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Rodrigues AMM, Barker JL, Robinson EJH. The evolution of intergroup cooperation. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220074. [PMID: 36802776 PMCID: PMC9939261 DOI: 10.1098/rstb.2022.0074] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Sociality is widespread among animals, and involves complex relationships within and between social groups. While intragroup interactions are often cooperative, intergroup interactions typically involve conflict, or at best tolerance. Active cooperation between members of distinct, separate groups occurs very rarely, predominantly in some primate and ant species. Here, we ask why intergroup cooperation is so rare, and what conditions favour its evolution. We present a model incorporating intra- and intergroup relationships and local and long-distance dispersal. We show that dispersal modes play a pivotal role in the evolution of intergroup interactions. Both long-distance and local dispersal processes drive population social structure, and the costs and benefits of intergroup conflict, tolerance and cooperation. Overall, the evolution of multi-group interaction patterns, including both intergroup aggression and intergroup tolerance, or even altruism, is more likely with mostly localized dispersal. However, the evolution of these intergroup relationships may have significant ecological impacts, and this feedback may alter the ecological conditions that favour its own evolution. These results show that the evolution of intergroup cooperation is favoured by a specific set of conditions, and may not be evolutionarily stable. We discuss how our results relate to empirical evidence of intergroup cooperation in ants and primates. This article is part of a discussion meeting issue 'Collective behaviour through time'.
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Affiliation(s)
- António M. M. Rodrigues
- School of Biology, University of St Andrews, St Andrews, KY16 9TH, UK,Schools of Medicine and Engineering, Stanford University, Stanford, CA 94305, USA,Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, USA
| | - Jessica L. Barker
- Surgo Ventures, Washington, DC 20036, USA,Interacting Minds Centre, Aarhus University, 8000 Aarhus, Denmark,Division of Population Health Sciences, University of Alaska Anchorage, Anchorage, AK 99508, USA
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2
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Glowacki L. The evolution of peace. Behav Brain Sci 2022; 47:e1. [PMID: 36524358 DOI: 10.1017/s0140525x22002862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
While some species have affiliative and even cooperative interactions between individuals of different social groups, humans are alone in having durable, positive-sum, interdependent relationships across unrelated social groups. Our capacity to have harmonious relationships that cross group boundaries is an important aspect of our species' success, allowing for the exchange of ideas, materials, and ultimately enabling cumulative cultural evolution. Knowledge about the conditions required for peaceful intergroup relationships is critical for understanding the success of our species and building a more peaceful world. How do humans create harmonious relationships across group boundaries and when did this capacity emerge in the human lineage? Answering these questions involves considering the costs and benefits of intergroup cooperation and aggression, for oneself, one's group, and one's neighbor. Taking a game theoretical perspective provides new insights into the difficulties of removing the threat of war and reveals an ironic logic to peace - the factors that enable peace also facilitate the increased scale and destructiveness of conflict. In what follows, I explore the conditions required for peace, why they are so difficult to achieve, and when we expect peace to have emerged in the human lineage. I argue that intergroup cooperation was an important component of human relationships and a selective force in our species history beginning at least 300 thousand years. But the preconditions for peace only emerged in the past 100 thousand years and likely coexisted with intermittent intergroup violence which would have also been an important and selective force in our species' history.
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Affiliation(s)
- Luke Glowacki
- Department of Anthropology, Boston University, Boston, MA, USA ://www.hsb-lab.org/
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3
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Rodrigues AMM, Barker JL, Robinson EJH. From inter-group conflict to inter-group cooperation: insights from social insects. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210466. [PMID: 35369743 PMCID: PMC8977659 DOI: 10.1098/rstb.2021.0466] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 01/22/2022] [Indexed: 01/18/2023] Open
Abstract
The conflict between social groups is widespread, often imposing significant costs across multiple groups. The social insects make an ideal system for investigating inter-group relationships, because their interaction types span the full harming-helping continuum, from aggressive conflict, to mutual tolerance, to cooperation between spatially separate groups. Here we review inter-group conflict in the social insects and the various means by which they reduce the costs of conflict, including individual or colony-level avoidance, ritualistic behaviours and even group fusion. At the opposite extreme of the harming-helping continuum, social insect groups may peacefully exchange resources and thus cooperate between groups in a manner rare outside human societies. We discuss the role of population viscosity in favouring inter-group cooperation. We present a model encompassing intra- and inter-group interactions, and local and long-distance dispersal. We show that in this multi-level population structure, the increased likelihood of cooperative partners being kin is balanced by increased kin competition, such that neither cooperation (helping) nor conflict (harming) is favoured. This model provides a baseline context in which other intra- and inter-group processes act, tipping the balance toward or away from conflict. We discuss future directions for research into the ecological factors shaping the evolution of inter-group interactions. This article is part of the theme issue 'Intergroup conflict across taxa'.
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Affiliation(s)
| | - Jessica L. Barker
- Interacting Minds Centre, Aarhus University, Aarhus, 8000 Aarhus, Denmark
- Department of Population Health Sciences, University of Alaska, Anchorage, AK 99503, USA
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4
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Lecheval V, Larson H, Burns DDR, Ellis S, Powell S, Donaldson-Matasci MC, Robinson EJH. From foraging trails to transport networks: how the quality-distance trade-off shapes network structure. Proc Biol Sci 2021; 288:20210430. [PMID: 33878925 PMCID: PMC8059596 DOI: 10.1098/rspb.2021.0430] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Biological systems are typically dependent on transportation networks for the efficient distribution of resources and information. Revealing the decentralized mechanisms underlying the generative process of these networks is key in our global understanding of their functions and is of interest to design, manage and improve human transport systems. Ants are a particularly interesting taxon to address these issues because some species build multi-sink multi-source transport networks analogous to human ones. Here, by combining empirical field data and modelling at several scales of description, we show that pre-existing mechanisms of recruitment with positive feedback involved in foraging can account for the structure of complex ant transport networks. Specifically, we find that emergent group-level properties of these empirical networks, such as robustness, efficiency and cost, can arise from models built on simple individual-level behaviour addressing a quality-distance trade-off by the means of pheromone trails. Our work represents a first step in developing a theory for the generation of effective multi-source multi-sink transport networks based on combining exploration and positive reinforcement of best sources.
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Affiliation(s)
| | - Hannah Larson
- Department of Biology, Harvey Mudd College, Claremont, CA, USA
| | | | - Samuel Ellis
- Centre for Research in Animal Behaviour, University of Exeter, UK
| | - Scott Powell
- Department of Biological Sciences, George Washington University, Washington, DC, USA
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5
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Pacheco PSM, Del-Claro K. Spatio-temporal variation influences the division of labour in Pseudomyrmex concolor Smith (Formicidae: Pseudomyrmecinae). J ETHOL 2021. [DOI: 10.1007/s10164-021-00695-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Burns DDR, Franks DW, Parr C, Robinson EJH. Ant colony nest networks adapt to resource disruption. J Anim Ecol 2020; 90:143-152. [PMID: 32141609 DOI: 10.1111/1365-2656.13198] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Accepted: 01/30/2020] [Indexed: 01/03/2023]
Abstract
Animal social structure is shaped by environmental conditions, such as food availability. This is important as conditions are likely to change in the future and changes to social structure can have cascading ecological effects. Wood ants are a useful taxon for the study of the relationship between social structure and environmental conditions, as some populations form large nest networks and they are ecologically dominant in many northern hemisphere woodlands. Nest networks are formed when a colony inhabits more than one nest, known as polydomy. Polydomous colonies are composed of distinct sub-colonies that inhabit spatially distinct nests and that share resources with each other. In this study, we performed a controlled experiment on 10 polydomous wood ant (Formica lugubris) colonies to test how changing the resource environment affects the social structure of a polydomous colony. We took network maps of all colonies for 5 years before the experiment to assess how the networks changes under natural conditions. After this period, we prevented ants from accessing an important food source for a year in five colonies and left the other five colonies undisturbed. We found that preventing access to an important food source causes polydomous wood ant colony networks to fragment into smaller components and begin foraging on previously unused food sources. These changes were not associated with a reduction in the growth of populations inhabiting individual nests (sub-colonies), foundation of new nests or survival, when compared with control colonies. Colony splitting likely occurred as the availability of food in each nest changed causing sub-colonies to change their inter-nest connections. Consequently, our results demonstrate that polydomous colonies can adjust to environmental changes by altering their social network.
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Affiliation(s)
- Dominic D R Burns
- Department of Biology, University of York, York, UK.,York Cross-disciplinary Centre for Systems Analysis, University of York, York, UK
| | - Daniel W Franks
- Department of Biology, University of York, York, UK.,York Cross-disciplinary Centre for Systems Analysis, University of York, York, UK.,Department of Computer Science, University of York, York, UK
| | - Catherine Parr
- Department of Earth, Ocean and Ecological Sciences, University of Liverpool, Liverpool, UK.,Centre for African Ecology, School of Animal, Plant and Environmental Sciences, University of Witwatersrand, Johannesburg, South Africa.,Department of Zoology & Entomology, University of Pretoria, Pretoria, South Africa
| | - Elva J H Robinson
- Department of Biology, University of York, York, UK.,York Cross-disciplinary Centre for Systems Analysis, University of York, York, UK
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Stroeymeyt N, Joye P, Keller L. Polydomy enhances foraging performance in ant colonies. Proc Biol Sci 2017; 284:20170269. [PMID: 28446699 PMCID: PMC5413928 DOI: 10.1098/rspb.2017.0269] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2017] [Accepted: 03/21/2017] [Indexed: 11/12/2022] Open
Abstract
Collective foraging confers benefits in terms of reduced predation risk and access to social information, but it heightens local competition when resources are limited. In social insects, resource limitation has been suggested as a possible cause for the typical decrease in per capita productivity observed with increasing colony size, a phenomenon known as Michener's paradox. Polydomy (distribution of a colony's brood and workers across multiple nests) is believed to help circumvent this paradox through its positive effect on foraging efficiency, but there is still little supporting evidence for this hypothesis. Here, we show experimentally that polydomy enhances the foraging performance of food-deprived Temnothorax nylanderi ant colonies via several mechanisms. First, polydomy influences task allocation within colonies, resulting in faster retrieval of protein resources. Second, communication between sister nests reduces search times for far away resources. Third, colonies move queens, brood and workers across available nest sites in response to spatial heterogeneities in protein and carbohydrate resources. This suggests that polydomy represents a flexible mechanism for space occupancy, helping ant colonies adjust to the environment.
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Affiliation(s)
- N Stroeymeyt
- Department of Ecology and Evolution, Biophore, UNIL-Sorge, University of Lausanne, 1015 Lausanne, Switzerland
| | - P Joye
- Department of Ecology and Evolution, Biophore, UNIL-Sorge, University of Lausanne, 1015 Lausanne, Switzerland
| | - L Keller
- Department of Ecology and Evolution, Biophore, UNIL-Sorge, University of Lausanne, 1015 Lausanne, Switzerland
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Robinson EJH, Barker JL. Inter-group cooperation in humans and other animals. Biol Lett 2017; 13:20160793. [PMID: 28250206 PMCID: PMC5377026 DOI: 10.1098/rsbl.2016.0793] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 02/02/2017] [Indexed: 01/07/2023] Open
Abstract
Social interactions are often characterized by cooperation within groups and conflict or competition between groups. In certain circumstances, however, cooperation can arise between social groups. Here, we examine the circumstances under which inter-group cooperation is expected to emerge and present examples with particular focus on groups in two well-studied but dissimilar taxa: humans and ants. Drivers for the evolution of inter-group cooperation include overarching threats from predators, competitors or adverse conditions, and group-level resource asymmetries. Resources can differ between groups in both quantity and type. Where the difference is in type, inequalities can lead to specialization and division of labour between groups, a phenomenon characteristic of human societies, but rarely seen in other animals. The ability to identify members of one's own group is essential for social coherence; we consider the proximate roles of identity effects in shaping inter-group cooperation and allowing membership of multiple groups. Finally, we identify numerous valuable avenues for future research that will improve our understanding of the processes shaping inter-group cooperation.
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Affiliation(s)
- Elva J H Robinson
- Department of Biology and York Centre for Complex Systems Analysis, University of York, York, UK
| | - Jessica L Barker
- Aarhus Institute of Advanced Studies, Aarhus University, Aarhus, Denmark
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Ellis S, Franks DW, Robinson EJH. Ecological consequences of colony structure in dynamic ant nest networks. Ecol Evol 2017; 7:1170-1180. [PMID: 28303187 PMCID: PMC5306006 DOI: 10.1002/ece3.2749] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 11/15/2016] [Accepted: 12/21/2016] [Indexed: 11/22/2022] Open
Abstract
Access to resources depends on an individual's position within the environment. This is particularly important to animals that invest heavily in nest construction, such as social insects. Many ant species have a polydomous nesting strategy: a single colony inhabits several spatially separated nests, often exchanging resources between the nests. Different nests in a polydomous colony potentially have differential access to resources, but the ecological consequences of this are unclear. In this study, we investigate how nest survival and budding in polydomous wood ant (Formica lugubris) colonies are affected by being part of a multi-nest system. Using field data and novel analytical approaches combining survival models with dynamic network analysis, we show that the survival and budding of nests within a polydomous colony are affected by their position in the nest network structure. Specifically, we find that the flow of resources through a nest, which is based on its position within the wider nest network, determines a nest's likelihood of surviving and of founding new nests. Our results highlight how apparently disparate entities in a biological system can be integrated into a functional ecological unit. We also demonstrate how position within a dynamic network structure can have important ecological consequences.
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Affiliation(s)
- Samuel Ellis
- Centre for Research in Animal BehaviourUniversity of ExeterExeterUK
| | - Daniel W. Franks
- York Centre for Complex Systems Analysis & Department of BiologyUniversity of YorkYorkUK
| | - Elva J. H. Robinson
- York Centre for Complex Systems Analysis & Department of BiologyUniversity of YorkYorkUK
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10
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Ellis S, Procter DS, Buckham-Bonnett P, Robinson EJH. Inferring polydomy: a review of functional, spatial and genetic methods for identifying colony boundaries. INSECTES SOCIAUX 2016; 64:19-37. [PMID: 28255180 PMCID: PMC5310590 DOI: 10.1007/s00040-016-0534-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 11/04/2016] [Accepted: 11/06/2016] [Indexed: 06/06/2023]
Abstract
Identifying the boundaries of a social insect colony is vital for properly understanding its ecological function and evolution. Many species of ants are polydomous: colonies inhabit multiple, spatially separated, nests. Ascertaining which nests are parts of the same colony is an important consideration when studying polydomous populations. In this paper, we review the methods that are used to identify which nests are parts of the same polydomous colony and to determine the boundaries of colonies. Specifically, we define and discuss three broad categories of approach: identifying nests sharing resources, identifying nests sharing space, and identifying nests sharing genes. For each of these approaches, we review the theoretical basis, the limitations of the approach and the methods that can be used to implement it. We argue that all three broad approaches have merits and weaknesses, and provide a methodological comparison to help researchers select the tool appropriate for the biological question they are investigating.
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Affiliation(s)
- S. Ellis
- Department of Biology and York Centre for Complex Systems Analysis, University of York, York, UK
- Centre for Research in Animal Behaviour, University of Exeter, Exeter, UK
| | - D. S. Procter
- Department of Biology and York Centre for Complex Systems Analysis, University of York, York, UK
- Centre for Exercise, Nutrition and Health Sciences, School of Policy Studies, University of Bristol, Bristol, UK
| | - P. Buckham-Bonnett
- Department of Biology and York Centre for Complex Systems Analysis, University of York, York, UK
| | - E. J. H. Robinson
- Department of Biology and York Centre for Complex Systems Analysis, University of York, York, UK
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11
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Procter DS, Cottrell JE, Watts K, A'Hara SW, Hofreiter M, Robinson EJH. Does cooperation mean kinship between spatially discrete ant nests? Ecol Evol 2016; 6:8846-8856. [PMID: 28035273 PMCID: PMC5192893 DOI: 10.1002/ece3.2590] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 10/04/2016] [Accepted: 10/06/2016] [Indexed: 11/26/2022] Open
Abstract
Eusociality is one of the most complex forms of social organization, characterized by cooperative and reproductive units termed colonies. Altruistic behavior of workers within colonies is explained by inclusive fitness, with indirect fitness benefits accrued by helping kin. Members of a social insect colony are expected to be more closely related to one another than they are to other conspecifics. In many social insects, the colony can extend to multiple socially connected but spatially separate nests (polydomy). Social connections, such as trails between nests, promote cooperation and resource exchange, and we predict that workers from socially connected nests will have higher internest relatedness than those from socially unconnected, and noncooperating, nests. We measure social connections, resource exchange, and internest genetic relatedness in the polydomous wood ant Formica lugubris to test whether (1) socially connected but spatially separate nests cooperate, and (2) high internest relatedness is the underlying driver of this cooperation. Our results show that socially connected nests exhibit movement of workers and resources, which suggests they do cooperate, whereas unconnected nests do not. However, we find no difference in internest genetic relatedness between socially connected and unconnected nest pairs, both show high kinship. Our results suggest that neighboring pairs of connected nests show a social and cooperative distinction, but no genetic distinction. We hypothesize that the loss of a social connection may initiate ecological divergence within colonies. Genetic divergence between neighboring nests may build up only later, as a consequence rather than a cause of colony separation.
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Affiliation(s)
- Duncan S. Procter
- York Centre for Complex Systems Analysis & Department of BiologyUniversity of YorkYorkUK
- Centre for Exercise, Nutrition and Health SciencesSchool for Policy StudiesUniversity of BristolBristolUK
| | | | | | | | - Michael Hofreiter
- Institut für Biochemie und BiologieUniversität PotsdamPotsdamGermany
| | - Elva J. H. Robinson
- York Centre for Complex Systems Analysis & Department of BiologyUniversity of YorkYorkUK
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12
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Ellis S, Robinson EJH. The Role of Non-Foraging Nests in Polydomous Wood Ant Colonies. PLoS One 2015; 10:e0138321. [PMID: 26465750 PMCID: PMC4605684 DOI: 10.1371/journal.pone.0138321] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/28/2015] [Indexed: 11/18/2022] Open
Abstract
A colony of red wood ants can inhabit more than one spatially separated nest, in a strategy called polydomy. Some nests within these polydomous colonies have no foraging trails to aphid colonies in the canopy. In this study we identify and investigate the possible roles of non-foraging nests in polydomous colonies of the wood ant Formica lugubris. To investigate the role of non-foraging nests we: (i) monitored colonies for three years; (ii) observed the resources being transported between non-foraging nests and the rest of the colony; (iii) measured the amount of extra-nest activity around non-foraging and foraging nests. We used these datasets to investigate the extent to which non-foraging nests within polydomous colonies are acting as: part of the colony expansion process; hunting and scavenging specialists; brood-development specialists; seasonal foragers; or a selfish strategy exploiting the foraging effort of the rest of the colony. We found that, rather than having a specialised role, non-foraging nests are part of the process of colony expansion. Polydomous colonies expand by founding new nests in the area surrounding the existing nests. Nests founded near food begin foraging and become part of the colony; other nests are not founded near food sources and do not initially forage. Some of these non-foraging nests eventually begin foraging; others do not and are abandoned. This is a method of colony growth not available to colonies inhabiting a single nest, and may be an important advantage of the polydomous nesting strategy, allowing the colony to expand into profitable areas.
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Affiliation(s)
- Samuel Ellis
- Department of Biology, University of York, York, YO10 5DD, United Kingdom
- York Centre for Complex Systems Analysis, University of York, York, YO10 5DD, United Kingdom
| | - Elva J. H. Robinson
- Department of Biology, University of York, York, YO10 5DD, United Kingdom
- York Centre for Complex Systems Analysis, University of York, York, YO10 5DD, United Kingdom
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