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Schultner E, Wallner T, Dofka B, Brülhart J, Heinze J, Freitak D, Pokorny T, Oettler J. Queens control caste allocation in the ant Cardiocondyla obscurior. Proc Biol Sci 2023; 290:20221784. [PMID: 36750190 PMCID: PMC9904955 DOI: 10.1098/rspb.2022.1784] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 01/17/2023] [Indexed: 02/09/2023] Open
Abstract
Social insect queens and workers can engage in conflict over reproductive allocation when they have different fitness optima. Here, we show that queens have control over queen-worker caste allocation in the ant Cardiocondyla obscurior, a species in which workers lack reproductive organs. We describe crystalline deposits that distinguish castes from the egg stage onwards, providing the first report of a discrete trait that can be used to identify ant caste throughout pre-imaginal development. The comparison of queen and worker-destined eggs and larvae revealed size and weight differences in late development, but no discernible differences in traits that may be used in social interactions, including hair morphology and cuticular odours. In line with a lack of caste-specific traits, adult workers treated developing queens and workers indiscriminately. Together with previous studies demonstrating queen control over sex allocation, these results show that queens control reproductive allocation in C. obscurior and suggest that the fitness interests of colony members are aligned to optimize resource allocation in this ant.
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Affiliation(s)
- Eva Schultner
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Tobias Wallner
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Benjamin Dofka
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Jeanne Brülhart
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Jürgen Heinze
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Dalial Freitak
- Institute for Biology, University of Graz, Universitätsplatz 2, 8010 Graz, Austria
| | - Tamara Pokorny
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
| | - Jan Oettler
- Zoology/Evolutionary Biology, University of Regensburg, Universitätsstrasse 31, 93053 Regensburg, Germany
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2
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Lecocq de Pletincx N, Aron S. Sociogenetic Organization of the Red Honey Ant ( Melophorus bagoti). INSECTS 2020; 11:E755. [PMID: 33158025 PMCID: PMC7693516 DOI: 10.3390/insects11110755] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 10/28/2020] [Accepted: 11/02/2020] [Indexed: 11/21/2022]
Abstract
Kin selection and inclusive fitness are thought to be key factors explaining the reproductive altruism displayed by workers in eusocial insect species. However, when a colony's queen has mated with <2 males, workers may increase their fitness by producing their own male offspring. Conversely, when the queen has mated with ≥2 males, workers are expected to increase their inclusive fitness by eschewing the production of their sons and preventing other workers from reproducing as well. Here, we investigated sociogenetic structure and worker reproduction in the red honey ant, Melophorus bagoti. Morphometric analyses revealed that workers belong to one of two distinct subcastes: they are either majors or minors. Using DNA microsatellite markers, we showed that all the colonies had a single, multiple-mated queen and that there was no relationship between worker patriline and worker subcaste. Furthermore, we found that workers were producing males in the presence of the queen, which contrasts with the predictions of inclusive fitness theory. Although our results are based on a small sample, they can serve as the foundation for future research examining worker reproduction in M. bagoti.
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Gloag R, Beekman M. The brood parasite's guide to inclusive fitness theory. Philos Trans R Soc Lond B Biol Sci 2020; 374:20180198. [PMID: 30967088 DOI: 10.1098/rstb.2018.0198] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Hamilton's theory of inclusive fitness provides a framework for understanding the evolution of social behaviour between kin, including parental and alloparental care. Brood parasitism is a reproductive tactic in which parasites exploit the care of other individuals of the same species (conspecific parasitism) or different species (interspecific parasitism) to rear their brood. Here, drawing from examples in birds and social insects, we identify two insights into brood parasitism that stem from inclusive fitness theory. First, the kin structure within nests, or between neighbouring nests, can create a niche space favouring the evolution of conspecific parasitism. For example, low average relatedness within social insect nests can increase selection for reproductive cheats. Likewise, high average relatedness between adjacent nests of some birds can increase a female's tolerance of parasitism by her neighbour. Second, intrabrood conflict will be high in parasitized broods, from the perspective of both parasite and host young, relative to unparasitized broods. We also discuss offspring recognition by hosts as an example of discrimination in a kin-selected social behaviour. We conclude that the inclusive fitness framework is instructive for understanding aspects of brood parasite and host evolution. In turn, brood parasites present some unique opportunities to test the predictions of inclusive fitness theory. This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.
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Affiliation(s)
- Ros Gloag
- School of Life and Environmental Sciences, University of Sydney , Sydney, 2006 , Australia
| | - Madeleine Beekman
- School of Life and Environmental Sciences, University of Sydney , Sydney, 2006 , Australia
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Vollet-Neto A, Imperatriz-Fonseca VL, Ratnieks FLW. Queen Execution, Diploid Males, and Selection For and Against Polyandry in the Brazilian Stingless Bee Scaptotrigona depilis. Am Nat 2019; 194:725-735. [PMID: 31613668 DOI: 10.1086/705393] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Female mating frequency varies. Determining the causes of this variation is an active research area. We tested the hypothesis that in stingless bees, Meliponini, single mating is due to the execution of queens that make a matched mating at the complementary sex determination locus and have diploid male offspring. We studied the Brazilian species Scaptotrigona depilis. We made up 70 test colonies so that 50% (single matched mating), 25% (double mating), 12.5% (quadruple mating), or 0% (single nonmatched mating) of the emerging brood were diploid males. Queen execution following diploid male emergence was equal and high in colonies producing 50% (77% executed) and 25% (75%) diploid males versus equal and low in colonies producing 12.5% (7%) and 0% (0%) diploid males. These results show that queens that mate with two males with similar paternity suffer an increased chance of being executed, which selects against double mating. However, double mating with unequal paternity (e.g., 25∶75), which occasionally occurs in S. depilis, is selectively neutral. Single mating and double mating with unequal paternity form one adaptive peak. The results show a second adaptive peak at quadruple mating. However, this is inaccessible via gradual evolutionary change in a selective landscape with reduced fitness at double mating.
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Avila P, Fromhage L, Lehmann L. Sex-allocation conflict and sexual selection throughout the lifespan of eusocial colonies. Evolution 2019; 73:1116-1132. [PMID: 31004345 PMCID: PMC6593813 DOI: 10.1111/evo.13746] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 03/28/2019] [Indexed: 11/30/2022]
Abstract
Models of sex‐allocation conflict are central to evolutionary biology but have mostly assumed static decisions, where resource allocation strategies are constant over colony lifespan. Here, we develop a model to study how the evolution of dynamic resource allocation strategies is affected by the queen‐worker conflict in annual eusocial insects. We demonstrate that the time of dispersal of sexuals affects the sex‐allocation ratio through sexual selection on males. Furthermore, our model provides three predictions that depart from established results of classic static allocation models. First, we find that the queen wins the sex‐allocation conflict, while the workers determine the maximum colony size and colony productivity. Second, male‐biased sex allocation and protandry evolve if sexuals disperse directly after eclosion. Third, when workers are more related to new queens, then the proportional investment into queens is expected to be lower, which results from the interacting effect of sexual selection (selecting for protandry) and sex‐allocation conflict (selecting for earlier switch to producing sexuals). Overall, we find that colony ontogeny crucially affects the outcome of sex‐allocation conflict because of the evolution of distinct colony growth phases, which decouples how queens and workers affect allocation decisions and can result in asymmetric control.
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Affiliation(s)
- Piret Avila
- Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland
| | - Lutz Fromhage
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, Jyväskylä FI-40014, Finland
| | - Laurent Lehmann
- Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland
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6
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Nonacs P. Hamilton's rule is essential but insufficient for understanding monogamy's role in social evolution. ROYAL SOCIETY OPEN SCIENCE 2019; 6:180913. [PMID: 30800348 PMCID: PMC6366207 DOI: 10.1098/rsos.180913] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 12/19/2018] [Indexed: 06/09/2023]
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Abstract
Evolutionary conflict occurs when two parties can each affect a joint phenotype, but they gain from pushing it in opposite directions. Conflicts occur across many biological levels and domains but share many features. They are a major source of biological maladaptation. They affect biological diversity, often increasing it, at almost every level. Because opponents create selection that can be strong, persistent, and malevolent, conflict often leads to accelerated evolution and arms races. Conflicts might even drive the majority of adaptation, with pathogens leading the way as selective forces. The evolution of conflicts is complex, with outcomes determined partly by the relative evolvability of each party and partly by the kinds of power that each evolves. Power is a central issue in biology. In addition to physical strength and weapons, it includes strength from numbers and complexity; abilities to bind and block; advantageous timing; and abilities to acquire, use, and distort information.
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Affiliation(s)
- David C. Queller
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130, USA;,
| | - Joan E. Strassmann
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri 63130, USA;,
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8
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Schultner E, Oettler J, Helanterä H. The Role of Brood in Eusocial Hymenoptera. QUARTERLY REVIEW OF BIOLOGY 2018; 92:39-78. [PMID: 29558609 DOI: 10.1086/690840] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Study of social traits in offspring traditionally reflects on interactions in simple family groups, with famous examples including parent-offspring conflict and sibling rivalry in birds and mammals. In contrast, studies of complex social groups such as the societies of ants, bees, and wasps focus mainly on adults and, in particular, on traits and interests of queens and workers. The social role of developing individuals in complex societies remains poorly understood. We attempt to fill this gap by illustrating that development in social Hymenoptera constitutes a crucial life stage with important consequences for the individual as well as the colony. We begin by describing the complex social regulatory network that modulates development in Hymenoptera societies. By highlighting the inclusive fitness interests of developing individuals, we show that they may differ from those of other colony members. We then demonstrate that offspring have evolved specialized traits that allow them to play a functional, cooperative role within colonies and give them the potential power to act toward increasing their inclusive fitness. We conclude by providing testable predictions for investigating the role of brood in colony interactions and giving a general outlook on what can be learned from studying offspring traits in hymenopteran societies.
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9
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Boomsma JJ, Gawne R. Superorganismality and caste differentiation as points of no return: how the major evolutionary transitions were lost in translation. Biol Rev Camb Philos Soc 2017; 93:28-54. [PMID: 28508537 DOI: 10.1111/brv.12330] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 03/04/2017] [Accepted: 03/08/2017] [Indexed: 12/27/2022]
Abstract
More than a century ago, William Morton Wheeler proposed that social insect colonies can be regarded as superorganisms when they have morphologically differentiated reproductive and nursing castes that are analogous to the metazoan germ-line and soma. Following the rise of sociobiology in the 1970s, Wheeler's insights were largely neglected, and we were left with multiple new superorganism concepts that are mutually inconsistent and uninformative on how superorganismality originated. These difficulties can be traced to the broadened sociobiological concept of eusociality, which denies that physical queen-worker caste differentiation is a universal hallmark of superorganismal colonies. Unlike early evolutionary naturalists and geneticists such as Weismann, Huxley, Fisher and Haldane, who set out to explain the acquisition of an unmated worker caste, the goal of sociobiology was to understand the evolution of eusociality, a broad-brush convenience category that covers most forms of cooperative breeding. By lumping a diverse spectrum of social systems into a single category, and drawing attention away from the evolution of distinct quantifiable traits, the sociobiological tradition has impeded straightforward connections between inclusive fitness theory and the major evolutionary transitions paradigm for understanding irreversible shifts to higher organizational complexity. We evaluate the history by which these inconsistencies accumulated, develop a common-cause approach for understanding the origins of all major transitions in eukaryote hierarchical complexity, and use Hamilton's rule to argue that they are directly comparable. We show that only Wheeler's original definition of superorganismality can be unambiguously linked to irreversible evolutionary transitions from context-dependent reproductive altruism to unconditional differentiation of permanently unmated castes in the ants, corbiculate bees, vespine wasps and higher termites. We argue that strictly monogamous parents were a necessary, albeit not sufficient condition for all transitions to superorganismality, analogous to single-zygote bottlenecking being a necessary but not sufficient condition for the convergent origins of complex soma across multicellular eukaryotes. We infer that conflict reduction was not a necessary condition for the origin of any of these major transitions, and conclude that controversies over the status of inclusive fitness theory primarily emanate from the arbitrarily defined sociobiological concepts of superorganismality and eusociality, not from the theory itself.
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Affiliation(s)
- Jacobus J Boomsma
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark.,Department of Zoology, University of Oxford, South Parks Road, Oxford, OX1 3PS, UK
| | - Richard Gawne
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100, Copenhagen, Denmark.,Department of Biology, Duke University, 130 Science Drive, Durham, NC, 27708, USA
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10
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Barker JL, Bronstein JL, Friesen ML, Jones EI, Reeve HK, Zink AG, Frederickson ME. Synthesizing perspectives on the evolution of cooperation within and between species. Evolution 2017; 71:814-825. [PMID: 28071790 DOI: 10.1111/evo.13174] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2016] [Revised: 12/24/2016] [Accepted: 01/04/2017] [Indexed: 12/11/2022]
Abstract
Cooperation is widespread both within and between species, but are intraspecific and interspecific cooperation fundamentally similar or qualitatively different phenomena? This review evaluates this question, necessary for a general understanding of the evolution of cooperation. First, we outline three advantages of cooperation relative to noncooperation (acquisition of otherwise inaccessible goods and services, more efficient acquisition of resources, and buffering against variability), and predict when individuals should cooperate with a conspecific versus a heterospecific partner to obtain these advantages. Second, we highlight five axes along which heterospecific and conspecific partners may differ: relatedness and fitness feedbacks, competition and resource use, resource-generation abilities, relative evolutionary rates, and asymmetric strategy sets and outside options. Along all of these axes, certain asymmetries between partners are more common in, but not exclusive to, cooperation between species, especially complementary resource use and production. We conclude that cooperation within and between species share many fundamental qualities, and that differences between the two systems are explained by the various asymmetries between partners. Consideration of the parallels between intra- and interspecific cooperation facilitates application of well-studied topics in one system to the other, such as direct benefits within species and kin-selected cooperation between species, generating promising directions for future research.
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Affiliation(s)
- Jessica L Barker
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, 85721.,Current Address: Aarhus Institute of Advanced Studies, Aarhus University, 8000, Aarhus C, Denmark
| | - Judith L Bronstein
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona, 85721
| | - Maren L Friesen
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824
| | - Emily I Jones
- Department of BioSciences, Rice University, Houston, Texas, 77005
| | - H Kern Reeve
- Department of Neurobiology and Behavior, Cornell University, Ithaca, New York, 14853
| | - Andrew G Zink
- Department of Biology, San Francisco State University, San Francisco, California, 94132
| | - Megan E Frederickson
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada
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11
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McAuliffe K, Wrangham R, Glowacki L, Russell AF. When cooperation begets cooperation: the role of key individuals in galvanizing support. Philos Trans R Soc Lond B Biol Sci 2016; 370:20150012. [PMID: 26503685 PMCID: PMC4633848 DOI: 10.1098/rstb.2015.0012] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Life abounds with examples of conspecifics actively cooperating to a common end, despite conflicts of interest being expected concerning how much each individual should contribute. Mathematical models typically find that such conflict can be resolved by partial-response strategies, leading investors to contribute relatively equitably. Using a case study approach, we show that such model expectations can be contradicted in at least four disparate contexts: (i) bi-parental care; (ii) cooperative breeding; (iii) cooperative hunting; and (iv) human cooperation. We highlight that: (a) marked variation in contributions is commonplace; and (b) individuals can often respond positively rather than negatively to the contributions of others. Existing models have surprisingly limited power in explaining these phenomena. Here, we propose that, although among-individual variation in cooperative contributions will be influenced by differential costs and benefits, there is likely to be a strong genetic or epigenetic component. We then suggest that selection can maintain high investors (key individuals) when their contributions promote support by increasing the benefits and/or reducing the costs for others. Our intentions are to raise awareness in—and provide testable hypotheses of—two of the most poorly understood, yet integral, questions regarding cooperative ventures: why do individuals vary in their contributions and when does cooperation beget cooperation?
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Affiliation(s)
- Katherine McAuliffe
- Department of Psychology, Yale University, 2 Hillhouse Avenue, New Haven, CT 06520, USA Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA Department of Psychology, Boston College, Chestnut Hill, MA 02467, USA
| | - Richard Wrangham
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA
| | - Luke Glowacki
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA Program for Evolutionary Dynamics, Harvard University, 1 Brattle Square, Cambridge, MA 02138, USA
| | - Andrew F Russell
- Department of Human Evolutionary Biology, Harvard University, 11 Divinity Avenue, Cambridge, MA 02138, USA Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Treliever Road, Penryn, Cornwall TR10 9FE, UK
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12
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Context dependent bias in honeybee queen selection: swarm versus emergency queens. Behav Ecol Sociobiol 2016. [DOI: 10.1007/s00265-016-2151-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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13
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Loope KJ. Matricide and queen sex allocation in a yellowjacket wasp. Naturwissenschaften 2016; 103:57. [PMID: 27350328 DOI: 10.1007/s00114-016-1384-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 05/11/2016] [Accepted: 06/09/2016] [Indexed: 11/25/2022]
Abstract
In many colonies of social insects, the workers compete with each other and with the queen over the production of the colony's males. In some species of social bees and wasps with annual societies, this intra-colony conflict even results in matricide-the killing of the colony's irreplaceable queen by a daughter worker. In colonies with low effective paternity and high worker-worker relatedness, workers value worker-laid males more than queen-laid males, and thus may benefit from queen killing. Workers gain by eliminating the queen because she is a competing source of male eggs and actively inhibits worker reproduction through policing. However, matricide may be costly to workers if it reduces the production of valuable new queens and workers. Here, I test a theoretical prediction regarding the timing of matricide in a wasp, Dolichovespula arenaria, recently shown to have facultative matricide based on intra-colony relatedness. Using analyses of collected, mature colonies and a surgical manipulation preventing queens from laying female eggs, I show that workers do not preferentially kill queens who are only producing male eggs. Instead, workers sometimes kill queens laying valuable females, suggesting a high cost of matricide. Although matricide is common and typically occurs only in low-paternity colonies, it seems that workers sometimes pay substantial costs in this expression of conflict over male parentage.
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Affiliation(s)
- Kevin J Loope
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY, USA.
- Department of Entomology, University of California-Riverside, Riverside, CA, USA.
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14
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Ronai I, Vergoz V, Oldroyd B. The Mechanistic, Genetic, and Evolutionary Basis of Worker Sterility in the Social Hymenoptera. ADVANCES IN THE STUDY OF BEHAVIOR 2016. [DOI: 10.1016/bs.asb.2016.03.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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15
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Barker JL, Loope KJ, Reeve HK. Asymmetry within social groups: division of labour and intergroup competition. J Evol Biol 2015; 29:560-71. [PMID: 26663312 PMCID: PMC4784174 DOI: 10.1111/jeb.12805] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Revised: 10/22/2015] [Accepted: 12/01/2015] [Indexed: 11/28/2022]
Abstract
Social animals vary in their ability to compete with group members over shared resources and also vary in their cooperative efforts to produce these resources. Competition among groups can promote within-group cooperation, but many existing models of intergroup cooperation do not explicitly account for observations that group members invest differentially in cooperation and that there are often within-group competitive or power asymmetries. We present a game theoretic model of intergroup competition that investigates how such asymmetries affect within-group cooperation. In this model, group members adopt one of two roles, with relative competitive efficiency and the number of individuals varying between roles. Players in each role make simultaneous, coevolving decisions. The model predicts that although intergroup competition increases cooperative contributions to group resources by both roles, contributions are predominantly from individuals in the less competitively efficient role, whereas individuals in the more competitively efficient role generally gain the larger share of these resources. When asymmetry in relative competitive efficiency is greater, a group's per capita cooperation (averaged across both roles) is higher, due to increased cooperation from the competitively inferior individuals. For extreme asymmetry in relative competitive efficiency, per capita cooperation is highest in groups with a single competitively superior individual and many competitively inferior individuals, because the latter acquiesce and invest in cooperation rather than within-group competition. These predictions are consistent with observed features of many societies, such as monogynous Hymenoptera with many workers and caste dimorphism.
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Affiliation(s)
- J L Barker
- Department of Neurobiology & Behavior, Cornell University, Ithaca, NY, USA
| | - K J Loope
- Department of Neurobiology & Behavior, Cornell University, Ithaca, NY, USA
| | - H K Reeve
- Department of Neurobiology & Behavior, Cornell University, Ithaca, NY, USA
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16
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Villalta I, Angulo E, Devers S, Cerdá X, Boulay R. Regulation of worker egg laying by larvae in a fission-performing ant. Anim Behav 2015. [DOI: 10.1016/j.anbehav.2015.05.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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17
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Schultner E, Gardner A, Karhunen M, Helanterä H. Ant Larvae as Players in Social Conflict: Relatedness and Individual Identity Mediate Cannibalism Intensity. Am Nat 2014; 184:E161-74. [DOI: 10.1086/678459] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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18
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Stürup M, Nash DR, Hughes WOH, Boomsma JJ. Sperm mixing in the polyandrous leaf-cutting ant Acromyrmex echinatior. Ecol Evol 2014; 4:3571-82. [PMID: 25478149 PMCID: PMC4224532 DOI: 10.1002/ece3.1176] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Revised: 06/25/2014] [Accepted: 07/02/2014] [Indexed: 11/08/2022] Open
Abstract
The insemination of queens by sperm from multiple males (polyandry) has evolved in a number of eusocial insect lineages despite the likely costs of the behavior. The selective advantages in terms of colony fitness must therefore also be significant and there is now good evidence that polyandry increases genetic variation among workers, thereby improving the efficiency of division of labor, resistance against disease, and diluting the impact of genetically incompatible matings. However, these advantages will only be maximized if the sperm of initially discrete ejaculates are mixed when stored in queen spermathecae and used for egg fertilization in a "fair raffle." Remarkably, however, very few studies have addressed the level of sperm mixing in social insects. Here we analyzed sperm use over time in the highly polyandrous leaf-cutting ant Acromyrmex echinatior. We genotyped cohorts of workers produced either 2 months apart or up to over a year apart, and batches of eggs laid up to over 2 years apart, and tested whether fluctuations in patriline distributions deviated from random. We show that the representation of father males in both egg and worker cohorts does not change over time, consistent with obligatorily polyandrous queens maximizing their fitness when workers are as genetically diverse as possible.
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Affiliation(s)
- Marlene Stürup
- Department of Biology, Centre for Social Evolution, University of Copenhagen Universitetsparken 15, Copenhagen, 2100, Denmark
| | - David R Nash
- Department of Biology, Centre for Social Evolution, University of Copenhagen Universitetsparken 15, Copenhagen, 2100, Denmark
| | - William O H Hughes
- Department of Biology, Centre for Social Evolution, University of Copenhagen Universitetsparken 15, Copenhagen, 2100, Denmark ; School of Life Sciences, University of Sussex Brighton, BN1 9QG, UK
| | - Jacobus J Boomsma
- Department of Biology, Centre for Social Evolution, University of Copenhagen Universitetsparken 15, Copenhagen, 2100, Denmark
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19
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Abstract
Lack of information is a constraint but ignorance can sometimes assist the evolution of cooperation by constraining selfishness. We discuss examples involving both ignorance of role or pay-off and ignorance of relatedness. Ignorance can favour cooperative traits like grouping and warning coloration and reduce conflicts from meiotic drive, imprinting, greenbeards and various forms of nepotism.
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Affiliation(s)
- David C Queller
- Department of Biology CB1137, Washington University in St Louis, , One Brookings Drive, St Louis, MO 63130, USA
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Holmes MJ, Oldroyd BP, Duncan M, Allsopp MH, Beekman M. Cheaters sometimes prosper: targeted worker reproduction in honeybee (Apis mellifera) colonies during swarming. Mol Ecol 2013; 22:4298-4306. [PMID: 23889604 DOI: 10.1111/mec.12387] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/08/2013] [Accepted: 05/12/2013] [Indexed: 11/29/2022]
Abstract
Kin selection theory predicts that honeybee (Apis mellifera) workers should largely refrain from producing their own offspring, as the workers collectively have higher inclusive fitness if they rear the sons of their mother, the queen. Studies that have quantified levels of ovary activation and reproduction among workers have largely supported this prediction. We sampled pre-emergent male pupae and adult workers from seven colonies at regular intervals throughout the reproductive part of the season. We show that the overall contribution of workers to male (drone) production is 4.2%, nearly 40 times higher than is generally reported, and is highest during reproductive swarming, when an average of 6.2% of the males genotyped are worker-produced. Similarly, workers in our samples were 100 times more likely to have active ovaries than previously assumed. Worker reproduction is seasonally influenced and peaks when colonies are rearing new queens. Not all worker subfamilies contribute equally to reproduction. Instead, certain subfamilies are massively over-represented in drone brood. By laying eggs within the period in which many colonies produce virgin queens, these rare worker subfamilies increase their direct fitness via their well-timed sons.
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Affiliation(s)
- Michael J Holmes
- Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences, University of Sydney, Macleay A12, Science Road, Sydney, NSW, 2006, Australia
| | - Benjamin P Oldroyd
- Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences, University of Sydney, Macleay A12, Science Road, Sydney, NSW, 2006, Australia
| | - Michael Duncan
- Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences, University of Sydney, Macleay A12, Science Road, Sydney, NSW, 2006, Australia
| | - Michael H Allsopp
- Honeybee Research Section, ARC-Plant Protection Research Institute, Private Bag X5017, Stellenbosch, 7599, South Africa
| | - Madeleine Beekman
- Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences, University of Sydney, Macleay A12, Science Road, Sydney, NSW, 2006, Australia
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Teseo S, Kronauer DJC, Jaisson P, Châline N. Enforcement of reproductive synchrony via policing in a clonal ant. Curr Biol 2013; 23:328-32. [PMID: 23375892 DOI: 10.1016/j.cub.2013.01.011] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 01/02/2013] [Accepted: 01/03/2013] [Indexed: 12/16/2022]
Abstract
In insect societies, worker policing controls genetic conflicts between individuals and increases colony efficiency. However, disentangling relatedness from colony-level effects is usually impossible. We studied policing in the parthenogenetic ant Cerapachys biroi, where genetic conflicts are absent due to clonality and reproduction is synchronized through stereotyped colony cycles. We show that larval cues regulate the cycles by suppressing ovarian activity and that individuals that fail to respond to these cues are policed and executed by their nestmates. These individuals are genetically identical to other colony members, confirming the absence of intracolonial genetic conflicts. At the same time, they bear distinct cuticular hydrocarbon profiles, which could serve as proximate recognition cues for policing. Policing in C. biroi keeps uncontrolled reproduction at bay and thereby maintains the colony-level phenotype. This study shows that policing can enforce adaptive colony-level phenotypes in societies with minimal or no potential genetic conflicts. In analogy to immunosurveillance on cancer cells in genetically homogeneous multicellular organisms, colony efficiency is improved via the control of individuals that do not respond properly to regulatory signals and compromise the functioning of the higher-level unit.
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Affiliation(s)
- Serafino Teseo
- Laboratoire d'Ethologie Expérimentale et Comparée, EA4443, Université Paris 13, Sorbonne Paris Cité, 99 Avenue J.B. Clément, 93430 Villetaneuse, France.
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Dobata S. ARMS RACE BETWEEN SELFISHNESS AND POLICING: TWO-TRAIT QUANTITATIVE GENETIC MODEL FOR CASTE FATE CONFLICT IN EUSOCIAL HYMENOPTERA. Evolution 2012. [DOI: 10.1111/j.1558-5646.2012.01745.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Lahdenperä M, Gillespie DOS, Lummaa V, Russell AF. Severe intergenerational reproductive conflict and the evolution of menopause. Ecol Lett 2012; 15:1283-1290. [DOI: 10.1111/j.1461-0248.2012.01851.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 05/10/2012] [Accepted: 07/19/2012] [Indexed: 11/30/2022]
Affiliation(s)
- Mirkka Lahdenperä
- Section of Ecology; Department of Biology; University of Turku; FIN-20014 Turku Finland
| | | | - Virpi Lummaa
- Department of Animal & Plant Sciences; University of Sheffield; Sheffield S10 2TN UK
- Wissenschaftskolleg zu Berlin; Institute for Advanced Study; Wallotstraße 19 D-14193 Berlin Germany
| | - Andrew F. Russell
- Centre for Ecology & Conservation; College of Life & Environmental Sciences; University of Exeter; Penryn TR10 9EZ UK
- Station d'Ecologie Expérimentale du CNRS USR 2936; 09200 Moulis France
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Barrette MF, Monfort SL, Festa-Bianchet M, Clutton-Brock TH, Russell AF. Reproductive rate, not dominance status, affects fecal glucocorticoid levels in breeding female meerkats. Horm Behav 2012; 61:463-71. [PMID: 22210199 DOI: 10.1016/j.yhbeh.2011.12.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2011] [Revised: 12/06/2011] [Accepted: 12/09/2011] [Indexed: 10/14/2022]
Abstract
Glucocorticoid hormones (GCs) have been studied intensively to understand the associations between physiological stress and reproductive skew in animal societies. However, we have little appreciation of the range of either natural levels within and among individuals, or the associations among dominance status, reproductive rate and GCs levels during breeding. To address these shortcomings, we examined variation in fecal glucocorticoid metabolites (fGC) during breeding periods in free-ranging female meerkats (Suricata suricatta) over 11 years. The vast majority of variation in fGC levels was found within breeding events by the same female (~87%), with the remaining variation arising among breeding events and among females. Concentrations of fGC generally tripled as pregnancy progressed. However, females with a high reproductive rate, defined as those conceiving within a month following parturition (mean = 9 days postpartum), showed significant reductions in fGC in the final 2 weeks before parturition. Despite these reductions, females with a high reproductive rate had higher fGC levels at conception of the following litter than those breeding at a low rate. After controlling for the higher reproductive rate of dominants, we found no association between levels of fGC and either age or dominance status. Our results suggest that one should be cautious about interpreting associations between dominance status, reproductive skew and GCs levels, without knowledge of the natural variation in GCs levels within and among females.
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Smith AA, Hölldobler B, Liebig J. Queen-specific signals and worker punishment in the ant Aphaenogaster cockerelli: the role of the Dufour’s gland. Anim Behav 2012. [DOI: 10.1016/j.anbehav.2011.12.024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Kümmerli R, Keller L. Between-year variation in population sex ratio increases with complexity of the breeding system in Hymenoptera. Am Nat 2011; 177:835-46. [PMID: 21597259 DOI: 10.1086/659951] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
While adaptive adjustment of sex ratio in the function of colony kin structure and food availability commonly occurs in social Hymenoptera, long-term studies have revealed substantial unexplained between-year variation in sex ratio at the population level. In order to identify factors that contribute to increased between-year variation in population sex ratio, we conducted a comparative analysis across 47 Hymenoptera species differing in their breeding system. We found that between-year variation in population sex ratio steadily increased as one moved from solitary species, to primitively eusocial species, to single-queen eusocial species, to multiple-queen eusocial species. Specifically, between-year variation in population sex ratio was low (6.6% of total possible variation) in solitary species, which is consistent with the view that in solitary species, sex ratio can vary only in response to fluctuations in ecological factors such as food availability. In contrast, we found significantly higher (19.5%) between-year variation in population sex ratio in multiple-queen eusocial species, which supports the view that in these species, sex ratio can also fluctuate in response to temporal changes in social factors such as queen number and queen-worker control over sex ratio, as well as factors influencing caste determination. The simultaneous adjustment of sex ratio in response to temporal fluctuations in ecological and social factors seems to preclude the existence of a single sex ratio optimum. The absence of such an optimum may reflect an additional cost associated with the evolution of complex breeding systems in Hymenoptera societies.
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Affiliation(s)
- Rolf Kümmerli
- Department of Environmental Microbiology, Swiss Federal Institute of Aquatic Science and Technology (Eawag), Überlandstrasse, Dübendorf, Switzerland.
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Strassmann JE, Queller DC. Evolution of cooperation and control of cheating in a social microbe. Proc Natl Acad Sci U S A 2011; 108 Suppl 2:10855-62. [PMID: 21690338 PMCID: PMC3131822 DOI: 10.1073/pnas.1102451108] [Citation(s) in RCA: 118] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Much of what we know about the evolution of altruism comes from animals. Here, we show that studying a microbe has yielded unique insights, particularly in understanding how social cheaters are controlled. The social stage of Dictylostelium discoideum occurs when the amoebae run out of their bacterial prey and aggregate into a multicellular, motile slug. This slug forms a fruiting body in which about a fifth of cells die to form a stalk that supports the remaining cells as they form hardy dispersal-ready spores. Because this social stage forms from aggregation, it is analogous to a social group, or a chimeric multicellular organism, and is vulnerable to internal conflict. Advances in cell labeling, microscopy, single-gene knockouts, and genomics, as well as the results of decades of study of D. discoideum as a model for development, allow us to explore the genetic basis of social contests and control of cheaters in unprecedented detail. Cheaters are limited from exploiting other clones by high relatedness, kin discrimination, pleiotropy, noble resistance, and lottery-like role assignment. The active nature of these limits is reflected in the elevated rates of change in social genes compared with nonsocial genes. Despite control of cheaters, some conflict is still expressed in chimeras, with slower movement of slugs, slightly decreased investment in stalk compared with spore cells, and differential contributions to stalk and spores. D. discoideum is rapidly becoming a model system of choice for molecular studies of social evolution.
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Affiliation(s)
- Joan E Strassmann
- Ecology and Evolutionary Biology, Rice University, Houston, TX 77005, USA.
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Abstract
Understanding which parties regulate reproduction is fundamental to understanding conflict resolution in animal societies. In social insects, workers can influence male production and sex ratio. Surprisingly, few studies have investigated worker influence over which queen(s) reproduce(s) in multiple queen (MQ) colonies (skew), despite skew determining worker-brood relatedness and so worker fitness. We provide evidence for worker influence over skew in a functionally monogynous population of the ant Leptothorax acervorum. Observations of MQ colonies leading up to egg laying showed worker aggressive and non-aggressive behaviour towards queens and predicted which queen monopolized reproduction. In contrast, among-queen interactions were rare and did not predict queen reproduction. Furthermore, parentage analysis showed workers favoured their mother when present, ensuring closely related fullsibs (average r = 0.5) were reared instead of less related offspring of other resident queens (r ≤ 0.375). Discrimination among queens using relatedness-based cues, however, seems unlikely as workers also biased their behaviour in colonies without a mother queen. In other polygynous populations of this species, workers are not aggressive towards queens and MQs reproduce, showing the outcome of social conflicts varies within species. In conclusion, this study supports non-reproductive parties having the power and information to influence skew within cooperative breeding groups.
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Affiliation(s)
- Richard J Gill
- Department of Biological Sciences, University of Hull, Cottingham Road, Hull HU6 7RX, UK
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Holmes MJ, Oldroyd BP, Allsopp MH, Lim J, Wossler TC, Beekman M. Maternity of emergency queens in the Cape honey bee, Apis mellifera capensis. Mol Ecol 2010; 19:2792-9. [PMID: 20546135 DOI: 10.1111/j.1365-294x.2010.04683.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
During reproductive swarming, some workers of the Cape honey bee, Apis mellifera capensis, lay eggs in queen cells, many of which are reared to maturity. However, it is unknown if workers are able to lay in queen cells immediately after queen loss during an episode of emergency queen rearing. In this study we experimentally de-queened colonies and determined the maternity of larvae and pupae that were reared as queens. This allowed us to determine how soon after queen loss workers contribute to the production of new queens. We were further interested to see if workers would preferentially raise new queens from queen-laid brood if this was introduced later. We performed our manipulations in two different settings: an apiary setting where colonies were situated close together and a more natural situation in which the colonies were well separated. This allowed us to determine how the vicinity of other colonies affects the presence of parasites. We found that workers do indeed contribute to queen cell production immediately after the loss of their queen, thus demonstrating that some workers either have activated ovaries even when their colony has a queen or are able to activate their ovaries extremely rapidly. Queen-laid brood introduced days after queen loss was ignored, showing that workers do not prefer to raise new queens from queen brood when given a choice. We also detected non-natal parasitism of queen cells in both settings. We therefore conclude that some A. m. capensis genotypes specialize in parasitizing queen cells.
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Affiliation(s)
- Michael J Holmes
- Behaviour and Genetics of Social Insects Lab, School of Biological Sciences A12, University of Sydney, Sydney, NSW 2006, Australia
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Affiliation(s)
- Joan E Strassmann
- Department of Ecology and Evolutionary Biology, MS 170, Rice University, 6100 Main St., Houston, TX 77005-1892, USA.
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Keller L. Adaptation and the genetics of social behaviour. Philos Trans R Soc Lond B Biol Sci 2010; 364:3209-16. [PMID: 19805428 DOI: 10.1098/rstb.2009.0108] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
In recent years much progress has been made towards understanding the selective forces involved in the evolution of social behaviour including conflicts over reproduction among group members. Here, I argue that an important additional step necessary for advancing our understanding of the resolution of potential conflicts within insect societies is to consider the genetics of the behaviours involved. First, I discuss how epigenetic modifications of behaviour may affect conflict resolution within groups. Second, I review known natural polymorphisms of social organization to demonstrate that a lack of consideration of the genetic mechanisms involved may lead to erroneous explanations of the adaptive significance of behaviour. Third, I suggest that, on the basis of recent genetic studies of sexual conflict in Drosophila, it is necessary to reconsider the possibility of within-group manipulation by means of chemical substances (i.e. pheromones). Fourth, I address the issue of direct versus indirect genetic effects, which is of particular importance for the study of behaviour in social groups. Fifth, I discuss the issue of how a genetic influence on dominance hierarchies and reproductive division of labour can have secondary effects, for example in the evolution of promiscuity. Finally, because the same sets of genes (e.g. those implicated in chemical signalling and the responses that are triggered) may be used even in species as divergent as ants, cooperative breeding birds and primates, an integration of genetic mechanisms into the field of social evolution may also provide unifying ideas.
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Affiliation(s)
- Laurent Keller
- Department of Ecology and Evolution, University of Lausanne, Biophore, Lausanne 1015, Switzerland.
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Ratnieks FLW, Helanterä H. The evolution of extreme altruism and inequality in insect societies. Philos Trans R Soc Lond B Biol Sci 2010; 364:3169-79. [PMID: 19805425 DOI: 10.1098/rstb.2009.0129] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In eusocial organisms, some individuals specialize in reproduction and others in altruistic helping. The evolution of eusociality is, therefore, also the evolution of remarkable inequality. For example, a colony of honeybees (Apis mellifera) may contain 50 000 females all of whom can lay eggs. But 100 per cent of the females and 99.9 per cent of the males are offspring of the queen. How did such extremes evolve? Phylogenetic analyses show that high relatedness was almost certainly necessary for the origin of eusociality. However, even the highest family levels of kinship are insufficient to cause the extreme inequality seen in e.g. honeybees via 'voluntary altruism'. 'Enforced altruism' is needed, i.e. social pressures that deter individuals from attempting to reproduce. Coercion acts at two stages in an individual's life cycle. Queens are typically larger so larvae can be coerced into developing into workers by being given less food. Workers are coerced into working by 'policing', in which workers or the queen eat worker-laid eggs or aggress fertile workers. In some cases, individuals rebel, such as when stingless bee larvae develop into dwarf queens. The incentive to rebel is strong as an individual is the most closely related to its own offspring. However, because individuals gain inclusive fitness by rearing relatives, there is also a strong incentive to 'acquiesce' to social coercion. In a queenright honeybee colony, the policing of worker-laid eggs is very effective, which results in most workers working instead of attempting to reproduce. Thus, extreme altruism is due to both kinship and coercion. Altruism is frequently seen as a Darwinian puzzle but was not a puzzle that troubled Darwin. Darwin saw his difficulty in explaining how individuals that did not reproduce could evolve, given that natural selection was based on the accumulation of small heritable changes. The recognition that altruism is an evolutionary puzzle, and the solution was to wait another 100 years for William Hamilton.
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Affiliation(s)
- Francis L W Ratnieks
- Laboratory of Apiculture and Social Insects, Department of Biological and Environmental Science, University of Sussex, Falmer, Brighton BN1 9QG, UK
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Dapporto L, Bruschini C, Cervo R, Petrocelli I, Turillazzi S. Hydrocarbon rank signatures correlate with differential oophagy and dominance behaviour in Polistes dominulus foundresses. J Exp Biol 2010; 213:453-8. [DOI: 10.1242/jeb.032938] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
Social life offers animals increased fitness opportunities. However, the advantages are not evenly distributed and some individuals benefit more than others. The ultimate advantage of reaching the highest rank in a dominance hierarchy is the achievement of reproduction monopoly. In social insects, dominant individuals and queens keep their reproductive control through differential oophagy of unwanted eggs (egg policing). Egg recognition is the main proximate mechanism for maintaining reproductive dominance. In the social wasp Polistes dominulus, subordinate queens often lay eggs in the presence of the dominant individual. Combining gas chromatography–mass spectrometry (GC-MS) analysis and laboratory bioassays, we found that chemical differences between eggs of subordinate and dominant foundresses can explain the differential success in oophagy enjoyed by dominant individuals. We propose that dominance behaviour is an investigative behaviour as well as a ritualized agonistic behaviour. In fact, the frequency of dominance acts increases with the chemical similarity of the surfaces of dominant- and subordinate-laid eggs. Therefore, dominant individuals probably perform dominance behaviour to test the cuticular signatures of subordinates and so better assess the chemical profiles of subordinate eggs. Finally, we provide evidence that in particular social contexts, subordinate Polistes foundresses can develop ovaries as large as those of dominant individuals but nevertheless lay very few eggs. The subordinates probably lay a limited number of eggs to avoid unnecessary energy loss, as a result of efficient queen policing, but will start laying eggs as soon as the queen fails.
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Affiliation(s)
- L. Dapporto
- Dipartimento di Biologia Evoluzionistica, Università di Firenze, Via Romana 17, 50125, Firenze, Italy
- Centro Interdipartimentale di Spettrometria di Massa, Università di Firenze, Viale G. Pieraccini 6, 50100, Firenze, Italy
| | - C. Bruschini
- Dipartimento di Biologia Evoluzionistica, Università di Firenze, Via Romana 17, 50125, Firenze, Italy
- Centro Interdipartimentale di Spettrometria di Massa, Università di Firenze, Viale G. Pieraccini 6, 50100, Firenze, Italy
| | - R. Cervo
- Dipartimento di Biologia Evoluzionistica, Università di Firenze, Via Romana 17, 50125, Firenze, Italy
| | - I. Petrocelli
- Dipartimento di Biologia Evoluzionistica, Università di Firenze, Via Romana 17, 50125, Firenze, Italy
| | - S. Turillazzi
- Dipartimento di Biologia Evoluzionistica, Università di Firenze, Via Romana 17, 50125, Firenze, Italy
- Centro Interdipartimentale di Spettrometria di Massa, Università di Firenze, Viale G. Pieraccini 6, 50100, Firenze, Italy
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Abstract
Traditional interpretations of the evolution of animal societies have suggested that their structure is a consequence of attempts by individuals to maximize their inclusive fitness within constraints imposed by their social and physical environments. In contrast, some recent re-interpretations have argued that many aspects of social organization should be interpreted as group-level adaptations maintained by selection operating between groups or populations. Here, I review our current understanding of the evolution of mammalian societies, focusing, in particular, on the evolution of reproductive strategies in societies where one dominant female monopolizes reproduction in each group and her offspring are reared by other group members. Recent studies of the life histories of females in these species show that dispersing females often have little chance of establishing new breeding groups and so are likely to maximize their inclusive fitness by helping related dominants to rear their offspring. As in eusocial insects, increasing group size can lead to a progressive divergence in the selection pressures operating on breeders and helpers and to increasing specialization in their behaviour and life histories. As yet, there is little need to invoke group-level adaptations in order to account for the behaviour of individuals or the structure of mammalian groups.
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Affiliation(s)
- Tim Clutton-Brock
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK.
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37
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Abstract
Insect colonies have been traditionally regarded as closed societies comprised of completely sterile workers ruled over by a single once-mated queen. However, over the past 15 years, microsatellite studies of parentage have revealed that this perception is far from the truth (Beekman & Oldroyd 2008). First, we learned that honey bee queens are far more promiscuous than we had previously imagined (Estoup et al. 1994), with one Apis dorsata queen clocked at over 100 mates (Wattanachaiyingcharoen et al. 2003). Then Oldroyd et al. (1994) reported a honey bee colony from Queensland, where virtually all the males were sons of a single patriline of workers - a clear case of a cheater mutant that promoted intra-colonial reproductive parasitism. Then we learned that both bumble bee colonies (Lopez-Vaamonde et al. 2004) and queenless honey bee colonies (Nanork et al. 2005, 2007) are routinely parasitized by workers from other nests that fly in and lay male-producing eggs that are then reared by the victim colony. There is even evidence that in a thelytokous honey bee population, workers lay female-destined eggs directly into queen cells, thus reincarnating themselves as a queen (Jordan et al. 2008). And let us not forget ants, where microsatellite studies have revealed equally bizarre and totally unexpected phenomena (e.g. Cahan & Keller 2003; Pearcy et al. 2004; Fournier et al. 2005). Now, in this issue, Alves et al. (2009) use microsatellites to provide yet another shocking and completely unexpected revelation about the nefarious goings-on in insect colonies: intergenerational reproductive parasitism by stingless bee workers.
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Affiliation(s)
- Benjamin P Oldroyd
- Behaviour and Genetics of Social Insects Laboratory, School of Biological Sciences, University of Sydney, NSW 2006, Australia.
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ALVES DA, IMPERATRIZ-FONSECA VL, FRANCOY TM, SANTOS-FILHO PS, NOGUEIRA-NETO P, BILLEN J, WENSELEERS T. The queen is dead-long live the workers: intraspecific parasitism by workers in the stingless beeMelipona scutellaris. Mol Ecol 2009; 18:4102-11. [DOI: 10.1111/j.1365-294x.2009.04323.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Debout GDG, Frederickson ME, Aron S, Yu DW. Unexplained split sex ratios in the neotropical plant-ant, Allomerus octoarticulatus var. demerarae (Myrmicinae): a test of hypotheses. Evolution 2009; 64:126-41. [PMID: 19703224 DOI: 10.1111/j.1558-5646.2009.00824.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We investigated sex allocation in the Neotropical ant Allomerus octoarticulatus var. demerarae. Because Allomerus is a plant symbiont, we could make geographically extensive collections of complete colonies and of foundresses in saplings, allowing us to estimate not only population- and colony-level sex allocation but also colony resource levels and the relatedness of competing ant foundresses. This species exhibits a strongly split sex ratio, with 80% of mature colonies producing >or=90% of one sex or the other. Our genetic analyses (DNA microsatellites) reveal that Allomerus has a breeding system characterized by almost complete monogyny and a low frequency of polyandry. Contrary to theoretical explanations, we find no difference in worker relatedness asymmetries between female- and male-specialist colonies. Furthermore, no clear link was found between colony sex allocation and life history traits such as the number of mates per queen, or colony size, resource level, or fecundity. We also failed to find significant support for male production by workers, infection by Wolbachia, local resource competition, or local mate competition. We are left with the possibility that Allomerus exhibits split sex ratios because of the evolution of alternative biasing strategies in queens or workers, as recently proposed in the literature.
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Affiliation(s)
- Gabriel D G Debout
- Ecology, Conservation, and Environment Center, State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Science, Kunming, Yunnan 65022, China
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Abstract
Sex allocation in colonies of eusocial Hymenoptera is one of the best studied social conflicts. We outline a framework for analysing conflict outcome through power and the costs of manipulation and suggest that the conflict will often be unresolved because both major parties of interest, the queen and the workers, should manipulate allocation even at considerable costs to the colony. We suggest future work for analysing power in the conflict between queen and workers over sex allocation and discuss the extent of male power.
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Affiliation(s)
- Heikki Helanterä
- Laboratory of Apiculture and Social Insects, Department of Biological and Environmental Science, University of Sussex, Falmer, Brighton BN1 9QG, UK.
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41
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Shuker DM, Moynihan AM, Ross L. Sexual conflict, sex allocation and the genetic system. Biol Lett 2009; 5:682-5. [PMID: 19605386 DOI: 10.1098/rsbl.2009.0427] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Decisions over what sex ratio to produce can have far-reaching evolutionary consequences, for both offspring and parents. However, the extent to which males and females come into evolutionary conflict over aspects of sex allocation depends on the genetic system: when genes are passed to the next generation unequally by the two sexes (as in haplodiploidy, for example), this biased transmission can facilitate a range of conflicts not seen in diploids. However, much less attention has been paid to these forms of sexual conflict, not least because it has not always been clear how the conflicts could be realized. Here we consider how biased gene transmission, as expressed in different genetic systems, enhances the opportunity for sex ratio conflict and give empirical examples that confirm that males and females have the opportunity to influence sex ratios.
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Affiliation(s)
- David M Shuker
- School of Biology, University of St Andrews, Harold Mitchell Building, St Andrews, Fife KY16 9TH, UK.
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JOHNSON ELIZABETHL, CUNNINGHAM TYLERW, MARRINER SARAHM, KOVACS JENNIFERL, HUNT BRENDANG, BHAKTA DIMPALB, GOODISMAN MICHAELAD. Resource allocation in a social wasp: effects of breeding system and life cycle on reproductive decisions. Mol Ecol 2009; 18:2908-20. [DOI: 10.1111/j.1365-294x.2009.04240.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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BEEKMAN MADELEINE, ALLSOPP MICHAELH, JORDAN LYNDONA, LIM JULIANNE, OLDROYD BENJAMINP. A quantitative study of worker reproduction in queenright colonies of the Cape honey bee,Apis mellifera capensis. Mol Ecol 2009; 18:2722-7. [DOI: 10.1111/j.1365-294x.2009.04224.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Russell AF, Lummaa V. Maternal effects in cooperative breeders: from hymenopterans to humans. Philos Trans R Soc Lond B Biol Sci 2009; 364:1143-67. [PMID: 19324618 PMCID: PMC2666687 DOI: 10.1098/rstb.2008.0298] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The environment that an offspring experiences during its development can have lifelong consequences for its morphology, anatomy, physiology and behaviour that are strong enough to span generations. One aspect of an offspring's environment that can have particularly pronounced and long-lasting effects is that provided by its parent(s) (maternal effects). Some disciplines in biology have been quicker to appreciate maternal effects than others, and some organisms provide better model systems for understanding the causes and consequences of the maternal environment for ecology and evolution than others. One field in which maternal effects has been poorly represented, and yet is likely to represent a particularly fruitful area for research, is the field of cooperative breeding (i.e. systems where offspring are reared by carers in addition to parent(s)). Here, we attempt to illustrate the scope of cooperative breeding systems for maternal effects research and, conversely, highlight the importance of maternal effects research for understanding cooperative breeding systems. To this end, we first outline why mothers will commonly benefit from affecting the phenotype of their offspring in cooperative breeding systems, present potential strategies that mothers could employ in order to do so and offer predictions regarding the circumstances under which different types of maternal effects might be expected. Second, we highlight why a neglect of maternal strategies and the effects that they have on their offspring could lead to miscalculations of helper/worker fitness gains and a misunderstanding of the factors selecting for the evolution and maintenance of cooperative breeding. Finally, we introduce the possibility that maternal effects could have significant consequences for our understanding of both the evolutionary origins of cooperative breeding and the rise of social complexity in cooperative systems.
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Affiliation(s)
- Andrew F Russell
- Department of Animal & Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK.
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Kümmerli R, Keller L. Patterns of split sex ratio in ants have multiple evolutionary causes based on different within-colony conflicts. Biol Lett 2009; 5:713-6. [PMID: 19457886 DOI: 10.1098/rsbl.2009.0295] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Split sex ratio-a pattern where colonies within a population specialize in either male or queen production-is a widespread phenomenon in ants and other social Hymenoptera. It has often been attributed to variation in colony kin structure, which affects the degree of queen-worker conflict over optimal sex allocation. However, recent findings suggest that split sex ratio is a more diverse phenomenon, which can evolve for multiple reasons. Here, we provide an overview of the main conditions favouring split sex ratio. We show that each split sex-ratio type arises due to a different combination of factors determining colony kin structure, queen or worker control over sex ratio and the type of conflict between colony members.
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Affiliation(s)
- Rolf Kümmerli
- Institute of Evolutionary Biology, University of Edinburgh, West Mains Road, Edinburgh EH9 3JT, UK.
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Dijkstra MB, Boomsma JJ. Sex allocation in fungus-growing ants: worker or queen control without symbiont-induced female bias. OIKOS 2008. [DOI: 10.1111/j.1600-0706.2008.16822.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Jordan LA, Allsopp MH, Oldroyd BP, Wossler TC, Beekman M. Cheating honeybee workers produce royal offspring. Proc Biol Sci 2008; 275:345-51. [PMID: 18048282 DOI: 10.1098/rspb.2007.1422] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Cape bee (Apis mellifera capensis) is unique among honeybees in that workers can lay eggs that instead of developing into males develop into females via thelytokous parthenogenesis. We show that this ability allows workers to compete directly with the queen over the production of new queens. Genetic analyses using microsatellites revealed that 23 out of 39 new queens produced by seven colonies were offspring of workers and not the resident queen. Of these, eight were laid by resident workers, but the majority were offspring of parasitic workers from other colonies. The parasites were derived from several clonal lineages that entered the colonies and successfully targeted queen cells for parasitism. Hence, these parasitic workers had the potential to become genetically reincarnated as queens. Of the daughter queens laid by the resident queen, three were produced asexually, suggesting that queens can 'choose' to produce daughter queens clonally and thus have the potential for genetic immortality.
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Affiliation(s)
- Lyndon A Jordan
- School of Biological Sciences A12, University of Sydney, New South Wales 2006, Australia
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Kümmerli R, Keller L. Reproductive parameters vary with social and ecological factors in the polygynous ant Formica exsecta. OIKOS 2008. [DOI: 10.1111/j.0030-1299.2008.16207.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Denis D, Chameron S, Costille L, Pocheville A, Châline N, Fresneau D. Workers agonistic interactions in queenright and queenless nests of a polydomous ant society. Anim Behav 2008. [DOI: 10.1016/j.anbehav.2007.06.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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