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Johnston SE. Understanding the Genetic Basis of Variation in Meiotic Recombination: Past, Present, and Future. Mol Biol Evol 2024; 41:msae112. [PMID: 38959451 PMCID: PMC11221659 DOI: 10.1093/molbev/msae112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 06/03/2024] [Accepted: 06/05/2024] [Indexed: 07/05/2024] Open
Abstract
Meiotic recombination is a fundamental feature of sexually reproducing species. It is often required for proper chromosome segregation and plays important role in adaptation and the maintenance of genetic diversity. The molecular mechanisms of recombination are remarkably conserved across eukaryotes, yet meiotic genes and proteins show substantial variation in their sequence and function, even between closely related species. Furthermore, the rate and distribution of recombination shows a huge diversity within and between chromosomes, individuals, sexes, populations, and species. This variation has implications for many molecular and evolutionary processes, yet how and why this diversity has evolved is not well understood. A key step in understanding trait evolution is to determine its genetic basis-that is, the number, effect sizes, and distribution of loci underpinning variation. In this perspective, I discuss past and current knowledge on the genetic basis of variation in recombination rate and distribution, explore its evolutionary implications, and present open questions for future research.
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Affiliation(s)
- Susan E Johnston
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3FL, UK
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2
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Joseph J, Prentout D, Laverré A, Tricou T, Duret L. High prevalence of PRDM9-independent recombination hotspots in placental mammals. Proc Natl Acad Sci U S A 2024; 121:e2401973121. [PMID: 38809707 PMCID: PMC11161765 DOI: 10.1073/pnas.2401973121] [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: 02/08/2024] [Accepted: 04/26/2024] [Indexed: 05/31/2024] Open
Abstract
In many mammals, recombination events are concentrated in hotspots directed by a sequence-specific DNA-binding protein named PRDM9. Intriguingly, PRDM9 has been lost several times in vertebrates, and notably among mammals, it has been pseudogenized in the ancestor of canids. In the absence of PRDM9, recombination hotspots tend to occur in promoter-like features such as CpG islands. It has thus been proposed that one role of PRDM9 could be to direct recombination away from PRDM9-independent hotspots. However, the ability of PRDM9 to direct recombination hotspots has been assessed in only a handful of species, and a clear picture of how much recombination occurs outside of PRDM9-directed hotspots in mammals is still lacking. In this study, we derived an estimator of past recombination activity based on signatures of GC-biased gene conversion in substitution patterns. We quantified recombination activity in PRDM9-independent hotspots in 52 species of boreoeutherian mammals. We observe a wide range of recombination rates at these loci: several species (such as mice, humans, some felids, or cetaceans) show a deficit of recombination, while a majority of mammals display a clear peak of recombination. Our results demonstrate that PRDM9-directed and PRDM9-independent hotspots can coexist in mammals and that their coexistence appears to be the rule rather than the exception. Additionally, we show that the location of PRDM9-independent hotspots is relatively more stable than that of PRDM9-directed hotspots, but that PRDM9-independent hotspots nevertheless evolve slowly in concert with DNA hypomethylation.
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Affiliation(s)
- Julien Joseph
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR 5558, Villeurbanne69100, France
| | - Djivan Prentout
- Department of Biological Sciences, Columbia University, New York, NY10027
| | - Alexandre Laverré
- Department of Ecology and Evolution, University of Lausanne, LausanneCH-1015, Switzerland
- Swiss Institute of Bioinformatics, LausanneCH-1015, Switzerland
| | - Théo Tricou
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR 5558, Villeurbanne69100, France
| | - Laurent Duret
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR 5558, Villeurbanne69100, France
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3
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Genestier A, Duret L, Lartillot N. Bridging the gap between the evolutionary dynamics and the molecular mechanisms of meiosis: A model based exploration of the PRDM9 intra-genomic Red Queen. PLoS Genet 2024; 20:e1011274. [PMID: 38768268 PMCID: PMC11142677 DOI: 10.1371/journal.pgen.1011274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Revised: 05/31/2024] [Accepted: 04/26/2024] [Indexed: 05/22/2024] Open
Abstract
Molecular dissection of meiotic recombination in mammals, combined with population-genetic and comparative studies, have revealed a complex evolutionary dynamic characterized by short-lived recombination hotspots. Hotspots are chromosome positions containing DNA sequences where the protein PRDM9 can bind and cause crossing-over. To explain these fast evolutionary dynamic, a so-called intra-genomic Red Queen model has been proposed, based on the interplay between two antagonistic forces: biased gene conversion, mediated by double-strand breaks, resulting in hotspot extinction (the hotspot conversion paradox), followed by positive selection favoring mutant PRDM9 alleles recognizing new sequence motifs. Although this model predicts many empirical observations, the exact causes of the positive selection acting on new PRDM9 alleles is still not well understood. In this direction, experiment on mouse hybrids have suggested that, in addition to targeting double strand breaks, PRDM9 has another role during meiosis. Specifically, PRDM9 symmetric binding (simultaneous binding at the same site on both homologues) would facilitate homology search and, as a result, the pairing of the homologues. Although discovered in hybrids, this second function of PRDM9 could also be involved in the evolutionary dynamic observed within populations. To address this point, here, we present a theoretical model of the evolutionary dynamic of meiotic recombination integrating current knowledge about the molecular function of PRDM9. Our modeling work gives important insights into the selective forces driving the turnover of recombination hotspots. Specifically, the reduced symmetrical binding of PRDM9 caused by the loss of high affinity binding sites induces a net positive selection eliciting new PRDM9 alleles recognizing new targets. The model also offers new insights about the influence of the gene dosage of PRDM9, which can paradoxically result in negative selection on new PRDM9 alleles entering the population, driving their eviction and thus reducing standing variation at this locus.
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Affiliation(s)
- Alice Genestier
- Universite Claude Bernard Lyon 1, LBBE, UMR 5558, CNRS, VAS, Villeurbanne, France
| | - Laurent Duret
- Universite Claude Bernard Lyon 1, LBBE, UMR 5558, CNRS, VAS, Villeurbanne, France
| | - Nicolas Lartillot
- Universite Claude Bernard Lyon 1, LBBE, UMR 5558, CNRS, VAS, Villeurbanne, France
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4
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AbuAlia KFN, Damm E, Ullrich KK, Mukaj A, Parvanov E, Forejt J, Odenthal-Hesse L. Natural variation in the zinc-finger-encoding exon of Prdm9 affects hybrid sterility phenotypes in mice. Genetics 2024; 226:iyae004. [PMID: 38217871 PMCID: PMC10917509 DOI: 10.1093/genetics/iyae004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2023] [Revised: 01/04/2024] [Accepted: 01/05/2024] [Indexed: 01/15/2024] Open
Abstract
PRDM9-mediated reproductive isolation was first described in the progeny of Mus musculus musculus (MUS) PWD/Ph and Mus musculus domesticus (DOM) C57BL/6J inbred strains. These male F1 hybrids fail to complete chromosome synapsis and arrest meiosis at prophase I, due to incompatibilities between the Prdm9 gene and hybrid sterility locus Hstx2. We identified 14 alleles of Prdm9 in exon 12, encoding the DNA-binding domain of the PRDM9 protein in outcrossed wild mouse populations from Europe, Asia, and the Middle East, 8 of which are novel. The same allele was found in all mice bearing introgressed t-haplotypes encompassing Prdm9. We asked whether 7 novel Prdm9 alleles in MUS populations and the t-haplotype allele in 1 MUS and 3 DOM populations induce Prdm9-mediated reproductive isolation. The results show that only combinations of the dom2 allele of DOM origin and the MUS msc1 allele ensure complete infertility of intersubspecific hybrids in outcrossed wild populations and inbred mouse strains examined so far. The results further indicate that MUS mice may share the erasure of PRDM9msc1 binding motifs in populations with different Prdm9 alleles, which implies that erased PRDM9 binding motifs may be uncoupled from their corresponding Prdm9 alleles at the population level. Our data corroborate the model of Prdm9-mediated hybrid sterility beyond inbred strains of mice and suggest that sterility alleles of Prdm9 may be rare.
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Affiliation(s)
- Khawla F N AbuAlia
- Research Group Meiotic Recombination and Genome Instability, Max Planck Institute for Evolutionary Biology, Plön D-24306, Germany
| | - Elena Damm
- Research Group Meiotic Recombination and Genome Instability, Max Planck Institute for Evolutionary Biology, Plön D-24306, Germany
| | - Kristian K Ullrich
- Research Group Meiotic Recombination and Genome Instability, Max Planck Institute for Evolutionary Biology, Plön D-24306, Germany
| | - Amisa Mukaj
- Laboratory of Mouse Molecular Genetics, Institute of Molecular Genetics, Czech Academy of Sciences, Vestec CZ-25250, Czech Republic
| | - Emil Parvanov
- Laboratory of Mouse Molecular Genetics, Institute of Molecular Genetics, Czech Academy of Sciences, Vestec CZ-25250, Czech Republic
- Department of Translational Stem Cell Biology, Research Institute of the Medical University of Varna, 9002 Varna, Bulgaria
- Ludwig Boltzmann Institute for Digital Health and Patient Safety, Medical University of Vienna, 1090 Vienna, Austria
| | - Jiri Forejt
- Laboratory of Mouse Molecular Genetics, Institute of Molecular Genetics, Czech Academy of Sciences, Vestec CZ-25250, Czech Republic
| | - Linda Odenthal-Hesse
- Research Group Meiotic Recombination and Genome Instability, Max Planck Institute for Evolutionary Biology, Plön D-24306, Germany
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5
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Baker Z, Przeworski M, Sella G. Down the Penrose stairs, or how selection for fewer recombination hotspots maintains their existence. eLife 2023; 12:e83769. [PMID: 37830496 DOI: 10.7554/elife.83769] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 10/12/2023] [Indexed: 10/14/2023] Open
Abstract
In many species, meiotic recombination events tend to occur in narrow intervals of the genome, known as hotspots. In humans and mice, double strand break (DSB) hotspot locations are determined by the DNA-binding specificity of the zinc finger array of the PRDM9 protein, which is rapidly evolving at residues in contact with DNA. Previous models explained this rapid evolution in terms of the need to restore PRDM9 binding sites lost to gene conversion over time, under the assumption that more PRDM9 binding always leads to more DSBs. This assumption, however, does not align with current evidence. Recent experimental work indicates that PRDM9 binding on both homologs facilitates DSB repair, and that the absence of sufficient symmetric binding disrupts meiosis. We therefore consider an alternative hypothesis: that rapid PRDM9 evolution is driven by the need to restore symmetric binding because of its role in coupling DSB formation and efficient repair. To this end, we model the evolution of PRDM9 from first principles: from its binding dynamics to the population genetic processes that govern the evolution of the zinc finger array and its binding sites. We show that the loss of a small number of strong binding sites leads to the use of a greater number of weaker ones, resulting in a sharp reduction in symmetric binding and favoring new PRDM9 alleles that restore the use of a smaller set of strong binding sites. This decrease, in turn, drives rapid PRDM9 evolutionary turnover. Our results therefore suggest that the advantage of new PRDM9 alleles is in limiting the number of binding sites used effectively, rather than in increasing net PRDM9 binding. By extension, our model suggests that the evolutionary advantage of hotspots may have been to increase the efficiency of DSB repair and/or homolog pairing.
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Affiliation(s)
- Zachary Baker
- Department of Systems Biology, Columbia University, New York, United States
- Department of Biological Sciences, Columbia University, New York, United States
| | - Molly Przeworski
- Department of Systems Biology, Columbia University, New York, United States
- Department of Biological Sciences, Columbia University, New York, United States
- Program for Mathematical Genomics, Columbia University, New York, United States
| | - Guy Sella
- Department of Biological Sciences, Columbia University, New York, United States
- Program for Mathematical Genomics, Columbia University, New York, United States
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Úbeda F, Fyon F, Bürger R. The Recombination Hotspot Paradox: Co-evolution between PRDM9 and its target sites. Theor Popul Biol 2023; 153:69-90. [PMID: 37451508 DOI: 10.1016/j.tpb.2023.07.001] [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: 12/21/2022] [Revised: 06/30/2023] [Accepted: 07/03/2023] [Indexed: 07/18/2023]
Abstract
Recombination often concentrates in small regions called recombination hotspots where recombination is much higher than the genome's average. In many vertebrates, including humans, gene PRDM9 specifies which DNA motifs will be the target for breaks that initiate recombination, ultimately determining the location of recombination hotspots. Because the sequence that breaks (allowing recombination) is converted into the sequence that does not break (preventing recombination), the latter sequence is over-transmitted to future generations and recombination hotspots are self-destructive. Given their self-destructive nature, recombination hotspots should eventually become extinct in genomes where they are found. While empirical evidence shows that individual hotspots do become inactive over time (die), hotspots are abundant in many vertebrates: a contradiction called the Recombination Hotspot Paradox. What saves recombination hotspots from their foretold extinction? Here we formulate a co-evolutionary model of the interaction among sequence-specific gene conversion, fertility selection, and recurrent mutation. We find that allelic frequencies oscillate leading to stable limit cycles. From a biological perspective this means that when fertility selection is weaker than gene conversion, it cannot stop individual hotspots from dying but can save them from extinction by driving their re-activation (resuscitation). In our model, mutation balances death and resuscitation of hotspots, thus maintaining their number over evolutionary time. Interestingly, we find that multiple alleles result in oscillations that are chaotic and multiple targets in oscillations that are asynchronous between targets thus helping to maintain the average genomic recombination probability constant. Furthermore, we find that the level of expression of PRDM9 should control for the fraction of targets that are hotspots and the overall temperature of the genome. Therefore, our co-evolutionary model improves our understanding of how hotspots may be replaced, thus contributing to solve the Recombination Hotspot Paradox. From a more applied perspective our work provides testable predictions regarding the relation between mutation probability and fertility selection with life expectancy of hotspots.
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Affiliation(s)
- Francisco Úbeda
- Department of Biology, Royal Holloway University of London, Egham TW20 0EX, UK.
| | - Frédéric Fyon
- Department of Biology, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Reinhard Bürger
- Faculty of Mathematics, University of Vienna, 1090 Vienna, Austria
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7
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Schreiber M, Gao Y, Koch N, Fuchs J, Heckmann S, Himmelbach A, Börner A, Özkan H, Maurer A, Stein N, Mascher M, Dreissig S. Recombination landscape divergence between populations is marked by larger low-recombining regions in domesticated rye. Mol Biol Evol 2022; 39:msac131. [PMID: 35687854 PMCID: PMC9218680 DOI: 10.1093/molbev/msac131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Revised: 06/03/2022] [Accepted: 06/07/2022] [Indexed: 11/13/2022] Open
Abstract
The genomic landscape of recombination plays an essential role in evolution. Patterns of recombination are highly variable along chromosomes, between sexes, individuals, populations, and species. In many eukaryotes, recombination rates are elevated in sub-telomeric regions and drastically reduced near centromeres, resulting in large low-recombining (LR) regions. The processes of recombination are influenced by genetic factors, such as different alleles of genes involved in meiosis and chromatin structure, as well as external environmental stimuli like temperature and overall stress. In this work, we focused on the genomic landscapes of recombination in a collection of 916 rye (Secale cereale) individuals. By analysing population structure among individuals of different domestication status and geographic origin, we detected high levels of admixture, reflecting the reproductive biology of a self-incompatible, wind-pollinating grass species. We then analysed patterns of recombination in overlapping subpopulations, which revealed substantial variation in the physical size of LR regions, with a tendency for larger LR regions in domesticated subpopulations. Genome-wide association scans (GWAS) for LR region size revealed a major quantitative-trait-locus (QTL) at which, among 18 annotated genes, an ortholog of histone H4 acetyltransferase ESA1 was located. Rye individuals belonging to domesticated subpopulations showed increased synaptonemal complex length, but no difference in crossover frequency, indicating that only the recombination landscape is different. Furthermore, the genomic region harbouring rye ScESA1 showed moderate patterns of selection in domesticated subpopulations, suggesting that larger LR regions were indirectly selected for during domestication to achieve more homogeneous populations for agricultural use.
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Affiliation(s)
- Mona Schreiber
- Department of Biology, University of Marburg, 35037 Marburg, Germany
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, OT Gatersleben, Germany
| | - Yixuan Gao
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Natalie Koch
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Joerg Fuchs
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, OT Gatersleben, Germany
| | - Stefan Heckmann
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, OT Gatersleben, Germany
| | - Axel Himmelbach
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, OT Gatersleben, Germany
| | - Andreas Börner
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, OT Gatersleben, Germany
| | - Hakan Özkan
- Faculty of Agriculture, Department of Field Crops, University of Cukurova, 01330 Adana, Turkey
| | - Andreas Maurer
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, 06120 Halle (Saale), Germany
| | - Nils Stein
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, OT Gatersleben, Germany
| | - Martin Mascher
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), 06466 Seeland, OT Gatersleben, Germany
- German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103 Leipzig, Germany
| | - Steven Dreissig
- Institute of Agricultural and Nutritional Sciences, Martin-Luther-University Halle-Wittenberg, 06120 Halle (Saale), Germany
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Damm E, Ullrich KK, Amos WB, Odenthal-Hesse L. Evolution of the recombination regulator PRDM9 in minke whales. BMC Genomics 2022; 23:212. [PMID: 35296233 PMCID: PMC8925151 DOI: 10.1186/s12864-022-08305-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 01/11/2022] [Indexed: 11/16/2022] Open
Abstract
Background PRDM9 is a key regulator of meiotic recombination in most metazoans, responsible for reshuffling parental genomes. During meiosis, the PRDM9 protein recognizes and binds specific target motifs via its array of C2H2 zinc-fingers encoded by a rapidly evolving minisatellite. The gene coding for PRDM9 is the only speciation gene identified in vertebrates to date and shows high variation, particularly in the DNA-recognizing positions of the zinc-finger array, within and between species. Across all vertebrate genomes studied for PRDM9 evolution, only one genome lacks variability between repeat types – that of the North Pacific minke whale. This study aims to understand the evolution and diversity of Prdm9 in minke whales, which display the most unusual genome reference allele of Prdm9 so far discovered in mammals. Results Minke whales possess all the features characteristic of PRDM9-directed recombination, including complete KRAB, SSXRD and SET domains and a rapidly evolving array of C2H2-type-Zincfingers (ZnF) with evidence of rapid evolution, particularly at DNA-recognizing positions that evolve under positive diversifying selection. Seventeen novel PRDM9 variants were identified within the Antarctic minke whale species, plus a single distinct PRDM9 variant in Common minke whales – shared across North Atlantic and North Pacific minke whale subspecies boundaries. Conclusion The PRDM9 ZnF array evolves rapidly, in minke whales, with at least one DNA-recognizing position under positive selection. Extensive PRDM9 diversity is observed, particularly in the Antarctic in minke whales. Common minke whales shared a specific Prdm9 allele across subspecies boundaries, suggesting incomplete speciation by the mechanisms associated with PRDM9 hybrid sterility. Supplementary Information The online version contains supplementary material available at 10.1186/s12864-022-08305-1.
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Affiliation(s)
- Elena Damm
- Department Evolutionary Genetics, Research Group Meiotic Recombination and Genome Instability, Max Planck Institute for Evolutionary Biology, August-Thienemann Str. 2, D-24306, Plön, Germany
| | - Kristian K Ullrich
- Department Evolutionary Genetics, Research Group Meiotic Recombination and Genome Instability, Max Planck Institute for Evolutionary Biology, August-Thienemann Str. 2, D-24306, Plön, Germany
| | - William B Amos
- Department of Zoology, University of Cambridge, Cambridge, UK
| | - Linda Odenthal-Hesse
- Department Evolutionary Genetics, Research Group Meiotic Recombination and Genome Instability, Max Planck Institute for Evolutionary Biology, August-Thienemann Str. 2, D-24306, Plön, Germany.
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9
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PRDM9 losses in vertebrates are coupled to those of paralogs ZCWPW1 and ZCWPW2. Proc Natl Acad Sci U S A 2022; 119:2114401119. [PMID: 35217607 PMCID: PMC8892340 DOI: 10.1073/pnas.2114401119] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2022] [Indexed: 01/12/2023] Open
Abstract
We take a phylogenetic approach to search for molecular partners of PRDM9, a key meiotic recombination gene, by leveraging the fact that the complete PRDM9 gene has been lost at least 13 times independently in vertebrates. We identify two genes, ZCWPW1 and its paralog ZCWPW2, whose presence or absence across vertebrates is coupled to that of PRDM9. ZCWPW1 was recently shown to be recruited to sites of PRDM9 binding and to aid in the repair of double strand breaks. ZCWPW2 is likely recruited to sites of PRDM9 binding as well; its tight coevolution with PRDM9 across vertebrates suggests that it too plays an important role in mammals and beyond, either in double strand break formation or repair. In most mammals and likely throughout vertebrates, the gene PRDM9 specifies the locations of meiotic double strand breaks; in mice and humans at least, it also aids in their repair. For both roles, many of the molecular partners remain unknown. Here, we take a phylogenetic approach to identify genes that may be interacting with PRDM9 by leveraging the fact that PRDM9 arose before the origin of vertebrates but was lost many times, either partially or entirely—and with it, its role in recombination. As a first step, we characterize PRDM9 domain composition across 446 vertebrate species, inferring at least 13 independent losses. We then use the interdigitation of PRDM9 orthologs across vertebrates to test whether it coevolved with any of 241 candidate genes coexpressed with PRDM9 in mice or associated with recombination phenotypes in mammals. Accounting for the phylogenetic relationship among a subsample of 189 species, we find two genes whose presence and absence is unexpectedly coincident with that of PRDM9: ZCWPW1, which was recently shown to facilitate double strand break repair, and its paralog ZCWPW2, as well as, more tentatively, TEX15 and FBXO47. ZCWPW2 is expected to be recruited to sites of PRDM9 binding; its tight coevolution with PRDM9 across vertebrates suggests that it is a key interactor within mammals and beyond, with a role either in recruiting the recombination machinery or in double strand break repair.
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10
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Abstract
Recombination increases the local GC-content in genomic regions through GC-biased gene conversion (gBGC). The recent discovery of a large genomic region with extreme GC-content in the fat sand rat Psammomys obesus provides a model to study the effects of gBGC on chromosome evolution. Here, we compare the GC-content and GC-to-AT substitution patterns across protein-coding genes of four gerbil species and two murine rodents (mouse and rat). We find that the known high-GC region is present in all the gerbils, and is characterized by high substitution rates for all mutational categories (AT-to-GC, GC-to-AT, and GC-conservative) both at synonymous and nonsynonymous sites. A higher AT-to-GC than GC-to-AT rate is consistent with the high GC-content. Additionally, we find more than 300 genes outside the known region with outlying values of AT-to-GC synonymous substitution rates in gerbils. Of these, over 30% are organized into at least 17 large clusters observable at the megabase-scale. The unusual GC-skewed substitution pattern suggests the evolution of genomic regions with very high recombination rates in the gerbil lineage, which can lead to a runaway increase in GC-content. Our results imply that rapid evolution of GC-content is possible in mammals, with gerbil species providing a powerful model to study the mechanisms of gBGC.
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Affiliation(s)
- Rodrigo Pracana
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | | | - John F Mulley
- School of Natural Sciences, Bangor University, Bangor, Gwynedd, United Kingdom
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11
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Spence JP, Song YS. Inference and analysis of population-specific fine-scale recombination maps across 26 diverse human populations. SCIENCE ADVANCES 2019; 5:eaaw9206. [PMID: 31681842 PMCID: PMC6810367 DOI: 10.1126/sciadv.aaw9206] [Citation(s) in RCA: 72] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 09/13/2019] [Indexed: 05/28/2023]
Abstract
Fine-scale rates of meiotic recombination vary by orders of magnitude across the genome and differ between species and even populations. Studying cross-population differences has been stymied by the confounding effects of demographic history. To address this problem, we developed a demography-aware method to infer fine-scale recombination rates and applied it to 26 diverse human populations, inferring population-specific recombination maps. These maps recapitulate many aspects of the history of these populations including signatures of the trans-Atlantic slave trade and the Iberian colonization of the Americas. We also investigated modulators of the local recombination rate, finding further evidence that Polycomb group proteins and the trimethylation of H3K27 elevate recombination rates. Further differences in the recombination landscape across the genome and between populations are driven by variation in the gene that encodes the DNA binding protein PRDM9, and we quantify the weak effect of meiotic drive acting to remove its binding sites.
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Affiliation(s)
- Jeffrey P. Spence
- Graduate Group in Computational Biology, University of California, Berkeley, Berkeley, CA, USA
| | - Yun S. Song
- Computer Science Division and Department of Statistics, University of California, Berkeley, Berkeley, CA, USA
- Chan Zuckerberg Biohub, San Francisco, CA, USA
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12
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Papanikos F, Clément JAJ, Testa E, Ravindranathan R, Grey C, Dereli I, Bondarieva A, Valerio-Cabrera S, Stanzione M, Schleiffer A, Jansa P, Lustyk D, Fei JF, Adams IR, Forejt J, Barchi M, de Massy B, Toth A. Mouse ANKRD31 Regulates Spatiotemporal Patterning of Meiotic Recombination Initiation and Ensures Recombination between X and Y Sex Chromosomes. Mol Cell 2019; 74:1069-1085.e11. [PMID: 31000436 DOI: 10.1016/j.molcel.2019.03.022] [Citation(s) in RCA: 65] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Revised: 02/01/2019] [Accepted: 03/20/2019] [Indexed: 12/31/2022]
Abstract
Orderly segregation of chromosomes during meiosis requires that crossovers form between homologous chromosomes by recombination. Programmed DNA double-strand breaks (DSBs) initiate meiotic recombination. We identify ANKRD31 as a key component of complexes of DSB-promoting proteins that assemble on meiotic chromosome axes. Genome-wide, ANKRD31 deficiency causes delayed recombination initiation. In addition, loss of ANKRD31 alters DSB distribution because of reduced selectivity for sites that normally attract DSBs. Strikingly, ANKRD31 deficiency also abolishes uniquely high rates of recombination that normally characterize pseudoautosomal regions (PARs) of X and Y chromosomes. Consequently, sex chromosomes do not form crossovers, leading to chromosome segregation failure in ANKRD31-deficient spermatocytes. These defects co-occur with a genome-wide delay in assembling DSB-promoting proteins on autosome axes and loss of a specialized PAR-axis domain that is highly enriched for DSB-promoting proteins in wild type. Thus, we propose a model for spatiotemporal patterning of recombination by ANKRD31-dependent control of axis-associated DSB-promoting proteins.
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Affiliation(s)
- Frantzeskos Papanikos
- Institute of Physiological Chemistry, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Julie A J Clément
- Institute of Human Genetics, UMR 9002, CNRS, Université de Montpellier, 34396 Montpellier Cedex 5, France
| | - Erika Testa
- Department of Biomedicine and Prevention, Faculty of Medicine, University of Rome Tor Vergata, Via Montpellier n.1, 00133 Rome, Italy
| | - Ramya Ravindranathan
- Institute of Physiological Chemistry, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Corinne Grey
- Institute of Human Genetics, UMR 9002, CNRS, Université de Montpellier, 34396 Montpellier Cedex 5, France
| | - Ihsan Dereli
- Institute of Physiological Chemistry, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Anastasiia Bondarieva
- Institute of Physiological Chemistry, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Sarai Valerio-Cabrera
- Institute of Physiological Chemistry, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Marcello Stanzione
- Institute of Physiological Chemistry, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany
| | - Alexander Schleiffer
- Research Institute of Molecular Pathology (IMP), Campus Vienna BioCenter 1, Vienna BioCenter (VBC), 1030 Vienna, Austria; Institute of Molecular Biotechnology (IMBA), Dr. Bohr-Gasse 3, Vienna BioCenter (VBC), 1030 Vienna, Austria
| | - Petr Jansa
- Institute of Molecular Genetics, Division BIOCEV, Prumyslova 595, 25250 Vestec, Czech Republic
| | - Diana Lustyk
- Institute of Molecular Genetics, Division BIOCEV, Prumyslova 595, 25250 Vestec, Czech Republic
| | - Ji-Feng Fei
- Institute for Brain Research and Rehabilitation, South China Normal University, 510631 Guangzhou, China
| | - Ian R Adams
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Jiri Forejt
- Institute of Molecular Genetics, Division BIOCEV, Prumyslova 595, 25250 Vestec, Czech Republic
| | - Marco Barchi
- Department of Biomedicine and Prevention, Faculty of Medicine, University of Rome Tor Vergata, Via Montpellier n.1, 00133 Rome, Italy
| | - Bernard de Massy
- Institute of Human Genetics, UMR 9002, CNRS, Université de Montpellier, 34396 Montpellier Cedex 5, France.
| | - Attila Toth
- Institute of Physiological Chemistry, Faculty of Medicine, Technische Universität Dresden, Fetscherstraße 74, 01307 Dresden, Germany.
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13
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Rousselle M, Laverré A, Figuet E, Nabholz B, Galtier N. Influence of Recombination and GC-biased Gene Conversion on the Adaptive and Nonadaptive Substitution Rate in Mammals versus Birds. Mol Biol Evol 2019; 36:458-471. [PMID: 30590692 PMCID: PMC6389324 DOI: 10.1093/molbev/msy243] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Recombination is expected to affect functional sequence evolution in several ways. On the one hand, recombination is thought to improve the efficiency of multilocus selection by dissipating linkage disequilibrium. On the other hand, natural selection can be counteracted by recombination-associated transmission distorters such as GC-biased gene conversion (gBGC), which tends to promote G and C alleles irrespective of their fitness effect in high-recombining regions. It has been suggested that gBGC might impact coding sequence evolution in vertebrates, and particularly the ratio of nonsynonymous to synonymous substitution rates (dN/dS). However, distinctive gBGC patterns have been reported in mammals and birds, maybe reflecting the documented contrasts in evolutionary dynamics of recombination rate between these two taxa. Here, we explore how recombination and gBGC affect coding sequence evolution in mammals and birds by analyzing proteome-wide data in six species of Galloanserae (fowls) and six species of catarrhine primates. We estimated the dN/dS ratio and rates of adaptive and nonadaptive evolution in bins of genes of increasing recombination rate, separately analyzing AT → GC, GC → AT, and G ↔ C/A ↔ T mutations. We show that in both taxa, recombination and gBGC entail a decrease in dN/dS. Our analysis indicates that recombination enhances the efficiency of purifying selection by lowering Hill-Robertson effects, whereas gBGC leads to an overestimation of the adaptive rate of AT → GC mutations. Finally, we report a mutagenic effect of recombination, which is independent of gBGC.
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Affiliation(s)
| | - Alexandre Laverré
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Emeric Figuet
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Benoit Nabholz
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Nicolas Galtier
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
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14
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Úbeda F, Russell TW, Jansen VAA. PRDM9 and the evolution of recombination hotspots. Theor Popul Biol 2019; 126:19-32. [PMID: 30660607 DOI: 10.1016/j.tpb.2018.12.005] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2018] [Revised: 12/29/2018] [Accepted: 12/30/2018] [Indexed: 02/05/2023]
Abstract
Recombination in mammals is not uniformly distributed along the chromosome but concentrated in small regions known as recombination hotspots. Recombination starts with the double-strand break of a chromosomal sequence and results in the transmission of the sequence that does not break (preventing recombination) more often than the sequence that breaks (allowing recombination). Thus recombination itself renders individual recombination hotspots inactive and over time should drive them to extinction in the genome. Empirical evidence shows that individual recombination hotspots die but, far from being driven to extinction, they are abundant in the genome: a contradiction referred to as the Recombination Hotspot Paradox. What saves recombination hotspots from extinction? The current answer relies in the formation of new recombination hotspots in new genomic sites driven by viability selection in favor of recombination. Here we formulate a population genetics model that incorporates the molecular mechanism initiating recombination in mammals (PRDM9-like genes), to provide an alternative solution to the paradox. We find that weak selection allows individual recombination hotspots to become inactive (die) while saving them from extinction in the genome by driving their re-activation (resurrection). Our model shows that when selection for recombination is weak, the introduction of rare variants causes recombination sites to oscillate between hot and cold phenotypes with a recombination hotspot dying only to come back. Counter-intuitively, we find that low viability selection leaves a hard selective sweep signature in the genome, with the selective sweep at the recombination hotspot being the hardest when viability selection is the lowest. Our model can help to understand the rapid evolution of PRDM9, the co-existence of two types of hotspots, the life expectancy of hotspots, and the volatility of the recombinational landscape (with hotspots rarely being shared between closely related species).
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Affiliation(s)
- Francisco Úbeda
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK.
| | - Timothy W Russell
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
| | - Vincent A A Jansen
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, UK
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15
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Dluzewska J, Szymanska M, Ziolkowski PA. Where to Cross Over? Defining Crossover Sites in Plants. Front Genet 2018; 9:609. [PMID: 30619450 PMCID: PMC6299014 DOI: 10.3389/fgene.2018.00609] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 11/19/2018] [Indexed: 12/16/2022] Open
Abstract
It is believed that recombination in meiosis serves to reshuffle genetic material from both parents to increase genetic variation in the progeny. At the same time, the number of crossovers is usually kept at a very low level. As a consequence, many organisms need to make the best possible use from the one or two crossovers that occur per chromosome in meiosis. From this perspective, the decision of where to allocate rare crossover events becomes an important issue, especially in self-pollinating plant species, which experience limited variation due to inbreeding. However, the freedom in crossover allocation is significantly limited by other, genetic and non-genetic factors, including chromatin structure. Here we summarize recent progress in our understanding of those processes with a special emphasis on plant genomes. First, we focus on factors which influence the distribution of recombination initiation sites and discuss their effects at both, the single hotspot level and at the chromosome scale. We also briefly explain the aspects of hotspot evolution and their regulation. Next, we analyze how recombination initiation sites translate into the development of crossovers and their location. Moreover, we provide an overview of the sequence polymorphism impact on crossover formation and chromosomal distribution.
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Affiliation(s)
- Julia Dluzewska
- Department of Genome Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznań, Poland
| | - Maja Szymanska
- Department of Genome Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznań, Poland
| | - Piotr A Ziolkowski
- Department of Genome Biology, Institute of Molecular Biology and Biotechnology, Adam Mickiewicz University, Poznań, Poland
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16
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Abstract
During meiosis, maternal and paternal chromosomes undergo exchanges by homologous recombination. This is essential for fertility and contributes to genome evolution. In many eukaryotes, sites of meiotic recombination, also called hotspots, are regions of accessible chromatin, but in many vertebrates, their location follows a distinct pattern and is specified by PR domain-containing protein 9 (PRDM9). The specification of meiotic recombination hotspots is achieved by the different activities of PRDM9: DNA binding, histone methyltransferase, and interaction with other proteins. Remarkably, PRDM9 activity leads to the erosion of its own binding sites and the rapid evolution of its DNA-binding domain. PRDM9 may also contribute to reproductive isolation, as it is involved in hybrid sterility potentially due to a reduction of its activity in specific heterozygous contexts.
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Affiliation(s)
- Corinne Grey
- Institut de Génétique Humaine, Centre National de la Recherche Scientifique, University of Montpellier, Montpellier, France
| | - Frédéric Baudat
- Institut de Génétique Humaine, Centre National de la Recherche Scientifique, University of Montpellier, Montpellier, France
| | - Bernard de Massy
- Institut de Génétique Humaine, Centre National de la Recherche Scientifique, University of Montpellier, Montpellier, France
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17
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Stapley J, Feulner PGD, Johnston SE, Santure AW, Smadja CM. Variation in recombination frequency and distribution across eukaryotes: patterns and processes. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0455. [PMID: 29109219 PMCID: PMC5698618 DOI: 10.1098/rstb.2016.0455] [Citation(s) in RCA: 212] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/08/2017] [Indexed: 01/04/2023] Open
Abstract
Recombination, the exchange of DNA between maternal and paternal chromosomes during meiosis, is an essential feature of sexual reproduction in nearly all multicellular organisms. While the role of recombination in the evolution of sex has received theoretical and empirical attention, less is known about how recombination rate itself evolves and what influence this has on evolutionary processes within sexually reproducing organisms. Here, we explore the patterns of, and processes governing recombination in eukaryotes. We summarize patterns of variation, integrating current knowledge with an analysis of linkage map data in 353 organisms. We then discuss proximate and ultimate processes governing recombination rate variation and consider how these influence evolutionary processes. Genome-wide recombination rates (cM/Mb) can vary more than tenfold across eukaryotes, and there is large variation in the distribution of recombination events across closely related taxa, populations and individuals. We discuss how variation in rate and distribution relates to genome architecture, genetic and epigenetic mechanisms, sex, environmental perturbations and variable selective pressures. There has been great progress in determining the molecular mechanisms governing recombination, and with the continued development of new modelling and empirical approaches, there is now also great opportunity to further our understanding of how and why recombination rate varies.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)
- Jessica Stapley
- Centre for Adaptation to a Changing Environment, IBZ, ETH Zürich, 8092 Zürich, Switzerland
| | - Philine G D Feulner
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland.,Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Susan E Johnston
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JY, UK
| | - Anna W Santure
- School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Carole M Smadja
- Institut des Sciences de l'Evolution UMR 5554, CNRS, IRD, EPHE, Université de Montpellier, 3095 Montpellier cedex 05, France
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18
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Stapley J, Feulner PGD, Johnston SE, Santure AW, Smadja CM. Recombination: the good, the bad and the variable. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2017.0279. [PMID: 29109232 PMCID: PMC5698631 DOI: 10.1098/rstb.2017.0279] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/21/2017] [Indexed: 12/17/2022] Open
Abstract
Recombination, the process by which DNA strands are broken and repaired, producing new combinations of alleles, occurs in nearly all multicellular organisms and has important implications for many evolutionary processes. The effects of recombination can be good, as it can facilitate adaptation, but also bad when it breaks apart beneficial combinations of alleles, and recombination is highly variable between taxa, species, individuals and across the genome. Understanding how and why recombination rate varies is a major challenge in biology. Most theoretical and empirical work has been devoted to understanding the role of recombination in the evolution of sex—comparing between sexual and asexual species or populations. How recombination rate evolves and what impact this has on evolutionary processes within sexually reproducing organisms has received much less attention. This Theme Issue focusses on how and why recombination rate varies in sexual species, and aims to coalesce knowledge of the molecular mechanisms governing recombination with our understanding of the evolutionary processes driving variation in recombination within and between species. By integrating these fields, we can identify important knowledge gaps and areas for future research, and pave the way for a more comprehensive understanding of how and why recombination rate varies.
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Affiliation(s)
- Jessica Stapley
- Centre for Adaptation to a Changing Environment, IBZ, ETH Zürich, Zürich, Switzerland
| | - Philine G D Feulner
- Department of Fish Ecology and Evolution, Centre of Ecology, Evolution and Biogeochemistry, EAWAG Swiss Federal Institute of Aquatic Science and Technology, 6047 Kastanienbaum, Switzerland.,Division of Aquatic Ecology and Evolution, Institute of Ecology and Evolution, University of Bern, 3012 Bern, Switzerland
| | - Susan E Johnston
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh EH9 3JY, UK
| | - Anna W Santure
- School of Biological Sciences, University of Auckland, Auckland 1142, New Zealand
| | - Carole M Smadja
- Institut des Sciences de l'Evolution UMR 5554, CNRS, IRD, EPHE, Université de Montpellier, 3095 Montpellier cedex 05, France
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19
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Paigen K, Petkov PM. PRDM9 and Its Role in Genetic Recombination. Trends Genet 2018; 34:291-300. [PMID: 29366606 DOI: 10.1016/j.tig.2017.12.017] [Citation(s) in RCA: 87] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 12/14/2017] [Accepted: 12/20/2017] [Indexed: 12/22/2022]
Abstract
PRDM9 is a zinc finger protein that binds DNA at specific locations in the genome where it trimethylates histone H3 at lysines 4 and 36 at surrounding nucleosomes. During meiosis in many species, including humans and mice where PRDM9 has been most intensely studied, these actions determine the location of recombination hotspots, where genetic recombination occurs. In addition, PRDM9 facilitates the association of hotspots with the chromosome axis, the site of the programmed DNA double-strand breaks (DSBs) that give rise to genetic exchange between chromosomes. In the absence of PRDM9 DSBs are not properly repaired. Collectively, these actions determine patterns of genetic linkage and the possibilities for chromosome reorganization over successive generations.
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20
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Haag CR, Theodosiou L, Zahab R, Lenormand T. Low recombination rates in sexual species and sex-asex transitions. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160461. [PMID: 29109224 PMCID: PMC5698623 DOI: 10.1098/rstb.2016.0461] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/24/2017] [Indexed: 12/11/2022] Open
Abstract
In most sexual, diploid eukaryotes, at least one crossover occurs between each pair of homologous chromosomes during meiosis, presumably in order to ensure proper segregation. Well-known exceptions to this rule are species in which one sex does not recombine and specific chromosomes lacking crossover. We review other possible exceptions, including species with chromosome maps of less than 50 cM in one or both sexes. We discuss the idea that low recombination rates may favour sex-asex transitions, or, alternatively may be a consequence of it. We then show that a yet undescribed species of brine shrimp Artemia from Kazakhstan (A sp. Kazakhstan), the closest known relative of the asexual Artemia parthenogenetica, has one of the shortest genetic linkage maps known. Based on a family of 42 individuals and 589 RAD markers, we find that many linkage groups are considerably shorter than 50 cM, suggesting either no obligate crossover or crossovers concentrated at terminal positions with little effect on recombination. We contrast these findings with the published map of the more distantly related sexual congener, A. franciscana, and conclude that the study of recombination in non-model systems is important to understand the evolutionary causes and consequences of recombination.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)
- 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-École Pratique des Hautes Études, 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - Loukas Theodosiou
- Research Group for Community Dynamics, Max Planck Institute for Evolutionary Biology, August-Thienemann-Straße 2, 24306 Plön, Germany
| | - Roula Zahab
- 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-École Pratique des Hautes Études, 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - 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-École Pratique des Hautes Études, 1919 Route de Mende, 34293 Montpellier Cedex 5, France
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