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Venu V, Harjunmaa E, Dreau A, Brady S, Absher D, Kingsley DM, Jones FC. Fine-scale contemporary recombination variation and its fitness consequences in adaptively diverging stickleback fish. Nat Ecol Evol 2024; 8:1337-1352. [PMID: 38839849 PMCID: PMC11239493 DOI: 10.1038/s41559-024-02434-4] [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: 08/21/2023] [Accepted: 05/02/2024] [Indexed: 06/07/2024]
Abstract
Despite deep evolutionary conservation, recombination rates vary greatly across the genome and among individuals, sexes and populations. Yet the impact of this variation on adaptively diverging populations is not well understood. Here we characterized fine-scale recombination landscapes in an adaptively divergent pair of marine and freshwater populations of threespine stickleback from River Tyne, Scotland. Through whole-genome sequencing of large nuclear families, we identified the genomic locations of almost 50,000 crossovers and built recombination maps for marine, freshwater and hybrid individuals at a resolution of 3.8 kb. We used these maps to quantify the factors driving variation in recombination rates. We found strong heterochiasmy between sexes but also differences in recombination rates among ecotypes. Hybrids showed evidence of significant recombination suppression in overall map length and in individual loci. Recombination rates were lower not only within individual marine-freshwater-adaptive loci, but also between loci on the same chromosome, suggesting selection on linked gene 'cassettes'. Through temporal sampling along a natural hybrid zone, we found that recombinants showed traits associated with reduced fitness. Our results support predictions that divergence in cis-acting recombination modifiers, whose functions are disrupted in hybrids, may play an important role in maintaining differences among adaptively diverging populations.
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Affiliation(s)
- Vrinda Venu
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany.
- Los Alamos National Laboratory, New Mexico, NM, USA.
| | - Enni Harjunmaa
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany
- CeGAT GmbH, Tübingen, Germany
| | - Andreea Dreau
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany
- Evotec SE 'Campus Curie', Toulouse, France
| | - Shannon Brady
- Deptartment of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
| | - Devin Absher
- HudsonAlpha Institute for Biotechnology, Huntsville, AL, USA
| | - David M Kingsley
- Deptartment of Developmental Biology, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, Chevy Chase, MD, USA
| | - Felicity C Jones
- Friedrich Miescher Laboratory of the Max Planck Society, Tübingen, Germany.
- Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, the Netherlands.
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2
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López-Pérez M, Aguirre-Garrido F, Herrera-Zúñiga L, Fernández FJ. Gene as a dynamical notion: An extensive and integrative vision. Redefining the gene concept, from traditional to genic-interaction, as a new dynamical version. Biosystems 2023; 234:105060. [PMID: 37844827 DOI: 10.1016/j.biosystems.2023.105060] [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: 04/27/2023] [Revised: 09/08/2023] [Accepted: 10/10/2023] [Indexed: 10/18/2023]
Abstract
The current concept of gene has been very useful during the 20th and 21st centuries. However, recent advances in molecular biology and bioinformatics, which have further diversified the functional and adaptive profile of genetic information and its integration with cell physiology and environmental response, have contributed to focusing on additional new gene properties besides the traditional definition. Considering the inherent complexity of gene expression, whose adaptive objective must be referred to the Tortoise-Hare model, in which two tendencies converge, one focused on rapid adaptation to achieve survival, and the other that prevents an over-adaptation effect. In this context, a revision of the gene concept must be made, which must include these new mechanisms and approaches. In this paper, we propose a new conception of the idea of a gene that moves from a static and defined version of hereditary information to a dynamic idea that preponderates gene interaction (circumscribed to that established between protein-protein, protein-nucleic acid, and nucleic acid-nucleic acid) and the selection it exerts, as the irreducible element that works in a coordinated way in a genomic regulatory network (GRN).
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Affiliation(s)
- Marcos López-Pérez
- Environmental Sciences Department, Universidad Autónoma Metropolitana (Lerma Unit) Av. de las Garzas N° 10, Col. El Panteón, Municipio de Lerma de Villada, Estado de México, C.P. 52005, Mexico.
| | - Félix Aguirre-Garrido
- Environmental Sciences Department, Universidad Autónoma Metropolitana (Lerma Unit) Av. de las Garzas N° 10, Col. El Panteón, Municipio de Lerma de Villada, Estado de México, C.P. 52005, Mexico
| | - Leonardo Herrera-Zúñiga
- Chemistry Department, Universidad Autónoma Metropolitana (Iztapalapa Unit), C.P. 09340, Mexico City, Mexico
| | - Francisco J Fernández
- Biotechnology Department, Universidad Autónoma Metropolitana (Iztapalapa Unit), C.P. 09340, Mexico City, Mexico.
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3
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Zhang H, Hansson B. RecView: an interactive R application for locating recombination positions using pedigree data. BMC Genomics 2023; 24:712. [PMID: 38007417 PMCID: PMC10676570 DOI: 10.1186/s12864-023-09807-2] [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: 08/28/2023] [Accepted: 11/14/2023] [Indexed: 11/27/2023] Open
Abstract
BACKGROUND Recombination reshuffles alleles at linked loci, allowing genes to evolve independently and consequently enhancing the efficiency of selection. This makes quantifying recombination along chromosomes an important goal for understanding how selection and drift are acting on genes and chromosomes. RESULTS We present RecView, an interactive R application and its homonymous R package, to facilitate locating recombination positions along chromosomes or scaffolds using whole-genome genotype data of a three-generation pedigree. RecView analyses and plots the grandparent-of-origin of all informative alleles along each chromosome of the offspring in the pedigree, and infers recombination positions with either of two built-in algorithms: one based on change in the proportion of the alleles with specific grandparent-of-origin, and one on the degree of continuity of alleles with the same grandparent-of-origin. RecView handles multiple offspring and chromosomes simultaneously, and all putative recombination positions are reported in base pairs together with an estimated precision based on the local density of informative alleles. We demonstrate RecView using genotype data of a passerine bird with an available reference genome, the great reed warbler (Acrocephalus arundinaceus), and show that recombination events can be located to specific positions. CONCLUSIONS RecView is an easy-to-use and highly effective application for locating recombination positions with high precision. RecView is available on GitHub ( https://github.com/HKyleZhang/RecView.git ).
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Affiliation(s)
- Hongkai Zhang
- Department of Biology, Lund University, Lund, 22362, Sweden.
| | - Bengt Hansson
- Department of Biology, Lund University, Lund, 22362, Sweden.
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4
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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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5
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El Kodsi DN, Tokarew JM, Sengupta R, Lengacher NA, Chatterji A, Nguyen AP, Boston H, Jiang Q, Palmberg C, Pileggi C, Holterman CE, Shutinoski B, Li J, Fehr TK, LaVoie MJ, Ratan RR, Shaw GS, Takanashi M, Hattori N, Kennedy CR, Harper ME, Holmgren A, Tomlinson JJ, Schlossmacher MG. Parkin coregulates glutathione metabolism in adult mammalian brain. Acta Neuropathol Commun 2023; 11:19. [PMID: 36691076 PMCID: PMC9869535 DOI: 10.1186/s40478-022-01488-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 12/01/2022] [Indexed: 01/24/2023] Open
Abstract
We recently discovered that the expression of PRKN, a young-onset Parkinson disease-linked gene, confers redox homeostasis. To further examine the protective effects of parkin in an oxidative stress model, we first combined the loss of prkn with Sod2 haploinsufficiency in mice. Although adult prkn-/-//Sod2± animals did not develop dopamine cell loss in the S. nigra, they had more reactive oxidative species and a higher concentration of carbonylated proteins in the brain; bi-genic mice also showed a trend for more nitrotyrosinated proteins. Because these redox changes were seen in the cytosol rather than mitochondria, we next explored the thiol network in the context of PRKN expression. We detected a parkin deficiency-associated increase in the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) in murine brain, PRKN-linked human cortex and several cell models. This shift resulted from enhanced recycling of GSSG back to GSH via upregulated glutathione reductase activity; it also correlated with altered activities of redox-sensitive enzymes in mitochondria isolated from mouse brain (e.g., aconitase-2; creatine kinase). Intriguingly, human parkin itself showed glutathione-recycling activity in vitro and in cells: For each GSSG dipeptide encountered, parkin regenerated one GSH molecule and was S-glutathionylated by the other (GSSG + P-SH [Formula: see text] GSH + P-S-SG), including at cysteines 59, 95 and 377. Moreover, parkin's S-glutathionylation was reversible by glutaredoxin activity. In summary, we found that PRKN gene expression contributes to the network of available thiols in the cell, including by parkin's participation in glutathione recycling, which involves a reversible, posttranslational modification at select cysteines. Further, parkin's impact on redox homeostasis in the cytosol can affect enzyme activities elsewhere, such as in mitochondria. We posit that antioxidant functions of parkin may explain many of its previously described, protective effects in vertebrates and invertebrates that are unrelated to E3 ligase activity.
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Affiliation(s)
- Daniel N El Kodsi
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Jacqueline M Tokarew
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Rajib Sengupta
- Department of Biochemistry, Karolinska Institute, Stockholm, Sweden
- Amity Institute of Biotechnology, Amity University, Kolkata, West Bengal, India
| | - Nathalie A Lengacher
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Ajanta Chatterji
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Angela P Nguyen
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Snyder Institute, University of Calgary, Calgary, AB, Canada
| | - Heather Boston
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Qiubo Jiang
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Carina Palmberg
- Department of Biochemistry, Karolinska Institute, Stockholm, Sweden
| | - Chantal Pileggi
- Department of Biochemistry, Microbiology and Immunology Faculty of Medicine, and Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada
| | - Chet E Holterman
- Kidney Research Center, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Bojan Shutinoski
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Juan Li
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
| | - Travis K Fehr
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada
| | - Matthew J LaVoie
- Department of Neurology, College of Medicine, University of Florida, Gainesville, FL, USA
| | - Rajiv R Ratan
- Burke Neurological Institute, Weill Cornell Medical School, White Plains, NY, USA
| | - Gary S Shaw
- Department of Biochemistry, University of Western Ontario, London, ON, Canada
| | - Masashi Takanashi
- Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan
| | - Nobutaka Hattori
- Department of Neurology, Juntendo University School of Medicine, Tokyo, Japan
| | | | - Mary-Ellen Harper
- Department of Biochemistry, Microbiology and Immunology Faculty of Medicine, and Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, ON, Canada
| | - Arne Holmgren
- Department of Biochemistry, Karolinska Institute, Stockholm, Sweden
| | - Julianna J Tomlinson
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.
| | - Michael G Schlossmacher
- Program in Neuroscience, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
- Department of Cellular and Molecular Medicine, University of Ottawa, Ottawa, ON, Canada.
- University of Ottawa Brain and Mind Research Institute, Ottawa, ON, Canada.
- Division of Neurology, Department of Medicine, The Ottawa Hospital, Ottawa, ON, Canada.
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6
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Arora UP, Dumont BL. Meiotic drive in house mice: mechanisms, consequences, and insights for human biology. Chromosome Res 2022; 30:165-186. [PMID: 35829972 PMCID: PMC9509409 DOI: 10.1007/s10577-022-09697-2] [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: 01/16/2022] [Revised: 04/20/2022] [Accepted: 04/27/2022] [Indexed: 11/27/2022]
Abstract
Meiotic drive occurs when one allele at a heterozygous site cheats its way into a disproportionate share of functional gametes, violating Mendel's law of equal segregation. This genetic conflict typically imposes a fitness cost to individuals, often by disrupting the process of gametogenesis. The evolutionary impact of meiotic drive is substantial, and the phenomenon has been associated with infertility and reproductive isolation in a wide range of organisms. However, cases of meiotic drive in humans remain elusive, a finding that likely reflects the inherent challenges of detecting drive in our species rather than unique features of human genome biology. Here, we make the case that house mice (Mus musculus) present a powerful model system to investigate the mechanisms and consequences of meiotic drive and facilitate translational inferences about the scope and potential mechanisms of drive in humans. We first detail how different house mouse resources have been harnessed to identify cases of meiotic drive and the underlying mechanisms utilized to override Mendel's rules of inheritance. We then summarize the current state of knowledge of meiotic drive in the mouse genome. We profile known mechanisms leading to transmission bias at several established drive elements. We discuss how a detailed understanding of meiotic drive in mice can steer the search for drive elements in our own species. Lastly, we conclude with a prospective look into how new technologies and molecular tools can help resolve lingering mysteries about the prevalence and mechanisms of selfish DNA transmission in mammals.
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Affiliation(s)
- Uma P Arora
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME, 04609, USA
- Graduate School of Biomedical Sciences, Tufts University, 136 Harrison Ave, Boston, MA, 02111, USA
| | - Beth L Dumont
- The Jackson Laboratory, 600 Main Street, Bar Harbor, ME, 04609, USA.
- Graduate School of Biomedical Sciences, Tufts University, 136 Harrison Ave, Boston, MA, 02111, USA.
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7
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Booker TR, Payseur BA, Tigano A. Background selection under evolving recombination rates. Proc Biol Sci 2022; 289:20220782. [PMID: 35730151 PMCID: PMC9233929 DOI: 10.1098/rspb.2022.0782] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Background selection (BGS), the effect that purifying selection exerts on sites linked to deleterious alleles, is expected to be ubiquitous across eukaryotic genomes. The effects of BGS reflect the interplay of the rates and fitness effects of deleterious mutations with recombination. A fundamental assumption of BGS models is that recombination rates are invariant over time. However, in some lineages, recombination rates evolve rapidly, violating this central assumption. Here, we investigate how recombination rate evolution affects genetic variation under BGS. We show that recombination rate evolution modifies the effects of BGS in a manner similar to a localized change in the effective population size, potentially leading to underestimation or overestimation of the genome-wide effects of selection. Furthermore, we find evidence that recombination rate evolution in the ancestors of modern house mice may have impacted inferences of the genome-wide effects of selection in that species.
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Affiliation(s)
- Tom R. Booker
- Department of Zoology, University of British Columbia, Vancouver Campus, Vancouver, BC, Canada
| | - Bret A. Payseur
- Laboratory of Genetics, University of Wisconsin - Madison, Madison, WI, USA
| | - Anna Tigano
- Department of Biology, University of British Columbia, Okanagan Campus, Kelowna, BC, Canada
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8
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Wei KHC, Mantha A, Bachtrog D. The Theory and Applications of Measuring Broad-Range and Chromosome-Wide Recombination Rate from Allele Frequency Decay around a Selected Locus. Mol Biol Evol 2020; 37:3654-3671. [PMID: 32658965 PMCID: PMC7743735 DOI: 10.1093/molbev/msaa171] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Recombination is the exchange of genetic material between homologous chromosomes via physical crossovers. High-throughput sequencing approaches detect crossovers genome wide to produce recombination rate maps but are difficult to scale as they require large numbers of recombinants individually sequenced. We present a simple and scalable pooled-sequencing approach to experimentally infer near chromosome-wide recombination rates by taking advantage of non-Mendelian allele frequency generated from a fitness differential at a locus under selection. As more crossovers decouple the selected locus from distal loci, the distorted allele frequency attenuates distally toward Mendelian and can be used to estimate the genetic distance. Here, we use marker selection to generate distorted allele frequency and theoretically derive the mathematical relationships between allele frequency attenuation, genetic distance, and recombination rate in marker-selected pools. We implemented nonlinear curve-fitting methods that robustly estimate the allele frequency decay from batch sequencing of pooled individuals and derive chromosome-wide genetic distance and recombination rates. Empirically, we show that marker-selected pools closely recapitulate genetic distances inferred from scoring recombinants. Using this method, we generated novel recombination rate maps of three wild-derived strains of Drosophila melanogaster, which strongly correlate with previous measurements. Moreover, we show that this approach can be extended to estimate chromosome-wide crossover interference with reciprocal marker selection and discuss how it can be applied in the absence of visible markers. Altogether, we find that our method is a simple and cost-effective approach to generate chromosome-wide recombination rate maps requiring only one or two libraries.
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Affiliation(s)
- Kevin H-C Wei
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA
| | - Aditya Mantha
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA
| | - Doris Bachtrog
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA
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9
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From molecules to populations: appreciating and estimating recombination rate variation. Nat Rev Genet 2020; 21:476-492. [DOI: 10.1038/s41576-020-0240-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/15/2020] [Indexed: 02/07/2023]
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10
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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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11
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Dapper AL, Payseur BA. Molecular evolution of the meiotic recombination pathway in mammals. Evolution 2019; 73:2368-2389. [PMID: 31579931 DOI: 10.1111/evo.13850] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2019] [Accepted: 09/07/2019] [Indexed: 02/06/2023]
Abstract
Meiotic recombination shapes evolution and helps to ensure proper chromosome segregation in most species that reproduce sexually. Recombination itself evolves, with species showing considerable divergence in the rate of crossing-over. However, the genetic basis of this divergence is poorly understood. Recombination events are produced via a complicated, but increasingly well-described, cellular pathway. We apply a phylogenetic comparative approach to a carefully selected panel of genes involved in the processes leading to crossovers-spanning double-strand break formation, strand invasion, the crossover/non-crossover decision, and resolution-to reconstruct the evolution of the recombination pathway in eutherian mammals and identify components of the pathway likely to contribute to divergence between species. Eleven recombination genes, predominantly involved in the stabilization of homologous pairing and the crossover/non-crossover decision, show evidence of rapid evolution and positive selection across mammals. We highlight TEX11 and associated genes involved in the synaptonemal complex and the early stages of the crossover/non-crossover decision as candidates for the evolution of recombination rate. Evolutionary comparisons to MLH1 count, a surrogate for the number of crossovers, reveal a positive correlation between genome-wide recombination rate and the rate of evolution at TEX11 across the mammalian phylogeny. Our results illustrate the power of viewing the evolution of recombination from a pathway perspective.
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Affiliation(s)
- Amy L Dapper
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, 53706.,Department of Biological Sciences, Mississippi State University, Mississippi, 39762
| | - Bret A Payseur
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin, 53706
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12
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Genome-wide recombination map construction from single individuals using linked-read sequencing. Nat Commun 2019; 10:4309. [PMID: 31541091 PMCID: PMC6754380 DOI: 10.1038/s41467-019-12210-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 08/28/2019] [Indexed: 12/19/2022] Open
Abstract
Meiotic recombination rates vary across the genome, often involving localized crossover hotspots and coldspots. Studying the molecular basis and mechanisms underlying this variation has been challenging due to the high cost and effort required to construct individualized genome-wide maps of recombination crossovers. Here we introduce a new method, called ReMIX, to detect crossovers from gamete DNA of a single individual using Illumina sequencing of 10X Genomics linked-read libraries. ReMIX reconstructs haplotypes and identifies the valuable rare molecules spanning crossover breakpoints, allowing quantification of the genomic location and intensity of meiotic recombination. Using a single mouse and stickleback fish, we demonstrate how ReMIX faithfully recovers recombination hotspots and landscapes that have previously been built using hundreds of offspring. ReMIX provides a high-resolution, high-throughput, and low-cost approach to quantify recombination variation across the genome, providing an exciting opportunity to study recombination among multiple individuals in diverse organisms. Variation of recombination rates within genomes has important implications in genetics and evolution. Here, the authors develop a method for building genome-wide recombination maps from single individuals using linked-read sequencing data, and report its application in mouse and stickleback fish.
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13
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Schwahn DJ, Wang RJ, White MA, Payseur BA. Genetic Dissection of Hybrid Male Sterility Across Stages of Spermatogenesis. Genetics 2018; 210:1453-1465. [PMID: 30333190 PMCID: PMC6283182 DOI: 10.1534/genetics.118.301658] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/12/2018] [Indexed: 12/19/2022] Open
Abstract
Hybrid sterility is a common form of reproductive isolation between nascent species. Although hybrid sterility is routinely documented and genetically dissected in speciation studies, its developmental basis is rarely examined, especially in generations beyond the F1 generation. To identify phenotypic and genetic determinants of hybrid male sterility from a developmental perspective, we characterized testis histology in 312 F2 hybrids generated by intercrossing inbred strains of Mus musculus domesticus and M. m. musculus, two subspecies of house mice. Hybrids display a range of histologic abnormalities that indicate defective spermatogenesis. Among these abnormalities, we quantified decreased testis size, reductions in spermatocyte and spermatid number, increased apoptosis of meiosis I spermatocytes, and more multinucleated syncytia. Collectively, our phenotypic data point to defects in meiosis I as a primary barrier to reproduction. We identified seven quantitative trait loci (QTL) controlling five histologic traits. A region of chromosome 17 that contains Prdm9, a gene known to confer F1 hybrid male sterility, affects multinucleated syncytia and round spermatids, potentially extending the phenotypic outcomes of this incompatibility. The X chromosome also plays a key role, with loci affecting multinucleated syncytia, apoptosis of round spermatids, and round spermatid numbers. We detected an epistatic interaction between QTL on chromosomes 17 and X for multinucleated syncytia. Our results refine the developmental basis of a key reproductive barrier in a classic model system for speciation genetics.
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Affiliation(s)
- Denise J Schwahn
- Research Animal Resources Center, University of Wisconsin-Madison, Wisconsin 53726
| | - Richard J Wang
- Laboratory of Genetics, University of Wisconsin-Madison, Wisconsin 53706
| | - Michael A White
- Laboratory of Genetics, University of Wisconsin-Madison, Wisconsin 53706
- Department of Genetics, University of Georgia, Athens, Georgia 30602
| | - Bret A Payseur
- Laboratory of Genetics, University of Wisconsin-Madison, Wisconsin 53706
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14
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Johnston SE, Huisman J, Pemberton JM. A Genomic Region Containing REC8 and RNF212B Is Associated with Individual Recombination Rate Variation in a Wild Population of Red Deer ( Cervus elaphus). G3 (BETHESDA, MD.) 2018; 8:2265-2276. [PMID: 29764960 PMCID: PMC6027875 DOI: 10.1534/g3.118.200063] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Recombination is a fundamental feature of sexual reproduction, ensuring proper disjunction, preventing mutation accumulation and generating new allelic combinations upon which selection can act. However it is also mutagenic, and breaks up favorable allelic combinations previously built up by selection. Identifying the genetic drivers of recombination rate variation is a key step in understanding the causes and consequences of this variation, how loci associated with recombination are evolving and how they affect the potential of a population to respond to selection. However, to date, few studies have examined the genetic architecture of recombination rate variation in natural populations. Here, we use pedigree data from ∼ 2,600 individuals genotyped at ∼ 38,000 SNPs to investigate the genetic architecture of individual autosomal recombination rate in a wild population of red deer (Cervus elaphus). Female red deer exhibited a higher mean and phenotypic variance in autosomal crossover counts (ACC). Animal models fitting genomic relatedness matrices showed that ACC was heritable in females ([Formula: see text] = 0.12) but not in males. A regional heritability mapping approach showed that almost all heritable variation in female ACC was explained by a genomic region on deer linkage group 12 containing the candidate loci REC8 and RNF212B, with an additional region on linkage group 32 containing TOP2B approaching genome-wide significance. The REC8/RNF212B region and its paralogue RNF212 have been associated with recombination in cattle, mice, humans and sheep. Our findings suggest that mammalian recombination rates have a relatively conserved genetic architecture in both domesticated and wild systems, and provide a foundation for understanding the association between recombination loci and individual fitness within this population.
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Affiliation(s)
- Susan E Johnston
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, EH9 3FL, United Kingdom
| | - Jisca Huisman
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, EH9 3FL, United Kingdom
| | - Josephine M Pemberton
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, EH9 3FL, United Kingdom
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15
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Dapper AL, Payseur BA. Connecting theory and data to understand recombination rate evolution. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0469. [PMID: 29109228 DOI: 10.1098/rstb.2016.0469] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/07/2017] [Indexed: 02/03/2023] Open
Abstract
Meiotic recombination is necessary for successful gametogenesis in most sexually reproducing organisms and is a fundamental genomic parameter, influencing the efficacy of selection and the fate of new mutations. The molecular and evolutionary functions of recombination should impose strong selective constraints on the range of recombination rates. Yet, variation in recombination rate is observed on a variety of genomic and evolutionary scales. In the past decade, empirical studies have described variation in recombination rate within genomes, between individuals, between sexes, between populations and between species. At the same time, theoretical work has provided an increasingly detailed picture of the evolutionary advantages to recombination. Perhaps surprisingly, the causes of natural variation in recombination rate remain poorly understood. We argue that empirical and theoretical approaches to understand the evolution of recombination have proceeded largely independently of each other. Most models that address the evolution of recombination rate were created to explain the evolutionary advantage of recombination rather than quantitative differences in rate among individuals. Conversely, most empirical studies aim to describe variation in recombination rate, rather than to test evolutionary hypotheses. In this Perspective, we argue that efforts to integrate the rich bodies of empirical and theoretical work on recombination rate are crucial to moving this field forward. We provide new directions for the development of theory and the production of data that will jointly close this gap.This article is part of the themed issue 'Evolutionary causes and consequences of recombination rate variation in sexual organisms'.
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Affiliation(s)
- Amy L Dapper
- Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
| | - Bret A Payseur
- Laboratory of Genetics, University of Wisconsin, Madison, WI 53706, USA
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16
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Comeron JM. Background selection as null hypothesis in population genomics: insights and challenges from Drosophila studies. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0471. [PMID: 29109230 PMCID: PMC5698629 DOI: 10.1098/rstb.2016.0471] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/04/2017] [Indexed: 12/11/2022] Open
Abstract
The consequences of selection at linked sites are multiple and widespread across the genomes of most species. Here, I first review the main concepts behind models of selection and linkage in recombining genomes, present the difficulty in parametrizing these models simply as a reduction in effective population size (Ne) and discuss the predicted impact of recombination rates on levels of diversity across genomes. Arguments are then put forward in favour of using a model of selection and linkage with neutral and deleterious mutations (i.e. the background selection model, BGS) as a sensible null hypothesis for investigating the presence of other forms of selection, such as balancing or positive. I also describe and compare two studies that have generated high-resolution landscapes of the predicted consequences of selection at linked sites in Drosophila melanogaster. Both studies show that BGS can explain a very large fraction of the observed variation in diversity across the whole genome, thus supporting its use as null model. Finally, I identify and discuss a number of caveats and challenges in studies of genetic hitchhiking that have been often overlooked, with several of them sharing a potential bias towards overestimating the evidence supporting recent selective sweeps to the detriment of a BGS explanation. One potential source of bias is the analysis of non-equilibrium populations: it is precisely because models of selection and linkage predict variation in Ne across chromosomes that demographic dynamics are not expected to be equivalent chromosome- or genome-wide. Other challenges include the use of incomplete genome annotations, the assumption of temporally stable recombination landscapes, the presence of genes under balancing selection and the consequences of ignoring non-crossover (gene conversion) recombination events. This article is part of the themed issue ‘Evolutionary causes and consequences of recombination rate variation in sexual organisms’.
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Affiliation(s)
- Josep M Comeron
- Department of Biology, University of Iowa, Iowa City, IA 52242, USA .,Interdisciplinary Program in Genetics, University of Iowa, Iowa City, IA 52242, USA
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17
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Wen T, Wu M, Shen C, Gao B, Zhu D, Zhang X, You C, Lin Z. Linkage and association mapping reveals the genetic basis of brown fibre (Gossypium hirsutum). PLANT BIOTECHNOLOGY JOURNAL 2018; 16:1654-1666. [PMID: 29476651 PMCID: PMC6097129 DOI: 10.1111/pbi.12902] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2017] [Revised: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 05/14/2023]
Abstract
Brown fibre cotton is an environmental-friendly resource that plays a key role in the textile industry. However, the fibre quality and yield of natural brown cotton are poor, and fundamental research on brown cotton is relatively scarce. To understand the genetic basis of brown fibre cotton, we constructed linkage and association populations to systematically examine brown fibre accessions. We fine-mapped the brown fibre region, Lc1 , and dissected it into 2 loci, qBF-A07-1 and qBF-A07-2. The qBF-A07-1 locus mediates the initiation of brown fibre production, whereas the shade of the brown fibre is affected by the interaction between qBF-A07-1 and qBF-A07-2. Gh_A07G2341 and Gh_A07G0100 were identified as candidate genes for qBF-A07-1 and qBF-A07-2, respectively. Haploid analysis of the signals significantly associated with these two loci showed that most tetraploid modern brown cotton accessions exhibit the introgression signature of Gossypium barbadense. We identified 10 quantitative trait loci (QTLs) for fibre yield and 19 QTLs for fibre quality through a genome-wide association study (GWAS) and found that qBF-A07-2 negatively affects fibre yield and quality through an epistatic interaction with qBF-A07-1. This study sheds light on the genetics of fibre colour and lint-related traits in brown fibre cotton, which will guide the elite cultivars breeding of brown fibre cotton.
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Affiliation(s)
- Tianwang Wen
- National Key Laboratory of Crop Genetic ImprovementCollege of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Mi Wu
- National Key Laboratory of Crop Genetic ImprovementCollege of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Chao Shen
- National Key Laboratory of Crop Genetic ImprovementCollege of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Bin Gao
- National Key Laboratory of Crop Genetic ImprovementCollege of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - De Zhu
- National Key Laboratory of Crop Genetic ImprovementCollege of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Xianlong Zhang
- National Key Laboratory of Crop Genetic ImprovementCollege of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
| | - Chunyuan You
- Cotton Research InstituteShihezi Academy of Agriculture ScienceShiheziXinjiangChina
| | - Zhongxu Lin
- National Key Laboratory of Crop Genetic ImprovementCollege of Plant Science and TechnologyHuazhong Agricultural UniversityWuhanChina
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18
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Hu J, Guo C, Wang B, Ye J, Liu M, Wu Z, Xiao Y, Zhang Q, Li H, King GJ, Liu K. Genetic Properties of a Nested Association Mapping Population Constructed With Semi-Winter and Spring Oilseed Rapes. FRONTIERS IN PLANT SCIENCE 2018; 9:1740. [PMID: 30534135 PMCID: PMC6275288 DOI: 10.3389/fpls.2018.01740] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2018] [Accepted: 11/08/2018] [Indexed: 05/17/2023]
Abstract
Nested association mapping (NAM) populations have been widely applied to dissect the genetic basis of complex quantitative traits in a variety of crops. In this study, we developed a Brassica napus NAM (BN-NAM) population consisting of 15 recombination inbred line (RIL) families with 2,425 immortal genotypes. Fifteen high-density genetic linkage maps were constructed by genotyping by sequencing (GBS) based on all RIL families, with further integration into a joint linkage map (JLM) having 30,209 unique markers in common with multiple linkage maps. Furthermore, an ultra-density whole-genome variation map was constructed by projecting 4,444,309 high-quality variants onto the JLM. The NAM population captured a total of 88,542 recombination events (REs). The uneven distribution of recombination rate along chromosomes is positively correlated with the densities of genes and markers, but negatively correlated with the density of transposable elements and linkage disequilibrium (LD). Analyses of population structure and principal components revealed that the BN-NAM population could be divided into three groups with weak stratification. The LD decay distance across genome varied between 170 and 2,400 Kb, with LD decay more rapid in the A than in the C sub-genome. The pericentromeric regions contained large LD blocks, especially in the C sub-genome. This NAM population provides a valuable resource for dissecting the genetic basis of important traits in rapeseed, especially in semi-winter oilseed rape.
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Affiliation(s)
- Jianlin Hu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Chaocheng Guo
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Bo Wang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Jiaqing Ye
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Meng Liu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Zhikun Wu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Yingjie Xiao
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Qinghua Zhang
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Haitao Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
| | - Graham J. King
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW, Australia
| | - Kede Liu
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, China
- *Correspondence: Kede Liu,
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19
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Lenormand T, Engelstädter J, Johnston SE, Wijnker E, Haag CR. Evolutionary mysteries in meiosis. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2016.0001. [PMID: 27619705 DOI: 10.1098/rstb.2016.0001] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2016] [Indexed: 01/25/2023] Open
Abstract
Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these often 'weird' features. We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots). We present the various evolutionary scenarios and selective pressures that have been proposed to account for these features, and we highlight that their evolutionary significance often remains largely mysterious. Resolving these mysteries will likely provide decisive steps towards understanding why sex and recombination are found in the majority of eukaryotes.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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Affiliation(s)
- Thomas Lenormand
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE)-Unité Mixte de Recherche 5175, Centre National de la Recherche Scientifique (CNRS), Université de Montpellier-Université Paul-Valéry Montpellier-Ecole Pratique des Hautes Etudes (EPHE), 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Susan E Johnston
- Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Erik Wijnker
- Laboratory of Genetics, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Christoph R Haag
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE)-Unité Mixte de Recherche 5175, Centre National de la Recherche Scientifique (CNRS), Université de Montpellier-Université Paul-Valéry Montpellier-Ecole Pratique des Hautes Etudes (EPHE), 1919 Route de Mende, 34293 Montpellier Cedex 5, France
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20
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Booker TR, Ness RW, Keightley PD. The Recombination Landscape in Wild House Mice Inferred Using Population Genomic Data. Genetics 2017; 207:297-309. [PMID: 28751421 PMCID: PMC5586380 DOI: 10.1534/genetics.117.300063] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 07/19/2017] [Indexed: 11/29/2022] Open
Abstract
Characterizing variation in the rate of recombination across the genome is important for understanding several evolutionary processes. Previous analysis of the recombination landscape in laboratory mice has revealed that the different subspecies have different suites of recombination hotspots. It is unknown, however, whether hotspots identified in laboratory strains reflect the hotspot diversity of natural populations or whether broad-scale variation in the rate of recombination is conserved between subspecies. In this study, we constructed fine-scale recombination rate maps for a natural population of the Eastern house mouse, Mus musculus castaneus We performed simulations to assess the accuracy of recombination rate inference in the presence of phase errors, and we used a novel approach to quantify phase error. The spatial distribution of recombination events is strongly positively correlated between our castaneus map, and a map constructed using inbred lines derived predominantly from M. m. domesticus Recombination hotspots in wild castaneus show little overlap, however, with the locations of double-strand breaks in wild-derived house mouse strains. Finally, we also find that genetic diversity in M. m. castaneus is positively correlated with the rate of recombination, consistent with pervasive natural selection operating in the genome. Our study suggests that recombination rate variation is conserved at broad scales between house mouse subspecies, but it is not strongly conserved at fine scales.
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Affiliation(s)
- Tom R Booker
- Institute of Evolutionary Biology, University of Edinburgh, EH9 3FL, United Kingdom
| | - Rob W Ness
- Department of Biology, University of Toronto Mississauga, Ontario, L5L 1C6, Canada
| | - Peter D Keightley
- Institute of Evolutionary Biology, University of Edinburgh, EH9 3FL, United Kingdom
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21
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Structural Variation Shapes the Landscape of Recombination in Mouse. Genetics 2017; 206:603-619. [PMID: 28592499 DOI: 10.1534/genetics.116.197988] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 03/13/2017] [Indexed: 01/02/2023] Open
Abstract
Meiotic recombination is an essential feature of sexual reproduction that ensures faithful segregation of chromosomes and redistributes genetic variants in populations. Multiparent populations such as the Diversity Outbred (DO) mouse stock accumulate large numbers of crossover (CO) events between founder haplotypes, and thus present a unique opportunity to study the role of genetic variation in shaping the recombination landscape. We obtained high-density genotype data from [Formula: see text] DO mice, and localized 2.2 million CO events to intervals with a median size of 28 kb. The resulting sex-averaged genetic map of the DO population is highly concordant with large-scale (order 10 Mb) features of previously reported genetic maps for mouse. To examine fine-scale (order 10 kb) patterns of recombination in the DO, we overlaid putative recombination hotspots onto our CO intervals. We found that CO intervals are enriched in hotspots compared to the genomic background. However, as many as [Formula: see text] of CO intervals do not overlap any putative hotspots, suggesting that our understanding of hotspots is incomplete. We also identified coldspots encompassing 329 Mb, or [Formula: see text] of observable genome, in which there is little or no recombination. In contrast to hotspots, which are a few kilobases in size, and widely scattered throughout the genome, coldspots have a median size of 2.1 Mb and are spatially clustered. Coldspots are strongly associated with copy-number variant (CNV) regions, especially multi-allelic clusters, identified from whole-genome sequencing of 228 DO mice. Genes in these regions have reduced expression, and epigenetic features of closed chromatin in male germ cells, which suggests that CNVs may repress recombination by altering chromatin structure in meiosis. Our findings demonstrate how multiparent populations, by bridging the gap between large-scale and fine-scale genetic mapping, can reveal new features of the recombination landscape.
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22
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Linkage Map of Lissotriton Newts Provides Insight into the Genetic Basis of Reproductive Isolation. G3-GENES GENOMES GENETICS 2017; 7:2115-2124. [PMID: 28500054 PMCID: PMC5499121 DOI: 10.1534/g3.117.041178] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Linkage maps are widely used to investigate structure, function, and evolution of genomes. In speciation research, maps facilitate the study of the genetic architecture of reproductive isolation by allowing identification of genomic regions underlying reduced fitness of hybrids. Here we present a linkage map for European newts of the Lissotriton vulgaris species complex, constructed using two families of F2 L. montandoni × L. vulgaris hybrids. The map consists of 1146 protein-coding genes on 12 linkage groups, equal to the haploid chromosome number, with a total length of 1484 cM (1.29 cM per marker). It is notably shorter than two other maps available for salamanders, but the differences in map length are consistent with cytogenetic estimates of the number of chiasmata per chromosomal arm. Thus, large salamander genomes do not necessarily translate into long linkage maps, as previously suggested. Consequently, salamanders are an excellent model to study evolutionary consequences of recombination rate variation in taxa with large genomes and a similar number of chromosomes. A complex pattern of transmission ratio distortion (TRD) was detected: TRD occurred mostly in one family, in one breeding season, and was clustered in two genomic segments. This is consistent with environment-dependent mortality of individuals carrying L. montandoni alleles in these two segments and suggests a role of TRD blocks in reproductive isolation. The reported linkage map will empower studies on the genomic architecture of divergence and interactions between the genomes of hybridizing newts.
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23
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X-Chromosome Control of Genome-Scale Recombination Rates in House Mice. Genetics 2017; 205:1649-1656. [PMID: 28159751 PMCID: PMC5378119 DOI: 10.1534/genetics.116.197533] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 01/24/2017] [Indexed: 12/19/2022] Open
Abstract
Sex differences in recombination are widespread in mammals, but the causes of this pattern are poorly understood. Previously, males from two interfertile subspecies of house mice, Mus musculus musculus and M. m. castaneus, were shown to exhibit a ∼30% difference in their global crossover frequencies. Much of this crossover rate divergence is explained by six autosomal loci and a large-effect locus on the X chromosome. Intriguingly, the allelic effects at this X-linked locus are transgressive, with the allele conferring increased crossover rate being transmitted by the low crossover rate M. m. castaneus parent. Despite the pronounced divergence between males, females from these subspecies exhibit similar crossover rates, raising the question of how recombination is genetically controlled in this sex. Here, I analyze publicly available genotype data from early generations of the Collaborative Cross, an eight-way panel of recombinant inbred strains, to estimate crossover frequencies in female mice with sex-chromosome genotypes of diverse subspecific origins. Consistent with the transgressive influence of the X chromosome in males, I show that females inheriting an M. m. castaneus X possess higher average crossover rates than females lacking the M. m. castaneus X chromosome. The differential inheritance of the X chromosome in males and females provides a simple genetic explanation for sex-limited evolution of this trait. Further, the presence of X-linked and autosomal crossover rate modifiers with antagonistic effects hints at an underlying genetic conflict fueled by selection for distinct crossover rate optima in males and females.
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24
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Wang RJ, Gray MM, Parmenter MD, Broman KW, Payseur BA. Recombination rate variation in mice from an isolated island. Mol Ecol 2016; 26:457-470. [PMID: 27864900 DOI: 10.1111/mec.13932] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Revised: 11/09/2016] [Accepted: 11/14/2016] [Indexed: 01/14/2023]
Abstract
Recombination rate is a heritable trait that varies among individuals. Despite the major impact of recombination rate on patterns of genetic diversity and the efficacy of selection, natural variation in this phenotype remains poorly characterized. We present a comparison of genetic maps, sampling 1212 meioses, from a unique population of wild house mice (Mus musculus domesticus) that recently colonized remote Gough Island. Crosses to a mainland reference strain (WSB/EiJ) reveal pervasive variation in recombination rate among Gough Island mice, including subchromosomal intervals spanning up to 28% of the genome. In spite of this high level of polymorphism, the genomewide recombination rate does not significantly vary. In general, we find that recombination rate varies more when measured in smaller genomic intervals. Using the current standard genetic map of the laboratory mouse to polarize intervals with divergent recombination rates, we infer that the majority of evolutionary change occurred in one of the two tested lines of Gough Island mice. Our results confirm that natural populations harbour a high level of recombination rate polymorphism and highlight the disparities in recombination rate evolution across genomic scales.
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Affiliation(s)
- Richard J Wang
- Laboratory of Genetics, University of Wisconsin - Madison, 425-G Henry Mall, 2428 Genetics, Madison, WI, 53706, USA
| | - Melissa M Gray
- Laboratory of Genetics, University of Wisconsin - Madison, 425-G Henry Mall, 2428 Genetics, Madison, WI, 53706, USA
| | - Michelle D Parmenter
- Laboratory of Genetics, University of Wisconsin - Madison, 425-G Henry Mall, 2428 Genetics, Madison, WI, 53706, USA
| | - Karl W Broman
- Department of Biostatistics & Medical Informatics, University of Wisconsin - Madison, Madison, WI, 53706, USA
| | - Bret A Payseur
- Laboratory of Genetics, University of Wisconsin - Madison, 425-G Henry Mall, 2428 Genetics, Madison, WI, 53706, USA
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25
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Adrian AB, Corchado JC, Comeron JM. Predictive Models of Recombination Rate Variation across the Drosophila melanogaster Genome. Genome Biol Evol 2016; 8:2597-612. [PMID: 27492232 PMCID: PMC5010912 DOI: 10.1093/gbe/evw181] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
In all eukaryotic species examined, meiotic recombination, and crossovers in particular, occur non‐randomly along chromosomes. The cause for this non-random distribution remains poorly understood but some specific DNA sequence motifs have been shown to be enriched near crossover hotspots in a number of species. We present analyses using machine learning algorithms to investigate whether DNA motif distribution across the genome can be used to predict crossover variation in Drosophila melanogaster, a species without hotspots. Our study exposes a combinatorial non-linear influence of motif presence able to account for a significant fraction of the genome-wide variation in crossover rates at all genomic scales investigated, from 20% at 5-kb to almost 70% at 2,500-kb scale. The models are particularly predictive for regions with the highest and lowest crossover rates and remain highly informative after removing sub-telomeric and -centromeric regions known to have strongly reduced crossover rates. Transcriptional activity during early meiosis and differences in motif use between autosomes and the X chromosome add to the predictive power of the models. Moreover, we show that population-specific differences in crossover rates can be partly explained by differences in motif presence. Our results suggest that crossover distribution in Drosophila is influenced by both meiosis-specific chromatin dynamics and very local constitutive open chromatin associated with DNA motifs that prevent nucleosome stabilization. These findings provide new information on the genetic factors influencing variation in recombination rates and a baseline to study epigenetic mechanisms responsible for plastic recombination as response to different biotic and abiotic conditions and stresses.
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Affiliation(s)
| | | | - Josep M Comeron
- Department of Biology, University of Iowa Interdisciplinary Graduate Program in Genetics, University of Iowa
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26
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Pan Q, Li L, Yang X, Tong H, Xu S, Li Z, Li W, Muehlbauer GJ, Li J, Yan J. Genome-wide recombination dynamics are associated with phenotypic variation in maize. THE NEW PHYTOLOGIST 2016; 210:1083-94. [PMID: 26720856 DOI: 10.1111/nph.13810] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 11/11/2015] [Indexed: 05/04/2023]
Abstract
Meiotic recombination is a major driver of genetic diversity, species evolution, and agricultural improvement. Thus, an understanding of the genetic recombination landscape across the maize (Zea mays) genome will provide insight and tools for further study of maize evolution and improvement. Here, we used c. 50 000 single nucleotide polymorphisms to precisely map recombination events in 12 artificial maize segregating populations. We observed substantial variation in the recombination frequency and distribution along the ten maize chromosomes among the 12 populations and identified 143 recombination hot regions. Recombination breakpoints were partitioned into intragenic and intergenic events. Interestingly, an increase in the number of genes containing recombination events was accompanied by a decrease in the number of recombination events per gene. This kept the overall number of intragenic recombination events nearly invariable in a given population, suggesting that the recombination variation observed among populations was largely attributed to intergenic recombination. However, significant associations between intragenic recombination events and variation in gene expression and agronomic traits were observed, suggesting potential roles for intragenic recombination in plant phenotypic diversity. Our results provide a comprehensive view of the maize recombination landscape, and show an association between recombination, gene expression and phenotypic variation, which may enhance crop genetic improvement.
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Affiliation(s)
- Qingchun Pan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China
| | - Lin Li
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China
- Department of Agronomy and Plant Genetics, University of Minnesota, Saint Paul, MN, 55108, USA
| | - Xiaohong Yang
- National Maize Improvement Center of China, China Agricultural University, Beijing, 100193, China
| | - Hao Tong
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China
| | - Shutu Xu
- National Maize Improvement Center of China, China Agricultural University, Beijing, 100193, China
| | - Zhigang Li
- National Maize Improvement Center of China, China Agricultural University, Beijing, 100193, China
| | - Weiya Li
- National Maize Improvement Center of China, China Agricultural University, Beijing, 100193, China
| | - Gary J Muehlbauer
- Department of Agronomy and Plant Genetics, University of Minnesota, Saint Paul, MN, 55108, USA
- Department of Plant Biology, University of Minnesota, Saint Paul, MN, 55108, USA
| | - Jiansheng Li
- National Maize Improvement Center of China, China Agricultural University, Beijing, 100193, China
| | - Jianbing Yan
- National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan, 430070, China
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Hybrid Sterility Locus on Chromosome X Controls Meiotic Recombination Rate in Mouse. PLoS Genet 2016; 12:e1005906. [PMID: 27104744 PMCID: PMC4841592 DOI: 10.1371/journal.pgen.1005906] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 02/08/2016] [Indexed: 11/28/2022] Open
Abstract
Meiotic recombination safeguards proper segregation of homologous chromosomes into gametes, affects genetic variation within species, and contributes to meiotic chromosome recognition, pairing and synapsis. The Prdm9 gene has a dual role, it controls meiotic recombination by determining the genomic position of crossover hotspots and, in infertile hybrids of house mouse subspecies Mus m. musculus (Mmm) and Mus m. domesticus (Mmd), it further functions as the major hybrid sterility gene. In the latter role Prdm9 interacts with the hybrid sterility X 2 (Hstx2) genomic locus on Chromosome X (Chr X) by a still unknown mechanism. Here we investigated the meiotic recombination rate at the genome-wide level and its possible relation to hybrid sterility. Using immunofluorescence microscopy we quantified the foci of MLH1 DNA mismatch repair protein, the cytological counterparts of reciprocal crossovers, in a panel of inter-subspecific chromosome substitution strains. Two autosomes, Chr 7 and Chr 11, significantly modified the meiotic recombination rate, yet the strongest modifier, designated meiotic recombination 1, Meir1, emerged in the 4.7 Mb Hstx2 genomic locus on Chr X. The male-limited transgressive effect of Meir1 on recombination rate parallels the male-limited transgressive role of Hstx2 in hybrid male sterility. Thus, both genetic factors, the Prdm9 gene and the Hstx2/Meir1 genomic locus, indicate a link between meiotic recombination and hybrid sterility. A strong female-specific modifier of meiotic recombination rate with the effect opposite to Meir1 was localized on Chr X, distally to Meir1. Mapping Meir1 to a narrow candidate interval on Chr X is an important first step towards positional cloning of the respective gene(s) responsible for variation in the global recombination rate between closely related mouse subspecies. During differentiation of germ cells into gametes, a maternal and a paternal copy of each chromosome have to find each other, pair, and synapse in order to ensure proper chromosome segregation into the gametes. Because of the unique ability to identify homologous DNA sequences between homologous chromosomes, meiotic recombination is an essential step in proper chromosome pairing and synapsis in the majority of species. However, when the paternal and maternal sets of chromosomes come from different (sub)species, the recognition of homologs can be disturbed and result in sterility of male hybrids. In this study we investigated the genetic control of variation in the global recombination rate between two closely related mouse subspecies with regard to the known infertility of their F1 hybrids. We show that the variation in the global recombination rate between both subspecies is under the control of three genomic loci. The strongest one appeared within the hybrid sterility X2 genomic locus on Chromosome X. Our findings will allow positional cloning of the gene and will shed new light on the role of meiotic recombination in reproductive isolation between closely related species.
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Metzger CMJA, Luijckx P, Bento G, Mariadassou M, Ebert D. The Red Queen lives: Epistasis between linked resistance loci. Evolution 2016; 70:480-7. [DOI: 10.1111/evo.12854] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 01/04/2016] [Accepted: 01/05/2016] [Indexed: 02/05/2023]
Affiliation(s)
| | - Pepijn Luijckx
- Zoological Institute; University of Basel; CH-4051 Basel Switzerland
- Department of Ecology & Evolutionary Biology; University of Toronto; M5S 3B2 Toronto Ontario Canada
| | - Gilberto Bento
- Zoological Institute; University of Basel; CH-4051 Basel Switzerland
| | - Mahendra Mariadassou
- Zoological Institute; University of Basel; CH-4051 Basel Switzerland
- INRA, UR1404 Unité Mathématique et Informatique Appliquées du Génome à l'Environnement; 78350 Jouy-en-Josas France
| | - Dieter Ebert
- Zoological Institute; University of Basel; CH-4051 Basel Switzerland
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The Founder Strains of the Collaborative Cross Express a Complex Combination of Advantageous and Deleterious Traits for Male Reproduction. G3-GENES GENOMES GENETICS 2015; 5:2671-83. [PMID: 26483008 PMCID: PMC4683640 DOI: 10.1534/g3.115.020172] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Surveys of inbred strains of mice are standard approaches to determine the heritability and range of phenotypic variation for biomedical traits. In addition, they may lead to the identification of novel phenotypes and models of human disease. Surprisingly, male reproductive phenotypes are among the least-represented traits in the Mouse Phenome Database. Here we report the results of a broad survey of the eight founder inbred strains of both the Collaborative Cross (CC) and the Diversity Outbred populations, two new mouse resources that are being used as platforms for systems genetics and sources of mouse models of human diseases. Our survey includes representatives of the three main subspecies of the house mice and a mix of classical and wild-derived inbred strains. In addition to standard staples of male reproductive phenotyping such as reproductive organ weights, sperm counts, and sperm morphology, our survey includes sperm motility and the first detailed survey of testis histology. As expected for such a broad survey, heritability varies widely among traits. We conclude that although all eight inbred strains are fertile, most display a mix of advantageous and deleterious male reproductive traits. The CAST/EiJ strain is an outlier, with an unusual combination of deleterious male reproductive traits including low sperm counts, high levels of morphologically abnormal sperm, and poor motility. In contrast, sperm from the PWK/PhJ and WSB/EiJ strains had the greatest percentages of normal morphology and vigorous motility. Finally, we report an abnormal testis phenotype that is highly heritable and restricted to the WSB/EiJ strain. This phenotype is characterized by the presence of a large, but variable, number of vacuoles in at least 10% of the seminiferous tubules. The onset of the phenotype between 2 and 3 wk of age is temporally correlated with the formation of the blood-testis barrier. We speculate that this phenotype may play a role in high rates of extinction in the CC project and in the phenotypes associated with speciation in genetic crosses that use the WSB/EiJ strain as representative of the Mus muculus domesticus subspecies.
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Charlesworth D. The status of supergenes in the 21st century: recombination suppression in Batesian mimicry and sex chromosomes and other complex adaptations. Evol Appl 2015; 9:74-90. [PMID: 27087840 PMCID: PMC4780387 DOI: 10.1111/eva.12291] [Citation(s) in RCA: 90] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 06/16/2015] [Indexed: 02/06/2023] Open
Abstract
I review theoretical models for the evolution of supergenes in the cases of Batesian mimicry in butterflies, distylous plants and sex chromosomes. For each of these systems, I outline the genetic evidence that led to the proposal that they involve multiple genes that interact during ‘complex adaptations’, and at which the mutations involved are not unconditionally advantageous, but show advantages that trade‐off against some disadvantages. I describe recent molecular genetic studies of these systems and questions they raise about the evolution of suppressed recombination. Nonrecombining regions of sex chromosomes have long been known, but it is not yet fully understood why recombination suppression repeatedly evolved in systems in distantly related taxa, but does not always evolve. Recent studies of distylous plants are tending to support the existence of recombination‐suppressed genome regions, which may include modest numbers of genes and resemble recently evolved sex‐linked regions. For Batesian mimicry, however, molecular genetic work in two butterfly species suggests a new supergene scenario, with a single gene mutating to produce initial adaptive phenotypes, perhaps followed by modifiers specifically refining and perfecting the new phenotype.
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31
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Vrooman LA, Oatley JM, Griswold JE, Hassold TJ, Hunt PA. Estrogenic exposure alters the spermatogonial stem cells in the developing testis, permanently reducing crossover levels in the adult. PLoS Genet 2015; 11:e1004949. [PMID: 25615633 PMCID: PMC4304829 DOI: 10.1371/journal.pgen.1004949] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 12/09/2014] [Indexed: 12/19/2022] Open
Abstract
Bisphenol A (BPA) and other endocrine disrupting chemicals have been reported to induce negative effects on a wide range of physiological processes, including reproduction. In the female, BPA exposure increases meiotic errors, resulting in the production of chromosomally abnormal eggs. Although numerous studies have reported that estrogenic exposures negatively impact spermatogenesis, a direct link between exposures and meiotic errors in males has not been evaluated. To test the effect of estrogenic chemicals on meiotic chromosome dynamics, we exposed male mice to either BPA or to the strong synthetic estrogen, ethinyl estradiol during neonatal development when the first cells initiate meiosis. Although chromosome pairing and synapsis were unperturbed, exposed outbred CD-1 and inbred C3H/HeJ males had significantly reduced levels of crossovers, or meiotic recombination (as defined by the number of MLH1 foci in pachytene cells) by comparison with placebo. Unexpectedly, the effect was not limited to cells exposed at the time of meiotic entry but was evident in all subsequent waves of meiosis. To determine if the meiotic effects induced by estrogen result from changes to the soma or germline of the testis, we transplanted spermatogonial stem cells from exposed males into the testes of unexposed males. Reduced recombination was evident in meiocytes derived from colonies of transplanted cells. Taken together, our results suggest that brief exogenous estrogenic exposure causes subtle changes to the stem cell pool that result in permanent alterations in spermatogenesis (i.e., reduced recombination in descendent meiocytes) in the adult male.
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Affiliation(s)
- Lisa A. Vrooman
- School of Molecular Biosciences, Center for Reproductive Biology, Washington State University, Pullman, Washington, United States of America
| | - Jon M. Oatley
- School of Molecular Biosciences, Center for Reproductive Biology, Washington State University, Pullman, Washington, United States of America
| | - Jodi E. Griswold
- School of Molecular Biosciences, Center for Reproductive Biology, Washington State University, Pullman, Washington, United States of America
| | - Terry J. Hassold
- School of Molecular Biosciences, Center for Reproductive Biology, Washington State University, Pullman, Washington, United States of America
| | - Patricia A. Hunt
- School of Molecular Biosciences, Center for Reproductive Biology, Washington State University, Pullman, Washington, United States of America
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Kessler MD, Dean MD. Effective population size does not predict codon usage bias in mammals. Ecol Evol 2014; 4:3887-900. [PMID: 25505518 PMCID: PMC4242573 DOI: 10.1002/ece3.1249] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 08/04/2014] [Accepted: 08/07/2014] [Indexed: 12/20/2022] Open
Abstract
Synonymous codons are not used at equal frequency throughout the genome, a phenomenon termed codon usage bias (CUB). It is often assumed that interspecific variation in the intensity of CUB is related to species differences in effective population sizes (Ne), with selection on CUB operating less efficiently in species with small Ne. Here, we specifically ask whether variation in Ne predicts differences in CUB in mammals and report two main findings. First, across 41 mammalian genomes, CUB was not correlated with two indirect proxies of Ne (body mass and generation time), even though there was statistically significant evidence of selection shaping CUB across all species. Interestingly, autosomal genes showed higher codon usage bias compared to X-linked genes, and high-recombination genes showed higher codon usage bias compared to low recombination genes, suggesting intraspecific variation in Ne predicts variation in CUB. Second, across six mammalian species with genetic estimates of Ne (human, chimpanzee, rabbit, and three mouse species: Mus musculus, M. domesticus, and M. castaneus), Ne and CUB were weakly and inconsistently correlated. At least in mammals, interspecific divergence in Ne does not strongly predict variation in CUB. One hypothesis is that each species responds to a unique distribution of selection coefficients, confounding any straightforward link between Ne and CUB.
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Affiliation(s)
- Michael D Kessler
- Molecular and Computational Biology, University of Southern California 1050 Childs Way, Los Angeles, California, 90089
| | - Matthew D Dean
- Molecular and Computational Biology, University of Southern California 1050 Childs Way, Los Angeles, California, 90089
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The genetic architecture of coordinately evolving male wing pigmentation and courtship behavior in Drosophila elegans and Drosophila gunungcola. G3-GENES GENOMES GENETICS 2014; 4:2079-93. [PMID: 25168010 PMCID: PMC4232533 DOI: 10.1534/g3.114.013037] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Many adaptive phenotypes consist of combinations of simpler traits that act synergistically, such as morphological traits and the behaviors that use those traits. Genetic correlations between components of such combinatorial traits, in the form of pleiotropic or tightly linked genes, can in principle promote the evolution and maintenance of these traits. In the Oriental Drosophila melanogaster species group, male wing pigmentation shows phylogenetic correlations with male courtship behavior; species with male-specific apical wing melanin spots also exhibit male visual wing displays, whereas species lacking these spots generally lack the displays. In this study, we investigated the quantitative genetic basis of divergence in male wing spots and displays between D. elegans, which possesses both traits, and its sibling species D. gunungcola, which lacks them. We found that divergence in wing spot size is determined by at least three quantitative trait loci (QTL) and divergence in courtship score is determined by at least four QTL. On the autosomes, QTL locations for pigmentation and behavior were generally separate, but on the X chromosome two clusters of QTL were found affecting both wing pigmentation and courtship behavior. We also examined the genetic basis of divergence in three components of male courtship, wing display, circling, and body shaking. Each of these showed a distinct genetic architecture, with some QTL mapping to similar positions as QTL for overall courtship score. Pairwise tests for interactions between marker loci revealed evidence of epistasis between putative QTL for wing pigmentation but not those for courtship behavior. The clustering of X-linked QTL for male pigmentation and behavior is consistent with the concerted evolution of these traits and motivates fine-scale mapping studies to elucidate the nature of the contributing genetic factors in these intervals.
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34
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Abstract
One approach to understanding the genetic basis of speciation is to scan the genomes of recently diverged taxa to identify highly differentiated regions. The house mouse, Mus musculus, provides a useful system for the study of speciation. Three subspecies (M. m. castaneus, M. m. domesticus, and M. m. musculus) diverged ∼350 KYA, are distributed parapatrically, show varying degrees of reproductive isolation in laboratory crosses, and hybridize in nature. We sequenced the testes transcriptomes of multiple wild-derived inbred lines from each subspecies to identify highly differentiated regions of the genome, to identify genes showing high expression divergence, and to compare patterns of differentiation among subspecies that have different demographic histories and exhibit different levels of reproductive isolation. Using a sliding-window approach, we found many genomic regions with high levels of sequence differentiation in each of the pairwise comparisons among subspecies. In all comparisons, the X chromosome was more highly differentiated than the autosomes. Sequence differentiation and expression divergence were greater in the M. m. domesticus-M. m. musculus comparison than in either pairwise comparison with M. m. castaneus, which is consistent with laboratory crosses that show the greatest reproductive isolation between M. m. domesticus and M. m. musculus. Coalescent simulations suggest that differences in estimates of effective population size can account for many of the observed patterns. However, there was an excess of highly differentiated regions relative to simulated distributions under a wide range of demographic scenarios. Overlap of some highly differentiated regions with previous results from QTL mapping and hybrid zone studies points to promising candidate regions for reproductive isolation.
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35
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Kawakami T, Smeds L, Backström N, Husby A, Qvarnström A, Mugal CF, Olason P, Ellegren H. A high-density linkage map enables a second-generation collared flycatcher genome assembly and reveals the patterns of avian recombination rate variation and chromosomal evolution. Mol Ecol 2014; 23:4035-58. [PMID: 24863701 PMCID: PMC4149781 DOI: 10.1111/mec.12810] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2014] [Revised: 05/08/2014] [Accepted: 05/09/2014] [Indexed: 12/15/2022]
Abstract
Detailed linkage and recombination rate maps are necessary to use the full potential of genome sequencing and population genomic analyses. We used a custom collared flycatcher 50 K SNP array to develop a high-density linkage map with 37 262 markers assigned to 34 linkage groups in 33 autosomes and the Z chromosome. The best-order map contained 4215 markers, with a total distance of 3132 cm and a mean genetic distance between markers of 0.12 cm. Facilitated by the array being designed to include markers from most scaffolds, we obtained a second-generation assembly of the flycatcher genome that approaches full chromosome sequences (N50 super-scaffold size 20.2 Mb and with 1.042 Gb (of 1.116 Gb) anchored to and mostly ordered and oriented along chromosomes). We found that flycatcher and zebra finch chromosomes are entirely syntenic but that inversions at mean rates of 1.5–2.0 event (6.6–7.5 Mb) per My have changed the organization within chromosomes, rates high enough for inversions to potentially have been involved with many speciation events during avian evolution. The mean recombination rate was 3.1 cm/Mb and correlated closely with chromosome size, from 2 cm/Mb for chromosomes >100 Mb to >10 cm/Mb for chromosomes <10 Mb. This size dependence seemed entirely due to an obligate recombination event per chromosome; if 50 cm was subtracted from the genetic lengths of chromosomes, the rate per physical unit DNA was constant across chromosomes. Flycatcher recombination rate showed similar variation along chromosomes as chicken but lacked the large interior recombination deserts characteristic of zebra finch chromosomes.
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Affiliation(s)
- Takeshi Kawakami
- Department of Evolutionary Biology, Evolutionary Biology Centre (EBC), Uppsala University, Norbyvägen 18D, SE-752 36, Uppsala, Sweden
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Baier B, Hunt P, Broman KW, Hassold T. Variation in genome-wide levels of meiotic recombination is established at the onset of prophase in mammalian males. PLoS Genet 2014; 10:e1004125. [PMID: 24497841 PMCID: PMC3907295 DOI: 10.1371/journal.pgen.1004125] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2013] [Accepted: 12/04/2013] [Indexed: 11/18/2022] Open
Abstract
Segregation of chromosomes during the first meiotic division relies on crossovers established during prophase. Although crossovers are strictly regulated so that at least one occurs per chromosome, individual variation in crossover levels is not uncommon. In an analysis of different inbred strains of male mice, we identified among-strain variation in the number of foci for the crossover-associated protein MLH1. We report studies of strains with “low” (CAST/EiJ), “medium” (C3H/HeJ), and “high” (C57BL/6J) genome-wide MLH1 values to define factors responsible for this variation. We utilized immunofluorescence to analyze the number and distribution of proteins that function at different stages in the recombination pathway: RAD51 and DMC1, strand invasion proteins acting shortly after double-strand break (DSB) formation, MSH4, part of the complex stabilizing double Holliday junctions, and the Bloom helicase BLM, thought to have anti-crossover activity. For each protein, we identified strain-specific differences that mirrored the results for MLH1; i.e., CAST/EiJ mice had the lowest values, C3H/HeJ mice intermediate values, and C57BL/6J mice the highest values. This indicates that differences in the numbers of DSBs (as identified by RAD51 and DMC1) are translated into differences in the number of crossovers, suggesting that variation in crossover levels is established by the time of DSB formation. However, DSBs per se are unlikely to be the primary determinant, since allelic variation for the DSB-inducing locus Spo11 resulted in differences in the numbers of DSBs but not the number of MLH1 foci. Instead, chromatin conformation appears to be a more important contributor, since analysis of synaptonemal complex length and DNA loop size also identified consistent strain-specific differences; i.e., crossover frequency increased with synaptonemal complex length and was inversely related to chromatin loop size. This indicates a relationship between recombination and chromatin compaction that may develop as DSBs form or earlier during establishment of the meiotic axis. During prophase of meiosis, homologous chromosomes exchange genetic material, in a process known as crossing-over. Crossovers are thought to be essential for proper separation of chromosomes during meiosis but, surprisingly, most mammalian species exhibit substantial individual variation in the number of crossovers per cell. We investigated the basis for this variation by examining localization patterns of crossover-associated proteins in inbred strains of male mice with differing average numbers of crossovers per spermatocyte. Our results indicate that the strain-specific variation is established early in meiotic prophase, possibly even before the DNA is broken in advance of subsequent exchanges between homologous chromosomes.
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Affiliation(s)
- Brian Baier
- School of Molecular Biosciences, Washington State University, Pullman, Washington, United States of America
| | - Patricia Hunt
- School of Molecular Biosciences, Washington State University, Pullman, Washington, United States of America
| | - Karl W. Broman
- Department of Biostatistics and Medical Informatics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Terry Hassold
- School of Molecular Biosciences, Washington State University, Pullman, Washington, United States of America
- * E-mail:
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Adrian AB, Comeron JM. The Drosophila early ovarian transcriptome provides insight to the molecular causes of recombination rate variation across genomes. BMC Genomics 2013; 14:794. [PMID: 24228734 PMCID: PMC3840681 DOI: 10.1186/1471-2164-14-794] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Accepted: 11/06/2013] [Indexed: 11/10/2022] Open
Abstract
Background Evidence in yeast indicates that gene expression is correlated with recombination activity and double-strand break (DSB) formation in some hotspots. Studies of nucleosome occupancy in yeast and mice also suggest that open chromatin influences the formation of DSBs. In Drosophila melanogaster, high-resolution recombination maps show an excess of DSBs within annotated transcripts relative to intergenic sequences. The impact of active transcription on recombination landscapes, however, remains unexplored in a multicellular organism. We then investigated the transcription profile during early meiosis in D. melanogaster females to obtain a glimpse at the relevant transcriptional dynamics during DSB formation, and test the specific hypothesis that DSBs preferentially target transcriptionally active genomic regions. Results Our study of transcript profiles of early- and late-meiosis using mRNA-seq revealed, 1) significant differences in gene expression, 2) new genes and exons, 3) parent-of-origin effects on transcription in early-meiosis stages, and 4) a nonrandom genomic distribution of transcribed genes. Importantly, genomic regions that are more actively transcribed during early meiosis show higher rates of recombination, and we ruled out DSB preference for genic regions that are not transcribed. Conclusions Our results provide evidence in a multicellular organism that transcription during the initial phases of meiosis increases the likelihood of DSB and give insight into the molecular determinants of recombination rate variation across the D. melanogaster genome. We propose that a model where variation in gene expression plays a role altering the recombination landscape across the genome could provide a molecular, heritable and plastic mechanism to observed patterns of recombination variation, from the high level of intra-specific variation to the known influence of environmental factors and stress conditions.
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Affiliation(s)
| | - Josep M Comeron
- Department of Biology, University of Iowa, Iowa City, Iowa, USA.
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Clément Y, Arndt PF. Meiotic recombination strongly influences GC-content evolution in short regions in the mouse genome. Mol Biol Evol 2013; 30:2612-8. [PMID: 24030552 DOI: 10.1093/molbev/mst154] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Meiotic recombination is known to influence GC-content evolution in large regions of mammalian genomes by favoring the fixation of G and C alleles and increasing the rate of A/T to G/C substitutions. This process is known as GC-biased gene conversion (gBGC). Until recently, genome-wide measures of fine-scale recombination activity were unavailable in mice. Additionally, comparative studies focusing on mouse were limited as the closest organism with its genome fully sequenced was rat. Here, we make use of the recent mapping of double strand breaks (DSBs), the first step of meiotic recombination, in the mouse genome and of the sequencing of mouse closely related subspecies to analyze the fine-scale evolutionary signature of meiotic recombination on GC-content evolution in recombination hotspots, short regions that undergo extreme rates of recombination. We measure substitution rates around DSB hotspots and observe that gBGC is affecting a very short region (≈ 1 kbp) in length around these hotspots. Furthermore, we can infer that the locations of hotspots evolved rapidly during mouse evolution.
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Affiliation(s)
- Yves Clément
- Montpellier SupAgro, Unité Mixte de Recherche 1334, Amélioration Génétique et Adaptation des Plantes Méditerranéennes et Tropicales, Montpellier, France
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39
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Genomic signatures of selection at linked sites: unifying the disparity among species. Nat Rev Genet 2013; 14:262-74. [PMID: 23478346 DOI: 10.1038/nrg3425] [Citation(s) in RCA: 315] [Impact Index Per Article: 28.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Population genetics theory supplies powerful predictions about how natural selection interacts with genetic linkage to sculpt the genomic landscape of nucleotide polymorphism. Both the spread of beneficial mutations and the removal of deleterious mutations act to depress polymorphism levels, especially in low-recombination regions. However, empiricists have documented extreme disparities among species. Here we characterize the dominant features that could drive differences in linked selection among species--including roles for selective sweeps being 'hard' or 'soft'--and the concealing effects of demography and confounding genomic variables. We advocate targeted studies of closely related species to unify our understanding of how selection and linkage interact to shape genome evolution.
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40
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Comeron JM, Ratnappan R, Bailin S. The many landscapes of recombination in Drosophila melanogaster. PLoS Genet 2012; 8:e1002905. [PMID: 23071443 PMCID: PMC3469467 DOI: 10.1371/journal.pgen.1002905] [Citation(s) in RCA: 332] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2012] [Accepted: 07/02/2012] [Indexed: 01/06/2023] Open
Abstract
Recombination is a fundamental biological process with profound evolutionary implications. Theory predicts that recombination increases the effectiveness of selection in natural populations. Yet, direct tests of this prediction have been restricted to qualitative trends due to the lack of detailed characterization of recombination rate variation across genomes and within species. The use of imprecise recombination rates can also skew population genetic analyses designed to assess the presence and mode of selection across genomes. Here we report the first integrated high-resolution description of genomic and population variation in recombination, which also distinguishes between the two outcomes of meiotic recombination: crossing over (CO) and gene conversion (GC). We characterized the products of 5,860 female meioses in Drosophila melanogaster by genotyping a total of 139 million informative SNPs and mapped 106,964 recombination events at a resolution down to 2 kilobases. This approach allowed us to generate whole-genome CO and GC maps as well as a detailed description of variation in recombination among individuals of this species. We describe many levels of variation in recombination rates. At a large-scale (100 kb), CO rates exhibit extreme and highly punctuated variation along chromosomes, with hot and coldspots. We also show extensive intra-specific variation in CO landscapes that is associated with hotspots at low frequency in our sample. GC rates are more uniformly distributed across the genome than CO rates and detectable in regions with reduced or absent CO. At a local scale, recombination events are associated with numerous sequence motifs and tend to occur within transcript regions, thus suggesting that chromatin accessibility favors double-strand breaks. All these non-independent layers of variation in recombination across genomes and among individuals need to be taken into account in order to obtain relevant estimates of recombination rates, and should be included in a new generation of population genetic models of the interaction between selection and linkage.
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Affiliation(s)
- Josep M Comeron
- Department of Biology, University of Iowa, Iowa City, Iowa, USA.
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Cattani MV, Kingan SB, Presgraves DC. Cis
‐
and
trans
‐acting genetic factors contribute to heterogeneity in the rate of crossing over between the
D
rosophila simulans
clade species. J Evol Biol 2012; 25:2014-2022. [DOI: 10.1111/j.1420-9101.2012.02578.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2012] [Revised: 06/25/2012] [Accepted: 06/26/2012] [Indexed: 12/19/2022]
Affiliation(s)
- M. V. Cattani
- Department of Biology University of Rochester Rochester NY USA
| | - S. B. Kingan
- Department of Biology University of Rochester Rochester NY USA
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White MA, Stubbings M, Dumont BL, Payseur BA. Genetics and evolution of hybrid male sterility in house mice. Genetics 2012; 191:917-34. [PMID: 22554891 PMCID: PMC3389984 DOI: 10.1534/genetics.112.140251] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2012] [Accepted: 04/23/2012] [Indexed: 12/12/2022] Open
Abstract
Comparative genetic mapping provides insights into the evolution of the reproductive barriers that separate closely related species. This approach has been used to document the accumulation of reproductive incompatibilities over time, but has only been applied to a few taxa. House mice offer a powerful system to reconstruct the evolution of reproductive isolation between multiple subspecies pairs. However, studies of the primary reproductive barrier in house mice-hybrid male sterility-have been restricted to a single subspecies pair: Mus musculus musculus and Mus musculus domesticus. To provide a more complete characterization of reproductive isolation in house mice, we conducted an F(2) intercross between wild-derived inbred strains from Mus musculus castaneus and M. m. domesticus. We identified autosomal and X-linked QTL associated with a range of hybrid male sterility phenotypes, including testis weight, sperm density, and sperm morphology. The pseudoautosomal region (PAR) was strongly associated with hybrid sterility phenotypes when heterozygous. We compared QTL found in this cross with QTL identified in a previous F(2) intercross between M. m. musculus and M. m. domesticus and found three shared autosomal QTL. Most QTL were not shared, demonstrating that the genetic basis of hybrid male sterility largely differs between these closely related subspecies pairs. These results lay the groundwork for identifying genes responsible for the early stages of speciation in house mice.
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Affiliation(s)
| | - Maria Stubbings
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706
| | | | - Bret A. Payseur
- Laboratory of Genetics, University of Wisconsin, Madison, Wisconsin 53706
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43
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Nachman MW, Payseur BA. Recombination rate variation and speciation: theoretical predictions and empirical results from rabbits and mice. Philos Trans R Soc Lond B Biol Sci 2012; 367:409-21. [PMID: 22201170 DOI: 10.1098/rstb.2011.0249] [Citation(s) in RCA: 248] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Recently diverged taxa may continue to exchange genes. A number of models of speciation with gene flow propose that the frequency of gene exchange will be lower in genomic regions of low recombination and that these regions will therefore be more differentiated. However, several population-genetic models that focus on selection at linked sites also predict greater differentiation in regions of low recombination simply as a result of faster sorting of ancestral alleles even in the absence of gene flow. Moreover, identifying the actual amount of gene flow from patterns of genetic variation is tricky, because both ancestral polymorphism and migration lead to shared variation between recently diverged taxa. New analytic methods have been developed to help distinguish ancestral polymorphism from migration. Along with a growing number of datasets of multi-locus DNA sequence variation, these methods have spawned a renewed interest in speciation models with gene flow. Here, we review both speciation and population-genetic models that make explicit predictions about how the rate of recombination influences patterns of genetic variation within and between species. We then compare those predictions with empirical data of DNA sequence variation in rabbits and mice. We find strong support for the prediction that genomic regions experiencing low levels of recombination are more differentiated. In most cases, reduced gene flow appears to contribute to the pattern, although disentangling the relative contribution of reduced gene flow and selection at linked sites remains a challenge. We suggest fruitful areas of research that might help distinguish between different models.
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Affiliation(s)
- Michael W Nachman
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA.
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44
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Abstract
Recombination events are not uniformly distributed and often cluster in narrow regions known as recombination hotspots. Several studies using different approaches have dramatically advanced our understanding of recombination hotspot regulation. Population genetic data have been used to map and quantify hotspots in the human genome. Genetic variation in recombination rates and hotspots usage have been explored in human pedigrees, mouse intercrosses, and by sperm typing. These studies pointed to the central role of the PRDM9 gene in hotspot modulation. In this study, we used single nucleotide polymorphisms (SNPs) from whole-genome resequencing and genotyping studies of mouse inbred strains to estimate recombination rates across the mouse genome and identified 47,068 historical hotspots--an average of over 2477 per chromosome. We show by simulation that inbred mouse strains can be used to identify positions of historical hotspots. Recombination hotspots were found to be enriched for the predicted binding sequences for different alleles of the PRDM9 protein. Recombination rates were on average lower near transcription start sites (TSS). Comparing the inferred historical recombination hotspots with the recent genome-wide mapping of double-strand breaks (DSBs) in mouse sperm revealed a significant overlap, especially toward the telomeres. Our results suggest that inbred strains can be used to characterize and study the dynamics of historical recombination hotspots. They also strengthen previous findings on mouse recombination hotspots, and specifically the impact of sequence variants in Prdm9.
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45
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Smukowski CS, Noor MAF. Recombination rate variation in closely related species. Heredity (Edinb) 2011; 107:496-508. [PMID: 21673743 PMCID: PMC3242630 DOI: 10.1038/hdy.2011.44] [Citation(s) in RCA: 139] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2010] [Revised: 03/21/2011] [Accepted: 04/27/2011] [Indexed: 11/09/2022] Open
Abstract
Despite their importance to successful meiosis and various evolutionary processes, meiotic recombination rates sometimes vary within species or between closely related species. For example, humans and chimpanzees share virtually no recombination hotspot locations in the surveyed portion of the genomes. However, conservation of recombination rates between closely related species has also been documented, raising an apparent contradiction. Here, we evaluate how and why conflicting patterns of recombination rate conservation and divergence may be observed, with particular emphasis on features that affect recombination, and the scale and method with which recombination is surveyed. Additionally, we review recent studies identifying features influencing fine-scale and broad-scale recombination patterns and informing how quickly recombination rates evolve, how changes in recombination impact selection and evolution in natural populations, and more broadly, which forces influence genome evolution.
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Affiliation(s)
- C S Smukowski
- Department of Biology, Duke University, Durham, NC 27708, USA.
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Geraldes A, Basset P, Smith KL, Nachman MW. Higher differentiation among subspecies of the house mouse (Mus musculus) in genomic regions with low recombination. Mol Ecol 2011; 20:4722-36. [PMID: 22004102 DOI: 10.1111/j.1365-294x.2011.05285.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In the early stages of reproductive isolation, genomic regions of reduced recombination are expected to show greater levels of differentiation, either because gene flow between species is reduced in these regions or because the effects of selection at linked sites within species are enhanced in these regions. Here, we study the patterns of DNA sequence variation at 27 autosomal loci among populations of Mus musculus musculus, M. m. domesticus, and M. m. castaneus, three subspecies of house mice with collinear genomes. We found that some loci exhibit considerable shared variation among subspecies, while others exhibit fixed differences. We used an isolation-with-gene-flow model to estimate divergence times and effective population sizes (N(e) ) and to disentangle ancestral variation from gene flow. Estimates of divergence time indicate that all three subspecies diverged from one another within a very short period of time approximately 350,000 years ago. Overall, N(e) for each subspecies was associated with the degree of genetic differentiation: M. m. musculus had the smallest N(e) and the greatest proportion of monophyletic gene genealogies, while M. m. castaneus had the largest N(e) and the smallest proportion of monophyletic gene genealogies. M. m. domesticus and M. m. musculus were more differentiated from each other than either were from M. m. castaneus, consistent with greater reproductive isolation between M. m. domesticus and M. m. musculus. F(ST) was significantly greater at loci experiencing low recombination rates compared to loci experiencing high recombination rates in comparisons between M. m. castaneus and M. m. musculus or M. m. domesticus. These results provide evidence that genomic regions with less recombination show greater differentiation, even in the absence of chromosomal rearrangements.
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Affiliation(s)
- A Geraldes
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA
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Abstract
The effective population size (N(e)) is one of the most fundamental parameters in population genetics. It is thought to vary across the genome as a consequence of differences in the rate of recombination and the density of selected sites due to the processes of genetic hitchhiking and background selection. Although it is known that there is intragenomic variation in the effective population size in some species, it is not known whether this is widespread or how much variation in the effective population size there is. Here, we test whether the effective population size varies across the genome, between protein-coding genes, in 10 eukaryotic species by considering whether there is significant variation in neutral diversity, taking into account differences in the mutation rate between loci by using the divergence between species. In most species we find significant evidence of variation. We investigate whether the variation in N(e) is correlated to recombination rate and the density of selected sites in four species, for which these data are available. We find that N(e) is positively correlated to recombination rate in one species, Drosophila melanogaster, and negatively correlated to a measure of the density of selected sites in two others, humans and Arabidopsis thaliana. However, much of the variation remains unexplained. We use a hierarchical Bayesian analysis to quantify the amount of variation in the effective population size and show that it is quite modest in all species-most genes have an N(e) that is within a few fold of all other genes. Nonetheless we show that this modest variation in N(e) is sufficient to cause significant differences in the efficiency of natural selection across the genome, by demonstrating that the ratio of the number of nonsynonymous to synonymous polymorphisms is significantly correlated to synonymous diversity and estimates of N(e), even taking into account the obvious nonindependence between these measures.
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Late replicating domains are highly recombining in females but have low male recombination rates: implications for isochore evolution. PLoS One 2011; 6:e24480. [PMID: 21949720 PMCID: PMC3176772 DOI: 10.1371/journal.pone.0024480] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Accepted: 08/11/2011] [Indexed: 01/01/2023] Open
Abstract
In mammals sequences that are either late replicating or highly recombining have high rates of evolution at putatively neutral sites. As early replicating domains and highly recombining domains both tend to be GC rich we a priori expect these two variables to covary. If so, the relative contribution of either of these variables to the local neutral substitution rate might have been wrongly estimated owing to covariance with the other. Against our expectations, we find that sex-averaged recombination rates show little or no correlation with replication timing, suggesting that they are independent determinants of substitution rates. However, this result masks significant sex-specific complexity: late replicating domains tend to have high recombination rates in females but low recombination rates in males. That these trends are antagonistic explains why sex-averaged recombination is not correlated with replication timing. This unexpected result has several important implications. First, although both male and female recombination rates covary significantly with intronic substitution rates, the magnitude of this correlation is moderately underestimated for male recombination and slightly overestimated for female recombination, owing to covariance with replicating timing. Second, the result could explain why male recombination is strongly correlated with GC content but female recombination is not. If to explain the correlation between GC content and replication timing we suppose that late replication forces reduced GC content, then GC promotion by biased gene conversion during female recombination is partly countered by the antagonistic effect of later replicating sequence tending increase AT content. Indeed, the strength of the correlation between female recombination rate and local GC content is more than doubled by control for replication timing. Our results underpin the need to consider sex-specific recombination rates and potential covariates in analysis of GC content and rates of evolution.
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Abstract
Related individuals share potentially long chromosome segments that trace to a common ancestor. We describe a phasing algorithm (ChromoPhase) that utilizes this characteristic of finite populations to phase large sections of a chromosome. In addition to phasing, our method imputes missing genotypes in individuals genotyped at lower marker density when more densely genotyped relatives are available. ChromoPhase uses a pedigree to collect an individual's (the proband) surrogate parents and offspring and uses genotypic similarity to identify its genomic surrogates. The algorithm then cycles through the relatives and genomic surrogates one at a time to find shared chromosome segments. Once a segment has been identified, any missing information in the proband is filled in with information from the relative. We tested ChromoPhase in a simulated population consisting of 400 individuals at a marker density of 1500/M, which is approximately equivalent to a 50K bovine single nucleotide polymorphism chip. In simulated data, 99.9% loci were correctly phased and, when imputing from 100 to 1500 markers, more than 87% of missing genotypes were correctly imputed. Performance increased when the number of generations available in the pedigree increased, but was reduced when the sparse genotype contained fewer loci. However, in simulated data, ChromoPhase correctly imputed at least 12% more genotypes than fastPHASE, depending on sparse marker density. We also tested the algorithm in a real Holstein cattle data set to impute 50K genotypes in animals with a sparse 3K genotype. In these data 92% of genotypes were correctly imputed in animals with a genotyped sire. We evaluated the accuracy of genomic predictions with the dense, sparse, and imputed simulated data sets and show that the reduction in genomic evaluation accuracy is modest even with imperfectly imputed genotype data. Our results demonstrate that imputation of missing genotypes, and potentially full genome sequence, using long-range phasing is feasible.
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Caenorhabditis briggsae recombinant inbred line genotypes reveal inter-strain incompatibility and the evolution of recombination. PLoS Genet 2011; 7:e1002174. [PMID: 21779179 PMCID: PMC3136444 DOI: 10.1371/journal.pgen.1002174] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 05/23/2011] [Indexed: 12/16/2022] Open
Abstract
The nematode Caenorhabditis briggsae is an emerging model organism that allows evolutionary comparisons with C. elegans and exploration of its own unique biological attributes. To produce a high-resolution C. briggsae recombination map, recombinant inbred lines were generated from reciprocal crosses between two strains and genotyped at over 1,000 loci. A second set of recombinant inbred lines involving a third strain was also genotyped at lower resolution. The resulting recombination maps exhibit discrete domains of high and low recombination, as in C. elegans, indicating these are a general feature of Caenorhabditis species. The proportion of a chromosome's physical size occupied by the central, low-recombination domain is highly correlated between species. However, the C. briggsae intra-species comparison reveals striking variation in the distribution of recombination between domains. Hybrid lines made with the more divergent pair of strains also exhibit pervasive marker transmission ratio distortion, evidence of selection acting on hybrid genotypes. The strongest effect, on chromosome III, is explained by a developmental delay phenotype exhibited by some hybrid F2 animals. In addition, on chromosomes IV and V, cross direction-specific biases towards one parental genotype suggest the existence of cytonuclear epistatic interactions. These interactions are discussed in relation to surprising mitochondrial genome polymorphism in C. briggsae, evidence that the two strains diverged in allopatry, the potential for local adaptation, and the evolution of Dobzhansky-Muller incompatibilities. The genetic and genomic resources resulting from this work will support future efforts to understand inter-strain divergence as well as facilitate studies of gene function, natural variation, and the evolution of recombination in Caenorhabditis nematodes.
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