1
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Liberti J, Engel P, Cabirol A. Interplay between gut symbionts and behavioral variation in social insects. CURRENT OPINION IN INSECT SCIENCE 2024; 65:101233. [PMID: 39019113 DOI: 10.1016/j.cois.2024.101233] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Revised: 05/27/2024] [Accepted: 07/09/2024] [Indexed: 07/19/2024]
Abstract
Social insects exhibit a high degree of intraspecific behavioral variation. Moreover, they often harbor specialized microbial communities in their gut. Recent studies suggest that these two characteristics of social insects are interlinked: insect behavioral phenotypes affect their gut microbiota composition, partly through exposure to different environments and diet, and in return, the gut microbiota has been shown to influence insect behavior. Here, we discuss the bidirectional relationship existing between intraspecific variation in gut microbiota composition and behavioral phenotypes in social insects.
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Affiliation(s)
- Joanito Liberti
- Department of Fundamental Microbiology, University of Lausanne, Switzerland; Department of Ecology and Evolution, University of Lausanne, Switzerland.
| | - Philipp Engel
- Department of Fundamental Microbiology, University of Lausanne, Switzerland
| | - Amélie Cabirol
- Department of Fundamental Microbiology, University of Lausanne, Switzerland.
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2
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De Gasperin O, Blacher P, Sarton-Lohéac S, Grasso G, Corliss MK, Nicole S, Chérasse S, Aron S, Chapuisat M. A supergene-controlling social structure in Alpine ants also affects the dispersal ability and fecundity of each sex. Proc Biol Sci 2024; 291:20240494. [PMID: 38864332 DOI: 10.1098/rspb.2024.0494] [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: 11/15/2023] [Accepted: 04/18/2024] [Indexed: 06/13/2024] Open
Abstract
Social organization, dispersal and fecundity coevolve, but whether they are genetically linked remains little known. Supergenes are prime candidates for coupling adaptive traits and mediating sex-specific trade-offs. Here, we test whether a supergene that controls social structure in Formica selysi also influences dispersal-related traits and fecundity within each sex. In this ant species, single-queen colonies contain only the ancestral supergene haplotype M and produce MM queens and M males, while multi-queen colonies contain the derived haplotype P and produce MP queens, PP queens and P males. By combining multiple experiments, we show that the M haplotype induces phenotypes with higher dispersal potential and higher fecundity in both sexes. Specifically, MM queens, MP queens and M males are more aerodynamic and more fecund than PP queens and P males, respectively. Differences between MP and PP queens from the same colonies reveal a direct genetic effect of the supergene on dispersal-related traits and fecundity. The derived haplotype P, associated with multi-queen colonies, produces queens and males with reduced dispersal abilities and lower fecundity. More broadly, similarities between the Formica and Solenopsis systems reveal that supergenes play a major role in linking behavioural, morphological and physiological traits associated with intraspecific social polymorphisms.
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Affiliation(s)
- Ornela De Gasperin
- Department of Ecology and Evolution, University of Lausanne , Lausanne 1015, Switzerland
- Red de Ecoetología, Instituto de Ecología, A. C. , Xalapa, Veracruz 91073, Mexico
| | - Pierre Blacher
- Department of Ecology and Evolution, University of Lausanne , Lausanne 1015, Switzerland
| | - Solenn Sarton-Lohéac
- Department of Ecology and Evolution, University of Lausanne , Lausanne 1015, Switzerland
| | - Guglielmo Grasso
- Department of Ecology and Evolution, University of Lausanne , Lausanne 1015, Switzerland
- University of Manchester , Manchester M13 9PL, UK
| | - Mia Kotur Corliss
- Department of Ecology and Evolution, University of Lausanne , Lausanne 1015, Switzerland
| | - Sidonie Nicole
- Department of Ecology and Evolution, University of Lausanne , Lausanne 1015, Switzerland
| | | | - Serge Aron
- Universite libre de Bruxelles , Brussels 1050, Belgium
| | - Michel Chapuisat
- Department of Ecology and Evolution, University of Lausanne , Lausanne 1015, Switzerland
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3
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Zink AG, Miller JS. Queen-Worker Conflict over Acceptance of Secondary Queens in Eusocial Insects. Am Nat 2024; 203:139-146. [PMID: 38207139 DOI: 10.1086/727650] [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: 01/13/2024]
Abstract
AbstractThe coexistence of multiple reproductives in eusocial insects is widespread, yet the decisions leading to additional queen acceptance are not well understood. Unlike in vertebrates, acceptance decisions are likely controlled by the more numerous helper population rather than the parent reproductive. Yet there are likely to be queen-worker differences in acceptance criteria because workers and queens differ in their relatedness to a secondary queen. We develop a model that examines queen-worker conflict in two scenarios: accepting a queen's sister or daughter. We additionally ask how the mating frequency and split sex ratios affect the outcomes of these conflicts. Our results reveal that conflict over queen acceptance is highest in monandrous mating systems. We identify a "window of conflict" in which a queen is selected to accept her sister but her workers do not. Our result, that polyandry neutralizes conflict over acceptance thresholds, suggests that conflict suppression may be an additional contributor to the maintenance of polyandrous mating systems.
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4
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Scarparo G, Palanchon M, Brelsford A, Purcell J. Social antagonism facilitates supergene expansion in ants. Curr Biol 2023; 33:5085-5095.e4. [PMID: 37979579 DOI: 10.1016/j.cub.2023.10.049] [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: 04/26/2023] [Revised: 08/07/2023] [Accepted: 10/25/2023] [Indexed: 11/20/2023]
Abstract
Antagonistic selection has long been considered a major driver of the formation and expansion of sex chromosomes. For example, sexually antagonistic variation on an autosome can select for suppressed recombination between that autosome and the sex chromosome, leading to a neo-sex chromosome. Autosomal supergenes, chromosomal regions containing tightly linked variants affecting the same complex trait, share similarities with sex chromosomes, raising the possibility that sex chromosome evolution models can explain the evolution of genome structure and recombination in other contexts. We tested this premise in a Formica ant species, wherein we identified four supergene haplotypes on chromosome 3 underlying colony social organization and sex ratio. We discovered a novel rearranged supergene variant (9r) on chromosome 9 underlying queen miniaturization. The 9r is in strong linkage disequilibrium with one chromosome 3 haplotype (P2) found in multi-queen (polygyne) colonies. We suggest that queen miniaturization is strongly disfavored in the single-queen (monogyne) background and is thus socially antagonistic. As such, divergent selection experienced by ants living in alternative social "environments" (monogyne and polygyne) may have contributed to the emergence of a genetic polymorphism on chromosome 9 and associated queen-size dimorphism. Consequently, an ancestral polygyne-associated haplotype may have expanded to include the polymorphism on chromosome 9, resulting in a larger region of suppressed recombination spanning two chromosomes. This process is analogous to the formation of neo-sex chromosomes and consistent with models of expanding regions of suppressed recombination. We propose that miniaturized queens, 16%-20% smaller than queens without 9r, could be incipient intraspecific social parasites.
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Affiliation(s)
- Giulia Scarparo
- Department of Entomology, University of California, Riverside, 165 Entomology Bldg. Citrus Drive, Riverside, CA 92521, USA.
| | - Marie Palanchon
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, 2710 Life Science Bldg., Riverside, CA 92521, USA
| | - Alan Brelsford
- Department of Evolution, Ecology, and Organismal Biology, University of California, Riverside, 2710 Life Science Bldg., Riverside, CA 92521, USA
| | - Jessica Purcell
- Department of Entomology, University of California, Riverside, 165 Entomology Bldg. Citrus Drive, Riverside, CA 92521, USA.
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5
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Gokhman VE. Chromosome study of the Hymenoptera (Insecta): from cytogenetics to cytogenomics. COMPARATIVE CYTOGENETICS 2023; 17:239-250. [PMID: 37953851 PMCID: PMC10632776 DOI: 10.3897/compcytogen.17.112332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Accepted: 10/19/2023] [Indexed: 11/14/2023]
Abstract
A brief overview of the current stage of the chromosome study of the insect order Hymenoptera is given. It is demonstrated that, in addition to routine staining and other traditional techniques of chromosome research, karyotypes of an increasing number of hymenopterans are being studied using molecular methods, e.g., staining with base-specific fluorochromes and fluorescence in situ hybridization (FISH), including microdissection and chromosome painting. Due to the advent of whole genome sequencing and other molecular techniques, together with the "big data" approach to the chromosomal data, the current stage of the chromosome research on Hymenoptera represents a transition from Hymenoptera cytogenetics to cytogenomics.
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Affiliation(s)
- Vladimir E. Gokhman
- Botanical Garden, Moscow State University, Moscow 119234, RussiaMoscow State UniversityMoscowRussia
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6
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Arsenault SV, Riba-Grognuz O, Shoemaker D, Hunt BG, Keller L. Direct and indirect genetic effects of a social supergene. Mol Ecol 2023; 32:1087-1097. [PMID: 36541826 DOI: 10.1111/mec.16830] [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: 05/31/2022] [Revised: 12/15/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022]
Abstract
Indirect genetic effects describe phenotypic variation that results from differences in the genotypic composition of social partners. Such effects represent heritable sources of environmental variation in eusocial organisms because individuals are typically reared by their siblings. In the fire ant Solenopsis invicta, a social supergene exhibits striking indirect genetic effects on worker regulation of colony queen number, such that the genotypic composition of workers at the supergene determines whether colonies contain a single or multiple queens. We assessed the direct and indirect genetic effects of this supergene on gene expression in brains and abdominal tissues from laboratory-reared workers and compared these with previously published data from field-collected prereproductive queens. We found that direct genetic effects caused larger gene expression changes and were more consistent across tissue types and castes than indirect genetic effects. Indirect genetic effects influenced the expression of many loci but were generally restricted to the abdominal tissues. Further, indirect genetic effects were only detected when the genotypic composition of social partners differed throughout the development and adult life of focal workers, and were often only significant with relatively lenient statistical cutoffs. Our study provides insight into direct and indirect genetic effects of a social supergene on gene regulatory dynamics across tissues and castes in a complex society.
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Affiliation(s)
| | - Oksana Riba-Grognuz
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - DeWayne Shoemaker
- Department of Entomology and Plant Pathology, University of Tennessee, Knoxville, Tennessee, USA
| | - Brendan G Hunt
- Department of Entomology, University of Georgia, Athens, Georgia, USA
| | - Laurent Keller
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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7
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Blacher P, De Gasperin O, Grasso G, Sarton-Lohéac S, Allemann R, Chapuisat M. Cryptic recessive lethality of a supergene controlling social organization in ants. Mol Ecol 2023; 32:1062-1072. [PMID: 36504171 DOI: 10.1111/mec.16821] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Revised: 11/23/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022]
Abstract
Supergenes are clusters of linked loci that control complex phenotypes, such as alternative forms of social organization in ants. Explaining the long-term maintenance of supergenes is challenging, particularly when the derived haplotype lacks homozygous lethality and causes gene drive. In the Alpine silver ant, Formica selysi, a large and ancient social supergene with two haplotypes, M and P, controls colony social organization. Single-queen colonies only contain MM females, while multiqueen colonies contain MP and PP females. The derived P haplotype, found only in multiqueen colonies, selfishly enhances its transmission through maternal effect killing, which could have led to its fixation. A population genetic model showed that a stable social polymorphism can only be maintained under a narrow set of conditions, which includes partial assortative mating by social form (which is known to occur in the wild), and low fitness of PP queens. With a combination of field and laboratory experiments, we show that the P haplotype has deleterious effects on female fitness. The survival rate of PP queens and workers was around half that of other genotypes. Moreover, P-carrying queens had lower fertility and fecundity compared to other queens. We discuss how cryptic lethal effects of the P haplotype help stabilize this ancient polymorphism.
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Affiliation(s)
- Pierre Blacher
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Ornela De Gasperin
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Red de Ecoetología, Instituto de Ecología A. C., Veracruz, Mexico
| | - Guglielmo Grasso
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,University of Manchester, Manchester, UK
| | - Solenn Sarton-Lohéac
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Roxane Allemann
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Michel Chapuisat
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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8
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Trible W, Chandra V, Lacy KD, Limón G, McKenzie SK, Olivos-Cisneros L, Arsenault SV, Kronauer DJC. A caste differentiation mutant elucidates the evolution of socially parasitic ants. Curr Biol 2023; 33:1047-1058.e4. [PMID: 36858043 PMCID: PMC10050096 DOI: 10.1016/j.cub.2023.01.067] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 08/31/2022] [Accepted: 01/31/2023] [Indexed: 03/03/2023]
Abstract
Most ant species have two distinct female castes-queens and workers-yet the developmental and genetic mechanisms that produce these alternative phenotypes remain poorly understood. Working with a clonal ant, we discovered a variant strain that expresses queen-like traits in individuals that would normally become workers. The variants show changes in morphology, behavior, and fitness that cause them to rely on workers in wild-type (WT) colonies for survival. Overall, they resemble the queens of many obligately parasitic ants that have evolutionarily lost the worker caste and live inside colonies of closely related hosts. The prevailing theory for the evolution of these workerless social parasites is that they evolve from reproductively isolated populations of facultative intermediates that acquire parasitic phenotypes in a stepwise fashion. However, empirical evidence for such facultative ancestors remains weak, and it is unclear how reproductive isolation could gradually arise in sympatry. In contrast, we isolated these variants just a few generations after they arose within their WT parent colony, implying that the complex phenotype reported here was induced in a single genetic step. This suggests that a single genetic module can decouple the coordinated mechanisms of caste development, allowing an obligately parasitic variant to arise directly from a free-living ancestor. Consistent with this hypothesis, the variants have lost one of the two alleles of a putative supergene that is heterozygous in WTs. These findings provide a plausible explanation for the evolution of ant social parasites and implicate new candidate molecular mechanisms for ant caste differentiation.
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Affiliation(s)
- Waring Trible
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; John Harvard Distinguished Science Fellowship Program, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA.
| | - Vikram Chandra
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Department of Organismic and Evolutionary Biology, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA
| | - Kip D Lacy
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Gina Limón
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Department of Microbiology, New York University School of Medicine, 430 E. 29th Street, New York, NY 10016, USA
| | - Sean K McKenzie
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Oxford Nanopore Technologies, Oxford OX4 4DQ, UK
| | - Leonora Olivos-Cisneros
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA
| | - Samuel V Arsenault
- John Harvard Distinguished Science Fellowship Program, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA; Department of Organismic and Evolutionary Biology, Harvard University, 52 Oxford Street, Cambridge, MA 02138, USA
| | - Daniel J C Kronauer
- Laboratory of Social Evolution and Behavior, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Howard Hughes Medical Institute, New York, NY 10065, USA.
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9
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Campoy E, Puig M, Yakymenko I, Lerga-Jaso J, Cáceres M. Genomic architecture and functional effects of potential human inversion supergenes. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210209. [PMID: 35694745 PMCID: PMC9189494 DOI: 10.1098/rstb.2021.0209] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Supergenes are involved in adaptation in multiple organisms, but they are little known in humans. Genomic inversions are the most common mechanism of supergene generation and maintenance. Here, we review the information about two large inversions that are the best examples of potential human supergenes. In addition, we do an integrative analysis of the newest data to understand better their functional effects and underlying genetic changes. We have found that the highly divergent haplotypes of the 17q21.31 inversion of approximately 1.5 Mb have multiple phenotypic associations, with consistent effects in brain-related traits, red and white blood cells, lung function, male and female characteristics and disease risk. By combining gene expression and nucleotide variation data, we also analysed the molecular differences between haplotypes, including gene duplications, amino acid substitutions and regulatory changes, and identify CRHR1, KANLS1 and MAPT as good candidates to be responsible for these phenotypes. The situation is more complex for the 8p23.1 inversion, where there is no clear genetic differentiation. However, the inversion is associated with several related phenotypes and gene expression differences that could be linked to haplotypes specific of one orientation. Our work, therefore, contributes to the characterization of both exceptional variants and illustrates the important role of inversions. This article is part of the theme issue 'Genomic architecture of supergenes: causes and evolutionary consequences'.
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Affiliation(s)
- Elena Campoy
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain
| | - Marta Puig
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain.,Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain
| | - Illya Yakymenko
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain
| | - Jon Lerga-Jaso
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain
| | - Mario Cáceres
- Institut de Biotecnologia i de Biomedicina, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain.,ICREA, Barcelona, Spain
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10
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Berdan EL, Flatt T, Kozak GM, Lotterhos KE, Wielstra B. Genomic architecture of supergenes: connecting form and function. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210192. [PMID: 35694757 PMCID: PMC9189501 DOI: 10.1098/rstb.2021.0192] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Supergenes are tightly linked sets of loci that are inherited together and control complex phenotypes. While classical supergenes-governing traits such as wing patterns in Heliconius butterflies or heterostyly in Primula-have been studied since the Modern Synthesis, we still understand very little about how they evolve and persist in nature. The genetic architecture of supergenes is a critical factor affecting their evolutionary fate, as it can change key parameters such as recombination rate and effective population size, potentially redirecting molecular evolution of the supergene in addition to the surrounding genomic region. To understand supergene evolution, we must link genomic architecture with evolutionary patterns and processes. This is now becoming possible with recent advances in sequencing technology and powerful forward computer simulations. The present theme issue brings together theoretical and empirical papers, as well as opinion and synthesis papers, which showcase the architectural diversity of supergenes and connect this to critical processes in supergene evolution, such as polymorphism maintenance and mutation accumulation. Here, we summarize those insights to highlight new ideas and methods that illuminate the path forward for the study of supergenes in nature. This article is part of the theme issue 'Genomic architecture of supergenes: causes and evolutionary consequences'.
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Affiliation(s)
- Emma L Berdan
- Institute of Biology Leiden, Leiden University, PO Box 9505, 2300 RA, Leiden, The Netherlands.,Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, The Netherlands.,Tjärnö Marine Laboratory, Department of Marine Sciences, University of Gothenburg, 45296 Strömstad, Sweden
| | - Thomas Flatt
- Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Genevieve M Kozak
- Department of Biology, University of Massachusetts Dartmouth, 285 Old Westport Road, MA 02747, USA
| | - Katie E Lotterhos
- Department of Marine and Environmental Sciences, Northeastern University, 430 Nahant Road, Nahant, MA 01908, USA
| | - Ben Wielstra
- Institute of Biology Leiden, Leiden University, PO Box 9505, 2300 RA, Leiden, The Netherlands.,Naturalis Biodiversity Center, PO Box 9517, 2300 RA Leiden, The Netherlands
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11
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Tafreshi AG, Otto SP, Chapuisat M. Unbalanced selection: the challenge of maintaining a social polymorphism when a supergene is selfish. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210197. [PMID: 35694754 PMCID: PMC9189496 DOI: 10.1098/rstb.2021.0197] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Supergenes often have multiple phenotypic effects, including unexpected detrimental ones, because recombination suppression maintains associations among co-adapted alleles but also allows the accumulation of recessive deleterious mutations and selfish genetic elements. Yet, supergenes often persist over long evolutionary periods. How are such polymorphisms maintained in the face of selection, drive and drift? We present a population genetic model that investigates the conditions necessary for a stable polymorphic equilibrium when one of the supergene haplotypes is a selfish genetic element. The model fits the characteristics of the Alpine silver ant, Formica selysi, in which a large supergene underlies colony social organization, and one haplotype distorts Mendelian transmission by killing progeny that did not inherit it. The model shows that such maternal-effect killing strongly limits the maintenance of social polymorphism. Under random mating, transmission ratio distortion prevents rare single-queen colonies from invading populations of multiple-queen colonies, regardless of the fitness of each genotype. A stable polymorphic equilibrium can, however, be reached when high rates of assortative mating are combined with large fitness differences among supergene genotypes. The model reveals that the persistence of the social polymorphism is non-trivial and expected to occur only under restrictive conditions that deserve further empirical investigation. This article is part of the theme issue 'Genomic architecture of supergenes: causes and evolutionary consequences'.
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Affiliation(s)
- Alireza G Tafreshi
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Sarah P Otto
- Department of Zoology and Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4
| | - Michel Chapuisat
- Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland
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12
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Schaal SM, Haller BC, Lotterhos KE. Inversion invasions: when the genetic basis of local adaptation is concentrated within inversions in the face of gene flow. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210200. [PMID: 35694752 PMCID: PMC9189506 DOI: 10.1098/rstb.2021.0200] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Accepted: 05/09/2022] [Indexed: 12/29/2022] Open
Abstract
Across many species where inversions have been implicated in local adaptation, genomes often evolve to contain multiple, large inversions that arise early in divergence. Why this occurs has yet to be resolved. To address this gap, we built forward-time simulations in which inversions have flexible characteristics and can invade a metapopulation undergoing spatially divergent selection for a highly polygenic trait. In our simulations, inversions typically arose early in divergence, captured standing genetic variation upon mutation, and then accumulated many small-effect loci over time. Under special conditions, inversions could also arise late in adaptation and capture locally adapted alleles. Polygenic inversions behaved similarly to a single supergene of large effect and were detectable by genome scans. Our results show that characteristics of adaptive inversions found in empirical studies (e.g. multiple large, old inversions that are FST outliers, sometimes overlapping with other inversions) are consistent with a highly polygenic architecture, and inversions do not need to contain any large-effect genes to play an important role in local adaptation. By combining a population and quantitative genetic framework, our results give a deeper understanding of the specific conditions needed for inversions to be involved in adaptation when the genetic architecture is polygenic. This article is part of the theme issue 'Genomic architecture of supergenes: causes and evolutionary consequences'.
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Affiliation(s)
- Sara M. Schaal
- Department of Marine and Environmental Sciences, Northeastern University, Nahant, MA, USA
| | - Benjamin C. Haller
- Department of Computational Biology, Cornell University, Ithaca, NY, USA
| | - Katie E. Lotterhos
- Department of Marine and Environmental Sciences, Northeastern University, Nahant, MA, USA
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13
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Berdan EL, Blanckaert A, Butlin RK, Flatt T, Slotte T, Wielstra B. Mutation accumulation opposes polymorphism: supergenes and the curious case of balanced lethals. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210199. [PMID: 35694750 PMCID: PMC9189497 DOI: 10.1098/rstb.2021.0199] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 03/24/2022] [Indexed: 12/26/2022] Open
Abstract
Supergenes offer spectacular examples of long-term balancing selection in nature, but their origin and maintenance remain a mystery. Reduced recombination between arrangements, a critical aspect of many supergenes, protects adaptive multi-trait phenotypes but can lead to mutation accumulation. Mutation accumulation can stabilize the system through the emergence of associative overdominance (AOD), destabilize the system, or lead to new evolutionary outcomes. One outcome is the formation of maladaptive balanced lethal systems, where only heterozygotes remain viable and reproduce. We investigated the conditions under which these different outcomes occur, assuming a scenario of introgression after divergence. We found that AOD aided the invasion of a new supergene arrangement and the establishment of a polymorphism. However, this polymorphism was easily destabilized by further mutation accumulation, which was often asymmetric, disrupting the quasi-equilibrium state. Mechanisms that accelerated degeneration tended to amplify asymmetric mutation accumulation between the supergene arrangements and vice-versa. As the evolution of balanced lethal systems requires symmetric degeneration of both arrangements, this leaves only restricted conditions for their evolution, namely small population sizes and low rates of gene conversion. The dichotomy between the persistence of polymorphism and degeneration of supergene arrangements likely underlies the rarity of balanced lethal systems in nature. This article is part of the theme issue 'Genomic architecture of supergenes: causes and evolutionary consequences'.
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Affiliation(s)
- Emma L. Berdan
- Naturalis Biodiversity Center, PO Box 9517, 2300 RA, Leiden, The Netherlands
- Institute of Biology Leiden, Leiden University, PO Box 9505, 2300 RA, Leiden, The Netherlands
- Tjarnö Marine Laboratory, Department of Marine Sciences, University of Gothenburg, 45296 Stromstad, Sweden
| | - Alexandre Blanckaert
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI, USA
- cE3c – Centre for Ecology, Evolution and Environmental Changes, Faculdade de Ciências, Universidade de Lisboa, Campo Grande, 1749-016, Lisboa, Portugal
| | - Roger K. Butlin
- Tjarnö Marine Laboratory, Department of Marine Sciences, University of Gothenburg, 45296 Stromstad, Sweden
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK
| | - Thomas Flatt
- Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Tanja Slotte
- Department of Ecology, Environment and Plant Sciences, Science for Life Laboratory, Stockholm University, 106 91 Stockholm, Sweden
| | - Ben Wielstra
- Naturalis Biodiversity Center, PO Box 9517, 2300 RA, Leiden, The Netherlands
- Institute of Biology Leiden, Leiden University, PO Box 9505, 2300 RA, Leiden, The Netherlands
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