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Liberti J, Frank ET, Kay T, Kesner L, Monié--Ibanes M, Quinn A, Schmitt T, Keller L, Engel P. Gut microbiota influences onset of foraging-related behavior but not physiological hallmarks of division of labor in honeybees. mBio 2024; 15:e0103424. [PMID: 39072646 PMCID: PMC11389387 DOI: 10.1128/mbio.01034-24] [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: 05/04/2024] [Accepted: 06/28/2024] [Indexed: 07/30/2024] Open
Abstract
Gut microbes can impact cognition and behavior, but whether they regulate the division of labor in animal societies is unknown. We addressed this question using honeybees since they exhibit division of labor between nurses and foragers and because their gut microbiota can be manipulated. Using automated behavioral tracking and controlling for co-housing effects, we show that gut microbes influence the age at which bees start expressing foraging-like behaviors in the laboratory but have no effects on the time spent in a foraging arena and number of foraging trips. Moreover, the gut microbiota did not influence hallmarks of behavioral maturation such as body weight, cuticular hydrocarbon profile, hypopharyngeal gland size, gene expression, and the proportion of bees maturing into foragers. Overall, this study shows that the honeybee gut microbiota plays a role in controlling the onset of foraging-related behavior without permanent consequences on colony-level division of labor and several physiological hallmarks of behavioral maturation. IMPORTANCE The honeybee is emerging as a model system for studying gut microbiota-host interactions. Previous studies reported gut microbiota effects on multiple worker bee phenotypes, all of which change during behavioral maturation-the transition from nursing to foraging. We tested whether the documented effects may stem from an effect of the microbiota on behavioral maturation. The gut microbiota only subtly affected maturation: it accelerated the onset of foraging without affecting the overall proportion of foragers or their average output. We also found no effect of the microbiota on host weight, cuticular hydrocarbon (CHC) profile, hypopharyngeal gland size, and the expression of behavioral maturation-related genes. These results are inconsistent with previous studies reporting effects of the gut microbiota on bee weight and CHC profile. Our experiments revealed that co-housed bees tend to converge in behavior and physiology, suggesting that spurious associations may emerge when rearing environments are not replicated sufficiently or accounted for analytically.
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Affiliation(s)
- Joanito Liberti
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Erik T. Frank
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Department of Animal Ecology and Tropical Biology, University of Würzburg, Würzburg, Germany
| | - Tomas Kay
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Lucie Kesner
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | | | - Andrew Quinn
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
| | - Thomas Schmitt
- Department of Animal Ecology and Tropical Biology, University of Würzburg, Würzburg, Germany
| | - Laurent Keller
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Philipp Engel
- Department of Fundamental Microbiology, University of Lausanne, Lausanne, Switzerland
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2
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Erezyilmaz D. The genetic determination of alternate stages in polyphenic insects. Evol Dev 2024; 26:e12485. [PMID: 38867484 DOI: 10.1111/ede.12485] [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: 12/06/2023] [Revised: 02/23/2024] [Accepted: 05/14/2024] [Indexed: 06/14/2024]
Abstract
Molt-based transitions in form are a central feature of insect life that have enabled adaptation to diverse and changing environments. The endocrine regulation of these transitions is well established, but an understanding of their genetic regulation has only recently emerged from insect models. The pupal and adult stages of metamorphosing insects are determined by the stage specifying transcription factors broad-complex (br) and Ecdysone inducible protein 93 (E93), respectively. A probable larval determinant, chronologically inappropriate metamorphosis (chinmo), has just recently been characterized. Expression of these three transcription factors in the metamorphosing insects is regulated by juvenile hormone with ecdysteroid hormones, and by mutual repression between the stage-specific transcription factors. This review explores the hypothesis that variations in the onset, duration, and tissue-specific expression of chinmo, br, and E93 underlie other polyphenisms that have arisen throughout insects, including the castes of social insects, aquatic stages of mayflies, and the neoteny of endoparasites. The mechanisms that constrain how chinmo, br, and E93 expression may vary will also constrain the ways that insect life history may evolve. I find that four types of expression changes are associated with novel insect forms: (1) heterochronic shift in the turnover of expression, (2) expansion or contraction of expression, (3) tissue-specific expression, and (4) redeployment of stage-specific expression. While there is more to be learned about chinmo, br, and E93 function in diverse insect taxa, the studies outlined here show that insect stages are modular units in developmental time and a substrate for evolutionary forces to act upon.
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Affiliation(s)
- Deniz Erezyilmaz
- Department of Physiology, Anatomy and Genetics, Centre for Neural Circuits and Behavior, University of Oxford, Oxford, UK
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3
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Carmona-Aldana F, Yong LW, Reinberg D, Desplan C. Phenomenon of reproductive plasticity in ants. CURRENT OPINION IN INSECT SCIENCE 2024; 63:101197. [PMID: 38583769 PMCID: PMC11139587 DOI: 10.1016/j.cois.2024.101197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Revised: 03/26/2024] [Accepted: 03/31/2024] [Indexed: 04/09/2024]
Abstract
Ant colonies are organized in castes with distinct behaviors that together allow the colony to strive. Reproduction relies on one or a few queens that stay in the nest producing eggs, while females of the worker caste do not reproduce and instead engage in colony maintenance and brood caretaking. Yet, in spite of this clear separation of functions, workers can become reproductive under defined circumstances. Here, we review the context in which workers become reproductive, exhibiting asexual or sexual reproduction depending on the species. Remarkably, the activation of reproduction in these workers can be quite stable, with changes that include behavior and a dramatic extension of lifespan. We compare these changes between species that do or do not have a queen caste. We discuss how the mechanisms underlying reproductive plasticity include changes in hormonal functions and in epigenetic configurations. Further studies are warranted to elucidate not only how reproductive functions have been gradually restricted to the queen caste during evolution but also how reproductive plasticity remains possible in workers of some species.
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Affiliation(s)
| | - Luok Wen Yong
- Department of Biology, New York University, NY 10003, USA
| | - Danny Reinberg
- Dr. John T. Macdonald Foundation Department of Human Genetics, University of Miami, Coral Gables, FL 33124, USA.
| | - Claude Desplan
- Department of Biology, New York University, NY 10003, USA; Center for Genomics and Systems Biology, New York University, Abu Dhabi 51133, United Arab Emirates.
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4
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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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5
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Uller T, Milocco L, Isanta-Navarro J, Cornwallis CK, Feiner N. Twenty years on from Developmental Plasticity and Evolution: middle-range theories and how to test them. J Exp Biol 2024; 227:jeb246375. [PMID: 38449333 DOI: 10.1242/jeb.246375] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2024]
Abstract
In Developmental Plasticity and Evolution, Mary-Jane West-Eberhard argued that the developmental mechanisms that enable organisms to respond to their environment are fundamental causes of adaptation and diversification. Twenty years after publication of this book, this once so highly controversial claim appears to have been assimilated by a wealth of studies on 'plasticity-led' evolution. However, we suggest that the role of development in explanations for adaptive evolution remains underappreciated in this body of work. By combining concepts of evolvability from evolutionary developmental biology and quantitative genetics, we outline a framework that is more appropriate to identify developmental causes of adaptive evolution. This framework demonstrates how experimental and comparative developmental biology and physiology can be leveraged to put the role of plasticity in evolution to the test.
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Affiliation(s)
- Tobias Uller
- Department of Biology, Lund University, 223 62 Lund, Sweden
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6
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Lin S, Elsner D, Ams L, Korb J, Rosengaus R. A genetic toolkit underlying the queen phenotype in termites with totipotent workers. Sci Rep 2024; 14:2214. [PMID: 38278833 PMCID: PMC10817970 DOI: 10.1038/s41598-024-51772-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 01/09/2024] [Indexed: 01/28/2024] Open
Abstract
Social insect castes (e.g., queens, workers) are prime examples of phenotypic plasticity (i.e., different phenotypes arising from the same genotype). Yet, the mechanisms that give rise to highly fertile, long-lived queens versus non-reproducing, short-lived workers are not well understood. Recently, a module of co-expressed genes has been identified that characterizes queens compared to workers of the termite Cryptotermes secundus (Kalotermitidae): the Queen Central Module (QCM). We tested whether the QCM is shared in termite species, in which queens gradually develop via early larval and late larval instars, the latter functioning as totipotent workers (linear development). Similar as in C. secundus, gene expression profiles revealed an enrichment of QCM genes in Zootermopsis angusticollis queens, a species from another termite family (Archotermopsidae). The expression of these QCM genes became gradually enriched during development from early larval instars via workers to queens. Thus, our results support the hypothesis of a conserved genetic toolkit that characterizes termite queens with gradual linear development. Our data also imply a strong caste-specific tissue specificity with the QCM signal being restricted to head-prothorax tissues in termite queens. This tissue-specific expression of key aging-related genes might have facilitated the evolution of a long lifespan in termite queens.
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Affiliation(s)
- Silu Lin
- Evolutionary Biology and Ecology, University of Freiburg, 79104, Freiburg, Germany
| | - Daniel Elsner
- Evolutionary Biology and Ecology, University of Freiburg, 79104, Freiburg, Germany
| | - Leon Ams
- Evolutionary Biology and Ecology, University of Freiburg, 79104, Freiburg, Germany
| | - Judith Korb
- Evolutionary Biology and Ecology, University of Freiburg, 79104, Freiburg, Germany.
- Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina Campus, Darwin, NT, 0909, Australia.
| | - Rebeca Rosengaus
- Department of Marine and Environmental Sciences, Northeastern University, Boston, MA, 02115, USA.
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Taylor BA, Taylor D, Bodrug‐Schepers A, Câmara Ferreira F, Stralis‐Pavese N, Himmelbauer H, Guigó R, Reuter M, Sumner S. Molecular signatures of alternative reproductive strategies in a facultatively social hover wasp. Mol Ecol 2024; 33:e17217. [PMID: 38014715 PMCID: PMC10953455 DOI: 10.1111/mec.17217] [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: 04/27/2023] [Revised: 11/09/2023] [Accepted: 11/13/2023] [Indexed: 11/29/2023]
Abstract
Social insect reproductives and non-reproductives represent ideal models with which to understand the expression and regulation of alternative phenotypes. Most research in this area has focused on the developmental regulation of reproductive phenotypes in obligately social taxa such as honey bees, while relatively few studies have addressed the molecular correlates of reproductive differentiation in species in which the division of reproductive labour is established only in plastic dominance hierarchies. To address this knowledge gap, we generate the first genome for any stenogastrine wasp and analyse brain transcriptomic data for non-reproductives and reproductives of the facultatively social species Liostenogaster flavolineata, a representative of one of the simplest forms of social living. By experimentally manipulating the reproductive 'queues' exhibited by social colonies of this species, we show that reproductive division of labour in this species is associated with transcriptomic signatures that are more subtle and variable than those observed in social taxa in which colony living has become obligate; that variation in gene expression among non-reproductives reflects their investment into foraging effort more than their social rank; and that genes associated with reproductive division of labour overlap to some extent with those underlying division of labour in the separate polistine origin of wasp sociality but only explain a small portion of overall variation in this trait. These results indicate that broad patterns of within-colony transcriptomic differentiation in this species are similar to those in Polistinae but offer little support for the existence of a strongly conserved 'toolkit' for sociality.
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Affiliation(s)
- Benjamin A. Taylor
- Centre for Biodiversity & Environment ResearchUniversity College LondonLondonUK
- Department of Genetics, Evolution & EnvironmentUniversity College LondonLondonUK
| | - Daisy Taylor
- School of Biological SciencesUniversity of BristolBristolUK
| | | | | | - Nancy Stralis‐Pavese
- Department of BiotechnologyUniversity of Natural Resources and Life SciencesViennaAustria
| | - Heinz Himmelbauer
- Department of BiotechnologyUniversity of Natural Resources and Life SciencesViennaAustria
| | - Roderic Guigó
- Centre for Genomic RegulationBarcelona Institute of Science and TechnologyBarcelonaSpain
- Universitat Pompeu FabraBarcelonaSpain
| | - Max Reuter
- Department of Genetics, Evolution & EnvironmentUniversity College LondonLondonUK
- Centre for Life's Origins and EvolutionUniversity College LondonLondonUK
| | - Seirian Sumner
- Centre for Biodiversity & Environment ResearchUniversity College LondonLondonUK
- Department of Genetics, Evolution & EnvironmentUniversity College LondonLondonUK
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8
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Caminer MA, Libbrecht R, Majoe M, Ho DV, Baumann P, Foitzik S. Task-specific odorant receptor expression in worker antennae indicates that sensory filters regulate division of labor in ants. Commun Biol 2023; 6:1004. [PMID: 37783732 PMCID: PMC10545721 DOI: 10.1038/s42003-023-05273-4] [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: 04/18/2023] [Accepted: 08/22/2023] [Indexed: 10/04/2023] Open
Abstract
Division of labor (DOL) is a characteristic trait of insect societies, where tasks are generally performed by specialized individuals. Inside workers focus on brood or nest care, while others take risks by foraging outside. Theory proposes that workers have different thresholds to perform certain tasks when confronted with task-related stimuli, leading to specialization and consequently DOL. Workers are presumed to vary in their response to task-related cues rather than in how they perceive such information. Here, we test the hypothesis that DOL instead stems from workers varying in their efficiency to detect stimuli of specific tasks. We use transcriptomics to measure mRNA expression levels in the antennae and brain of nurses and foragers of the ant Temnothorax longispinosus. We find seven times as many genes to be differentially expressed between behavioral phenotypes in the antennae compared to the brain. Moreover, half of all odorant receptors are differentially expressed, with an overrepresentation of the 9-exon gene family upregulated in the antennae of nurses. Nurses and foragers thus apparently differ in the perception of their olfactory environment and task-related signals. Our study supports the hypothesis that antennal sensory filters predispose workers to specialize in specific tasks.
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Affiliation(s)
- Marcel A Caminer
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany.
| | - Romain Libbrecht
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
- Institut de Recherche sur la Biologie de l'Insecte, UMR 7261, CNRS, University of Tours, Tours, France
| | - Megha Majoe
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
| | - David V Ho
- Institute of Developmental and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Peter Baumann
- Institute of Developmental and Neurobiology, Johannes Gutenberg University Mainz, Mainz, Germany
- Institute of Molecular Biology, Mainz, Germany
| | - Susanne Foitzik
- Institute of Organismic and Molecular Evolution, Johannes Gutenberg University Mainz, Mainz, Germany
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9
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Orr SE, Goodisman MA. Social insect transcriptomics and the molecular basis of caste diversity. CURRENT OPINION IN INSECT SCIENCE 2023; 57:101040. [PMID: 37105497 DOI: 10.1016/j.cois.2023.101040] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 04/13/2023] [Accepted: 04/17/2023] [Indexed: 05/24/2023]
Abstract
Studies of gene expression provide fundamentally important information on the molecular mechanisms underlying variation in phenotype. Recent technological advances have allowed for the robust study of gene expression through analysis of whole transcriptomes. Here, we review current advances in social insect transcriptomics and discuss their implications in understanding phenotypic diversity. Recent transcriptomic studies provide detailed inventories of the genes involved in producing distinct phenotypes in social species. These investigations have identified key genes and networks involved in producing distinct social insect castes. Nevertheless, questions concerning the evolution of gene expression patterns remain. We suggest a path forward for studying gene expression in future studies of biological systems.
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Affiliation(s)
- Sarah E Orr
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA 30332, USA
| | - Michael Ad Goodisman
- School of Biological Sciences, Georgia Institute of Technology, 310 Ferst Drive, Atlanta, GA 30332, USA.
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10
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Smith CR. Sexual dimorphism as a facilitator of worker caste evolution in ants. Ecol Evol 2023; 13:e9825. [PMID: 36818531 PMCID: PMC9929627 DOI: 10.1002/ece3.9825] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/20/2023] [Accepted: 01/27/2023] [Indexed: 02/17/2023] Open
Abstract
Ant societies are primarily composed of females, whereby labor is divided into reproductive, or queen, and non-reproductive, or worker, castes. Workers and reproductive queens can differ greatly in behavior, longevity, physiology, and morphology, but queen-worker differences are usually modest relative to the differences in males. Males are short-lived, typically do not provide the colony with labor, often look like a different species, and only occur seasonally. It is these differences that have historically led to their neglect in social insect research, but also why they may facilitate novel phenotypic variation - by increasing the phenotypic variability that is available for selection. In this study, worker variation in multivariate size-shape space paralleled male-queen variation. As worker variation increased within species, so did sexual variation. Across species in two independent genera, using head width as a proxy for body size, sexual size dimorphism correlated with worker polymorphism regardless of whether the ancestral condition was large or small worker/sexual dimorphism. Mounting molecular data support the hypothesis that queen-worker caste determination has co-opted many genes/pathways from sex determination. The molecular evidence, coupled with the observations from this study, leads to the hypothesis that sexual selection and selection on colony-level traits are non-independent, and that sexual dimorphism may even have facilitated the evolution of the distinct worker caste.
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