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Resource sharing is sufficient for the emergence of division of labour. Nat Commun 2022; 13:7232. [PMID: 36433975 PMCID: PMC9700737 DOI: 10.1038/s41467-022-35038-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2022] [Accepted: 11/16/2022] [Indexed: 11/26/2022] Open
Abstract
Division of labour occurs in a broad range of organisms. Yet, how division of labour can emerge in the absence of pre-existing interindividual differences is poorly understood. Using a simple but realistic model, we show that in a group of initially identical individuals, division of labour emerges spontaneously if returning foragers share part of their resources with other group members. In the absence of resource sharing, individuals follow an activity schedule of alternating between foraging and other tasks. If non-foraging individuals are fed by other individuals, their alternating activity schedule becomes interrupted, leading to task specialisation and the emergence of division of labour. Furthermore, nutritional differences between individuals reinforce division of labour. Such differences can be caused by increased metabolic rates during foraging or by dominance interactions during resource sharing. Our model proposes a plausible mechanism for the self-organised emergence of division of labour in animal groups of initially identical individuals. This mechanism could also play a role for the emergence of division of labour during the major evolutionary transitions to eusociality and multicellularity.
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2
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Quque M, Villette C, Criscuolo F, Sueur C, Bertile F, Heintz D. Eusociality is linked to caste-specific differences in metabolism, immune system, and somatic maintenance-related processes in an ant species. Cell Mol Life Sci 2021; 79:29. [PMID: 34971425 PMCID: PMC11073003 DOI: 10.1007/s00018-021-04024-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 10/08/2021] [Accepted: 11/05/2021] [Indexed: 01/08/2023]
Abstract
The social organization of many primate, bird and rodent species and the role of individuals within that organization are associated with specific individual physiological traits. However, this association is perhaps most pronounced in eusocial insects (e.g., termites, ants). In such species, genetically close individuals show significant differences in behavior, physiology, and life expectancy. Studies addressing the metabolic changes according to the social role are still lacking. We aimed at understanding how sociality could influence essential molecular processes in a eusocial insect, the black garden ant (Lasius niger) where queens can live up to ten times longer than workers. Using mass spectrometry-based analysis, we explored the whole metabolome of queens, nest-workers and foraging workers. A former proteomics study done in the same species allowed us to compare the findings of both approaches. Confirming the former results at the proteome level, we showed that queens had fewer metabolites related to immunity. Contrary to our predictions, we did not find any metabolite linked to reproduction in queens. Among the workers, foragers had a metabolic signature reflecting a more stressful environment and a more highly stimulated immune system. We also found that nest-workers had more digestion-related metabolites. Hence, we showed that specific metabolic signatures match specific social roles. Besides, we identified metabolites differently expressed among behavioral castes and involved in nutrient sensing and longevity pathways (e.g., sirtuins, FOXO). The links between such molecular pathways and aging being found in an increasing number of taxa, our results confirm and strengthen their potential universality.
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Affiliation(s)
- Martin Quque
- Université de Strasbourg, CNRS, IPHC UMR 7178, 23 rue du Loess, F-67000, Strasbourg, France.
| | - Claire Villette
- Plant Imaging and Mass Spectrometry (PIMS), Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67000, Strasbourg, France
| | - François Criscuolo
- Université de Strasbourg, CNRS, IPHC UMR 7178, 23 rue du Loess, F-67000, Strasbourg, France
| | - Cédric Sueur
- Université de Strasbourg, CNRS, IPHC UMR 7178, 23 rue du Loess, F-67000, Strasbourg, France
- Institut Universitaire de France, 75005, Paris, France
| | - Fabrice Bertile
- Université de Strasbourg, CNRS, IPHC UMR 7178, 23 rue du Loess, F-67000, Strasbourg, France
- Infrastructure Nationale de Protéomique ProFI, FR2048, Strasbourg, France
| | - Dimitri Heintz
- Plant Imaging and Mass Spectrometry (PIMS), Institut de Biologie Moléculaire des Plantes, CNRS, Université de Strasbourg, 12 rue du Général Zimmer, F-67000, Strasbourg, France
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3
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Molecular underpinnings of division of labour among workers in a socially complex termite. Sci Rep 2021; 11:18269. [PMID: 34521896 PMCID: PMC8440649 DOI: 10.1038/s41598-021-97515-w] [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] [Received: 05/11/2021] [Accepted: 08/20/2021] [Indexed: 02/08/2023] Open
Abstract
Division of labour characterizes all major evolutionary transitions, such as the evolution of eukaryotic cells or multicellular organisms. Social insects are characterized by reproductive division of labour, with one or a few reproducing individuals (queens) and many non-reproducing nestmates (workers) forming a colony. Among the workers, further division of labour can occur with different individuals performing different tasks such as foraging, brood care or building. While mechanisms underlying task division are intensively studied in social Hymenoptera, less is known for termites, which independently evolved eusociality. We investigated molecular mechanisms underlying task division in termite workers to test for communality with social Hymenoptera. We compared similar-aged foraging workers with builders of the fungus-growing termite Macrotermes bellicosus using transcriptomes, endocrine measures and estimators of physiological condition. Based on results for social Hymenoptera and theory, we tested the hypotheses that (i) foragers are in worse physiological conditions than builders, (ii) builders are more similar in their gene expression profile to queens than foragers are, and (iii) builders invest more in anti-ageing mechanism than foragers. Our results support all three hypotheses. We found storage proteins to underlie task division of these similar-aged termite workers and these genes also characterize reproductive division of labour between queens and workers. This implies a co-option of nutrient-based pathways to regulate division of labour across lineages of termites and social Hymenoptera, which are separated by more than 133 million years.
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Mongkol W, Pomun T, Nguitragool W, Kumpitak C, Duangmanee A, Sattabongkot J, Kubera A. Anopheles dirus yellow-g mediates Plasmodium vivax infection. Trop Med Int Health 2021; 26:1029-1035. [PMID: 34089555 DOI: 10.1111/tmi.13635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Our previous transcriptome analysis of Anopheles dirus revealed upregulation of the An. dirus yellow-g gene upon ingestion of Plasmodium vivax-infected blood. This gene belongs to the yellow gene family, but its role regarding P. vivax infection is not known and remains to be validated. The aim of this study was to investigate the role of the An. dirus yellow-g gene in P. vivax infection. METHODS The qRT-PCR was used to detect the expression of the yellow-g gene in many organs of both male and female mosquitos. The yellow-g gene silencing was performed by dsRNA membrane feeding to An. dirus. These mosquitoes were later challenged by P. vivax-infected blood. The oocyst numbers were determined. RESULTS The yellow-g transcript was detected in several organs of both male and female An. dirus mosquitoes. Successful knockdown of yellow-g was achieved and resulted in reduced P. vivax infection in the mosquitoes. The decrease in yellow-g expression had no effect on the life span of the mosquitoes. CONCLUSIONS These results support the yellow-g gene as having an important function in Plasmodium development in Anopheles mosquitoes.
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Affiliation(s)
- Watcharakorn Mongkol
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Tippawan Pomun
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Wang Nguitragool
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Chalermpon Kumpitak
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Apisak Duangmanee
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Anchanee Kubera
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand
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He S, Sieksmeyer T, Che Y, Mora MAE, Stiblik P, Banasiak R, Harrison MC, Šobotník J, Wang Z, Johnston PR, McMahon DP. Evidence for reduced immune gene diversity and activity during the evolution of termites. Proc Biol Sci 2021; 288:20203168. [PMID: 33593190 PMCID: PMC7934958 DOI: 10.1098/rspb.2020.3168] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The evolution of biological complexity is associated with the emergence of bespoke immune systems that maintain and protect organism integrity. Unlike the well-studied immune systems of cells and individuals, little is known about the origins of immunity during the transition to eusociality, a major evolutionary transition comparable to the evolution of multicellular organisms from single-celled ancestors. We aimed to tackle this by characterizing the immune gene repertoire of 18 cockroach and termite species, spanning the spectrum of solitary, subsocial and eusocial lifestyles. We find that key transitions in termite sociality are correlated with immune gene family contractions. In cross-species comparisons of immune gene expression, we find evidence for a caste-specific social defence system in termites, which appears to operate at the expense of individual immune protection. Our study indicates that a major transition in organismal complexity may have entailed a fundamental reshaping of the immune system optimized for group over individual defence.
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Affiliation(s)
- Shulin He
- Institute of Biology, Freie Universität Berlin, Schwendenerstr. 1, 14195 Berlin, Germany.,Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany.,Faculty of Forestry and Wood Science, Czech University of Life Science Prague, Kamýcká 129, 16500 Prague, Czech Republic
| | - Thorben Sieksmeyer
- Institute of Biology, Freie Universität Berlin, Schwendenerstr. 1, 14195 Berlin, Germany.,Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany
| | - Yanli Che
- College of Plant Protection, Southwest University, Tiansheng 2, 400715 Chongqing, People's Republic of China
| | - M Alejandra Esparza Mora
- Institute of Biology, Freie Universität Berlin, Schwendenerstr. 1, 14195 Berlin, Germany.,Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany
| | - Petr Stiblik
- Faculty of Forestry and Wood Science, Czech University of Life Science Prague, Kamýcká 129, 16500 Prague, Czech Republic
| | - Ronald Banasiak
- Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany
| | - Mark C Harrison
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Jan Šobotník
- Faculty of Tropical AgriSciences, Czech University of Life Science Prague, Kamýcká 129, 16500 Prague, Czech Republic
| | - Zongqing Wang
- College of Plant Protection, Southwest University, Tiansheng 2, 400715 Chongqing, People's Republic of China
| | - Paul R Johnston
- Institute of Biology, Freie Universität Berlin, Schwendenerstr. 1, 14195 Berlin, Germany.,Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587 Berlin, Germany.,Berlin Center for Genomics in Biodiversity Research, Königin-Luise-Str. 6-8, 14195 Berlin, Germany
| | - Dino P McMahon
- Institute of Biology, Freie Universität Berlin, Schwendenerstr. 1, 14195 Berlin, Germany.,Department for Materials and Environment, BAM Federal Institute for Materials Research and Testing, Unter den Eichen 87, 12205 Berlin, Germany
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6
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Liu PC, Hao DJ, Hu HY, Wei JR. Sexual dimorphism and sex-biased gene expression in an egg parasitoid species, Anastatus disparis. BMC Genomics 2020; 21:492. [PMID: 32682391 PMCID: PMC7368684 DOI: 10.1186/s12864-020-06903-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 07/10/2020] [Indexed: 11/10/2022] Open
Abstract
Background Differences in the expression of genes present in both sexes are assumed to contribute to sex differences including behavioural, physiological and morphological dimorphisms. For enriching our knowledge of gender differences in an important egg parasitoid wasp, Anastatus disparis (Hymenoptera: Eupelmidae), sex-biased differences in gene expression were investigated using Illumina-based transcriptomic analysis. Results A total of 15,812 resulting unigenes were annotated, and a large set of genes accounting for 50.09% of the total showed sex-biased expression and included 630 sex-specific genes. Gene Ontology (GO) enrichment analyses showed that the functional categories associated with sex-biased genes were mainly related to reproduction. In addition, the transcriptome data provided evidence that sex pheromones in A. disparis are produced by the female, and activity of Δ12-desaturases appear to have been replaced by Δ9-desaturases playing roles in sex pheromone production. The large set of sex-biased genes identified in this study provide a molecular background for sexually dimorphic traits such as flyability, longevity, and aggression in this species and suggests candidate venom proteins expressed only in females that could be used for biological control. Conclusions This study provides comprehensive insight into sexually dimorphic traits of a parasitoid wasp and can inform future research into the molecular mechanisms underlying such traits and the application of parasitoids to the biological control of pest species.
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Affiliation(s)
- Peng-Cheng Liu
- The College of Ecology and Environment, Anhui Normal University, Wuhu, Anhui Province, China.
| | - De-Jun Hao
- The College of Forestry, Nanjing Forestry University, Nanjing, Jiangsu Province, China
| | - Hao-Yuan Hu
- The College of Ecology and Environment, Anhui Normal University, Wuhu, Anhui Province, China
| | - Jian-Rong Wei
- The College of Life Science, Hebei University, Baoding, Hebei Province, China
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7
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Quque M, Benhaim-Delarbre M, Deneubourg JL, Sueur C, Criscuolo F, Bertile F. Division of labour in the black garden ant (Lasius niger) leads to three distinct proteomes. JOURNAL OF INSECT PHYSIOLOGY 2019; 117:103907. [PMID: 31255645 DOI: 10.1016/j.jinsphys.2019.103907] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 06/26/2019] [Accepted: 06/26/2019] [Indexed: 06/09/2023]
Abstract
Task specialization in social insects leads to striking intra-specific differences in behaviour, morphology, physiology and longevity, but the underlying mechanisms remain not yet fully understood. Adult colonies of black garden ants (Lasius niger) have a single queen fertilized by one or a small number of males. The inter-individual genetic variability is thus relatively low, making it easier to focus on the individual molecular differences linked to the division of labour. Mass spectrometry-based proteomics enabled us to highlight which biological functions create the difference between queens, foragers and nest-workers. The proteome of each caste reflected nicely their social role: e.g., reproduction for queens, pesticide resistance for foragers - that are the most exposed to environmental risk factors - and, interestingly, digestion for nest-workers, thus highlighting proteomic profiles differences even among workers. Furthermore, our exploratory approach suggests energy trade-off mechanisms - in connection with the theory of social immunity - that might explain the difference in longevity between queens and workers. This study brings evidence that proteomics is able to highlight the subtle mechanisms of molecular regulation induced by social organization.
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Affiliation(s)
- Martin Quque
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France.
| | | | - Jean-Louis Deneubourg
- Université Libre de Bruxelles, CPBT, CP231, Av. F. Roosevelt 50, 1050 Bruxelles, Belgium
| | - Cédric Sueur
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
| | - François Criscuolo
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
| | - Fabrice Bertile
- Université de Strasbourg, CNRS, IPHC UMR 7178, F-67000 Strasbourg, France
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8
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Shilovsky GA, Putyatina TS, Ashapkin VV, Rozina AA, Lyubetsky VA, Minina EP, Bychkovskaia IB, Markov AV, Skulachev VP. Ants as Object of Gerontological Research. BIOCHEMISTRY (MOSCOW) 2019; 83:1489-1503. [PMID: 30878024 DOI: 10.1134/s0006297918120076] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Social insects with identical genotype that form castes with radically different lifespans are a promising model system for studying the mechanisms underlying longevity. The main direction of progressive evolution of social insects, in particular, ants, is the development of the social way of life inextricably linked with the increase in the colony size. Only in a large colony, it is possible to have a developed polyethism, create large food reserves, and actively regulate the nest microclimate. The lifespan of ants hugely varies among genetically similar queens, workers (unproductive females), and males. The main advantage of studies on insects is the determinism of ontogenetic processes, with a single genome leading to completely different lifespans in different castes. This high degree of determinacy is precisely the reason why some researchers (incorrectly) call a colony of ants the "superorganism", emphasizing the fact that during the development, depending on the community needs, ants can switch their ontogenetic programs, which influences their social roles, ability to learn (i.e., the brain [mushroom-like body] plasticity), and, respectively, the spectrum of tasks performed by a given individual. It has been shown that in many types of food behavior, older ants surpass young ones in both performing the tasks and transferring the experience. The balance between the need to reduce the "cost" of non-breeding individuals (short lifespan and small size of workers) and the benefit from experienced long-lived workers possessing useful skills (large size and "non-aging") apparently determines the differences in the lifespan and aging rate of workers in different species of ants. A large spectrum of rigidly determined ontogenetic trajectories in different castes with identical genomes and the possibility of comparison between "evolutionarily advanced" and "primitive" subfamilies (e.g., Formicinae and Ponerinae) make ants an attractive object in the studies of both normal aging and effects of anti-aging drugs.
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Affiliation(s)
- G A Shilovsky
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia. .,Lomonosov Moscow State University, Faculty of Biology, Moscow, 119234, Russia.,Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, 127051, Russia
| | - T S Putyatina
- Lomonosov Moscow State University, Faculty of Biology, Moscow, 119234, Russia
| | - V V Ashapkin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - A A Rozina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - V A Lyubetsky
- Institute for Information Transmission Problems, Russian Academy of Sciences, Moscow, 127051, Russia
| | - E P Minina
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - I B Bychkovskaia
- Nikiforov Center of Emergency and Radiation Medicine of the Russian Ministry of Emergency Control, St. Petersburg, 194044, Russia
| | - A V Markov
- Lomonosov Moscow State University, Faculty of Biology, Moscow, 119234, Russia
| | - V P Skulachev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119991, Russia
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9
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Giehr J, Heinze J. Queens stay, workers leave: caste-specific responses to fatal infections in an ant. BMC Evol Biol 2018; 18:202. [PMID: 30587108 PMCID: PMC6307282 DOI: 10.1186/s12862-018-1320-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 12/04/2018] [Indexed: 01/13/2023] Open
Abstract
Background The intense interactions among closely related individuals in animal societies provide perfect conditions for the spread of pathogens. Social insects have therefore evolved counter-measures on the cellular, individual, and social level to reduce the infection risk. One striking example is altruistic self-removal, i.e., lethally infected workers leave the nest and die in isolation to prevent the spread of a contagious disease to their nestmates. Because reproductive queens and egg-laying workers behave less altruistically than non-laying workers, e.g., when it comes to colony defense, we wondered whether moribund egg-layers would show the same self-removal as non-reproductive workers. Furthermore, we investigated how a lethal infection affects reproduction and studied if queens and egg-laying workers intensify their reproductive efforts when their residual reproductive value decreases (“terminal investment”). Results We treated queens, egg-laying workers from queenless colonies, and non-laying workers from queenright colonies of the monogynous (single-queened) ant Temnothorax crassispinus either with a control solution or a solution containing spores of the entomopathogenic fungus Metarhizium brunneum. Lethally infected workers left the nest and died away from it, regardless of their reproductive status. In contrast, infected queens never left the nest and were removed by workers only after they had died. The reproductive investment of queens strongly decreased after the treatment with both, the control solution and the Metarhizium brunneum suspension. The egg laying rate in queenless colonies was initially reduced in infected colonies but not in control colonies. Egg number increased again with decreasing number of infected workers. Conclusions Queens and workers of the ant Temnothorax crassispinus differ in their reaction to an infection risk and a reduced life expectancy. Workers isolate themselves to prevent contagion inside the colony, whereas queens stay in the nest. We did not find terminal investment; instead it appeared that egg-layers completely shut down egg production in response to the lethal infection. Workers in queenless colonies resumed reproduction only after all infected individuals had died, probably again to minimize the risk of infecting the offspring. Electronic supplementary material The online version of this article (10.1186/s12862-018-1320-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Julia Giehr
- Department of Zoology/ Evolutionary Biology, University of Regensburg, 93053, Regensburg, Germany.
| | - Jürgen Heinze
- Department of Zoology/ Evolutionary Biology, University of Regensburg, 93053, Regensburg, Germany
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10
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Libbrecht R, Oxley PR, Kronauer DJC. Clonal raider ant brain transcriptomics identifies candidate molecular mechanisms for reproductive division of labor. BMC Biol 2018; 16:89. [PMID: 30103762 PMCID: PMC6090591 DOI: 10.1186/s12915-018-0558-8] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 07/31/2018] [Indexed: 12/02/2022] Open
Abstract
BACKGROUND Division of labor between reproductive queens and workers that perform brood care is a hallmark of insect societies. However, studies of the molecular basis of this fundamental dichotomy are limited by the fact that the caste of an individual cannot typically be experimentally manipulated at the adult stage. Here we take advantage of the unique biology of the clonal raider ant, Ooceraea biroi, to study brain gene expression dynamics during experimentally induced transitions between reproductive and brood care behavior. RESULTS Introducing larvae that inhibit reproduction and induce brood care behavior causes much faster changes in adult gene expression than removing larvae. In addition, the general patterns of gene expression differ depending on whether ants transition from reproduction to brood care or vice versa, indicating that gene expression changes between phases are cyclic rather than pendular. Finally, we identify genes that could play upstream roles in regulating reproduction and behavior because they show large and early expression changes in one or both transitions. CONCLUSIONS Our analyses reveal that the nature and timing of gene expression changes differ substantially depending on the direction of the transition, and identify a suite of promising candidate molecular regulators of reproductive division of labor that can now be characterized further in both social and solitary animal models. This study contributes to understanding the molecular regulation of reproduction and behavior, as well as the organization and evolution of insect societies.
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Affiliation(s)
- Romain Libbrecht
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Johannes-von-Müller-Weg 6, 55128, Mainz, Germany.
| | - Peter R Oxley
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA
- Samuel J. Wood Library, Weill Cornell Medicine, 1300 York Avenue, New York, NY, 10065, USA
| | - Daniel J C Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY, 10065, USA.
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11
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Hawkings C, Tamborindeguy C. Expression analysis of vitellogenins in the workers of the red imported fire ant ( Solenopsis invicta). PeerJ 2018; 6:e4875. [PMID: 29868280 PMCID: PMC5978388 DOI: 10.7717/peerj.4875] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 05/09/2018] [Indexed: 01/27/2023] Open
Abstract
Vitellogenin has been proposed to regulate division of labor and social organization in social insects. The red imported fire ant (Solenopsis invicta) harbors four distinct, adjacent vitellogenin genes (Vg1, Vg2, Vg3, and Vg4). Contrary to honey bees that have a single Vg ortholog as well as potentially fertile nurses, and to other ant species that lay trophic eggs, S. invicta workers completely lack ovaries or the ability to lay eggs. This provides a unique model to investigate whether Vg duplication in S. invicta was followed by subfunctionalization to acquire non-reproductive functions and whether Vg was co-opted to regulate behavior within the worker caste. To investigate these questions, we compared the expression patterns of S. invicta Vg genes among workers from different morphological subcastes or performing different tasks. RT-qPCRs revealed higher relative expression of Vg1 in major workers compared to both medium and minor workers, and of Vg2 in major workers when compared to minor workers. Relative expression of Vg1 was also higher in carbohydrate foragers when compared to nurses and protein foragers. By contrast, the level of expression of Vg2, Vg3, and Vg4 were not significantly different among the workers performing the specific tasks. Additionally, we analyzed the relationship between the expression of the Vg genes and S-hydroprene, a juvenile hormone analog. No changes in Vg expression were recorded in workers 12 h after application of the analog. Our results suggest that in S. invicta the Vg gene underwent subfunctionalization after duplication to new functions based on the expression bias observed in these data. This may suggest an alternative and still unknown function for Vg in the workers that needs to be investigated further.
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Affiliation(s)
- Chloe Hawkings
- Department of Entomology, Texas A&M University, College Station, TX, USA
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12
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Pennell TM, Holman L, Morrow EH, Field J. Building a new research framework for social evolution: intralocus caste antagonism. Biol Rev Camb Philos Soc 2018; 93:1251-1268. [PMID: 29341390 PMCID: PMC5896731 DOI: 10.1111/brv.12394] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Revised: 12/06/2017] [Accepted: 12/18/2017] [Indexed: 01/02/2023]
Abstract
The breeding and non‐breeding ‘castes’ of eusocial insects provide a striking example of role‐specific selection, where each caste maximises fitness through different morphological, behavioural and physiological trait values. Typically, queens are long‐lived egg‐layers, while workers are short‐lived, largely sterile foragers. Remarkably, the two castes are nevertheless produced by the same genome. The existence of inter‐caste genetic correlations is a neglected consequence of this shared genome, potentially hindering the evolution of caste dimorphism: alleles that increase the productivity of queens may decrease the productivity of workers and vice versa, such that each caste is prevented from reaching optimal trait values. A likely consequence of this ‘intralocus caste antagonism’ should be the maintenance of genetic variation for fitness and maladaptation within castes (termed ‘caste load’), analogous to the result of intralocus sexual antagonism. The aim of this review is to create a research framework for understanding caste antagonism, drawing in part upon conceptual similarities with sexual antagonism. By reviewing both the social insect and sexual antagonism literature, we highlight the current empirical evidence for caste antagonism, discuss social systems of interest, how antagonism might be resolved, and challenges for future research. We also introduce the idea that sexual and caste antagonism could interact, creating a three‐way antagonism over gene expression. This includes unpacking the implications of haplodiploidy for the outcome of this complex interaction.
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Affiliation(s)
- Tanya M Pennell
- College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
| | - Luke Holman
- School of Biosciences, University of Melbourne, Parkville, Victoria, 3052, Australia
| | - Edward H Morrow
- Evolution Behaviour and Environment Group, School of Life Sciences, University of Sussex, Falmer, East Sussex, BN1 9QG, UK
| | - Jeremy Field
- College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, TR10 9FE, UK
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13
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Dhaygude K, Trontti K, Paviala J, Morandin C, Wheat C, Sundström L, Helanterä H. Transcriptome sequencing reveals high isoform diversity in the ant Formica exsecta. PeerJ 2017; 5:e3998. [PMID: 29177112 PMCID: PMC5701548 DOI: 10.7717/peerj.3998] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2017] [Accepted: 10/17/2017] [Indexed: 12/21/2022] Open
Abstract
Transcriptome resources for social insects have the potential to provide new insight into polyphenism, i.e., how divergent phenotypes arise from the same genome. Here we present a transcriptome based on paired-end RNA sequencing data for the ant Formica exsecta (Formicidae, Hymenoptera). The RNA sequencing libraries were constructed from samples of several life stages of both sexes and female castes of queens and workers, in order to maximize representation of expressed genes. We first compare the performance of common assembly and scaffolding software (Trinity, Velvet-Oases, and SOAPdenovo-trans), in producing de novo assemblies. Second, we annotate the resulting expressed contigs to the currently published genomes of ants, and other insects, including the honeybee, to filter genes that have annotation evidence of being true genes. Our pipeline resulted in a final assembly of altogether 39,262 mRNA transcripts, with an average coverage of >300X, belonging to 17,496 unique genes with annotation in the related ant species. From these genes, 536 genes were unique to one caste or sex only, highlighting the importance of comprehensive sampling. Our final assembly also showed expression of several splice variants in 6,975 genes, and we show that accounting for splice variants affects the outcome of downstream analyses such as gene ontologies. Our transcriptome provides an outstanding resource for future genetic studies on F. exsecta and other ant species, and the presented transcriptome assembly can be adapted to any non-model species that has genomic resources available from a related taxon.
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Affiliation(s)
- Kishor Dhaygude
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Kalevi Trontti
- Department of Biosciences, Neurogenomics Laboratory, University of Helsinki, Helsinki, Finland
| | - Jenni Paviala
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Claire Morandin
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - Christopher Wheat
- Department of Zoology Ecology, Stockholm University, Stockholm, Sweden
| | - Liselotte Sundström
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Helsinki, Finland
- Tvärminne Zoological Station, University of Helsinki, Hanko, Finland
| | - Heikki Helanterä
- Centre of Excellence in Biological Interactions, Department of Biosciences, University of Helsinki, Helsinki, Finland
- Tvärminne Zoological Station, University of Helsinki, Hanko, Finland
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14
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Kohlmeier P, Negroni MA, Kever M, Emmling S, Stypa H, Feldmeyer B, Foitzik S. Intrinsic worker mortality depends on behavioral caste and the queens' presence in a social insect. Naturwissenschaften 2017; 104:34. [PMID: 28353195 DOI: 10.1007/s00114-017-1452-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/20/2017] [Accepted: 02/22/2017] [Indexed: 12/30/2022]
Abstract
According to the classic life history theory, selection for longevity depends on age-dependant extrinsic mortality and fecundity. In social insects, the common life history trade-off between fecundity and longevity appears to be reversed, as the most fecund individual, the queen, often exceeds workers in lifespan several fold. But does fecundity directly affect intrinsic mortality also in social insect workers? And what is the effect of task on worker mortality? Here, we studied how social environment and behavioral caste affect intrinsic mortality of ant workers. We compared worker survival between queenless and queenright Temnothorax longispinosus nests and demonstrate that workers survive longer under the queens' absence. Temnothorax ant workers fight over reproduction when the queen is absent and dominant workers lay eggs. Worker fertility might therefore increase lifespan, possibly due to a positive physiological link between fecundity and longevity, or better care for fertile workers. In social insects, division of labor among workers is age-dependant with young workers caring for the brood and old ones going out to forage. We therefore expected nurses to survive longer than foragers, which is what we found. Surprisingly, inactive inside workers showed a lower survival than nurses but comparable to that of foragers. The reduced longevity of inactive workers could be due to them being older than the nurses, or due to a positive effect of activity on lifespan. Overall, our study points to behavioral caste-dependent intrinsic mortality rates and a positive association between fertility and longevity not only in queens but also in ant workers.
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Affiliation(s)
- Philip Kohlmeier
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Johannes von Müller Weg 6, 55128, Mainz, Germany.
| | - Matteo Antoine Negroni
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Johannes von Müller Weg 6, 55128, Mainz, Germany
| | - Marion Kever
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Johannes von Müller Weg 6, 55128, Mainz, Germany
| | - Stefanie Emmling
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Johannes von Müller Weg 6, 55128, Mainz, Germany
| | - Heike Stypa
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Johannes von Müller Weg 6, 55128, Mainz, Germany
| | - Barbara Feldmeyer
- Senckenberg Biodiversity and Climate Research Centre, Senckenberg Gesellschaft für Naturforschung, Senckenberganlage 25, D-60325, Frankfurt am Main, Germany
| | - Susanne Foitzik
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Johannes von Müller Weg 6, 55128, Mainz, Germany
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15
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Okada Y, Watanabe Y, Tin MMY, Tsuji K, Mikheyev AS. Social dominance alters nutrition-related gene expression immediately: transcriptomic evidence from a monomorphic queenless ant. Mol Ecol 2017; 26:2922-2938. [DOI: 10.1111/mec.13989] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Revised: 11/23/2016] [Accepted: 11/28/2016] [Indexed: 12/31/2022]
Affiliation(s)
- Yasukazu Okada
- Department of General Systems Studies; Graduate School of Arts and Sciences; The University of Tokyo; 3-8-1 Komaba Tokyo Japan
| | - Yutaka Watanabe
- Ecology and Evolution Unit; Okinawa Institute of Science and Technology; 1919-1 Tancha Onna-son Kunigami Okinawa 904-0495 Japan
| | - Mandy M. Y. Tin
- Ecology and Evolution Unit; Okinawa Institute of Science and Technology; 1919-1 Tancha Onna-son Kunigami Okinawa 904-0495 Japan
| | - Kazuki Tsuji
- Department of Subtropical Agro-Environmental Sciences; Faculty of Agriculture; University of the Ryukyus; Nishihara Okinawa 903-0213 Japan
| | - Alexander S. Mikheyev
- Ecology and Evolution Unit; Okinawa Institute of Science and Technology; 1919-1 Tancha Onna-son Kunigami Okinawa 904-0495 Japan
- Research School of Biology; Australian National University; Canberra ACT 0200 Australia
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16
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Pamminger T, Buttstedt A, Norman V, Schierhorn A, Botías C, Jones JC, Basley K, Hughes WOH. The effects of juvenile hormone on Lasius niger reproduction. JOURNAL OF INSECT PHYSIOLOGY 2016; 95:1-7. [PMID: 27614175 DOI: 10.1016/j.jinsphys.2016.09.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Revised: 09/05/2016] [Accepted: 09/05/2016] [Indexed: 06/06/2023]
Abstract
Reproduction has been shown to be costly for survival in a wide diversity of taxa. The resulting trade-off, termed the reproduction-survival trade-off, is thought to be one of the most fundamental forces of life-history evolution. In insects the pleiotropic effect of juvenile hormone (JH), antagonistically regulating reproduction and pathogen resistance, is suggested to underlie this phenomenon. In contrast to the majority of insects, reproductive individuals in many eusocial insects defy this trade-off and live both long and prosper. By remodelling the gonadotropic effects of JH in reproductive regulation, the queens of the long-lived black garden ant Lasius niger (living up to 27 years), have circumvented the reproduction-survival trade off enabling them to maximize both reproduction and pathogen resistance simultaneously. In this study we measure fertility, vitellogenin gene expression and protein levels after experimental manipulation of hormone levels. We use these measurements to investigate the mechanistic basis of endocrinological role remodelling in reproduction and determine how JH suppresses reproduction in this species, rather then stimulating it, like in the majority of insects. We find that JH likely inhibits three key aspects of reproduction both during vitellogenesis and oogenesis, including two previously unknown mechanisms. In addition, we document that juvenile hormone, as in the majority of insects, has retained some stimulatory function in regulating vitellogenin expression. We discuss the evolutionary consequences of this complex regulatory architecture of reproduction in L. niger, which might enable the evolution of similar reproductive phenotypes by alternate regulatory pathways, and the surprising flexibility regulatory role of juvenile hormone in this process.
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Affiliation(s)
- T Pamminger
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK.
| | - A Buttstedt
- Institut Für Biologie, Molekulare Ökologie, Martin-Luther-Universität Halle-Wittenberg, Halle 06099, Germany
| | - V Norman
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - A Schierhorn
- Institut Für Biochemie, Martin-Luther-Universität Halle Wittenberg, Halle 06099, Germany
| | - C Botías
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - J C Jones
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - K Basley
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
| | - W O H Hughes
- School of Life Sciences, University of Sussex, Brighton BN1 9QG, UK
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17
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Korb J. Genes Underlying Reproductive Division of Labor in Termites, with Comparisons to Social Hymenoptera. Front Ecol Evol 2016. [DOI: 10.3389/fevo.2016.00045] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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18
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Lockett GA, Almond EJ, Huggins TJ, Parker JD, Bourke AFG. Gene expression differences in relation to age and social environment in queen and worker bumble bees. Exp Gerontol 2016; 77:52-61. [PMID: 26883339 DOI: 10.1016/j.exger.2016.02.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/24/2016] [Accepted: 02/12/2016] [Indexed: 02/03/2023]
Abstract
Eusocial insects provide special insights into the genetic pathways influencing aging because of their long-lived queens and flexible aging schedules. Using qRT-PCR in the primitively eusocial bumble bee Bombus terrestris (Linnaeus), we investigated expression levels of four candidate genes associated with taxonomically widespread age-related pathways (coenzyme Q biosynthesis protein 7, COQ7; DNA methyltransferase 3, Dnmt3; foraging, for; and vitellogenin, vg). In Experiment 1, we tested how expression changes with queen relative age and productivity. We found a significant age-related increase in COQ7 expression in queen ovary. In brain, all four genes showed higher expression with increasing female (queen plus worker) production, with this relationship strengthening as queen age increased, suggesting a link with the positive association of fecundity and longevity found in eusocial insect queens. In Experiment 2, we tested effects of relative age and social environment (worker removal) in foundress queens and effects of age and reproductive status in workers. In this experiment, workerless queens showed significantly higher for expression in brain, as predicted if downregulation of for is associated with the cessation of foraging by foundress queens following worker emergence. Workers showed a significant age-related increase in Dnmt3 expression in fat body, suggesting a novel association between aging and methylation in B. terrestris. Ovary activation was associated with significantly higher vg expression in fat body and, in younger workers, in brain, consistent with vitellogenin's ancestral role in regulating egg production. Overall, our findings reveal a mixture of novel and conserved features in age-related genetic pathways under primitive eusociality.
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Affiliation(s)
- Gabrielle A Lockett
- School of Biological Sciences, University of Southampton, Life Sciences Building, Highfield Campus, Southampton SO17 1BJ, UK
| | - Edward J Almond
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Timothy J Huggins
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Joel D Parker
- School of Biological Sciences, University of Southampton, Life Sciences Building, Highfield Campus, Southampton SO17 1BJ, UK
| | - Andrew F G Bourke
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK.
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19
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Morandin C, Dhaygude K, Paviala J, Trontti K, Wheat C, Helanterä H. Caste-biases in gene expression are specific to developmental stage in the ant Formica exsecta. J Evol Biol 2015; 28:1705-18. [PMID: 26172873 DOI: 10.1111/jeb.12691] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 06/30/2015] [Accepted: 06/30/2015] [Indexed: 02/02/2023]
Abstract
Understanding how a single genome creates and maintains distinct phenotypes is a central goal in evolutionary biology. Social insects are a striking example of co-opted genetic backgrounds giving rise to dramatically different phenotypes, such as queen and worker castes. A conserved set of molecular pathways, previously envisioned as a set of 'toolkit' genes, has been hypothesized to underlie queen and worker phenotypes in independently evolved social insect lineages. Here, we investigated the toolkit from a developmental point of view, using RNA-Seq to compare caste-biased gene expression patterns across three life stages (pupae, emerging adult and old adult) and two female castes (queens and workers) in the ant Formica exsecta. We found that the number of genes with caste-biased expression increases dramatically from pupal to old adult stages. This result suggests that phenotypic differences between queens and workers at the pupal stage may derive from a relatively low number of caste-biased genes, compared to higher number of genes required to maintain caste differences at the adult stage. Gene expression patterns were more similar among castes within developmental stages than within castes despite the extensive phenotypic differences between queens and workers. Caste-biased expression was highly variable among life stages at the level of single genes, but more consistent when gene functions (gene ontology terms) were investigated. Finally, we found that a large part of putative toolkit genes were caste-biased at least in some life stages in F. exsecta, and the caste-biases, but not their direction, were more often shared between F. exsecta and other ant species than between F. exsecta and bees. Our results indicate that gene expression should be examined across several developmental stages to fully reveal the genetic basis of polyphenisms.
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Affiliation(s)
- C Morandin
- Centre of Excellence in Biological Interactions, Department of Biosciences, Helsinki University, Helsinki, Finland.,Tvärminne Zoological Station, University of Helsinki, Hanko, Finland
| | - K Dhaygude
- Centre of Excellence in Biological Interactions, Department of Biosciences, Helsinki University, Helsinki, Finland
| | - J Paviala
- Centre of Excellence in Biological Interactions, Department of Biosciences, Helsinki University, Helsinki, Finland
| | - K Trontti
- Centre of Excellence in Biological Interactions, Department of Biosciences, Helsinki University, Helsinki, Finland
| | - C Wheat
- Department of Zoology, Population Genetics, Stockholm University, Stockholm, Sweden
| | - H Helanterä
- Centre of Excellence in Biological Interactions, Department of Biosciences, Helsinki University, Helsinki, Finland.,Tvärminne Zoological Station, University of Helsinki, Hanko, Finland
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20
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Effects of overwintering temperature on the survival of the black garden ant (Lasius niger). J Therm Biol 2015; 49-50:112-8. [PMID: 25774034 DOI: 10.1016/j.jtherbio.2015.02.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Revised: 02/23/2015] [Accepted: 02/24/2015] [Indexed: 11/23/2022]
Abstract
The overwintering temperatures of ants might well be elevated due to climate change. We studied whether the overwintering temperature affects the survival of the queens and whole colonies of the black garden ant, Lasius niger (Linnaeus, 1758). In two consecutive years (2009, 2010) we collected mated, colony founding queens (n = 280) from the urban area of Turku, Finland. Half of the queens overwintered in +7 to +8 °C and the other half in +2 °C. After the overwintering period, we determined their survival rate and measured the body fat content, body size and immune defence (encapsulation rate) of overwintering queens. Using the same setup, we studied the survival of 1-year-old L. niger colonies (queen & workers). Overwintering at a lower temperature (+2 °C) decreased the survival of workers. The survival of colony founding queens differed between years, but unlike with workers, the overwintering temperature did not affect their survival: neither in the colony experiment nor in the single queen experiment. All of the surviving queens managed to produce their worker offspring at the same rate. The relative amount of body fat of queens was higher for those who overwintered at a lower temperature, which is likely a result of lower energy consumption. We did not detect differences in the encapsulation rate between the temperature treatment groups. The ability of colony founding queens to tolerate wide overwintering temperature variations present in urban environments may explain the success of the colony in urban areas. As the colony grows, the overwintering chambers may extend more deeply into the ground. Thus, workers may not have to cope with such cold conditions as colony founding queens.
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21
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LeBoeuf AC, Grozinger CM. Me and we: the interplay between individual and group behavioral variation in social collectives. CURRENT OPINION IN INSECT SCIENCE 2014; 5:16-24. [PMID: 32846737 DOI: 10.1016/j.cois.2014.09.010] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 09/12/2014] [Accepted: 09/17/2014] [Indexed: 06/11/2023]
Abstract
In social insects, substantial behavioral variation exists among individuals and across colonies. Here, we discuss the role of individual variation in shaping behavioral tendencies of social groups, and highlight gaps in our knowledge about the role of the social group in modulating individual behavioral tendencies. We summarize our knowledge of the genetic mechanisms underpinning these processes, and describe the use of genomic tools to better understand the influence of social context on individuals. We discuss rapid collective phasic transitions, in which a group of individuals engages in a common novel behavior together, as a potentially highly informative model system in which to comprehensively investigate the interplay between individual and group variation.
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Affiliation(s)
- Adria C LeBoeuf
- Department of Ecology and Evolution, Center for Integrative Genomics, University of Lausanne, UNIL-Sorge, Batiment Biophore, CH-1015 Lausanne, Switzerland
| | - Christina M Grozinger
- Department of Entomology, Center for Pollinator Research, Center for Chemical Ecology, The Pennsylvania State University, 1 Chemical Ecology Lab, Orchard Road, University Park, PA 16802, USA.
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22
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Frost CL, Pollock SW, Smith JE, Hughes WOH. Wolbachia in the flesh: symbiont intensities in germ-line and somatic tissues challenge the conventional view of Wolbachia transmission routes. PLoS One 2014; 9:e95122. [PMID: 24988478 PMCID: PMC4079706 DOI: 10.1371/journal.pone.0095122] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2013] [Accepted: 03/25/2014] [Indexed: 11/28/2022] Open
Abstract
Symbionts can substantially affect the evolution and ecology of their hosts. The investigation of the tissue-specific distribution of symbionts (tissue tropism) can provide important insight into host-symbiont interactions. Among other things, it can help to discern the importance of specific transmission routes and potential phenotypic effects. The intracellular bacterial symbiont Wolbachia has been described as the greatest ever panzootic, due to the wide array of arthropods that it infects. Being primarily vertically transmitted, it is expected that the transmission of Wolbachia would be enhanced by focusing infection in the reproductive tissues. In social insect hosts, this tropism would logically extend to reproductive rather than sterile castes, since the latter constitute a dead-end for vertically transmission. Here, we show that Wolbachia are not focused on reproductive tissues of eusocial insects, and that non-reproductive tissues of queens and workers of the ant Acromyrmex echinatior, harbour substantial infections. In particular, the comparatively high intensities of Wolbachia in the haemolymph, fat body, and faeces, suggest potential for horizontal transmission via parasitoids and the faecal-oral route, or a role for Wolbachia modulating the immune response of this host. It may be that somatic tissues and castes are not the evolutionary dead-end for Wolbachia that is commonly thought.
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Affiliation(s)
- Crystal L. Frost
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| | | | - Judith E. Smith
- School of Environment and Life Sciences, University of Salford, Salford, United Kingdom
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23
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Cuvillier-Hot V, Salin K, Devers S, Tasiemski A, Schaffner P, Boulay R, Billiard S, Lenoir A. Impact of ecological doses of the most widespread phthalate on a terrestrial species, the ant Lasius niger. ENVIRONMENTAL RESEARCH 2014; 131:104-110. [PMID: 24713390 DOI: 10.1016/j.envres.2014.03.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2013] [Revised: 12/03/2013] [Accepted: 03/18/2014] [Indexed: 06/03/2023]
Abstract
Phthalates are synthetic contaminants released into the environment notably by plastic waste. Semi-volatile, they adsorb to atmospheric particles and get distributed in all ecosystems. Effects of this major anthropogenic pollution in economical species in aquatic habitats have attracted large interest. On the contrary, very few studies have focused on wild terrestrial species. Yet, these lipophilic molecules are easily trapped by insect cuticle; ants and other insects have been shown to permanently bear among their cuticular components a non-negligible proportion of phthalates, meaning that they suffer from chronic exposure to these pollutants. Oral route could also be an additional way of contamination, as phthalates tend to stick to any organic particle. We show here via a food choice experiment that Lasius niger workers can detect, and avoid feeding on, food contaminated with DEHP (DiEthyl Hexyl Phthalate), the most widespread phthalate found in nature. This suggests that the main source of contamination for ants is atmosphere and that doses measured on the cuticle correspond to the chronic exposure levels for these animals. Such an ecologically relevant dose of DEHP was used to contaminate ants in lab and to investigate their physiological impact. Over a chronic exposure (1 dose per week for 5 weeks), the egg-laying rate of queens was significantly reduced lending credence to endocrine disruptive properties of such a pollutant, as also described for aquatic invertebrates. On the contrary, short term exposure (24h) to a single dose of DEHP does not induce oxidative stress in ant workers as expected, but leads to activation of the immune system. Because of their very large distribution, their presence in virtually all terrestrial ecosystems and their representation at all trophic levels, ants could be useful indicators of contamination by phthalates, especially via monitoring the level of activation of their immune state.
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Affiliation(s)
- Virginie Cuvillier-Hot
- Laboratoire GEPV - CNRS, UMR 8198 Université des Sciences et Technologies de Lille1, Villeneuve d'Ascq, France.
| | - Karine Salin
- Laboratoire d'Ecologie des Hydrosystèmes Naturels et Anthropisés (LEHNA) - CNRS, UMR 5023 Université Lyon1, Villeurbanne, France
| | - Séverine Devers
- IRBI, Institut de Recherche sur la Biologie de l'Insecte, Université François Rabelais, UMR CNRS 7261, Tours, France
| | - Aurélie Tasiemski
- Laboratoire GEPV - CNRS, UMR 8198 Université des Sciences et Technologies de Lille1, Villeneuve d'Ascq, France
| | - Pauline Schaffner
- Laboratoire GEPV - CNRS, UMR 8198 Université des Sciences et Technologies de Lille1, Villeneuve d'Ascq, France
| | - Raphaël Boulay
- IRBI, Institut de Recherche sur la Biologie de l'Insecte, Université François Rabelais, UMR CNRS 7261, Tours, France
| | - Sylvain Billiard
- Laboratoire GEPV - CNRS, UMR 8198 Université des Sciences et Technologies de Lille1, Villeneuve d'Ascq, France
| | - Alain Lenoir
- IRBI, Institut de Recherche sur la Biologie de l'Insecte, Université François Rabelais, UMR CNRS 7261, Tours, France
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24
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Koch SI, Groh K, Vogel H, Hannson BS, Kleineidam CJ, Grosse-Wilde E. Caste-specific expression patterns of immune response and chemosensory related genes in the leaf-cutting ant, Atta vollenweideri. PLoS One 2013; 8:e81518. [PMID: 24260580 PMCID: PMC3829964 DOI: 10.1371/journal.pone.0081518] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 10/14/2013] [Indexed: 02/07/2023] Open
Abstract
Leaf-cutting ants are evolutionary derived social insects with elaborated division of labor and tremendous colony sizes with millions of workers. Their social organization is mainly based on olfactory communication using different pheromones and is promoted by a pronounced size-polymorphism of workers that perform different tasks within the colony. The size polymorphism and associated behaviors are correlated to distinct antennal lobe (AL) phenotypes. Two worker phenotypes differ in number of olfactory glomeruli in the AL and the presence or absence of an extremely large glomerulus (macroglomerulus), involved in trail-pheromone reception. The males' AL contains three macroglomeruli which are presumably involved in detection of sex-pheromone components. We investigated the antennal transcriptome data of all major castes (males, queens and workers) and two worker subcastes (large and tiny workers). In order to identify putative odorant receptor genes involved in pheromone detection, we identified differentially expressed odorant receptor genes (OR-genes) using custom microarrays. In total, we found 185 OR-gene fragments that are clearly related to ORs and we identified orthologs for 70 OR-genes. Among them one OR-gene differs in relative expression between the two worker subcastes by a factor of >3 and thus is a very promising candidate gene for the trail-pheromone receptor. Using the relative expression of OR-genes in males versus queens, we identified 2 candidates for sex-pheromone receptor genes in males. In addition, we identified genes from all other chemosensory related gene families (13 chemosensory protein genes, 8 odorant binding protein genes, 2 sensory-neuron membrane protein genes, 7 ionotropic receptor genes, 2 gustatory receptor genes), and we found ant-specific expansions in the chemosensory protein gene family. In addition, a large number of genes involved in immune defense exhibited differential expression across the three different castes, and some genes even between the two worker subcastes.
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Affiliation(s)
- Sarah I. Koch
- Department of Biology, University of Konstanz, Konstanz, Germany
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Katrin Groh
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Heiko Vogel
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | - Bill S. Hannson
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
| | | | - Ewald Grosse-Wilde
- Department of Evolutionary Neuroethology, Max Planck Institute for Chemical Ecology, Jena, Germany
- * E-mail: (CJK); (EGW)
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Feldmeyer B, Elsner D, Foitzik S. Gene expression patterns associated with caste and reproductive status in ants: worker-specific genes are more derived than queen-specific ones. Mol Ecol 2013; 23:151-61. [PMID: 24118315 DOI: 10.1111/mec.12490] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 07/30/2013] [Accepted: 08/01/2013] [Indexed: 01/31/2023]
Abstract
Variation in gene expression leads to phenotypic diversity and plays a central role in caste differentiation of eusocial insect species. In social Hymenoptera, females with the same genetic background can develop into queens or workers, which are characterized by divergent morphologies, behaviours and lifespan. Moreover, many social insects exhibit behaviourally distinct worker castes, such as brood-tenders and foragers. Researchers have just started to explore which genes are differentially expressed to achieve this remarkable phenotypic plasticity. Although the queen is normally the only reproductive individual in the nest, following her removal, young brood-tending workers often develop ovaries and start to reproduce. Here, we make use of this ability in the ant Temnothorax longispinosus and compare gene expression patterns in the queens and three worker castes along a reproductive gradient. We found the largest expression differences between the queen and the worker castes (~2500 genes) and the smallest differences between infertile brood-tenders and foragers (~300 genes). The expression profile of fertile workers is more worker-like, but to a certain extent intermediate between the queen and the infertile worker castes. In contrast to the queen, a high number of differentially expressed genes in the worker castes are of unknown function, pointing to the derived status of hymenopteran workers within insects.
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Affiliation(s)
- B Feldmeyer
- Evolutionary Biology, Institute of Zoology, Johannes Gutenberg University Mainz, Johannes von Müller Weg 6, 55128, Mainz, Germany
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Scholes DR, Suarez AV, Paige KN. Can endopolyploidy explain body size variation within and between castes in ants? Ecol Evol 2013; 3:2128-37. [PMID: 23919157 PMCID: PMC3728952 DOI: 10.1002/ece3.623] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 04/30/2013] [Accepted: 05/06/2013] [Indexed: 11/13/2022] Open
Abstract
Endoreduplication is the process by which the nuclear genome is repeatedly replicated without mitotic cell division, resulting in nuclei that contain numerous additional genome copies. Endoreduplication occurs widely throughout Eucarya and is particularly common in angiosperms and insects. Although endoreduplication is an important process in the terminal differentiation of some specialized cell types, and often increases cell size and metabolism, the direct effects of increasing nuclear ploidy on cell function are not well resolved. Here, we examine if endoreduplication may play a role in body size and/or caste differentiation in ants. Nuclear ploidy was measured by flow cytometry of whole individuals (providing the basis for overall body size patterns) and individual body segments for multiple polymorphic ant species. We used cell cycle values, interpreted as the mean number of endocycles performed by each cell in the sample, as our measure of overall endoreduplication. Among females of four polymorphic ant species, endoreduplication was positively related with size within the worker caste, but was not related to caste generally in two species where we also examined queens. Additionally, abdomens had the greatest endoreduplication of all body parts regardless of caste or size. We also found that males, having derived from haploid unfertilized eggs, had the highest rates of endoreduplication and may compensate for their haploid origin by performing an additional endocycle relative to females. These results suggest that endoreduplication may play a role in body size variation in eusocial insects and the development of some segment-specific tissues.
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Affiliation(s)
- Daniel R Scholes
- Program in Ecology Evolution and Conservation Biology, University of Illinois at Urbana-Champaign 515 Morrill Hall, 505 S Goodwin Ave, Urbana, Illinois, 61801
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Jandt JM, Bengston S, Pinter-Wollman N, Pruitt JN, Raine NE, Dornhaus A, Sih A. Behavioural syndromes and social insects: personality at multiple levels. Biol Rev Camb Philos Soc 2013; 89:48-67. [PMID: 23672739 DOI: 10.1111/brv.12042] [Citation(s) in RCA: 205] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2012] [Revised: 04/09/2013] [Accepted: 04/17/2013] [Indexed: 11/28/2022]
Abstract
Animal personalities or behavioural syndromes are consistent and/or correlated behaviours across two or more situations within a population. Social insect biologists have measured consistent individual variation in behaviour within and across colonies for decades. The goal of this review is to illustrate the ways in which both the study of social insects and of behavioural syndromes has overlapped, and to highlight ways in which both fields can move forward through the synergy of knowledge from each. Here we, (i) review work to date on behavioural syndromes (though not always referred to as such) in social insects, and discuss mechanisms and fitness effects of maintaining individual behavioural variation within and between colonies; (ii) summarise approaches and principles from studies of behavioural syndromes, such as trade-offs, feedback, and statistical methods developed specifically to study behavioural consistencies and correlations, and discuss how they might be applied specifically to the study of social insects; (iii) discuss how the study of social insects can enhance our understanding of behavioural syndromes-research in behavioural syndromes is beginning to explore the role of sociality in maintaining or developing behavioural types, and work on social insects can provide new insights in this area; and (iv) suggest future directions for study, with an emphasis on examining behavioural types at multiple levels of organisation (genes, individuals, colonies, or groups of individuals).
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Affiliation(s)
- Jennifer M Jandt
- Department of Ecology, Evolutionary and Organismal Biology, Iowa State University, Ames, IA, 50011, USA
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Doums C, Cronin AL, Ruel C, Fédérici P, Haussy C, Tirard C, Monnin T. Facultative use of thelytokous parthenogenesis for queen production in the polyandrous ant Cataglyphis cursor. J Evol Biol 2013; 26:1431-44. [PMID: 23639217 DOI: 10.1111/jeb.12142] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 01/30/2013] [Accepted: 02/13/2013] [Indexed: 11/27/2022]
Abstract
The evolutionary paradox of sex remains one of the major debates in evolutionary biology. The study of species capable of both sexual and asexual reproduction can elucidate factors important in the evolution of sex. One such species is the ant Cataglyphis cursor, where the queen maximizes the transmission of her genes by producing new queens (gynes) asexually while simultaneously maintaining a genetically diverse workforce via the sexual production of workers. We show that the queen can also produce gynes sexually and may do so to offset the costs of asexual reproduction. We genotyped 235 gynes from 18 colonies and found that half were sexually produced. A few colonies contained both sexually and asexually produced gynes. Although workers in this species can also use thelytoky, we found no evidence of worker production of gynes based on genotypes of 471 workers from the six colonies producing sexual gynes. Gynes are thus mainly, and potentially exclusively, produced by the queen. Simulations of gynes inbreeding level following one to ten generations of automictic thelytoky suggest that the queen switches between or combines thelytoky and sex, which may reduce the costs of inbreeding. This is supported by the relatively small size of inbred gynes in one colony, although we found no relationship between the level of inbreeding and immune parameters. Such facultative use of sex and thelytoky by individual queens contrasts with other known forms of parthenogenesis in ants, which are typically characterized by distinct lineages specializing in one strategy or the other.
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Affiliation(s)
- C Doums
- Laboratoire Ecologie & Evolution CNRS UMR 7625, Université Pierre et Marie Curie, Paris, France.
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Holman L, Linksvayer TA, d'Ettorre P. Genetic constraints on dishonesty and caste dimorphism in an ant. Am Nat 2013; 181:161-70. [PMID: 23348771 DOI: 10.1086/668828] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The ultimate causes of honest signaling remain a subject of debate, with questions remaining over the relative importance of costs and constraints. Signal costs may make dishonesty prohibitively expensive, while genetic constraints could make it impossible. We investigated honest signaling using full-sib analysis and parent-offspring regression in the ant Lasius niger, in which queens produce a cuticular hydrocarbon-based pheromone that signals fertility and inhibits worker reproduction and aggression. We found multiple lines of evidence that cuticular hydrocarbon production is genetically correlated with oogenesis and that the queen pheromone 3-methylhentriacontane and other 3-methylalkanes have strong genetic links with fertility relative to other cuticular hydrocarbons. These genetic correlations may maintain honesty in the face of directional selection on signaling and explain the putatively widespread use of cuticular hydrocarbons in fertility signaling across the social insects. We also found evidence for a positive genetic correlation for fertility between the castes; that is, the most fertile queens produced especially fertile workers. These results highlight that intercaste genetic correlations could constrain the evolution of queen-worker dimorphism, such that worker reproduction may sometimes reflect a nonadaptive "caste load" rather than positively selected cheating.
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Affiliation(s)
- Luke Holman
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2200 Copenhagen, Denmark.
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Abstract
Social plasticity is a ubiquitous feature of animal behaviour. Animals must adjust the expression of their social behaviour to the nuances of daily social life and to the transitions between life-history stages, and the ability to do so affects their Darwinian fitness. Here, an integrative framework is proposed for understanding the proximate mechanisms and ultimate consequences of social plasticity. According to this framework, social plasticity is achieved by rewiring or by biochemically switching nodes of the neural network underlying social behaviour in response to perceived social information. Therefore, at the molecular level, it depends on the social regulation of gene expression, so that different brain genomic and epigenetic states correspond to different behavioural responses and the switches between states are orchestrated by signalling pathways that interface the social environment and the genotype. At the evolutionary scale, social plasticity can be seen as an adaptive trait that can be under positive selection when changes in the environment outpace the rate of genetic evolutionary change. In cases when social plasticity is too costly or incomplete, behavioural consistency can emerge by directional selection that recruits gene modules corresponding to favoured behavioural states in that environment. As a result of this integrative approach, how knowledge of the proximate mechanisms underlying social plasticity is crucial to understanding its costs, limits and evolutionary consequences is shown, thereby highlighting the fact that proximate mechanisms contribute to the dynamics of selection. The role of teleosts as a premier model to study social plasticity is also highlighted, given the diversity and plasticity that this group exhibits in terms of social behaviour. Finally, the proposed integrative framework to social plasticity also illustrates how reciprocal causation analysis of biological phenomena (i.e. considering the interaction between proximate factors and evolutionary explanations) can be a more useful approach than the traditional proximate-ultimate dichotomy, according to which evolutionary processes can be understood without knowledge on proximate causes, thereby black-boxing developmental and physiological mechanisms.
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Affiliation(s)
- R F Oliveira
- Unidade de Investigação em Eco-Etologia, ISPA - Instituto Universitário, Rua Jardim do Tabaco 34, 1149-041 Lisboa, Portugal.
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Transcriptome analysis of the Asian honey bee Apis cerana cerana. PLoS One 2012; 7:e47954. [PMID: 23112877 PMCID: PMC3480438 DOI: 10.1371/journal.pone.0047954] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 09/17/2012] [Indexed: 11/19/2022] Open
Abstract
Background The Eastern hive honey bee, Apis cerana cerana is a native and widely bred honey bee species in China. Molecular biology research about this honey bee species is scarce, and genomic information for A. c. cerana is not currently available. Transcriptome and expression profiling data for this species are therefore important resources needed to better understand the biological mechanisms of A. c. cerana. In this study, we obtained the transcriptome information of A. c. cerana by RNA-sequencing and compared gene expression differences between queens and workers of A. c. cerana by digital gene expression (DGE) analysis. Results Using high-throughput Illumina RNA sequencing we obtained 51,581,510 clean reads corresponding to 4.64 Gb total nucleotides from a single run. These reads were assembled into 46,999 unigenes with a mean length of 676 bp. Based on a sequence similarity search against the five public databases (NR, Swissport, GO, COG, KEGG) with a cut-off E-value of 10−5 using BLASTX, a total of 24,630 unigenes were annotated with gene descriptions, gene ontology terms, or metabolic pathways. Using these transcriptome data as references we analyzed the gene expression differences between the queens and workers of A. c. cerana using a tag-based digital gene expression method. We obtained 5.96 and 5.66 million clean tags from the queen and worker samples, respectively. A total of 414 genes were differentially expressed between them, with 189 up-regulated and 225 down-regulated in queens. Conclusions Our transcriptome data provide a comprehensive sequence resource for future A. c. cerana study, establishing an important public information platform for functional genomic studies in A. c. cerana. Furthermore, the DGE data provide comprehensive gene expression information for the queens and workers, which will facilitate our understanding of the molecular mechanisms of the different physiological aspects of the two castes.
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Taborsky B, Oliveira RF. Social competence: an evolutionary approach. Trends Ecol Evol 2012; 27:679-88. [PMID: 23040461 DOI: 10.1016/j.tree.2012.09.003] [Citation(s) in RCA: 255] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 09/05/2012] [Accepted: 09/06/2012] [Indexed: 01/03/2023]
Abstract
'Social competence' refers to the ability of an individual to optimise its social behaviour depending on available social information. Although such ability will enhance social interactions and thus raise Darwinian fitness, its evolutionary and ecological significance has been largely ignored. Social competence is based on behavioural flexibility. We propose that the study of social competence requires an integrative approach that aims to understand how the brain translates social information into flexible behavioural responses, how flexibility might be constrained by the developmental history of an individual or by trade-offs with other (ecological) competences, and how social plasticity feeds back on fitness. Finally we propose a hypothesis of how social competence can become a driver of social evolution.
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Affiliation(s)
- Barbara Taborsky
- Behavioural Ecology, Institute of Ecology and Evolution, University of Bern, Hinterkappelen, Switzerland.
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Senemorphism: a novel perspective on aging patterns and its implication for diet-related biology. Biogerontology 2012; 13:457-66. [PMID: 22555514 PMCID: PMC3407360 DOI: 10.1007/s10522-012-9383-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 04/20/2012] [Indexed: 01/08/2023]
Abstract
Aging can be described as the accumulation of changes in organisms over time. Aging in organisms undergoing caloric restriction (CR) is widely considered as a slowed version of aging under ad libitum (AL) conditions. However, here we argue that aging under optimized CR is fundamentally different from aging under AL based on the following facts: (1) Comparing the two dietary groups, several age-related changes run in the opposite direction over time; (2) Switching from an AL to a CR diet clearly reverts (not only delays) several "normal" accumulated changes; (3) major causes of death are as different between both groups as they are between species. These observations support the idea that CR and AL initially modulate different metabolic and physiological programs, which exclusively over time generate two biologically different organisms. Such distinct diet-related senescence is analogous to the divergent aging processes and causes of death observed between castes of social insects, such as queens versus workers ("caste-related-senescence") and also between breeding versus non-breeding semelparous animals ("reproduction-related-senescence"). All these aging phenotypes are different not because they accumulate changes at a different rate, but because they accumulate different changes over time. Thus, the environment does not simply affect the individual aging rate through stochastic effects (e.g. U.V.) but also modulates the activation of a particular program/strategy that influences lifespan (e.g. caste, calorie intake). We refer to the environment-dependent aging patterns encoded by the genome as "senemorphism". Based on this idea we propose experimental schemes for aging, evolution and biomedical research.
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OMETTO LINO, ROSS KENNETHG, SHOEMAKER D, KELLER LAURENT. Disruption of gene expression in hybrids of the fire antsSolenopsis invictaandSolenopsis richteri. Mol Ecol 2012; 21:2488-501. [DOI: 10.1111/j.1365-294x.2012.05544.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Colgan TJ, Carolan JC, Bridgett SJ, Sumner S, Blaxter ML, Brown MJ. Polyphenism in social insects: insights from a transcriptome-wide analysis of gene expression in the life stages of the key pollinator, Bombus terrestris. BMC Genomics 2011; 12:623. [PMID: 22185240 PMCID: PMC3276680 DOI: 10.1186/1471-2164-12-623] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Accepted: 12/20/2011] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Understanding polyphenism, the ability of a single genome to express multiple morphologically and behaviourally distinct phenotypes, is an important goal for evolutionary and developmental biology. Polyphenism has been key to the evolution of the Hymenoptera, and particularly the social Hymenoptera where the genome of a single species regulates distinct larval stages, sexual dimorphism and physical castes within the female sex. Transcriptomic analyses of social Hymenoptera will therefore provide unique insights into how changes in gene expression underlie such complexity. Here we describe gene expression in individual specimens of the pre-adult stages, sexes and castes of the key pollinator, the buff-tailed bumblebee Bombus terrestris. RESULTS cDNA was prepared from mRNA from five life cycle stages (one larva, one pupa, one male, one gyne and two workers) and a total of 1,610,742 expressed sequence tags (ESTs) were generated using Roche 454 technology, substantially increasing the sequence data available for this important species. Overlapping ESTs were assembled into 36,354 B. terrestris putative transcripts, and functionally annotated. A preliminary assessment of differences in gene expression across non-replicated specimens from the pre-adult stages, castes and sexes was performed using R-STAT analysis. Individual samples from the life cycle stages of the bumblebee differed in the expression of a wide array of genes, including genes involved in amino acid storage, metabolism, immunity and olfaction. CONCLUSIONS Detailed analyses of immune and olfaction gene expression across phenotypes demonstrated how transcriptomic analyses can inform our understanding of processes central to the biology of B. terrestris and the social Hymenoptera in general. For example, examination of immunity-related genes identified high conservation of important immunity pathway components across individual specimens from the life cycle stages while olfactory-related genes exhibited differential expression with a wider repertoire of gene expression within adults, especially sexuals, in comparison to immature stages. As there is an absence of replication across the samples, the results of this study are preliminary but provide a number of candidate genes which may be related to distinct phenotypic stage expression. This comprehensive transcriptome catalogue will provide an important gene discovery resource for directed programmes in ecology, evolution and conservation of a key pollinator.
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Affiliation(s)
- Thomas J Colgan
- Department of Zoology, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland.
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Duarte A, Weissing FJ, Pen I, Keller L. An Evolutionary Perspective on Self-Organized Division of Labor in Social Insects. ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2011. [DOI: 10.1146/annurev-ecolsys-102710-145017] [Citation(s) in RCA: 122] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Ana Duarte
- Department of Theoretical Biology, Center for Ecological and Evolutionary Studies, University of Groningen, Groningen, 9747 AG The Netherlands; , ,
| | - Franz J. Weissing
- Department of Theoretical Biology, Center for Ecological and Evolutionary Studies, University of Groningen, Groningen, 9747 AG The Netherlands; , ,
| | - Ido Pen
- Department of Theoretical Biology, Center for Ecological and Evolutionary Studies, University of Groningen, Groningen, 9747 AG The Netherlands; , ,
| | - Laurent Keller
- Department of Ecology and Evolution, University of Lausanne, Lausanne, CH-1015 Switzerland;
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Vitikainen E, Haag-Liautard C, Sundström L. INBREEDING AND REPRODUCTIVE INVESTMENT IN THE ANT FORMICA EXSECTA. Evolution 2011; 65:2026-37. [DOI: 10.1111/j.1558-5646.2011.01273.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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38
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Abstract
Ants have evolved very complex societies and are key ecosystem members. Some ants, such as the fire ant Solenopsis invicta, are also major pests. Here, we present a draft genome of S. invicta, assembled from Roche 454 and Illumina sequencing reads obtained from a focal haploid male and his brothers. We used comparative genomic methods to obtain insight into the unique features of the S. invicta genome. For example, we found that this genome harbors four adjacent copies of vitellogenin. A phylogenetic analysis revealed that an ancestral vitellogenin gene first underwent a duplication that was followed by possibly independent duplications of each of the daughter vitellogenins. The vitellogenin genes have undergone subfunctionalization with queen- and worker-specific expression, possibly reflecting differential selection acting on the queen and worker castes. Additionally, we identified more than 400 putative olfactory receptors of which at least 297 are intact. This represents the largest repertoire reported so far in insects. S. invicta also harbors an expansion of a specific family of lipid-processing genes, two putative orthologs to the transformer/feminizer sex differentiation gene, a functional DNA methylation system, and a single putative telomerase ortholog. EST data indicate that this S. invicta telomerase ortholog has at least four spliceforms that differ in their use of two sets of mutually exclusive exons. Some of these and other unique aspects of the fire ant genome are likely linked to the complex social behavior of this species.
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Ometto L, Shoemaker D, Ross KG, Keller L. Evolution of Gene Expression in Fire Ants: The Effects of Developmental Stage, Caste, and Species. Mol Biol Evol 2010; 28:1381-92. [DOI: 10.1093/molbev/msq322] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
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Ulrich Y, Sadd BM, Schmid-Hempel P. Strain filtering and transmission of a mixed infection in a social insect. J Evol Biol 2010; 24:354-62. [PMID: 21091570 DOI: 10.1111/j.1420-9101.2010.02172.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mixed-genotype infections have attracted considerable attention as drivers of pathogen evolution. However, experimental approaches often overlook essential features of natural host-parasite interactions, such as host heterogeneity, or the effects of between-host selection during transmission. Here, following inoculation of a mixed infection, we analyse the success of different strains of a trypanosome parasite throughout the colony cycle of its bumblebee host. We find that most colonies efficiently filter the circulating infection before it reaches the new queens, the only offspring that carry infections to the next season. A few colonies with a poor filtering ability thus contributed disproportionately to the parasite population in the next season. High strain diversity but not high infection intensity within colony was associated with an increased probability of transmission of the infection to new queens. Interestingly, the representation of the different strains changed dramatically over time, so that long-term parasite success could not be predicted from short-term observations. These findings highlight the shaping of within-colony parasite diversity through filtering as a crucial determinant of year-to-year pathogen transmission and emphasize the importance of host ecology and heterogeneity for disease dynamics.
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Affiliation(s)
- Y Ulrich
- ETH Zürich, Institute of Integrative Biology, Zürich, Switzerland.
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41
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Kawli T, He F, Tan MW. It takes nerves to fight infections: insights on neuro-immune interactions from C. elegans. Dis Model Mech 2010; 3:721-31. [PMID: 20829562 PMCID: PMC2965399 DOI: 10.1242/dmm.003871] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The innate immune response is evoked as a consequence of interactions between invading foreign infectious agents and host immune cells. A successful innate immune response is pivotal in maintaining the delicate balance between health and disease; an insufficient response results in infection, whereas an excessive response results in prolonged inflammation and tissue damage. Alterations in the state and function of the nervous system influence the immune response. The nervous system regulates innate immune responses through the release of neurotransmitters, neuropeptides and neurohormones. However, many questions related to the molecular and cellular mechanisms involved, the physiological role of the link between the immune and the nervous system, and the biological significance of neuro-immune interactions remain unresolved. The interactions between the nematode Caenorhabditis elegans and its pathogens provide insights into mechanisms of neuroendocrine regulation of immunity and address many outstanding issues related to neuro-immune interactions.
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Affiliation(s)
- Trupti Kawli
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 394305, USA
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Hunt BG, Goodisman MAD. Evolutionary variation in gene expression is associated with dimorphism in eusocial vespid wasps. INSECT MOLECULAR BIOLOGY 2010; 19:641-652. [PMID: 20546040 DOI: 10.1111/j.1365-2583.2010.01021.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Phenotypic diversity is frequently generated by differences in gene expression. In this study, we addressed the relationship between homology in gene expression and phenotype among four species of eusocial wasps. Specifically, we investigated the evolution of caste-specific and sex-specific gene expression patterns associated with caste polyphenisms and sexual dimorphisms. We also identified several genes with functions relevant to their phenotype-specific roles. Our results suggest that gene expression profiles associated with caste polyphenisms may evolve rapidly relative to those associated with sexes. Thus, caste-biased genes may undergo less regulatory constraint or be subject to greater neutral variation in expression than sex-biased genes.
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Affiliation(s)
- B G Hunt
- School of Biology, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Holman L, Jørgensen CG, Nielsen J, d'Ettorre P. Identification of an ant queen pheromone regulating worker sterility. Proc Biol Sci 2010; 277:3793-800. [PMID: 20591861 DOI: 10.1098/rspb.2010.0984] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The selective forces that shape and maintain eusocial societies are an enduring puzzle in evolutionary biology. Ordinarily sterile workers can usually reproduce given the right conditions, so the factors regulating reproductive division of labour may provide insight into why eusociality has persisted over evolutionary time. Queen-produced pheromones that affect worker reproduction have been implicated in diverse taxa, including ants, termites, wasps and possibly mole rats, but to date have only been definitively identified in the honeybee. Using the black garden ant Lasius niger, we isolate the first sterility-regulating ant queen pheromone. The pheromone is a cuticular hydrocarbon that comprises the majority of the chemical profile of queens and their eggs, and also affects worker behaviour, by reducing aggression towards objects bearing the pheromone. We further show that the pheromone elicits a strong response in worker antennae and that its production by queens is selectively reduced following an immune challenge. These results suggest that the pheromone has a central role in colony organization and support the hypothesis that worker sterility represents altruistic self-restraint in response to an honest quality signal.
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Affiliation(s)
- Luke Holman
- Centre for Social Evolution, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen, Denmark.
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Smith CR, Dolezal A, Eliyahu D, Holbrook CT, Gadau J. Ants (Formicidae): models for social complexity. Cold Spring Harb Protoc 2010; 2009:pdb.emo125. [PMID: 20147200 DOI: 10.1101/pdb.emo125] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The family Formicidae (ants) is composed of more than 12,000 described species that vary greatly in size, morphology, behavior, life history, ecology, and social organization. Ants occur in most terrestrial habitats and are the dominant animals in many of them. They have been used as models to address fundamental questions in ecology, evolution, behavior, and development. The literature on ants is extensive, and the natural history of many species is known in detail. Phylogenetic relationships for the family, as well as within many subfamilies, are known, enabling comparative studies. Their ease of sampling and ecological variation makes them attractive for studying populations and questions relating to communities. Their sociality and variation in social organization have contributed greatly to an understanding of complex systems, division of labor, and chemical communication. Ants occur in colonies composed of tens to millions of individuals that vary greatly in morphology, physiology, and behavior; this variation has been used to address proximate and ultimate mechanisms generating phenotypic plasticity. Relatedness asymmetries within colonies have been fundamental to the formulation and empirical testing of kin and group selection theories. Genomic resources have been developed for some species, and a whole-genome sequence for several species is likely to follow in the near future; comparative genomics in ants should provide new insights into the evolution of complexity and sociogenomics. Future studies using ants should help establish a more comprehensive understanding of social life, from molecules to colonies.
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Affiliation(s)
- Chris R Smith
- School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA.
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Koshikawa S, Cornette R, Matsumoto T, Miura T. The homolog of Ciboulot in the termite (Hodotermopsis sjostedti): a multimeric beta-thymosin involved in soldier-specific morphogenesis. BMC DEVELOPMENTAL BIOLOGY 2010; 10:63. [PMID: 20529303 PMCID: PMC2896938 DOI: 10.1186/1471-213x-10-63] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Accepted: 06/08/2010] [Indexed: 11/23/2022]
Abstract
Background Caste differentiation in social insects is a type of polyphenism that enables division of labor among members of a colony. This elaborate social integration has attracted broad interest, although little is known about its regulatory mechanisms, especially in Isoptera (termites). In this study, we analyzed soldier differentiation in the damp-wood termite Hodotermopsis sjostedti, focusing on a possible effector gene for caste development. The gene for an actin-binding protein, HsjCib, which shows a high level of expression in developing mandibles during soldier differentiation, is characterized in detail. Results To examine the HsjCib gene, full-length cDNAs were obtained by rapid amplification of cDNA ends-polymerase chain reaction (RACE-PCR) and sequencing. Multiple isoforms were identified, and on the basis of the results of northern and Southern hybridization analyses, these isoforms were considered to be transcriptional variants from a single gene. On the basis of their sequence similarity to homologous genes of other organisms, functions in actin assembly were assumed to be different among isoforms. Expression analysis revealed high expression in the head during soldier differentiation, which was consistent with their allometric growth. Although isoform expression was observed in various tissues, different expression levels were observed among tissues, suggesting the possibility of tissue-specific morphogenetic regulation by HsjCib isoforms. Conclusion This study revealed the characteristics and dynamics of the HsjCib gene during soldier differentiation as a potential representative of downstream effector genes in caste-specific morphogenesis. From the expression patterns observed, this gene is considered to be involved in cephalic morphogenesis and neural reorganization, resulting in the establishment of caste-specific morphology and behavior.
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Affiliation(s)
- Shigeyuki Koshikawa
- Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810, Japan
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Toth AL, Varala K, Henshaw MT, Rodriguez-Zas SL, Hudson ME, Robinson GE. Brain transcriptomic analysis in paper wasps identifies genes associated with behaviour across social insect lineages. Proc Biol Sci 2010; 277:2139-48. [PMID: 20236980 DOI: 10.1098/rspb.2010.0090] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Comparative sociogenomics has the potential to provide important insights into how social behaviour evolved. We examined brain gene expression profiles of the primitively eusocial wasp Polistes metricus and compared the results with a growing base of brain gene expression information for the advanced eusocial honeybee, Apis mellifera. We studied four female wasp groups that show variation in foraging/provisioning behaviour and reproductive status, using our newly developed microarray representing approximately 3248 P. metricus genes based on sequences generated from high-throughput pyrosequencing. We found differences in the expression of approximately 389 genes across the four groups. Pathways known from Drosophila melanogaster to be related to lipid metabolism, heat and stress response, and various forms of solitary behaviour were associated with behavioural differences among wasps. Forty-five per cent of differentially expressed transcripts showed significant associations with foraging/provisioning status, and 14 per cent with reproductive status. By comparing these two gene lists with lists of genes previously shown to be differentially expressed in association with honeybee division of labour, we found a significant overlap of genes associated with foraging/provisioning, but not reproduction, across the two species. These results suggest common molecular roots for foraging division of labour in two independently evolved social insect species and the possibility of more lineage-specific roots of reproductive behaviour. We explore the implications of these findings for the idea that there is a conserved 'genetic toolkit' for division of labour across multiple lineages.
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Affiliation(s)
- Amy L Toth
- Institute for Genomic Biology, University of Illinois, Urbana-Champaign, IL, USA.
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Wurm Y, Wang J, Keller L. Changes in reproductive roles are associated with changes in gene expression in fire ant queens. Mol Ecol 2010; 19:1200-11. [PMID: 20163551 DOI: 10.1111/j.1365-294x.2010.04561.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In species with social hierarchies, the death of dominant individuals typically upheaves the social hierarchy and provides an opportunity for subordinate individuals to become reproductives. Such a phenomenon occurs in the monogyne form of the fire ant, Solenopsis invicta, where colonies typically contain a single wingless reproductive queen, thousands of workers and hundreds of winged nonreproductive virgin queens. Upon the death of the mother queen, many virgin queens shed their wings and initiate reproductive development instead of departing on a mating flight. Workers progressively execute almost all of them over the following weeks. To identify the molecular changes that occur in virgin queens as they perceive the loss of their mother queen and begin to compete for reproductive dominance, we collected virgin queens before the loss of their mother queen, 6 h after orphaning and 24 h after orphaning. Their RNA was extracted and hybridized against microarrays to examine the expression levels of approximately 10,000 genes. We identified 297 genes that were consistently differentially expressed after orphaning. These include genes that are putatively involved in the signalling and onset of reproductive development, as well as genes underlying major physiological changes in the young queens.
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Affiliation(s)
- Yannick Wurm
- Department of Ecology and Evolution, Biophore, University of Lausanne, 1015 Lausanne, Switzerland.
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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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Abstract
A recent workshop held at the Arizona State University Center for Social Dynamics and Complexity gathered over 50 prominent researchers from around the globe to discuss the development of genomic resources for several ant species. Ants play crucial roles in many ecological niches and the sequencing of several ant genomes promises to elucidate topics ranging from the genetic basis for social complexity, longevity and behaviour to systems biology and the identification of novel antimicrobial compounds. Unlike other species, most ant genomes are being generated by individual labs and small collaborations without the annotation and computational resources that support prominent model organism genome databases such those for the fruitfly and roundworm. Attendees summarized their current progress and future plans for several ant genomes and discussed how best to coordinate the analysis and annotation of ant sequences to benefit the broad research interests of the social insect community.
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Weil T, Korb J, Rehli M. Comparison of queen-specific gene expression in related lower termite species. Mol Biol Evol 2009; 26:1841-50. [PMID: 19541881 DOI: 10.1093/molbev/msp095] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The molecular mechanisms regulating caste determination and reproductive division of labor, the hallmarks of insect societies, are poorly defined. The identification of key genes involved in these developmentally important processes will be essential to gain a better understanding of the mechanisms controlling one of the most impressive examples of polyphenism, the caste structure of eusocial species. Here, we applied representational difference analysis of cDNAs, to study differential gene expression between queens (female neotenics) and workers in the dry wood termite Cryptotermes cynocephalus and identified 13 genes that were highly expressed in queens. In addition, we partially cloned several homologous genes of the related termite species Cryptotermes secundus and compared the expression profiles of 10 homologous genes. In most cases, the preferential expression in female neotenics was not conserved between species, despite the close phylogenetic relationship of both Cryptotermes species. It is possible that these genes are associated with known species-specific differences in caste development modes. Only three genes (Neofem1, 2, and 3) showed a conserved and highly preferential expression in female neotenics, suggesting that their products may play important roles in female reproductives, in particular in controlling caste determination and reproductive division of labor.
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Affiliation(s)
- Tobias Weil
- Biology I, University of Regensburg, Regensburg, Germany
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