consider the different ways the terms ‘self–assembly’ and ‘self–organization’ have been used, from studies of molecules to studies of animal societies. By linking ‘self–assembly’ and ‘self–organization’ with division of labour, we not only put forward a distinction between the underlying concepts but we are also able to relate them to the question: Why has a certain structure been favoured by natural selection? Using the particularly instructive case of social resilience in ant colonies, we demonstrate that the principle of self–organizing self–assembly may apply to higher levels of biological organization than previously considered. We predict that at the level of interactions among organisms within the most advanced animal societies, specialization through learning has a crucial role to play in re–assembly processes. This review may also help important commonalities and differences to be recognized between ordering mechanisms up to the social level and those further up the biological hierarchy, at the level of ecological communities.

scholarly journals Does sexual cannibalism secure genetic benefits of polyandry in a size-dimorphic spider?

2020 ◽  
Vol 74 (9) ◽  
Author(s):  
Katharina Weiss ◽  
Jasmin Ruch ◽  
Stefanie S. Zimmer ◽  
Jutta M. Schneider
Keyword(s):  
Sexual Conflict ◽  
Survival Duration ◽  
Male Mating ◽  
Sexual Cannibalism ◽  
Indirect Benefits ◽  
Adult Body Mass ◽  
Genetic Benefits ◽  
Direct Benefits ◽  
Potential Benefits ◽  
Food Conditions

Abstract Females mate multiply despite numerous costs. It is well established that polyandry can result in sexual conflict, favoring male adaptations that prevent sperm competition often to the disadvantage of the female. Such adaptations are extreme in spiders with one-shot genitalia of which parts break off and act as mating plugs, rendering them dysfunctional. In the spider Argiope bruennichi, mating plugs effectively prevent further males from inseminating and males that inseminate and plug both genital openings of a female secure exclusive paternity. However, females frequently prevent monopolization by attacking and cannibalizing males during their first copulation, leaving their second spermatheca free for another male. Here, we test whether the high frequency of sexual cannibalism evolved as a female adaptation to resist monopolization and secure indirect benefits of polyandry. To standardize conditions, we double-mated females either with the same or two different males and prevented male consumption. Using a split-brood design, we raised offspring to maturity under poor and rich food conditions and measured their survival, duration of juvenile phase, and adult body mass. Under low food, daughters of polyandrous mothers matured later but slightly heavier than daughters of monandrous females. Since the adaptive value of this combination is unclear, these findings lend no conclusive support to our hypothesis. We discuss the stereotypic nature of the female attack in the context of antagonistic co-evolution considering previous studies that found modest direct benefits of cannibalism as well as a potential for non-additive benefits. Significance statement Sexual conflict is extreme in spiders where sexual cannibalism impairs male mating rates. Males of the spider Argiope bruennichi possess one-shot genitalia which they break off to plug female genital openings. They gain exclusive paternity with a female if two copulations are achieved and both genital openings plugged. Females, however, stereotypically attack every male at the onset of copulation, limiting most males to single copulation but retaining the option to secure potential benefits of polyandry. Previous studies revealed weak direct and non-additive indirect benefits of multiple mating. In this study, we tested for the presence of additive genetic benefits but again found only inconclusive evidence for adaptive differences in offspring quality between monandrous and polyandrous females. All results combined, we here speculate that the stereotypic female attack might be a ghost of a past antagonistic co-evolution.

scholarly journals Acoustic signalling reflects personality in a social mammal

2016 ◽  
Vol 3 (6) ◽  
pp. 160178 ◽  
Author(s):  
Mary Friel ◽  
Hansjoerg P. Kunc ◽  
Kym Griffin ◽  
Lucy Asher ◽  
Lisa M. Collins
Keyword(s):  
Social Interactions ◽  
Sus Scrofa ◽  
Acoustic Signals ◽  
Poor Quality ◽  
Enriched Environment ◽  
Domestic Pig ◽  
The Relationship ◽  
Sus Scrofa Domestica ◽  
Animal Societies ◽  
Social Behaviours

Social interactions among individuals are often mediated through acoustic signals. If acoustic signals are consistent and related to an individual's personality, these consistent individual differences in signalling may be an important driver in social interactions. However, few studies in non-human mammals have investigated the relationship between acoustic signalling and personality. Here we show that acoustic signalling rate is repeatable and strongly related to personality in a highly social mammal, the domestic pig ( Sus scrofa domestica ). Furthermore, acoustic signalling varied between environments of differing quality, with males from a poor-quality environment having a reduced vocalization rate compared with females and males from an enriched environment. Such differences may be mediated by personality with pigs from a poor-quality environment having more reactive and more extreme personality scores compared with pigs from an enriched environment. Our results add to the evidence that acoustic signalling reflects personality in a non-human mammal. Signals reflecting personalities may have far reaching consequences in shaping the evolution of social behaviours as acoustic communication forms an integral part of animal societies.

scholarly journals Group size and modularity interact to shape the spread of infection and information through animal societies

2021 ◽  
Vol 75 (12) ◽  
Author(s):  
Julian C. Evans ◽  
David J. Hodgson ◽  
Neeltje J. Boogert ◽  
Matthew J. Silk
Keyword(s):  
Group Size ◽  
Spread Of Infection ◽  
Animal Societies

scholarly journals Personality composition is more important than group size in determining collective foraging behaviour in the wild

2014 ◽  
Vol 281 (1796) ◽  
pp. 20141424 ◽  
Author(s):  
Carl N. Keiser ◽  
Jonathan N. Pruitt
Keyword(s):  
Group Size ◽  
Foraging Behaviour ◽  
Collective Behaviour ◽  
Nest Architecture ◽  
Social Spider ◽  
The Social ◽  
In The Wild ◽  
Behavioural Phenotypes ◽  
Collective Foraging ◽  
Animal Societies

Describing the factors that shape collective behaviour is central to our understanding of animal societies. Countless studies have demonstrated an effect of group size in the emergence of collective behaviours, but comparatively few have accounted for the composition/diversity of behavioural phenotypes, which is often conflated with group size. Here, we simultaneously examine the effect of personality composition and group size on nest architecture and collective foraging aggressiveness in the social spider Stegodyphus dumicola . We created colonies of two different sizes (10 or 30 individuals) and four compositions of boldness (all bold, all shy, mixed bold and shy, or average individuals) in the field and then measured their collective behaviour. Larger colonies produced bigger capture webs, while colonies containing a higher proportion of bold individuals responded to and attacked prey more rapidly. The number of attackers during collective foraging was determined jointly by composition and size, although composition had an effect size more than twice that of colony size: our results suggest that colonies of just 10 bold spiders would attack prey with as many attackers as colonies of 110 ‘average’ spiders. Thus, personality composition is a more potent (albeit more cryptic) determinant of collective foraging in these societies.

Does Mixotrophy in ciliates compensate for poor-quality prey? Experiments with heterotrophic–mixotrophic species pairs

2019 ◽  
Vol 41 (5) ◽  
pp. 583-593
Author(s):  
Stephen A Wickham ◽  
Romana Wimmer
Keyword(s):  
Poor Quality ◽  
The Other ◽  
Large Role ◽  
Limited Ability ◽  
Species Pairs ◽  
Aquatic Food ◽  
Alternate Source ◽  
Small Advantage ◽  
Mixotrophic Ciliates

Abstract Fatty acid and sterol profiles play a large role in determining the food quality of prey in aquatic food webs. Ciliates have limited ability to synthesize essential polyunsaturated fatty acids (PUFA) and sterols, and must obtain these from their food. Many mixotrophic ciliates, however, are in a symbiosis with Chlorella, and this may compensate for prey that is low in PUFA and sterols. Moreover, when PUFA-rich prey are P-limited, mixotrophs may be less dependent than heterotrophs on having the optimal mixture of PUFA-rich and P-rich prey. To test these hypotheses, experiments were conducted using heterotrophic-mixotrophic species pairs and prey mixes with varying proportions of good and poor quality prey. Prey proportions had clear effects on ciliate growth rates, often with a clear threshold. In only one species, however, did mixotrophy appeared to be advantageous, with growth independent of the proportion of PUFA-rich prey. In the other two species pairs, mixotrophy gave at best a small advantage over heterotrophy when there was a large proportion of PUFA-poor prey, independent of whether the PUFA-rich prey was P-limited or P-replete. While PUFA- and sterol-rich prey are important for heterotrophic ciliates, mixotrophy cannot be universally employed as an alternate source of these required nutrients.

scholarly journals Social complexity influences brain investment and neural operation costs in ants

2016 ◽  
Vol 283 (1841) ◽  
pp. 20161949 ◽  
Author(s):  
J. Frances Kamhi ◽  
Wulfila Gronenberg ◽  
Simon K. A. Robson ◽  
James F. A. Traniello
Keyword(s):  
Group Size ◽  
Social Complexity ◽  
Brain Size ◽  
Collective Intelligence ◽  
Brain Evolution ◽  
Division Of Labour ◽  
Adaptive Behaviour ◽  
Oecophylla Smaragdina ◽  
Energetic Costs ◽  
Cognitive Demands

The metabolic expense of producing and operating neural tissue required for adaptive behaviour is considered a significant selective force in brain evolution. In primates, brain size correlates positively with group size, presumably owing to the greater cognitive demands of complex social relationships in large societies. Social complexity in eusocial insects is also associated with large groups, as well as collective intelligence and division of labour among sterile workers. However, superorganism phenotypes may lower cognitive demands on behaviourally specialized workers resulting in selection for decreased brain size and/or energetic costs of brain metabolism. To test this hypothesis, we compared brain investment patterns and cytochrome oxidase (COX) activity, a proxy for ATP usage, in two ant species contrasting in social organization. Socially complex Oecophylla smaragdina workers had larger brain size and relative investment in the mushroom bodies (MBs)—higher order sensory processing compartments—than the more socially basic Formica subsericea workers . Oecophylla smaragdina workers, however, had reduced COX activity in the MBs. Our results suggest that as in primates, ant group size is associated with large brain size. The elevated costs of investment in metabolically expensive brain tissue in the socially complex O. smaragdina , however, appear to be offset by decreased energetic costs.

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