1
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Johnston SE. Understanding the Genetic Basis of Variation in Meiotic Recombination: Past, Present, and Future. Mol Biol Evol 2024; 41:msae112. [PMID: 38959451 PMCID: PMC11221659 DOI: 10.1093/molbev/msae112] [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: 04/17/2024] [Revised: 06/03/2024] [Accepted: 06/05/2024] [Indexed: 07/05/2024] Open
Abstract
Meiotic recombination is a fundamental feature of sexually reproducing species. It is often required for proper chromosome segregation and plays important role in adaptation and the maintenance of genetic diversity. The molecular mechanisms of recombination are remarkably conserved across eukaryotes, yet meiotic genes and proteins show substantial variation in their sequence and function, even between closely related species. Furthermore, the rate and distribution of recombination shows a huge diversity within and between chromosomes, individuals, sexes, populations, and species. This variation has implications for many molecular and evolutionary processes, yet how and why this diversity has evolved is not well understood. A key step in understanding trait evolution is to determine its genetic basis-that is, the number, effect sizes, and distribution of loci underpinning variation. In this perspective, I discuss past and current knowledge on the genetic basis of variation in recombination rate and distribution, explore its evolutionary implications, and present open questions for future research.
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Affiliation(s)
- Susan E Johnston
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, UK
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2
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Drury AL, Gout JF, Dapper AL. Modeling Recombination Rate as a Quantitative Trait Reveals New Insight into Selection in Humans. Genome Biol Evol 2023; 15:evad132. [PMID: 37506266 PMCID: PMC10404793 DOI: 10.1093/gbe/evad132] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 06/01/2023] [Accepted: 07/08/2023] [Indexed: 07/30/2023] Open
Abstract
Meiotic recombination is both a fundamental biological process required for proper chromosomal segregation during meiosis and an important genomic parameter that shapes major features of the genomic landscape. However, despite the central importance of this phenotype, we lack a clear understanding of the selective pressures that shape its variation in natural populations, including humans. While there is strong evidence of fitness costs of low rates of recombination, the possible fitness costs of high rates of recombination are less defined. To determine whether a single lower fitness bound can explain the variation in recombination rates observed in human populations, we simulated the evolution of recombination rates as a sexually dimorphic quantitative trait. Under each scenario, we statistically compared the resulting trait distribution with the observed distribution of recombination rates from a published study of the Icelandic population. To capture the genetic architecture of recombination rates in humans, we modeled it as a moderately complex trait with modest heritability. For our fitness function, we implemented a hyperbolic tangent curve with several flexible parameters to capture a wide range of existing hypotheses. We found that costs of low rates of recombination alone are likely insufficient to explain the current variation in recombination rates in both males and females, supporting the existence of fitness costs of high rates of recombination in humans. With simulations using both upper and lower fitness boundaries, we describe a parameter space for the costs of high recombination rates that produces results consistent with empirical observations.
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Affiliation(s)
- Austin L Drury
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
| | - Jean-Francois Gout
- Department of Biological Sciences, Mississippi State University, Mississippi State, Mississippi, USA
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3
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Näsvall K, Boman J, Talla V, Backström N. Base Composition, Codon Usage, and Patterns of Gene Sequence Evolution in Butterflies. Genome Biol Evol 2023; 15:evad150. [PMID: 37565492 PMCID: PMC10462419 DOI: 10.1093/gbe/evad150] [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: 11/22/2022] [Revised: 07/17/2023] [Accepted: 08/08/2023] [Indexed: 08/12/2023] Open
Abstract
Coding sequence evolution is influenced by both natural selection and neutral evolutionary forces. In many species, the effects of mutation bias, codon usage, and GC-biased gene conversion (gBGC) on gene sequence evolution have not been detailed. Quantification of how these forces shape substitution patterns is therefore necessary to understand the strength and direction of natural selection. Here, we used comparative genomics to investigate the association between base composition and codon usage bias on gene sequence evolution in butterflies and moths (Lepidoptera), including an in-depth analysis of underlying patterns and processes in one species, Leptidea sinapis. The data revealed significant G/C to A/T substitution bias at third codon position with some variation in the strength among different butterfly lineages. However, the substitution bias was lower than expected from previously estimated mutation rate ratios, partly due to the influence of gBGC. We found that A/T-ending codons were overrepresented in most species, but there was a positive association between the magnitude of codon usage bias and GC-content in third codon positions. In addition, the tRNA-gene population in L. sinapis showed higher GC-content at third codon positions compared to coding sequences in general and less overrepresentation of A/T-ending codons. There was an inverse relationship between synonymous substitutions and codon usage bias indicating selection on synonymous sites. We conclude that the evolutionary rate in Lepidoptera is affected by a complex interaction between underlying G/C -> A/T mutation bias and partly counteracting fixation biases, predominantly conferred by overall purifying selection, gBGC, and selection on codon usage.
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Affiliation(s)
- Karin Näsvall
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Uppsala, Sweden
| | - Jesper Boman
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Uppsala, Sweden
| | - Venkat Talla
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Uppsala, Sweden
| | - Niclas Backström
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Uppsala, Sweden
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4
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Parejo M, Talenti A, Richardson M, Vignal A, Barnett M, Wragg D. AmelHap: Leveraging drone whole-genome sequence data to create a honey bee HapMap. Sci Data 2023; 10:198. [PMID: 37037860 PMCID: PMC10086014 DOI: 10.1038/s41597-023-02097-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 03/22/2023] [Indexed: 04/12/2023] Open
Abstract
Honey bee, Apis mellifera, drones are typically haploid, developing from an unfertilized egg, inheriting only their queen's alleles and none from the many drones she mated with. Thus the ordered combination or 'phase' of alleles is known, making drones a valuable haplotype resource. We collated whole-genome sequence data for 1,407 drones, including 45 newly sequenced Scottish drones, collectively representing 19 countries, 8 subspecies and various hybrids. Following alignment to Amel_HAv3.1, variant calling and quality filtering, we retained 17.4 M high quality variants across 1,328 samples with a genotyping rate of 98.7%. We demonstrate the utility of this haplotype resource, AmelHap, for genotype imputation, returning >95% concordance when up to 61% of data is missing in haploids and up to 12% of data is missing in diploids. AmelHap will serve as a useful resource for the community for imputation from low-depth sequencing or SNP chip data, accurate phasing of diploids for association studies, and as a comprehensive reference panel for population genetic and evolutionary analyses.
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Affiliation(s)
- M Parejo
- Applied Genomics and Bioinformatics, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - A Talenti
- The Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian, UK
| | - M Richardson
- University of Edinburgh, King's Buildings Campus, Edinburgh, UK
- Beebytes Analytics CIC, Roslin Innovation Centre, Easter Bush Campus, Midlothian, UK
| | - A Vignal
- GenPhySE, Université de Toulouse, INRAE, INPT, INP-ENVT, 31326, Castanet Tolosan, France
| | - M Barnett
- Beebytes Analytics CIC, Roslin Innovation Centre, Easter Bush Campus, Midlothian, UK
| | - D Wragg
- The Roslin Institute, University of Edinburgh, Easter Bush Campus, Midlothian, UK.
- Beebytes Analytics CIC, Roslin Innovation Centre, Easter Bush Campus, Midlothian, UK.
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5
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Wragg D, Eynard SE, Basso B, Canale‐Tabet K, Labarthe E, Bouchez O, Bienefeld K, Bieńkowska M, Costa C, Gregorc A, Kryger P, Parejo M, Pinto MA, Bidanel J, Servin B, Le Conte Y, Vignal A. Complex population structure and haplotype patterns in the Western European honey bee from sequencing a large panel of haploid drones. Mol Ecol Resour 2022; 22:3068-3086. [PMID: 35689802 PMCID: PMC9796960 DOI: 10.1111/1755-0998.13665] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 05/26/2022] [Accepted: 06/01/2022] [Indexed: 01/07/2023]
Abstract
Honey bee subspecies originate from specific geographical areas in Africa, Europe and the Middle East, and beekeepers interested in specific phenotypes have imported genetic material to regions outside of the bees' original range for use either in pure lines or controlled crosses. Moreover, imported drones are present in the environment and mate naturally with queens from the local subspecies. The resulting admixture complicates population genetics analyses, and population stratification can be a major problem for association studies. To better understand Western European honey bee populations, we produced a whole genome sequence and single nucleotide polymorphism (SNP) genotype data set from 870 haploid drones and demonstrate its utility for the identification of nine genetic backgrounds and various degrees of admixture in a subset of 629 samples. Five backgrounds identified correspond to subspecies, two to isolated populations on islands and two to managed populations. We also highlight several large haplotype blocks, some of which coincide with the position of centromeres. The largest is 3.6 Mb long and represents 21% of chromosome 11, with two major haplotypes corresponding to the two dominant genetic backgrounds identified. This large naturally phased data set is available as a single vcf file that can now serve as a reference for subsequent populations genomics studies in the honey bee, such as (i) selecting individuals of verified homogeneous genetic backgrounds as references, (ii) imputing genotypes from a lower-density data set generated by an SNP-chip or by low-pass sequencing, or (iii) selecting SNPs compatible with the requirements of genotyping chips.
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Affiliation(s)
- David Wragg
- GenPhySEUniversité de Toulouse, INRAE, INPT, INP‐ENVTCastanet TolosanFrance,Roslin InstituteUniversity of EdinburghMidlothianUK
| | - Sonia E. Eynard
- GenPhySEUniversité de Toulouse, INRAE, INPT, INP‐ENVTCastanet TolosanFrance
| | - Benjamin Basso
- Institut de l'abeille (ITSAP), UMT PrADEAvignonFrance,INRAE, UR 406 Abeilles et Environment, UMT PrADEAvignonFrance
| | | | | | | | | | | | - Cecilia Costa
- CREA Research Centre for Agriculture and EnvironmentBolognaItaly
| | - Aleš Gregorc
- Faculty of Agriculture and Life SciencesUniversity of MariborPivolaSlovenia
| | - Per Kryger
- Department of Agroecology, Science and TechnologyAarhus UniversitySlagelseDenmark
| | - Melanie Parejo
- Agroscope, Swiss Bee Research CentreBernSwitzerland,Applied Genomics and Bioinformatics, Department of Genetics, Physical Anthropology and Animal PhysiologyUniversity of the Basque CountryLeioaSpain
| | - M. Alice Pinto
- Centro de Investigação de Montanha (CIMO)Instituto Politécnico de BragançaBragançaPortugal
| | | | - Bertrand Servin
- GenPhySEUniversité de Toulouse, INRAE, INPT, INP‐ENVTCastanet TolosanFrance
| | - Yves Le Conte
- INRAE, UR 406 Abeilles et Environment, UMT PrADEAvignonFrance
| | - Alain Vignal
- GenPhySEUniversité de Toulouse, INRAE, INPT, INP‐ENVTCastanet TolosanFrance
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6
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Ruiz-Herrera A, Waters PD. Fragile, unfaithful and persistent Ys-on how meiosis can shape sex chromosome evolution. Heredity (Edinb) 2022; 129:22-30. [PMID: 35459933 PMCID: PMC9273583 DOI: 10.1038/s41437-022-00532-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 03/27/2022] [Accepted: 03/28/2022] [Indexed: 12/28/2022] Open
Abstract
Sex-linked inheritance is a stark exception to Mendel's Laws of Heredity. Here we discuss how the evolution of heteromorphic sex chromosomes (mainly the Y) has been shaped by the intricacies of the meiotic programme. We propose that persistence of Y chromosomes in distantly related mammalian phylogroups can be explained in the context of pseudoautosomal region (PAR) size, meiotic pairing strategies, and the presence of Y-borne executioner genes that regulate meiotic sex chromosome inactivation. We hypothesise that variation in PAR size can be an important driver for the evolution of recombination frequencies genome wide, imposing constraints on Y fate. If small PAR size compromises XY segregation during male meiosis, the stress of producing aneuploid gametes could drive function away from the Y (i.e., a fragile Y). The Y chromosome can avoid fragility either by acquiring an achiasmatic meiotic XY pairing strategy to reduce aneuploid gamete production, or gain meiotic executioner protection (a persistent Y). Persistent Ys will then be under strong pressure to maintain high recombination rates in the PAR (and subsequently genome wide), as improper segregation has fatal consequences for germ cells. In the event that executioner protection is lost, the Y chromosome can be maintained in the population by either PAR rejuvenation (extension by addition of autosome material) or gaining achiasmatic meiotic pairing, the alternative is Y loss. Under this dynamic cyclic evolutionary scenario, understanding the meiotic programme in vertebrate and invertebrate species will be crucial to further understand the plasticity of the rise and fall of heteromorphic sex chromosomes.
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Affiliation(s)
- Aurora Ruiz-Herrera
- Genome Integrity and Instability Group, Institut de Biotecnologia i Biomedicina (IBB), Universitat Autònoma de Barcelona (UAB), Cerdanyola del Vallès, 08193, Spain. .,Departament de Biologia Cel·lular, Fisiologia i Immunologia, Universitat Autònoma de Barcelona (UAB), Cerdanyola del Vallès, 08193, Spain.
| | - Paul D Waters
- School of Biotechnology and Biomolecular Sciences, Faculty of Science, UNSW Sydney, Sydney, NSW, 2052, Australia.
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7
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Li Z, Zhao W, Zhang J, Pan Z, Bai S, Tong C. A Novel Strategy to Reveal the Landscape of Crossovers in an F1 Hybrid Population of Populus deltoides and Populus simonii. PLANTS 2022; 11:plants11081046. [PMID: 35448774 PMCID: PMC9025136 DOI: 10.3390/plants11081046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/03/2022] [Accepted: 04/07/2022] [Indexed: 11/16/2022]
Abstract
Although the crossover (CO) patterns of different species have been extensively investigated, little is known about the landscape of CO patterns in Populus because of its high heterozygosity and long-time generation. A novel strategy was proposed to reveal the difference of CO rate and interference between Populus deltoides and Populus simonii using their F1 hybrid population. We chose restriction site-associated DNA (RAD) tags that contained two SNPs, one only receiving the CO information from the female P. deltoides and the other from the male P. simonii. These RAD tags allowed us to investigate the CO patterns between the two outbred species, instead of using the traditional backcross populations in inbred lines. We found that the CO rate in P. deltoides was generally greater than that in P. simonii, and that the CO interference was a common phenomenon across the two genomes. The COs landscape of the different Populus species facilitates not only to understand the evolutionary mechanism for adaptability but also to rebuild the statistical model for precisely constructing genetic linkage maps that are critical in genome assembly in Populus. Additionally, the novel strategy could be applied in other outbred species for investigating the CO patterns.
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Affiliation(s)
| | | | | | | | | | - Chunfa Tong
- Correspondence: ; Tel.: +86-025-85428817 (ext. 815)
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8
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Christmas MJ, Jones JC, Olsson A, Wallerman O, Bunikis I, Kierczak M, Whitley KM, Sullivan I, Geib JC, Miller-Struttmann NE, Webster MT. A genomic and morphometric analysis of alpine bumblebees: Ongoing reductions in tongue length but no clear genetic component. Mol Ecol 2021; 31:1111-1127. [PMID: 34837435 DOI: 10.1111/mec.16291] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 11/16/2021] [Accepted: 11/22/2021] [Indexed: 11/29/2022]
Abstract
Over the last six decades, populations of the bumblebees Bombus sylvicola and Bombus balteatus in Colorado have experienced decreases in tongue length, a trait important for plant-pollinator mutualisms. It has been hypothesized that this observation reflects selection resulting from shifts in floral composition under climate change. Here we used morphometrics and population genomics to determine whether morphological change is ongoing, investigate the genetic basis of morphological variation, and analyse population structure in these populations. We generated a genome assembly of B. balteatus. We then analysed whole-genome sequencing data and morphometric measurements of 580 samples of both species from seven high-altitude localities. Out of 281 samples originally identified as B. sylvicola, 67 formed a separate genetic cluster comprising a newly-discovered cryptic species ("incognitus"). However, an absence of genetic structure within species suggests that gene flow is common between mountains. We found a significant decrease in tongue length between bees collected between 2012-2014 and in 2017, indicating that morphological shifts are ongoing. We did not discover any genetic associations with tongue length, but a SNP related to production of a proteolytic digestive enzyme was implicated in body size variation. We identified evidence of covariance between kinship and both tongue length and body size, which is suggestive of a genetic component of these traits, although it is possible that shared environmental effects between colonies are responsible. Our results provide evidence for ongoing modification of a morphological trait important for pollination and indicate that this trait probably has a complex genetic and environmental basis.
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Affiliation(s)
- Matthew J Christmas
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Julia C Jones
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.,School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | - Anna Olsson
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Ola Wallerman
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Ignas Bunikis
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Marcin Kierczak
- Department of Cell and Molecular Biology, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Kaitlyn M Whitley
- Department of Biology, Appalachian State University, Boone, North Carolina, USA.,U.S. Department of Agriculture, Agriculture Research Service, Charleston, South Carolina, USA
| | - Isabel Sullivan
- Department of Biology, Appalachian State University, Boone, North Carolina, USA.,Marine Estuarine Environmental Sciences, University of Maryland, College Park, Maryland, USA
| | - Jennifer C Geib
- Department of Biology, Appalachian State University, Boone, North Carolina, USA
| | | | - Matthew T Webster
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
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9
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Waiker P, de Abreu FCP, Luna-Lucena D, Freitas FCP, Simões ZLP, Rueppell O. Recombination mapping of the Brazilian stingless bee Frieseomelitta varia confirms high recombination rates in social hymenoptera. BMC Genomics 2021; 22:673. [PMID: 34536998 PMCID: PMC8449902 DOI: 10.1186/s12864-021-07987-3] [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: 04/07/2021] [Accepted: 09/04/2021] [Indexed: 11/26/2022] Open
Abstract
Background Meiotic recombination is a fundamental genetic process that shuffles allele combinations and promotes accurate segregation of chromosomes. Analyses of the ubiquitous variation of recombination rates within and across species suggest that recombination is evolving adaptively. All studied insects with advanced eusociality have shown exceptionally high recombination rates, which may represent a prominent case of adaptive evolution of recombination. However, our understanding of the relationship between social evolution and recombination rates is incomplete, partly due to lacking empirical data. Here, we present a linkage map of the monandrous, advanced eusocial Brazilian stingless bee, Frieseomelitta varia, providing the first recombination analysis in the diverse Meliponini (Hymenoptera, Apidae). Results Our linkage map includes 1417 markers in 19 linkage groups. This map spans approximately 2580 centimorgans, and comparisons to the physical genome assembly indicate that it covers more than 75 % of the 275 Megabasepairs (Mbp) F. varia genome. Thus, our study results in a genome-wide recombination rate estimate of 9.3–12.5 centimorgan per Mbp. This value is higher than estimates from nonsocial insects and comparable to other highly social species, although it does not support our prediction that monandry and strong queen-worker caste divergence of F. varia lead to even higher recombination rates than other advanced eusocial species. Conclusions Our study expands the association between elevated recombination and sociality in the order Hymenoptera and strengthens the support for the hypothesis that advanced social evolution in hymenopteran insects invariably selects for high genomic recombination rates. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-021-07987-3.
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Affiliation(s)
- Prashant Waiker
- Biology Department, University of North Carolina at Greensboro, 321 McIver St, Greensboro, NC, 27412, USA.
| | - Fabiano Carlos Pinto de Abreu
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, SP, Ribeirão Preto, Brazil
| | - Danielle Luna-Lucena
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil
| | - Flávia Cristina Paula Freitas
- Departamento de Genética, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.,Departamento de Biologia Celular e do Desenvolvimento, Instituto de Ciências Biomédicas, Universidade Federal de Alfenas, Alfenas, MG, Brazil
| | - Zilá Luz Paulino Simões
- Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, SP, Ribeirão Preto, Brazil
| | - Olav Rueppell
- Biology Department, University of North Carolina at Greensboro, 321 McIver St, Greensboro, NC, 27412, USA.,Department of Biological Sciences, University of Alberta, AB, T6G 2E9, Edmonton, Canada
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10
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Boman J, Mugal CF, Backström N. The Effects of GC-Biased Gene Conversion on Patterns of Genetic Diversity among and across Butterfly Genomes. Genome Biol Evol 2021; 13:evab064. [PMID: 33760095 PMCID: PMC8175052 DOI: 10.1093/gbe/evab064] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/22/2021] [Indexed: 12/28/2022] Open
Abstract
Recombination reshuffles the alleles of a population through crossover and gene conversion. These mechanisms have considerable consequences on the evolution and maintenance of genetic diversity. Crossover, for example, can increase genetic diversity by breaking the linkage between selected and nearby neutral variants. Bias in favor of G or C alleles during gene conversion may instead promote the fixation of one allele over the other, thus decreasing diversity. Mutation bias from G or C to A and T opposes GC-biased gene conversion (gBGC). Less recognized is that these two processes may-when balanced-promote genetic diversity. Here, we investigate how gBGC and mutation bias shape genetic diversity patterns in wood white butterflies (Leptidea sp.). This constitutes the first in-depth investigation of gBGC in butterflies. Using 60 resequenced genomes from six populations of three species, we find substantial variation in the strength of gBGC across lineages. When modeling the balance of gBGC and mutation bias and comparing analytical results with empirical data, we reject gBGC as the main determinant of genetic diversity in these butterfly species. As alternatives, we consider linked selection and GC content. We find evidence that high values of both reduce diversity. We also show that the joint effects of gBGC and mutation bias can give rise to a diversity pattern which resembles the signature of linked selection. Consequently, gBGC should be considered when interpreting the effects of linked selection on levels of genetic diversity.
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Affiliation(s)
- Jesper Boman
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Sweden
| | - Carina F Mugal
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Sweden
| | - Niclas Backström
- Evolutionary Biology Program, Department of Ecology and Genetics (IEG), Uppsala University, Sweden
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11
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Christmas MJ, Jones JC, Olsson A, Wallerman O, Bunikis I, Kierczak M, Peona V, Whitley KM, Larva T, Suh A, Miller-Struttmann NE, Geib JC, Webster MT. Genetic Barriers to Historical Gene Flow between Cryptic Species of Alpine Bumblebees Revealed by Comparative Population Genomics. Mol Biol Evol 2021; 38:3126-3143. [PMID: 33823537 PMCID: PMC8321533 DOI: 10.1093/molbev/msab086] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Evidence is accumulating that gene flow commonly occurs between recently diverged species, despite the existence of barriers to gene flow in their genomes. However, we still know little about what regions of the genome become barriers to gene flow and how such barriers form. Here, we compare genetic differentiation across the genomes of bumblebee species living in sympatry and allopatry to reveal the potential impact of gene flow during species divergence and uncover genetic barrier loci. We first compared the genomes of the alpine bumblebee Bombus sylvicola and a previously unidentified sister species living in sympatry in the Rocky Mountains, revealing prominent islands of elevated genetic divergence in the genome that colocalize with centromeres and regions of low recombination. This same pattern is observed between the genomes of another pair of closely related species living in allopatry (B. bifarius and B. vancouverensis). Strikingly however, the genomic islands exhibit significantly elevated absolute divergence (dXY) in the sympatric, but not the allopatric, comparison indicating that they contain loci that have acted as barriers to historical gene flow in sympatry. Our results suggest that intrinsic barriers to gene flow between species may often accumulate in regions of low recombination and near centromeres through processes such as genetic hitchhiking, and that divergence in these regions is accentuated in the presence of gene flow.
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Affiliation(s)
- Matthew J Christmas
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Julia C Jones
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.,School of Biology and Environmental Science, University College Dublin, Dublin, Ireland
| | - Anna Olsson
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Ola Wallerman
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Ignas Bunikis
- Department of Immunology, Genetics and Pathology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Marcin Kierczak
- Department of Cell and Molecular Biology, National Bioinformatics Infrastructure Sweden, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Valentina Peona
- Department of Organismal Biology-Systematic Biology, Uppsala University, Uppsala, Sweden
| | - Kaitlyn M Whitley
- Department of Biology, Appalachian State University, Boone, NC, USA.,U.S. Department of Agriculture, Agriculture Research Service, Charleston, SC, USA
| | - Tuuli Larva
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Alexander Suh
- Department of Organismal Biology-Systematic Biology, Uppsala University, Uppsala, Sweden.,School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | | | - Jennifer C Geib
- Department of Biology, Appalachian State University, Boone, NC, USA
| | - Matthew T Webster
- Department of Medical Biochemistry and Microbiology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
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DeLory T, Funderburk K, Miller K, Smith WZ, McPherson S, Pirk CW, Costa C, Teixeira ÉW, Dahle B, Rueppell O. Local Variation in Recombination Rates of the Honey Bee ( Apis mellifera) Genome among Samples from Six Disparate Populations. INSECTES SOCIAUX 2020; 67:127-138. [PMID: 33311731 PMCID: PMC7732154 DOI: 10.1007/s00040-019-00736-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Meiotic recombination is an essential component of eukaryotic sexual reproduction but its frequency varies within and between genomes. Although it is well-established that honey bees have a high recombination rate with about 20 cM/Mbp, the proximate and ultimate causes of this exceptional rate are poorly understood. Here, we describe six linkage maps of the Western Honey Bee Apis mellifera that were produced with consistent methodology from samples from distinct parts of the species' near global distribution. We compared the genome-wide rates and distribution of meiotic crossovers among the six maps and found considerable differences. Overall similarity of local recombination rates among our samples was unrelated to geographic or phylogenetic distance of the populations that our samples were derived from. However, the limited sampling constrains the interpretation of our results because it is unclear how representative these samples are. In contrast to previous studies, we found only in two datasets a significant relation between local recombination rate and GC content. Focusing on regions of particularly increased or decreased recombination in specific maps, we identified several enriched gene ontologies in these regions and speculate about their local adaptive relevance. These data are contributing to an increasing comparative effort to gain an understanding of the intra-specific variability of recombination rates and their evolutionary role in honey bees and other social insects.
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Affiliation(s)
- Timothy DeLory
- Department of Biology, University of North Carolina at Greensboro, NC, USA
- Current address: Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT, USA
| | - Karen Funderburk
- Department of Biology, University of North Carolina at Greensboro, NC, USA
- Current address: Applied Mathematics for the Life & Social Sciences, College of Liberal Arts and Sciences, Arizona State University, Tempe, AZ, USA
| | - Katelyn Miller
- Department of Biology, University of North Carolina at Greensboro, NC, USA
| | | | - Samantha McPherson
- Department of Biology, University of North Carolina at Greensboro, NC, USA
- Current address: Current address: NCSU Department of Entomology & Plant Pathology, Campus Box 7613, 100 Derieux Place, Raleigh, NC, USA
| | - Christian W. Pirk
- Social Insects Research Group, Department of Zoology & Entomology, University of Pretoria, South Africa
| | - Cecilia Costa
- Consiglio per la Ricerca in Agricolturae l’Analisi dell’Economia Agraria, Via Po, 14 - 00198 Rome, Italy
| | - Érica Weinstein Teixeira
- Honey Bee Health Specialized Laboratory, Biological Institute, São Paulo State Agribusiness Technology Agency, Av. Prof. Manoel César Ribeiro, 1920, Pindamonhangaba, São Paulo 12411-010, Brazil
| | - Bjørn Dahle
- Norwegian Beekeepers Association, Kløfta, Norway
- Faculty of Environmental Sciences and Natural Resource Management, Norwegian University of Life Sciences, Ås, Norway
| | - Olav Rueppell
- Department of Biology, University of North Carolina at Greensboro, NC, USA
- Corresponding author: 312 Eberhart Bldg, 321 McIver Street, Greensboro NC 27403, USA. Phone: (+1) 336-2562591,
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Talla V, Johansson A, Dincă V, Vila R, Friberg M, Wiklund C, Backström N. Lack of gene flow: Narrow and dispersed differentiation islands in a triplet ofLeptideabutterfly species. Mol Ecol 2019; 28:3756-3770. [DOI: 10.1111/mec.15188] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2018] [Revised: 07/08/2019] [Accepted: 07/12/2019] [Indexed: 01/02/2023]
Affiliation(s)
- Venkat Talla
- Department of Evolutionary Biology Evolutionary Biology Centre (EBC) Uppsala University Uppsala Sweden
| | - Anna Johansson
- Department of Medical Biochemistry and Microbiology Uppsala Biomedical Centre (BMC) Uppsala Sweden
| | - Vlad Dincă
- Department of Ecology and Genetics University of Oulu Oulu Finland
| | - Roger Vila
- Institut de Biologia Evolutiva (CSIC‐UPF) Barcelona Spain
| | - Magne Friberg
- Department of Biology, Biodiversity Unit Lund University Lund Sweden
| | - Christer Wiklund
- Division of Ecology Department of Zoology Stockholm University Stockholm Sweden
| | - Niclas Backström
- Department of Evolutionary Biology Evolutionary Biology Centre (EBC) Uppsala University Uppsala Sweden
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