1
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Peled O, Greenbaum G, Bloch G. Diversification of social complexity following a major evolutionary transition in bees. Curr Biol 2025; 35:981-993.e5. [PMID: 39933519 DOI: 10.1016/j.cub.2025.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2024] [Revised: 10/16/2024] [Accepted: 01/07/2025] [Indexed: 02/13/2025]
Abstract
How social complexity evolved remains a long-standing enigma. In most animal groups, social complexity is typically classified into a few discrete classes. This approach is oversimplified and constrains our inference of social evolution to a narrow trajectory consisting of transitions between classes. Such categorical classifications also limit quantitative studies on the molecular and environmental drivers of social complexity. The recent accumulation of relevant quantitative data has set the stage to overcome these limitations. Here, we propose a data-driven, high-dimensional approach for studying the full diversity of social phenotypes. We curated and analyzed a comprehensive dataset encompassing 17 social traits across 80 species and studied the evolution of social complexity in bees. We found that honey bees, stingless bees, and bumble bees underwent a major evolutionary transition ∼80 mya, inconsistent with the stepwise progression of the social ladder conceptual framework. This major evolutionary transition was followed by a phase of substantial phenotypic diversification of social complexity. Other bee lineages display a continuum of social complexity, ranging from solitary to simple societies, but do not reach the levels of social complexity seen in honey bees, stingless bees, and bumble bees. Bee evolution, therefore, provides a remarkable demonstration of a macroevolutionary process in which a major transition removed biological constraints and opened novel evolutionary opportunities, driving the exploration of the landscape of social phenotypes. Our approach can be extended to incorporate additional data types and readily applied to illuminate the evolution of social complexity in other animal groups.
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Affiliation(s)
- Ohad Peled
- Department of Ecology, Evolution, and Behavior, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Gili Greenbaum
- Department of Ecology, Evolution, and Behavior, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
| | - Guy Bloch
- Department of Ecology, Evolution, and Behavior, The Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
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2
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Brenman-Suttner DB, Rehan SM, Zayed A. Exploring the genetics of social behaviour in C. calcarata. Sci Rep 2025; 15:5580. [PMID: 39955334 PMCID: PMC11830030 DOI: 10.1038/s41598-025-89870-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2024] [Accepted: 02/10/2025] [Indexed: 02/17/2025] Open
Abstract
Studies investigating social evolution often focus on species that are obligately eusocial, where presumably all of the adaptive genetic changes associated with sociality have already been completed. To fully understand eusociality, we must study species with facultative social behaviour. The small carpenter bee Ceratina calcarata is an ideal model for studying the genetics and molecular biology of eusocial evolution as it can exhibit both subsocial behaviour with parental care and social behaviour facilitated by the altruistic dwarf eldest daughter. Here, we sequenced the genomes of subsocial and social C. calcarata to identify mutations and genes associated with social behaviour and used these data to test several hypotheses related to the evolution of eusociality. Many single nucleotide polymorphisms that had high levels of genetic differentiation (Fst) between social and subsocial C. calcarata were in or near genes or regions important for regulating gene expression. These results are consistent with the Genetic Toolkit Hypothesis of eusocial evolution. Our findings suggest that the low behavioural complexity observed in C. calcarata may involve modulation of existing regulatory genes and gene networks to generate phenotypes associated with social behaviour.
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Affiliation(s)
| | - Sandra M Rehan
- Department of Biology, York University, Toronto, ON, Canada
| | - Amro Zayed
- Department of Biology, York University, Toronto, ON, Canada.
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3
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Abstract
The evolution of eusociality in Hymenoptera-encompassing bees, ants, and wasps-is characterized by multiple gains and losses of social living, making this group a prime model to understand the mechanisms that underlie social behavior and social complexity. Our review synthesizes insights into the evolutionary history and molecular basis of eusociality. We examine new evidence for key evolutionary hypotheses and molecular pathways that regulate social behaviors, highlighting convergent evolution on a shared molecular toolkit that includes the insulin/insulin-like growth factor signaling (IIS) and target of rapamycin (TOR) pathways, juvenile hormone and ecdysteroid signaling, and epigenetic regulation. We emphasize how the crosstalk among these nutrient-sensing and endocrine signaling pathways enables social insects to integrate external environmental stimuli, including social cues, with internal physiology and behavior. We argue that examining these pathways as an integrated regulatory circuit and exploring how the regulatory architecture of this circuit evolves alongside eusociality can open the door to understanding the origin of the complex life histories and behaviors of this group.
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Affiliation(s)
- Sarah Kocher
- Department of Ecology and Evolutionary Biology, Lewis-Sigler Institute for Integrative Biology, and Howard Hughes Medical Institute, Princeton University, Princeton, New Jersey, USA;
| | - Callum Kingwell
- Smithsonian Tropical Research Institute, Ancon, Panama
- Department of Ecology and Evolutionary Biology, Lewis-Sigler Institute for Integrative Biology, and Howard Hughes Medical Institute, Princeton University, Princeton, New Jersey, USA;
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4
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Zhang H, Liu Z, Huang X. Social aphids: emerging model for studying insect sociality. CURRENT OPINION IN INSECT SCIENCE 2024; 64:101205. [PMID: 39084848 DOI: 10.1016/j.cois.2024.101205] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/14/2024] [Accepted: 05/05/2024] [Indexed: 08/02/2024]
Abstract
Sociality is also evolved in parthenogenetic herbivorous hemipteran aphids, encompassing species with complex life history traits and significant social diversity. Owing to their interesting biological characteristics comparing to other social insect groups, social aphids can be a good model for studying insect sociality. Here, we review the species, behavior, and trait diversity of social aphids, and present recent findings on environmental, physiological, and molecular regulations of caste differentiation and behavior in social aphids. We propose the unique value of social aphids in investigating the evolution and mechanisms of insect sociality as well as future research directions using the social aphid model, including social evolution, caste differentiation, behavioral polymorphism, morphological plasticity, physical mechanics, and interspecific interactions.
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Affiliation(s)
- Hui Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China; Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China
| | - Zhixiang Liu
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China
| | - Xiaolei Huang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China.
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5
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Mikhailova AA, Dohmen E, Harrison MC. Major changes in domain arrangements are associated with the evolution of termites. J Evol Biol 2024; 37:758-769. [PMID: 38630634 DOI: 10.1093/jeb/voae047] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 12/18/2023] [Accepted: 04/12/2024] [Indexed: 04/19/2024]
Abstract
Domains as functional protein units and their rearrangements along the phylogeny can shed light on the functional changes of proteomes associated with the evolution of complex traits like eusociality. This complex trait is associated with sterile soldiers and workers, and long-lived, highly fecund reproductives. Unlike in Hymenoptera (ants, bees, and wasps), the evolution of eusociality within Blattodea, where termites evolved from within cockroaches, was accompanied by a reduction in proteome size, raising the question of whether functional novelty was achieved with existing rather than novel proteins. To address this, we investigated the role of domain rearrangements during the evolution of termite eusociality. Analysing domain rearrangements in the proteomes of three solitary cockroaches and five eusocial termites, we inferred more than 5,000 rearrangements over the phylogeny of Blattodea. The 90 novel domain arrangements that emerged at the origin of termites were enriched for several functions related to longevity, such as protein homeostasis, DNA repair, mitochondrial activity, and nutrient sensing. Many domain rearrangements were related to changes in developmental pathways, important for the emergence of novel castes. Along with the elaboration of social complexity, including permanently sterile workers and larger, foraging colonies, we found 110 further domain arrangements with functions related to protein glycosylation and ion transport. We found an enrichment of caste-biased expression and splicing within rearranged genes, highlighting their importance for the evolution of castes. Furthermore, we found increased levels of DNA methylation among rearranged compared to non-rearranged genes suggesting fundamental differences in their regulation. Our findings indicate the importance of domain rearrangements in the generation of functional novelty necessary for termite eusociality to evolve.
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Affiliation(s)
- Alina A Mikhailova
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Elias Dohmen
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Mark C Harrison
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
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6
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Ewart KM, Ho SYW, Chowdhury AA, Jaya FR, Kinjo Y, Bennett J, Bourguignon T, Rose HA, Lo N. Pervasive relaxed selection in termite genomes. Proc Biol Sci 2024; 291:20232439. [PMID: 38772424 DOI: 10.1098/rspb.2023.2439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 05/02/2024] [Indexed: 05/23/2024] Open
Abstract
Genetic changes that enabled the evolution of eusociality have long captivated biologists. More recently, attention has focussed on the consequences of eusociality on genome evolution. Studies have reported higher molecular evolutionary rates in eusocial hymenopteran insects compared with their solitary relatives. To investigate the genomic consequences of eusociality in termites, we analysed nine genomes, including newly sequenced genomes from three non-eusocial cockroaches. Using a phylogenomic approach, we found that termite genomes have experienced lower rates of synonymous substitutions than those of cockroaches, possibly as a result of longer generation times. We identified higher rates of non-synonymous substitutions in termite genomes than in cockroach genomes, and identified pervasive relaxed selection in the former (24-31% of the genes analysed) compared with the latter (2-4%). We infer that this is due to reductions in effective population size, rather than gene-specific effects (e.g. indirect selection of caste-biased genes). We found no obvious signature of increased genetic load in termites, and postulate efficient purging of deleterious alleles at the colony level. Additionally, we identified genomic adaptations that may underpin caste differentiation, such as genes involved in post-translational modifications. Our results provide insights into the evolution of termites and the genomic consequences of eusociality more broadly.
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Affiliation(s)
- Kyle M Ewart
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Simon Y W Ho
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Al-Aabid Chowdhury
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Frederick R Jaya
- Ecology & Evolution, Research School of Biology, Australian National University, Acton, Australian Capital Territory, Australia
| | - Yukihiro Kinjo
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
- Okinawa International University, Okinawa, Japan
| | - Juno Bennett
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Thomas Bourguignon
- Okinawa Institute of Science and Technology Graduate University, Okinawa, Japan
| | - Harley A Rose
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
| | - Nathan Lo
- School of Life and Environmental Sciences, University of Sydney, Sydney, New South Wales, Australia
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7
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Pyenson BC, Rehan SM. Gene regulation supporting sociality shared across lineages and variation in complexity. Genome 2024; 67:99-108. [PMID: 38096504 DOI: 10.1139/gen-2023-0054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
Across evolutionary lineages, insects vary in social complexity, from those that exhibit extended parental care to those with elaborate divisions of labor. Here, we synthesize the sociogenomic resources from hundreds of species to describe common gene regulatory mechanisms in insects that regulate social organization across phylogeny and levels of social complexity. Different social phenotypes expressed by insects can be linked to the organization of co-expressing gene networks and features of the epigenetic landscape. Insect sociality also stems from processes like the emergence of parental care and the decoupling of ancestral genetic programs. One underexplored avenue is how variation in a group's social environment affects the gene expression of individuals. Additionally, an experimental reduction of gene expression would demonstrate how the activity of specific genes contributes to insect social phenotypes. While tissue specificity provides greater localization of the gene expression underlying social complexity, emerging transcriptomic analysis of insect brains at the cellular level provides even greater resolution to understand the molecular basis of social insect evolution.
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Affiliation(s)
| | - Sandra M Rehan
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada
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8
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Bastide H, Legout H, Dogbo N, Ogereau D, Prediger C, Carcaud J, Filée J, Garnery L, Gilbert C, Marion-Poll F, Requier F, Sandoz JC, Yassin A. The genome of the blind bee louse fly reveals deep convergences with its social host and illuminates Drosophila origins. Curr Biol 2024; 34:1122-1132.e5. [PMID: 38309271 DOI: 10.1016/j.cub.2024.01.034] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 10/22/2023] [Accepted: 01/12/2024] [Indexed: 02/05/2024]
Abstract
Social insects' nests harbor intruders known as inquilines,1 which are usually related to their hosts.2,3 However, distant non-social inquilines may also show convergences with their hosts,4,5 although the underlying genomic changes remain unclear. We analyzed the genome of the wingless and blind bee louse fly Braula coeca, an inquiline kleptoparasite of the western honey bee, Apis mellifera.6,7 Using large phylogenomic data, we confirmed recent accounts that the bee louse fly is a drosophilid8,9 and showed that it had likely evolved from a sap-breeder ancestor associated with honeydew and scale insects' wax. Unlike many parasites, the bee louse fly genome did not show significant erosion or strict reliance on an endosymbiont, likely due to a relatively recent age of inquilinism. However, we observed a horizontal transfer of a transposon and a striking parallel evolution in a set of gene families between the honey bee and the bee louse fly. Convergences included genes potentially involved in metabolism and immunity and the loss of nearly all bitter-tasting gustatory receptors, in agreement with life in a protective nest and a diet of honey, pollen, and beeswax. Vision and odorant receptor genes also exhibited rapid losses. Only genes whose orthologs in the closely related Drosophila melanogaster respond to honey bee pheromone components or floral aroma were retained, whereas the losses included orthologous receptors responsive to the anti-ovarian honey bee queen pheromones. Hence, deep genomic convergences can underlie major phenotypic transitions during the evolution of inquilinism between non-social parasites and their social hosts.
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Affiliation(s)
- Héloïse Bastide
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France.
| | - Hélène Legout
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Noé Dogbo
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - David Ogereau
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Carolina Prediger
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Julie Carcaud
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Jonathan Filée
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Lionel Garnery
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Clément Gilbert
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Frédéric Marion-Poll
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France; Université Paris-Saclay, AgroParisTech, 91123 Palaiseau Cedex, France
| | - Fabrice Requier
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Jean-Christophe Sandoz
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
| | - Amir Yassin
- Université Paris-Saclay, CNRS, IRD, UMR Évolution, Génomes, Comportement et Écologie, 91198 Gif-sur-Yvette, France
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9
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Mikhailova AA, Rinke S, Harrison MC. Genomic signatures of eusocial evolution in insects. CURRENT OPINION IN INSECT SCIENCE 2024; 61:101136. [PMID: 37922983 DOI: 10.1016/j.cois.2023.101136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 10/27/2023] [Accepted: 10/28/2023] [Indexed: 11/07/2023]
Abstract
The genomes of eusocial insects allow the production and regulation of highly distinct phenotypes, largely independent of genotype. Although rare, eusociality has evolved convergently in at least three insect orders (Hymenoptera, Blattodea and Coleoptera). Despite such disparate origins, eusocial phenotypes show remarkable similarity, exhibiting long-lived reproductives and short-lived sterile workers and soldiers. In this article, we review current knowledge on genomic signatures of eusocial evolution. We confirm that especially an increased regulatory complexity and the adaptive evolution of chemical communication are common to several origins of eusociality. Furthermore, colony life itself can shape genomes of divergent taxa in a similar manner. Future research should be geared towards generating more high-quality genomic resources, especially in hitherto understudied clades, such as ambrosia beetles and termites. The application of more sophisticated tools such as machine learning techniques may allow the detection of more subtle convergent genomic footprints of eusociality.
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Affiliation(s)
- Alina A Mikhailova
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasße 1, 48149 Münster, Germany
| | - Sarah Rinke
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasße 1, 48149 Münster, Germany
| | - Mark C Harrison
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasße 1, 48149 Münster, Germany.
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10
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Feldmeyer B, Bornberg-Bauer E, Dohmen E, Fouks B, Heckenhauer J, Huylmans AK, Jones ARC, Stolle E, Harrison MC. Comparative Evolutionary Genomics in Insects. Methods Mol Biol 2024; 2802:473-514. [PMID: 38819569 DOI: 10.1007/978-1-0716-3838-5_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2024]
Abstract
Genome sequencing quality, in terms of both read length and accuracy, is constantly improving. By combining long-read sequencing technologies with various scaffolding techniques, chromosome-level genome assemblies are now achievable at an affordable price for non-model organisms. Insects represent an exciting taxon for studying the genomic underpinnings of evolutionary innovations, due to ancient origins, immense species-richness, and broad phenotypic diversity. Here we summarize some of the most important methods for carrying out a comparative genomics study on insects. We describe available tools and offer concrete tips on all stages of such an endeavor from DNA extraction through genome sequencing, annotation, and several evolutionary analyses. Along the way we describe important insect-specific aspects, such as DNA extraction difficulties or gene families that are particularly difficult to annotate, and offer solutions. We describe results from several examples of comparative genomics analyses on insects to illustrate the fascinating questions that can now be addressed in this new age of genomics research.
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Affiliation(s)
- Barbara Feldmeyer
- Senckenberg Biodiversity and Climate Research Centre (SBiK-F), Molecular Ecology, Frankfurt, Germany
| | - Erich Bornberg-Bauer
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
- Department of Protein Evolution, Max Planck Institute for Developmental Biology, Tübingen, Germany
| | - Elias Dohmen
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Bertrand Fouks
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Jacqueline Heckenhauer
- LOEWE Centre for Translational Biodiversity Genomics (LOEWE-TBG), Frankfurt, Germany
- Department of Terrestrial Zoology, Senckenberg Research Institute and Natural History Museum Frankfurt, Frankfurt, Germany
| | - Ann Kathrin Huylmans
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University, Mainz, Germany
| | - Alun R C Jones
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Eckart Stolle
- Museum Koenig, Leibniz Institute for the Analysis of Biodiversity Change (LIB), Bonn, Germany
| | - Mark C Harrison
- Institute for Evolution and Biodiversity, University of Münster, Münster, Germany.
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11
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Favreau E, Cini A, Taylor D, Câmara Ferreira F, Bentley MA, Cappa F, Cervo R, Privman E, Schneider J, Thiéry D, Mashoodh R, Wyatt CDR, Brown RL, Bodrug-Schepers A, Stralis-Pavese N, Dohm JC, Mead D, Himmelbauer H, Guigo R, Sumner S. Putting hornets on the genomic map. Sci Rep 2023; 13:6232. [PMID: 37085574 PMCID: PMC10121689 DOI: 10.1038/s41598-023-31932-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Accepted: 03/20/2023] [Indexed: 04/23/2023] Open
Abstract
Hornets are the largest of the social wasps, and are important regulators of insect populations in their native ranges. Hornets are also very successful as invasive species, with often devastating economic, ecological and societal effects. Understanding why these wasps are such successful invaders is critical to managing future introductions and minimising impact on native biodiversity. Critical to the management toolkit is a comprehensive genomic resource for these insects. Here we provide the annotated genomes for two hornets, Vespa crabro and Vespa velutina. We compare their genomes with those of other social Hymenoptera, including the northern giant hornet Vespa mandarinia. The three hornet genomes show evidence of selection pressure on genes associated with reproduction, which might facilitate the transition into invasive ranges. Vespa crabro has experienced positive selection on the highest number of genes, including those putatively associated with molecular binding and olfactory systems. Caste-specific brain transcriptomic analysis also revealed 133 differentially expressed genes, some of which are associated with olfactory functions. This report provides a spring-board for advancing our understanding of the evolution and ecology of hornets, and opens up opportunities for using molecular methods in the future management of both native and invasive populations of these over-looked insects.
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Affiliation(s)
- Emeline Favreau
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK.
| | - Alessandro Cini
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
- Department of Biology, Università di Pisa, Via Volta 6, 56126, Pisa, Italy
| | - Daisy Taylor
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
| | | | - Michael A Bentley
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
| | - Federico Cappa
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino, Florence, Italy
| | - Rita Cervo
- Department of Biology, University of Florence, Via Madonna del Piano 6, 50019, Sesto Fiorentino, Florence, Italy
| | - Eyal Privman
- Department of Evolutionary and Environmental Biology, Institute of Evolution, University of Haifa, Abba Hushi 199, 3498838, Haifa, Israel
| | - Jadesada Schneider
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
| | - Denis Thiéry
- INRAe, UMR 1065 Santé et Agroécologie du Vignoble, Bordeaux Sciences Agro, ISVV, Université de Bordeaux, 33883, Villenave d'Ornon, France
| | - Rahia Mashoodh
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
| | - Christopher D R Wyatt
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK
| | - Robert L Brown
- Manaaki Whenua - Landcare Research, 54 Gerald Street, Lincoln, 7608, New Zealand
| | - Alexandrina Bodrug-Schepers
- Department of Biotechnology, Institute of Computational Biology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190, Vienna, Austria
| | - Nancy Stralis-Pavese
- Department of Biotechnology, Institute of Computational Biology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190, Vienna, Austria
| | - Juliane C Dohm
- Department of Biotechnology, Institute of Computational Biology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190, Vienna, Austria
| | - Daniel Mead
- Tree of Life Programme, Wellcome Sanger Institute, Hinxton, CB10 1SA, UK
| | - Heinz Himmelbauer
- Department of Biotechnology, Institute of Computational Biology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18, 1190, Vienna, Austria
| | - Roderic Guigo
- Centre for Genomic Regulation, Dr. Aiguader 88, 08003, Barcelona, Spain
- Universitat Pompeu Fabra, Barcelona, Spain
| | - Seirian Sumner
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London, WC1E 6BT, UK.
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12
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Sumner S, Favreau E, Geist K, Toth AL, Rehan SM. Molecular patterns and processes in evolving sociality: lessons from insects. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220076. [PMID: 36802779 PMCID: PMC9939270 DOI: 10.1098/rstb.2022.0076] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2022] [Accepted: 09/16/2022] [Indexed: 02/21/2023] Open
Abstract
Social insects have provided some of the clearest insights into the origins and evolution of collective behaviour. Over 20 years ago, Maynard Smith and Szathmáry defined the most complex form of insect social behaviour-superorganismality-among the eight major transitions in evolution that explain the emergence of biological complexity. However, the mechanistic processes underlying the transition from solitary life to superorganismal living in insects remain rather elusive. An overlooked question is whether this major transition arose via incremental or step-wise modes of evolution. We suggest that examination of the molecular processes underpinning different levels of social complexity represented across the major transition from solitary to complex sociality can help address this question. We present a framework for using molecular data to assess to what extent the mechanistic processes that take place in the major transition to complex sociality and superorganismality involve nonlinear (implying step-wise evolution) or linear (implying incremental evolution) changes in the underlying molecular mechanisms. We assess the evidence for these two modes using data from social insects and discuss how this framework can be used to test the generality of molecular patterns and processes across other major transitions. This article is part of a discussion meeting issue 'Collective behaviour through time'.
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Affiliation(s)
- Seirian Sumner
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Emeline Favreau
- Centre for Biodiversity and Environmental Research, Department of Genetics, Evolution and Environment, University College London, Gower Street, London WC1E 6BT, UK
| | - Katherine Geist
- Department of Ecology, Evolution and Organismal Biology, and Department of Entomology, Iowa State University, Ames, IA 50011, USA
| | - Amy L. Toth
- Department of Ecology, Evolution and Organismal Biology, and Department of Entomology, Iowa State University, Ames, IA 50011, USA
| | - Sandra M. Rehan
- Department of Biology, York University, Toronto, Canada M3J 1P3
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Wyatt CDR, Bentley MA, Taylor D, Favreau E, Brock RE, Taylor BA, Bell E, Leadbeater E, Sumner S. Social complexity, life-history and lineage influence the molecular basis of castes in vespid wasps. Nat Commun 2023; 14:1046. [PMID: 36828829 PMCID: PMC9958023 DOI: 10.1038/s41467-023-36456-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Accepted: 01/31/2023] [Indexed: 02/26/2023] Open
Abstract
A key mechanistic hypothesis for the evolution of division of labour in social insects is that a shared set of genes co-opted from a common solitary ancestral ground plan (a genetic toolkit for sociality) regulates caste differentiation across levels of social complexity. Using brain transcriptome data from nine species of vespid wasps, we test for overlap in differentially expressed caste genes and use machine learning models to predict castes using different gene sets. We find evidence of a shared genetic toolkit across species representing different levels of social complexity. We also find evidence of additional fine-scale differences in predictive gene sets, functional enrichment and rates of gene evolution that are related to level of social complexity, lineage and of colony founding. These results suggest that the concept of a shared genetic toolkit for sociality may be too simplistic to fully describe the process of the major transition to sociality.
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Affiliation(s)
- Christopher Douglas Robert Wyatt
- Centre for Biodiversity and Environment Research, Dept Genetics, Evolution & Environment, University College London, London, WC1E 6BT, UK.
| | - Michael Andrew Bentley
- Centre for Biodiversity and Environment Research, Dept Genetics, Evolution & Environment, University College London, London, WC1E 6BT, UK
| | - Daisy Taylor
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
| | - Emeline Favreau
- Centre for Biodiversity and Environment Research, Dept Genetics, Evolution & Environment, University College London, London, WC1E 6BT, UK
| | - Ryan Edward Brock
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
- Department of Crop Genetics, John Innes Centre, Norwich Research Park, Norwich, Norfolk, NR4 7UH, UK
| | - Benjamin Aaron Taylor
- Centre for Biodiversity and Environment Research, Dept Genetics, Evolution & Environment, University College London, London, WC1E 6BT, UK
| | - Emily Bell
- School of Biological Sciences, University of Bristol, Bristol, BS8 1TQ, UK
| | - Ellouise Leadbeater
- Department of Biological Sciences, Royal Holloway University of London, Egham, TW20 0EX, UK
| | - Seirian Sumner
- Centre for Biodiversity and Environment Research, Dept Genetics, Evolution & Environment, University College London, London, WC1E 6BT, UK.
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Favreau E, Geist KS, Wyatt CDR, Toth AL, Sumner S, Rehan SM. Co-expression Gene Networks and Machine-learning Algorithms Unveil a Core Genetic Toolkit for Reproductive Division of Labour in Rudimentary Insect Societies. Genome Biol Evol 2023; 15:evac174. [PMID: 36527688 PMCID: PMC9830183 DOI: 10.1093/gbe/evac174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 12/06/2022] [Accepted: 12/10/2022] [Indexed: 12/23/2022] Open
Abstract
The evolution of eusociality requires that individuals forgo some or all their own reproduction to assist the reproduction of others in their group, such as a primary egg-laying queen. A major open question is how genes and genetic pathways sculpt the evolution of eusociality, especially in rudimentary forms of sociality-those with smaller cooperative nests when compared with species such as honeybees that possess large societies. We lack comprehensive comparative studies examining shared patterns and processes across multiple social lineages. Here we examine the mechanisms of molecular convergence across two lineages of bees and wasps exhibiting such rudimentary societies. These societies consist of few individuals and their life histories range from facultative to obligately social. Using six species across four independent origins of sociality, we conduct a comparative meta-analysis of publicly available transcriptomes. Standard methods detected little similarity in patterns of differential gene expression in brain transcriptomes among reproductive and non-reproductive individuals across species. By contrast, both supervised machine learning and consensus co-expression network approaches uncovered sets of genes with conserved expression patterns among reproductive and non-reproductive phenotypes across species. These sets overlap substantially, and may comprise a shared genetic "toolkit" for sociality across the distantly related taxa of bees and wasps and independently evolved lineages of sociality. We also found many lineage-specific genes and co-expression modules associated with social phenotypes and possible signatures of shared life-history traits. These results reveal how taxon-specific molecular mechanisms complement a core toolkit of molecular processes in sculpting traits related to the evolution of eusociality.
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Affiliation(s)
- Emeline Favreau
- Department of Genetics, Environment, Evolution, University College London, London WC1E 6BT, United Kingdom
| | - Katherine S Geist
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011
| | - Christopher D R Wyatt
- Department of Genetics, Environment, Evolution, University College London, London WC1E 6BT, United Kingdom
| | - Amy L Toth
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011
| | - Seirian Sumner
- Department of Genetics, Environment, Evolution, University College London, London WC1E 6BT, United Kingdom
| | - Sandra M Rehan
- Department of Biology, York University, Toronto, ON M3J 1P3, Canada
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Saleh NW, Henske J, Ramírez SR. Experimental disruption of social structure reveals totipotency in the orchid bee, Euglossa dilemma. Evolution 2022; 76:1529-1545. [PMID: 35589274 DOI: 10.1111/evo.14513] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 03/29/2022] [Accepted: 04/07/2022] [Indexed: 01/22/2023]
Abstract
Eusociality has evolved multiple times across the insect phylogeny. Social insects with greater levels of social complexity tend to exhibit specialized castes with low levels of individual phenotypic plasticity. In contrast, species with simple social groups may consist of totipotent individuals that transition among behavioral and reproductive states. However, recent work has shown that in simple social groups, there can still be constraint on individual plasticity, caused by differences in maternal nourishment or social interaction. It is not well understood how these constraints arise, ultimately leading to the evolution of nonreproductive workers. Some species of orchid bees form social groups of a dominant and-one to two subordinate helpers where all individuals are reproductive. Females can also disperse to start their own nest as a solitary foundress, which includes a nonreproductive phase characterized by ovary inactivation, not typically expressed by subordinates. Little is known about individual flexibility across these trajectories. Here, using the orchid bee Euglossa dilemma, we assess the plasticity of subordinate helpers, finding that they are capable of the same behavioral, physiological, transcriptomic, and chemical changes seen in foundresses. Our results suggest that the lack of nonreproductive workers in E. dilemma is not due to a lack of subordinate plasticity.
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Affiliation(s)
- Nicholas W Saleh
- Entomology and Nematology Department, Fort Lauderdale Research and Education Center, University of Florida, Davie, Florida, USA.,Center for Population Biology, University of California, Davis, California, USA
| | - Jonas Henske
- Department of Animal Ecology, Evolution and Biodiversity, Ruhr University Bochum, Bochum, Germany
| | - Santiago R Ramírez
- Center for Population Biology, University of California, Davis, California, USA
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Shell WA, Rehan SM. Social divergence: molecular pathways underlying castes and longevity in a facultatively eusocial small carpenter bee. Proc Biol Sci 2022; 289:20212663. [PMID: 35317677 PMCID: PMC8941392 DOI: 10.1098/rspb.2021.2663] [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: 01/09/2023] Open
Abstract
Unravelling the evolutionary origins of eusocial life is a longstanding endeavour in the field of evolutionary-developmental biology. Descended from solitary ancestors, eusocial insects such as honeybees have evolved ontogenetic division of labour in which short-lived workers perform age-associated tasks, while a long-lived queen produces brood. It is hypothesized that (i) eusocial caste systems evolved through the co-option of deeply conserved genes and (ii) longevity may be tied to oxidative damage mitigation capacity. To date, however, these hypotheses have been examined primarily among only obligately eusocial corbiculate bees. We present brain transcriptomic data from a Japanese small carpenter bee, Ceratina japonica (Apidae: Xylocopinae), which demonstrates both solitary and eusocial nesting in sympatry and lives 2 or more years in the wild. Our dataset captures gene expression patterns underlying first- and second-year solitary females, queens and workers, providing an unprecedented opportunity to explore the molecular mechanisms underlying caste-antecedent phenotypes in a long-lived and facultatively eusocial bee. We find that C. japonica's queens and workers are underpinned by divergent gene regulatory pathways, involving many differentially expressed genes well-conserved among other primitively eusocial bee lineages. We also find support for oxidative damage reduction as a proximate mechanism of longevity in C. japonica.
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Affiliation(s)
- Wyatt A. Shell
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
| | - Sandra M. Rehan
- Department of Biology, York University, 4700 Keele Street, Toronto, Ontario, Canada M3J 1P3
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Jeanne RL, Loope KJ, Bouwma AM, Nordheim EV, Smith ML. Five decades of misunderstanding in the social Hymenoptera: a review and meta-analysis of Michener's paradox. Biol Rev Camb Philos Soc 2022; 97:1559-1611. [PMID: 35338566 PMCID: PMC9546470 DOI: 10.1111/brv.12854] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 03/15/2022] [Accepted: 03/17/2022] [Indexed: 12/22/2022]
Abstract
In a much-cited 1964 paper entitled "Reproductive efficiency in relation to colony size in hymenopterous societies," Charles Michener investigated the correlation between a colony's size and its reproductive efficiency - the ability of its adult females to produce reproductives, measured as per-capita output. Based on his analysis of published data from destructively sampled colonies in 18 species, he reported that in most of these species efficiency decreased with increasing colony size. His conclusion that efficiency is higher in smaller groups has since gained widespread acceptance. But it created a seeming paradox: how can natural selection maintain social behaviour when a female apparently enjoys her highest per-capita output by working alone? Here we treat Michener's pattern as a hypothesis and perform the first large-scale test of its prediction across the eusocial Hymenoptera. Because data on actual output of reproductives were not available for most species, Michener used various proxies, such as nest size, numbers of brood, or amounts of stored food. We show that for each of Michener's data sets the reported decline in per-capita productivity can be explained by factors other than decreasing efficiency, calling into question his conclusion that declining efficiency is the cause of the pattern. The most prominent cause of bias is the failure of the proxy to capture all forms of output in which the colony invests during the course of its ontogeny. Other biasing factors include seasonal effects and a variety of methodological flaws in the data sets he used. We then summarize the results of 215 data sets drawn from post-1964 studies of 80 species in 33 genera that better control for these factors. Of these, 163 data sets are included in two meta-analyses that statistically synthesize the available data on the relationship between colony size and efficiency, accounting for variable sample sizes and non-independence among the data sets. The overall effect, and those for most taxonomic subgroups, indicates no loss of efficiency with increasing colony size. Two exceptional taxa, the halictid bees and independent-founding paper wasps, show negative trends consistent with the Michener hypothesis in some species. We conclude that in most species, particularly those with large colony sizes, the hypothesis of decreasing efficiency with increasing colony size is not supported. Finally, we explore potential mechanisms through which the level of efficiency can decrease, be maintained, or even increase, as colonies increase in size.
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Affiliation(s)
- Robert L Jeanne
- Department of Entomology, University of Wisconsin, 1630 Linden Drive, Madison, WI, 53706, U.S.A
| | - Kevin J Loope
- Department of Fish and Wildlife Conservation, Virginia Polytechnic Institute and State University (Virginia Tech), Cheatham Hall, 310 W. Campus Drive, Blacksburg, VA, 24060, U.S.A
| | - Andrew M Bouwma
- Department of Integrative Biology, Oregon State University, Cordley Hall, 3029, 2701 SW Campus Way, Corvallis, OR, 97331, U.S.A
| | - Erik V Nordheim
- Department of Statistics, University of Wisconsin, 1300 University Avenue, Madison, WI, 53706, U.S.A
| | - Michael L Smith
- Department of Biological Sciences, Auburn University, Auburn, AL, 36849, U.S.A
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Costa CP, Okamoto N, Orr M, Yamanaka N, Woodard SH. Convergent Loss of Prothoracicotropic Hormone, A Canonical Regulator of Development, in Social Bee Evolution. Front Physiol 2022; 13:831928. [PMID: 35242055 PMCID: PMC8887954 DOI: 10.3389/fphys.2022.831928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 01/20/2022] [Indexed: 11/21/2022] Open
Abstract
The evolution of insect sociality has repeatedly involved changes in developmental events and their timing. Here, we propose the hypothesis that loss of a canonical regulator of moulting and metamorphosis, prothoracicotropic hormone (PTTH), and its receptor, Torso, is associated with the evolution of sociality in bees. Specifically, we posit that the increasing importance of social influences on early developmental timing in social bees has led to their decreased reliance on PTTH, which connects developmental timing with abiotic cues in solitary insects. At present, the evidence to support this hypothesis includes the absence of genes encoding PTTH and Torso from all fully-sequenced social bee genomes and its presence in all available genomes of solitary bees. Based on the bee phylogeny, the most parsimonious reconstruction of evolutionary events is that this hormone and its receptor have been lost multiple times, across independently social bee lineages. These gene losses shed light on possible molecular and cellular mechanisms that are associated with the evolution of social behavior in bees. We outline the available evidence for our hypothesis, and then contextualize it in light of what is known about developmental cues in social and solitary bees, and the multiple precedences of major developmental changes in social insects.
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Affiliation(s)
- Claudinéia P Costa
- Department of Entomology, University of California, Riverside, Riverside, CA, United States
| | - Naoki Okamoto
- Department of Entomology, University of California, Riverside, Riverside, CA, United States.,Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Japan
| | - Michael Orr
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Naoki Yamanaka
- Department of Entomology, University of California, Riverside, Riverside, CA, United States
| | - S Hollis Woodard
- Department of Entomology, University of California, Riverside, Riverside, CA, United States
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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: 1.5] [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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