1
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Brazier T, Glémin S. Diversity in Recombination Hotspot Characteristics and Gene Structure Shape Fine-Scale Recombination Patterns in Plant Genomes. Mol Biol Evol 2024; 41:msae183. [PMID: 39302634 DOI: 10.1093/molbev/msae183] [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: 06/27/2024] [Accepted: 08/20/2024] [Indexed: 09/22/2024] Open
Abstract
During the meiosis of many eukaryote species, crossovers tend to occur within narrow regions called recombination hotspots. In plants, it is generally thought that gene regulatory sequences, especially promoters and 5' to 3' untranslated regions, are enriched in hotspots, but this has been characterized in a handful of species only. We also lack a clear description of fine-scale variation in recombination rates within genic regions and little is known about hotspot position and intensity in plants. To address this question, we constructed fine-scale recombination maps from genetic polymorphism data and inferred recombination hotspots in 11 plant species. We detected gradients of recombination in genic regions in most species, yet gradients varied in intensity and shape depending on specific hotspot locations and gene structure. To further characterize recombination gradients, we decomposed them according to gene structure by rank and number of exons. We generalized the previously observed pattern that recombination hotspots are organized around the boundaries of coding sequences, especially 5' promoters. However, our results also provided new insight into the relative importance of the 3' end of genes in some species and the possible location of hotspots away from genic regions in some species. Variation among species seemed driven more by hotspot location among and within genes than by differences in size or intensity among species. Our results shed light on the variation in recombination rates at a very fine scale, revealing the diversity and complexity of genic recombination gradients emerging from the interaction between hotspot location and gene structure.
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Affiliation(s)
- Thomas Brazier
- Unité Mixte de Recherche (UMR) 6553 - ECOBIO (Ecosystems, Biodiversity, Evolution), University of Rennes, CNRS, Rennes, France
| | - Sylvain Glémin
- Unité Mixte de Recherche (UMR) 6553 - ECOBIO (Ecosystems, Biodiversity, Evolution), University of Rennes, CNRS, Rennes, France
- Department of Ecology and Genetics, Evolutionary Biology Center and Science for Life Laboratory, Uppsala University, Uppsala, Sweden
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2
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Takayama J, Makino S, Funayama T, Ueki M, Narita A, Murakami K, Orui M, Ishikuro M, Obara T, Kuriyama S, Yamamoto M, Tamiya G. A fine-scale genetic map of the Japanese population. Clin Genet 2024; 106:284-292. [PMID: 38719617 DOI: 10.1111/cge.14536] [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: 10/03/2023] [Revised: 04/13/2024] [Accepted: 04/15/2024] [Indexed: 08/13/2024]
Abstract
Genetic maps are fundamental resources for linkage and association studies. A fine-scale genetic map can be constructed by inferring historical recombination events from the genome-wide structure of linkage disequilibrium-a non-random association of alleles among loci-by using population-scale sequencing data. We constructed a fine-scale genetic map and identified recombination hotspots from 10 092 551 bi-allelic high-quality autosomal markers segregating among 150 unrelated Japanese individuals whose genotypes were determined by high-coverage (30×) whole-genome sequencing, and the genotype quality was carefully controlled by using their parents' and offspring's genotypes. The pedigree information was also utilized for haplotype phasing. The resulting genome-wide recombination rate profiles were concordant with those of the worldwide population on a broad scale, and the resolution was much improved. We identified 9487 recombination hotspots and confirmed the enrichment of previously known motifs in the hotspots. Moreover, we demonstrated that the Japanese genetic map improved the haplotype phasing and genotype imputation accuracy for the Japanese population. The construction of a population-specific genetic map will help make genetics research more accurate.
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Affiliation(s)
- Jun Takayama
- Department of AI and Innovative Medicine, Tohoku University School of Medicine, Sendai, Japan
- Department of Integrative Genomics, Tohoku Medical Megabank Organization (ToMMo) Tohoku University, Sendai, Japan
- Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project, Tokyo, Japan
| | - Satoshi Makino
- Department of Integrative Genomics, Tohoku Medical Megabank Organization (ToMMo) Tohoku University, Sendai, Japan
| | - Takamitsu Funayama
- Department of Integrative Genomics, Tohoku Medical Megabank Organization (ToMMo) Tohoku University, Sendai, Japan
- Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project, Tokyo, Japan
| | - Masao Ueki
- Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project, Tokyo, Japan
| | - Akira Narita
- Department of Integrative Genomics, Tohoku Medical Megabank Organization (ToMMo) Tohoku University, Sendai, Japan
| | - Keiko Murakami
- Department of Preventive Medicine and Epidemiology, ToMMo, Tohoku University, Sendai, Japan
| | - Masatsugu Orui
- Department of Preventive Medicine and Epidemiology, ToMMo, Tohoku University, Sendai, Japan
- Department of Molecular Epidemiology, Tohoku University School of Medicine, Sendai, Japan
| | - Mami Ishikuro
- Department of Preventive Medicine and Epidemiology, ToMMo, Tohoku University, Sendai, Japan
- Department of Molecular Epidemiology, Tohoku University School of Medicine, Sendai, Japan
| | - Taku Obara
- Department of Preventive Medicine and Epidemiology, ToMMo, Tohoku University, Sendai, Japan
- Department of Molecular Epidemiology, Tohoku University School of Medicine, Sendai, Japan
| | - Shinichi Kuriyama
- Department of Preventive Medicine and Epidemiology, ToMMo, Tohoku University, Sendai, Japan
- Department of Molecular Epidemiology, Tohoku University School of Medicine, Sendai, Japan
| | - Masayuki Yamamoto
- Department of Integrative Genomics, Tohoku Medical Megabank Organization (ToMMo) Tohoku University, Sendai, Japan
| | - Gen Tamiya
- Department of AI and Innovative Medicine, Tohoku University School of Medicine, Sendai, Japan
- Department of Integrative Genomics, Tohoku Medical Megabank Organization (ToMMo) Tohoku University, Sendai, Japan
- Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project, Tokyo, Japan
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3
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Okamoto AS, Capellini TD. Parallel Evolution at the Regulatory Base-Pair Level Contributes to Mammalian Interspecific Differences in Polygenic Traits. Mol Biol Evol 2024; 41:msae157. [PMID: 39073613 PMCID: PMC11321361 DOI: 10.1093/molbev/msae157] [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: 04/22/2024] [Revised: 07/02/2024] [Accepted: 07/23/2024] [Indexed: 07/30/2024] Open
Abstract
Parallel evolution occurs when distinct lineages with similar ancestral states converge on a new phenotype. Parallel evolution has been well documented at the organ, gene pathway, and amino acid sequence level but in theory, it can also occur at individual nucleotides within noncoding regions. To examine the role of parallel evolution in shaping the biology of mammalian complex traits, we used data on single-nucleotide polymorphisms (SNPs) influencing human intraspecific variation to predict trait values in other species for 11 complex traits. We found that the alleles at SNP positions associated with human intraspecific height and red blood cell (RBC) count variation are associated with interspecific variation in the corresponding traits across mammals. These associations hold for deeper branches of mammalian evolution as well as between strains of collaborative cross mice. While variation in RBC count between primates uses both ancient and more recently evolved genomic regions, we found that only primate-specific elements were correlated with primate body size. We show that the SNP positions driving these signals are flanked by conserved sequences, maintain synteny with target genes, and overlap transcription factor binding sites. This work highlights the potential of conserved but tunable regulatory elements to be reused in parallel to facilitate evolutionary adaptation in mammals.
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Affiliation(s)
- Alexander S Okamoto
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
| | - Terence D Capellini
- Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
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4
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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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5
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Joseph J. Increased Positive Selection in Highly Recombining Genes Does not Necessarily Reflect an Evolutionary Advantage of Recombination. Mol Biol Evol 2024; 41:msae107. [PMID: 38829800 PMCID: PMC11173204 DOI: 10.1093/molbev/msae107] [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: 01/30/2024] [Revised: 04/08/2024] [Accepted: 05/28/2024] [Indexed: 06/05/2024] Open
Abstract
It is commonly thought that the long-term advantage of meiotic recombination is to dissipate genetic linkage, allowing natural selection to act independently on different loci. It is thus theoretically expected that genes with higher recombination rates evolve under more effective selection. On the other hand, recombination is often associated with GC-biased gene conversion (gBGC), which theoretically interferes with selection by promoting the fixation of deleterious GC alleles. To test these predictions, several studies assessed whether selection was more effective in highly recombining genes (due to dissipation of genetic linkage) or less effective (due to gBGC), assuming a fixed distribution of fitness effects (DFE) for all genes. In this study, I directly derive the DFE from a gene's evolutionary history (shaped by mutation, selection, drift, and gBGC) under empirical fitness landscapes. I show that genes that have experienced high levels of gBGC are less fit and thus have more opportunities for beneficial mutations. Only a small decrease in the genome-wide intensity of gBGC leads to the fixation of these beneficial mutations, particularly in highly recombining genes. This results in increased positive selection in highly recombining genes that is not caused by more effective selection. Additionally, I show that the death of a recombination hotspot can lead to a higher dN/dS than its birth, but with substitution patterns biased towards AT, and only at selected positions. This shows that controlling for a substitution bias towards GC is therefore not sufficient to rule out the contribution of gBGC to signatures of accelerated evolution. Finally, although gBGC does not affect the fixation probability of GC-conservative mutations, I show that by altering the DFE, gBGC can also significantly affect nonsynonymous GC-conservative substitution patterns.
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Affiliation(s)
- Julien Joseph
- Laboratoire de Biométrie et Biologie Evolutive, Université Lyon 1, CNRS, UMR 5558, Villeurbanne, France
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6
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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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7
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Przeworski M. 2023 ASHG Scientific Achievement Award. Am J Hum Genet 2024; 111:425-427. [PMID: 38458164 PMCID: PMC10995464 DOI: 10.1016/j.ajhg.2023.12.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2023] [Accepted: 12/12/2023] [Indexed: 03/10/2024] Open
Abstract
This article is based on the address given by the author at the 2023 meeting of The American Society of Human Genetics (ASHG) in Washington, D.C. A video of the original address can be found at the ASHG website.
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Affiliation(s)
- Molly Przeworski
- Departments of Biological Sciences and Systems Biology, Columbia University, New York, NY, USA.
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8
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Chase MA, Vilcot M, Mugal CF. The role of recombination dynamics in shaping signatures of direct and indirect selection across the Ficedula flycatcher genome †. Proc Biol Sci 2024; 291:20232382. [PMID: 38228173 DOI: 10.1098/rspb.2023.2382] [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: 10/20/2022] [Accepted: 12/14/2023] [Indexed: 01/18/2024] Open
Abstract
Recombination is a central evolutionary process that reshuffles combinations of alleles along chromosomes, and consequently is expected to influence the efficacy of direct selection via Hill-Robertson interference. Additionally, the indirect effects of selection on neutral genetic diversity are expected to show a negative relationship with recombination rate, as background selection and genetic hitchhiking are stronger when recombination rate is low. However, owing to the limited availability of recombination rate estimates across divergent species, the impact of evolutionary changes in recombination rate on genomic signatures of selection remains largely unexplored. To address this question, we estimate recombination rate in two Ficedula flycatcher species, the taiga flycatcher (Ficedula albicilla) and collared flycatcher (Ficedula albicollis). We show that recombination rate is strongly correlated with signatures of indirect selection, and that evolutionary changes in recombination rate between species have observable impacts on this relationship. Conversely, signatures of direct selection on coding sequences show little to no relationship with recombination rate, even when restricted to genes where recombination rate is conserved between species. Thus, using measures of indirect and direct selection that bridge micro- and macro-evolutionary timescales, we demonstrate that the role of recombination rate and its dynamics varies for different signatures of selection.
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Affiliation(s)
- Madeline A Chase
- Department of Ecology and Genetics, Uppsala University, 75236 Uppsala, Sweden
- Swiss Ornithological Institute, 6204 Sempach, Switzerland
| | - Maurine Vilcot
- Department of Ecology and Genetics, Uppsala University, 75236 Uppsala, Sweden
- CEFE, University of Montpellier, CNRS, EPHE, IRD, 34293 Montpellier 5, France
| | - Carina F Mugal
- Department of Ecology and Genetics, Uppsala University, 75236 Uppsala, Sweden
- Laboratory of Biometry and Evolutionary Biology, University of Lyon 1, CNRS UMR 5558, 69622 Villeurbanne cedex, France
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9
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Versoza CJ, Weiss S, Johal R, La Rosa B, Jensen JD, Pfeifer SP. Novel Insights into the Landscape of Crossover and Noncrossover Events in Rhesus Macaques (Macaca mulatta). Genome Biol Evol 2024; 16:evad223. [PMID: 38051960 PMCID: PMC10773715 DOI: 10.1093/gbe/evad223] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Revised: 11/04/2023] [Accepted: 11/28/2023] [Indexed: 12/07/2023] Open
Abstract
Meiotic recombination landscapes differ greatly between distantly and closely related taxa, populations, individuals, sexes, and even within genomes; however, the factors driving this variation are yet to be well elucidated. Here, we directly estimate contemporary crossover rates and, for the first time, noncrossover rates in rhesus macaques (Macaca mulatta) from four three-generation pedigrees comprising 32 individuals. We further compare these results with historical, demography-aware, linkage disequilibrium-based recombination rate estimates. From paternal meioses in the pedigrees, 165 crossover events with a median resolution of 22.3 kb were observed, corresponding to a male autosomal map length of 2,357 cM-approximately 15% longer than an existing linkage map based on human microsatellite loci. In addition, 85 noncrossover events with a mean tract length of 155 bp were identified-similar to the tract lengths observed in the only other two primates in which noncrossovers have been studied to date, humans and baboons. Consistent with observations in other placental mammals with PRDM9-directed recombination, crossover (and to a lesser extent noncrossover) events in rhesus macaques clustered in intergenic regions and toward the chromosomal ends in males-a pattern in broad agreement with the historical, sex-averaged recombination rate estimates-and evidence of GC-biased gene conversion was observed at noncrossover sites.
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Affiliation(s)
- Cyril J Versoza
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
| | - Sarah Weiss
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Ravneet Johal
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Bruno La Rosa
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
| | - Jeffrey D Jensen
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
| | - Susanne P Pfeifer
- School of Life Sciences, Arizona State University, Tempe, AZ, USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
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10
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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: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 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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11
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Rivas-González I, Rousselle M, Li F, Zhou L, Dutheil JY, Munch K, Shao Y, Wu D, Schierup MH, Zhang G. Pervasive incomplete lineage sorting illuminates speciation and selection in primates. Science 2023; 380:eabn4409. [PMID: 37262154 DOI: 10.1126/science.abn4409] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 01/19/2023] [Indexed: 06/03/2023]
Abstract
Incomplete lineage sorting (ILS) causes the phylogeny of some parts of the genome to differ from the species tree. In this work, we investigate the frequencies and determinants of ILS in 29 major ancestral nodes across the entire primate phylogeny. We find up to 64% of the genome affected by ILS at individual nodes. We exploit ILS to reconstruct speciation times and ancestral population sizes. Estimated speciation times are much more recent than genomic divergence times and are in good agreement with the fossil record. We show extensive variation of ILS along the genome, mainly driven by recombination but also by the distance to genes, highlighting a major impact of selection on variation along the genome. In many nodes, ILS is reduced more on the X chromosome compared with autosomes than expected under neutrality, which suggests higher impacts of natural selection on the X chromosome. Finally, we show an excess of ILS in genes with immune functions and a deficit of ILS in housekeeping genes. The extensive ILS in primates discovered in this study provides insights into the speciation times, ancestral population sizes, and patterns of natural selection that shape primate evolution.
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Affiliation(s)
- Iker Rivas-González
- Bioinformatics Research Centre, Aarhus University, DK-8000 Aarhus C, Denmark
| | | | - Fang Li
- BGI-Research, BGI-Wuhan, Wuhan 430074, China
- Institute of Animal Sex and Development, ZhejiangWanli University, Ningbo 315104, China
- BGI-Research, BGI-Shenzhen, Shenzhen 518083, China
| | - Long Zhou
- Evolutionary & Organismal Biology Research Center, Zhejiang University School of Medicine, Hangzhou 310058, China
- Women's Hospital, School of Medicine, Zhejiang University, Shangcheng District, Hangzhou 310006, China
| | - Julien Y Dutheil
- Max Planck Institute for Evolutionary Biology, Plön, Germany
- Institute of Evolution Sciences of Montpellier (ISEM), CNRS, University of Montpellier, IRD, EPHE, 34095 Montpellier, France
| | - Kasper Munch
- Bioinformatics Research Centre, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Yong Shao
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
| | - Dongdong Wu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
- Center for Excellence in Animal Evolution and Genetics, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
- National Resource Center for Non-Human Primates, Kunming Primate Research Center, and National Research Facility for Phenotypic and Genetic Analysis of Model Animals (Primate Facility), Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650107, China
- Kunming Natural History Museum of Zoology, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
| | - Mikkel H Schierup
- Bioinformatics Research Centre, Aarhus University, DK-8000 Aarhus C, Denmark
| | - Guojie Zhang
- Evolutionary & Organismal Biology Research Center, Zhejiang University School of Medicine, Hangzhou 310058, China
- Women's Hospital, School of Medicine, Zhejiang University, Shangcheng District, Hangzhou 310006, China
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, Yunnan 650223, China
- Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou 311121, China
- Villum Centre for Biodiversity Genomics, Section for Ecology and Evolution, Department of Biology, University of Copenhagen, DK-2100 Copenhagen, Denmark
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12
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Ghafoor S, Santos J, Versoza CJ, Jensen JD, Pfeifer SP. The Impact of Sample Size and Population History on Observed Mutational Spectra: A Case Study in Human and Chimpanzee Populations. Genome Biol Evol 2023; 15:7039701. [PMID: 36790107 PMCID: PMC9989333 DOI: 10.1093/gbe/evad019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 01/20/2023] [Accepted: 02/08/2023] [Indexed: 02/16/2023] Open
Abstract
Recent studies have highlighted variation in the mutational spectra among human populations as well as closely related hominoids-yet little remains known about the genetic and nongenetic factors driving these rate changes across the genome. Pinpointing the root causes of these differences is an important endeavor that requires careful comparative analyses of population-specific mutational landscapes at both broad and fine genomic scales. However, several factors can confound such analyses. Although previous studies have shown that technical artifacts, such as sequencing errors and batch effects, can contribute to observed mutational shifts, other potentially confounding parameters have received less attention thus far. Using population genetic simulations of human and chimpanzee populations as an illustrative example, we here show that the sample size required for robust inference of mutational spectra depends on the population-specific demographic history. As a consequence, the power to detect rate changes is high in certain hominoid populations while, for others, currently available sample sizes preclude analyses at fine genomic scales.
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Affiliation(s)
- Suhail Ghafoor
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
| | - João Santos
- School of Life Sciences, Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
| | - Cyril J Versoza
- School of Life Sciences, Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
| | - Jeffrey D Jensen
- School of Life Sciences, Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
| | - Susanne P Pfeifer
- School of Life Sciences, Center for Evolution and Medicine, Arizona State University, Tempe, AZ, USA
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13
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Wooldridge LK, Dumont BL. Rapid Evolution of the Fine-scale Recombination Landscape in Wild House Mouse (Mus musculus) Populations. Mol Biol Evol 2022; 40:6889355. [PMID: 36508360 PMCID: PMC9825251 DOI: 10.1093/molbev/msac267] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2021] [Revised: 11/23/2022] [Accepted: 11/30/2022] [Indexed: 12/14/2022] Open
Abstract
Meiotic recombination is an important evolutionary force and an essential meiotic process. In many species, recombination events concentrate into hotspots defined by the site-specific binding of PRMD9. Rapid evolution of Prdm9's zinc finger DNA-binding array leads to remarkably abrupt shifts in the genomic distribution of hotspots between species, but the question of how Prdm9 allelic variation shapes the landscape of recombination between populations remains less well understood. Wild house mice (Mus musculus) harbor exceptional Prdm9 diversity, with >150 alleles identified to date, and pose a particularly powerful system for addressing this open question. We employed a coalescent-based approach to construct broad- and fine-scale sex-averaged recombination maps from contemporary patterns of linkage disequilibrium in nine geographically isolated wild house mouse populations, including multiple populations from each of three subspecies. Comparing maps between wild mouse populations and subspecies reveals several themes. First, we report weak fine- and broad-scale recombination map conservation across subspecies and populations, with genetic divergence offering no clear prediction for recombination map divergence. Second, most hotspots are unique to one population, an outcome consistent with minimal sharing of Prdm9 alleles between surveyed populations. Finally, by contrasting aggregate hotspot activity on the X versus autosomes, we uncover evidence for population-specific differences in the degree and direction of sex dimorphism for recombination. Overall, our findings illuminate the variability of both the broad- and fine-scale recombination landscape in M. musculus and underscore the functional impact of Prdm9 allelic variation in wild mouse populations.
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14
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Lynch M, Ye Z, Urban L, Maruki T, Wei W. The Linkage-Disequilibrium and Recombinational Landscape in Daphnia pulex. Genome Biol Evol 2022; 14:evac145. [PMID: 36170345 PMCID: PMC9642108 DOI: 10.1093/gbe/evac145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2022] [Indexed: 11/24/2022] Open
Abstract
By revealing the influence of recombinational activity beyond what can be achieved with controlled crosses, measures of linkage disequilibrium (LD) in natural populations provide a powerful means of defining the recombinational landscape within which genes evolve. In one of the most comprehensive studies of this sort ever performed, involving whole-genome analyses on nearly 1,000 individuals of the cyclically parthenogenetic microcrustacean Daphnia pulex, the data suggest a relatively uniform pattern of recombination across the genome. Patterns of LD are quite consistent among populations; average rates of recombination are quite similar for all chromosomes; and although some chromosomal regions have elevated recombination rates, the degree of inflation is not large, and the overall spatial pattern of recombination is close to the random expectation. Contrary to expectations for models in which crossing-over is the primary mechanism of recombination, and consistent with data for other species, the distance-dependent pattern of LD indicates excessively high levels at both short and long distances and unexpectedly low levels of decay at long distances, suggesting significant roles for factors such as nonindependent mutation, population subdivision, and recombination mechanisms unassociated with crossing over. These observations raise issues regarding the classical LD equilibrium model widely applied in population genetics to infer recombination rates across various length scales on chromosomes.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287, USA
| | - Zhiqiang Ye
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287, USA
| | - Lina Urban
- Department for Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, 24306 Plön, Germany
| | - Takahiro Maruki
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287, USA
| | - Wen Wei
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287, USA
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15
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Bergman J, Schierup MH. Evolutionary dynamics of pseudoautosomal region 1 in humans and great apes. Genome Biol 2022; 23:215. [PMID: 36253794 PMCID: PMC9575207 DOI: 10.1186/s13059-022-02784-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Accepted: 09/30/2022] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND The pseudoautosomal region 1 (PAR1) is a 2.7 Mb telomeric region of human sex chromosomes. PAR1 has a crucial role in ensuring proper segregation of sex chromosomes during male meiosis, exposing it to extreme recombination and mutation processes. We investigate PAR1 evolution using population genomic datasets of extant humans, eight populations of great apes, and two archaic human genome sequences. RESULTS We find that PAR1 is fast evolving and closer to evolutionary nucleotide equilibrium than autosomal telomeres. We detect a difference between substitution patterns and extant diversity in PAR1, mainly driven by the conflict between strong mutation and recombination-associated fixation bias at CpG sites. We detect excess C-to-G mutations in PAR1 of all great apes, specific to the mutagenic effect of male recombination. Despite recent evidence for Y chromosome introgression from humans into Neanderthals, we find that the Neanderthal PAR1 retained similarity to the Denisovan sequence. We find differences between substitution spectra of these archaics suggesting rapid evolution of PAR1 in recent hominin history. Frequency analysis of alleles segregating in females and males provided no evidence for recent sexual antagonism in this region. We study repeat content and double-strand break hotspot regions in PAR1 and find that they may play roles in ensuring the obligate X-Y recombination event during male meiosis. CONCLUSIONS Our study provides an unprecedented quantification of population genetic forces governing PAR1 biology across extant and extinct hominids. PAR1 evolutionary dynamics are predominantly governed by recombination processes with a strong impact on mutation patterns across all species.
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Affiliation(s)
- Juraj Bergman
- Bioinformatics Research Centre, Aarhus University, DK-8000 Aarhus C, Denmark
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16
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Pawar H, Ostridge HJ, Schmidt JM, Andrés AM. Genetic adaptations to SIV across chimpanzee populations. PLoS Genet 2022; 18:e1010337. [PMID: 36007015 PMCID: PMC9467346 DOI: 10.1371/journal.pgen.1010337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 09/12/2022] [Accepted: 07/12/2022] [Indexed: 11/18/2022] Open
Abstract
Central and eastern chimpanzees are infected with Simian Immunodeficiency Virus (SIV) in the wild, typically without developing acute immunodeficiency. Yet the recent zoonotic transmission of chimpanzee SIV to humans, which were naïve to the virus, gave rise to the Human Immunodeficiency Virus (HIV), which causes AIDS and is responsible for one of the deadliest pandemics in human history. Chimpanzees have likely been infected with SIV for tens of thousands of years and have likely evolved to reduce its pathogenicity, becoming semi-natural hosts that largely tolerate the virus. In support of this view, central and eastern chimpanzees show evidence of positive selection in genes involved in SIV/HIV cell entry and immune response to SIV, respectively. We hypothesise that the population first infected by SIV would have experienced the strongest selective pressure to control the lethal potential of zoonotic SIV, and that population genetics will reveal those first critical adaptations. With that aim we used population genetics to investigate signatures of positive selection in the common ancestor of central-eastern chimpanzees. The genes with signatures of positive selection in the ancestral population are significantly enriched in SIV-related genes, especially those involved in the immune response to SIV and those encoding for host genes that physically interact with SIV/HIV (VIPs). This supports a scenario where SIV first infected the central-eastern ancestor and where this population was under strong pressure to adapt to zoonotic SIV. Interestingly, integrating these genes with candidates of positive selection in the two infected subspecies reveals novel patterns of adaptation to SIV. Specifically, we observe evidence of positive selection in numerous steps of the biological pathway responsible for T-helper cell differentiation, including CD4 and multiple genes that SIV/HIV use to infect and control host cells. This pathway is active only in CD4+ cells which SIV/HIV infects, and it plays a crucial role in shaping the immune response so it can efficiently control the virus. Our results confirm the importance of SIV as a selective factor, identify specific genetic changes that may have allowed our closest living relatives to reduce SIV’s pathogenicity, and demonstrate the potential of population genomics to reveal the evolutionary mechanisms used by naïve hosts to reduce the pathogenicity of zoonotic pathogens. Chimpanzees are at the origin of HIV-1, a virus that generates an incurable disease and that generated a pandemic that has claimed 35 million lives. Chimpanzees have evolved to control the pathogenicity of the virus, which does not typically develop into AIDS in the same way as in humans. Identifying the genetic adaptations responsible for this process provides critical knowledge about SIV and HIV. Our analysis of chimpanzee genetic adaptations identified specific genes and molecular pathways involved in adaptation to SIV, providing important insights into the mechanisms that likely allowed our closest living relatives to control SIV/HIV. Further, we establish SIV as a strong and recurrent selective pressure in central and eastern chimpanzees, two important subspecies of large mammals that are currently endangered.
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Affiliation(s)
- Harvinder Pawar
- UCL Genetics Institute, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Harrison J. Ostridge
- UCL Genetics Institute, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Joshua M. Schmidt
- UCL Genetics Institute, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- Department of Ecology and Evolution, School of Biological Sciences, University of Adelaide, Adelaide, Australia
- * E-mail: (JMS); (AMA)
| | - Aida M. Andrés
- UCL Genetics Institute, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- * E-mail: (JMS); (AMA)
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17
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van Eeden G, Uren C, Pless E, Mastoras M, van der Spuy GD, Tromp G, Henn BM, Möller M. The recombination landscape of the Khoe-San likely represents the upper limits of recombination divergence in humans. Genome Biol 2022; 23:172. [PMID: 35945619 PMCID: PMC9361568 DOI: 10.1186/s13059-022-02744-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 08/01/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Recombination maps are important resources for epidemiological and evolutionary analyses; however, there are currently no recombination maps representing any African population outside of those with West African ancestry. We infer the demographic history for the Nama, an indigenous Khoe-San population of southern Africa, and derive a novel, population-specific recombination map from the whole genome sequencing of 54 Nama individuals. We hypothesise that there are no publicly available recombination maps representative of the Nama, considering the deep population divergence and subsequent isolation of the Khoe-San from other African groups. RESULTS We show that the recombination landscape of the Nama does not cluster with any continental groups with publicly available representative recombination maps. Finally, we use selection scans as an example of how fine-scale differences between the Nama recombination map and the combined Phase II HapMap recombination map can impact the outcome of selection scans. CONCLUSIONS Fine-scale differences in recombination can meaningfully alter the results of a selection scan. The recombination map we infer likely represents an upper bound on the extent of divergence we expect to see for a recombination map in humans and would be of interest to any researcher that wants to test the sensitivity of population genetic or GWAS analysis to recombination map input.
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Affiliation(s)
- Gerald van Eeden
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
| | - Caitlin Uren
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
- Centre for Bioinformatics and Computational Biology, Stellenbosch University, Stellenbosch, 7602 South Africa
| | - Evlyn Pless
- Department of Anthropology, Center for Population Biology and the Genome Center, University of California (UC) Davis, Davis, CA USA
| | - Mira Mastoras
- Department of Anthropology, Center for Population Biology and the Genome Center, University of California (UC) Davis, Davis, CA USA
| | - Gian D. van der Spuy
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
- Centre for Bioinformatics and Computational Biology, Stellenbosch University, Stellenbosch, 7602 South Africa
- SAMRC-SHIP South African Tuberculosis Bioinformatics Initiative (SATBBI), Center for Bioinformatics and Computational Biology, Cape Town, South Africa
| | - Gerard Tromp
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
- Centre for Bioinformatics and Computational Biology, Stellenbosch University, Stellenbosch, 7602 South Africa
- SAMRC-SHIP South African Tuberculosis Bioinformatics Initiative (SATBBI), Center for Bioinformatics and Computational Biology, Cape Town, South Africa
| | - Brenna M. Henn
- Department of Anthropology, Center for Population Biology and the Genome Center, University of California (UC) Davis, Davis, CA USA
| | - Marlo Möller
- DSI-NRF Centre of Excellence for Biomedical Tuberculosis Research, South African Medical Research Council Centre for Tuberculosis Research, Division of Molecular Biology and Human Genetics, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa
- Centre for Bioinformatics and Computational Biology, Stellenbosch University, Stellenbosch, 7602 South Africa
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18
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Wilcox JJS, Arca-Ruibal B, Samour J, Mateuta V, Idaghdour Y, Boissinot S. Linked-Read Sequencing of Eight Falcons Reveals a Unique Genomic Architecture in Flux. Genome Biol Evol 2022; 14:evac090. [PMID: 35700227 PMCID: PMC9214253 DOI: 10.1093/gbe/evac090] [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: 11/12/2021] [Revised: 05/27/2022] [Accepted: 06/06/2022] [Indexed: 11/12/2022] Open
Abstract
Falcons are diverse birds of cultural and economic importance. They have undergone major lineage-specific chromosomal rearrangements, resulting in greatly-reduced chromosome counts relative to other birds. Here, we use 10X Genomics linked reads to provide new high-contiguity genomes for two gyrfalcons, a saker falcon, a lanner falcon, three subspecies of peregrine falcons, and the common kestrel. Assisted by a transcriptome sequenced from 22 gyrfalcon tissues, we annotate these genomes for a variety of genomic features, estimate historical demography, and then investigate genomic equilibrium in the context of falcon-specific chromosomal rearrangements. We find that falcon genomes are not in AT-GC equilibrium with a bias in substitutions towards higher AT content; this bias is predominantly but not exclusively driven by hypermutability of CpG sites. Small indels and large structural variants were also biased towards insertions rather than deletions. Patterns of disequilibrium were linked to chromosomal rearrangements: falcons have lost GC content in regions that have fused to larger chromosomes from microchromosomes and gained GC content in regions of macrochromosomes that have translocated to microchromosomes. Inserted bases have accumulated on regions ancestrally belonging to microchromosomes, consistent with insertion-biased gene conversion. We also find an excess of interspersed repeats on regions of microchromosomes that have fused to macrochromosomes. Our results reveal that falcon genomes are in a state of flux. They further suggest that many of the key differences between microchromosomes and macrochromosomes are driven by differences in chromosome size, and indicate a clear role for recombination and biased-gene-conversion in determining genomic equilibrium.
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Affiliation(s)
- Justin J S Wilcox
- Center for Genomics & Systems Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
| | | | - Jaime Samour
- Wildlife Management and Falcon Medicine and Breeding Consultancy, Abu Dhabi, United Arab Emirates
| | | | - Youssef Idaghdour
- Center for Genomics & Systems Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
- Biology Program, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
| | - Stéphane Boissinot
- Center for Genomics & Systems Biology, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
- Biology Program, New York University Abu Dhabi, Saadiyat Island, Abu Dhabi, United Arab Emirates
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19
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Population dynamics and genetic connectivity in recent chimpanzee history. CELL GENOMICS 2022; 2:None. [PMID: 35711737 PMCID: PMC9188271 DOI: 10.1016/j.xgen.2022.100133] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 12/29/2021] [Accepted: 04/15/2022] [Indexed: 11/22/2022]
Abstract
Knowledge on the population history of endangered species is critical for conservation, but whole-genome data on chimpanzees (Pan troglodytes) is geographically sparse. Here, we produced the first non-invasive geolocalized catalog of genomic diversity by capturing chromosome 21 from 828 non-invasive samples collected at 48 sampling sites across Africa. The four recognized subspecies show clear genetic differentiation correlating with known barriers, while previously undescribed genetic exchange suggests that these have been permeable on a local scale. We obtained a detailed reconstruction of population stratification and fine-scale patterns of isolation, migration, and connectivity, including a comprehensive picture of admixture with bonobos (Pan paniscus). Unlike humans, chimpanzees did not experience extended episodes of long-distance migrations, which might have limited cultural transmission. Finally, based on local rare variation, we implement a fine-grained geolocalization approach demonstrating improved precision in determining the origin of confiscated chimpanzees.
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20
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Johri P, Aquadro CF, Beaumont M, Charlesworth B, Excoffier L, Eyre-Walker A, Keightley PD, Lynch M, McVean G, Payseur BA, Pfeifer SP, Stephan W, Jensen JD. Recommendations for improving statistical inference in population genomics. PLoS Biol 2022; 20:e3001669. [PMID: 35639797 PMCID: PMC9154105 DOI: 10.1371/journal.pbio.3001669] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The field of population genomics has grown rapidly in response to the recent advent of affordable, large-scale sequencing technologies. As opposed to the situation during the majority of the 20th century, in which the development of theoretical and statistical population genetic insights outpaced the generation of data to which they could be applied, genomic data are now being produced at a far greater rate than they can be meaningfully analyzed and interpreted. With this wealth of data has come a tendency to focus on fitting specific (and often rather idiosyncratic) models to data, at the expense of a careful exploration of the range of possible underlying evolutionary processes. For example, the approach of directly investigating models of adaptive evolution in each newly sequenced population or species often neglects the fact that a thorough characterization of ubiquitous nonadaptive processes is a prerequisite for accurate inference. We here describe the perils of these tendencies, present our consensus views on current best practices in population genomic data analysis, and highlight areas of statistical inference and theory that are in need of further attention. Thereby, we argue for the importance of defining a biologically relevant baseline model tuned to the details of each new analysis, of skepticism and scrutiny in interpreting model fitting results, and of carefully defining addressable hypotheses and underlying uncertainties.
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Affiliation(s)
- Parul Johri
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Charles F. Aquadro
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Mark Beaumont
- School of Biological Sciences, University of Bristol, Bristol, United Kingdom
| | - Brian Charlesworth
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Laurent Excoffier
- Institute of Ecology and Evolution, University of Berne, Berne, Switzerland
| | - Adam Eyre-Walker
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Peter D. Keightley
- Institute of Ecology and Evolution, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Michael Lynch
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | - Gil McVean
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
| | - Bret A. Payseur
- Laboratory of Genetics, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
| | - Susanne P. Pfeifer
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
| | | | - Jeffrey D. Jensen
- School of Life Sciences, Arizona State University, Tempe, Arizona, United States of America
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21
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Wall JD, Robinson JA, Cox LA. High-Resolution Estimates of Crossover and Noncrossover Recombination from a Captive Baboon Colony. Genome Biol Evol 2022; 14:evac040. [PMID: 35325119 PMCID: PMC9048888 DOI: 10.1093/gbe/evac040] [Citation(s) in RCA: 6] [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] [Accepted: 03/02/2022] [Indexed: 11/17/2022] Open
Abstract
Homologous recombination has been extensively studied in humans and a handful of model organisms. Much less is known about recombination in other species, including nonhuman primates. Here, we present a study of crossovers (COs) and noncrossover (NCO) recombination in olive baboons (Papio anubis) from two pedigrees containing a total of 20 paternal and 17 maternal meioses, and compare these results to linkage disequilibrium (LD) based recombination estimates from 36 unrelated olive baboons. We demonstrate how COs, combined with LD-based recombination estimates, can be used to identify genome assembly errors. We also quantify sex-specific differences in recombination rates, including elevated male CO and reduced female CO rates near telomeres. Finally, we add to the increasing body of evidence suggesting that while most NCO recombination tracts in mammals are short (e.g., <500 bp), there is a non-negligible fraction of longer (e.g., >1 kb) NCO tracts. For NCO tracts shorter than 10 kb, we fit a mixture of two (truncated) geometric distributions model to the NCO tract length distribution and estimate that >99% of all NCO tracts are very short (mean 24 bp), but the remaining tracts can be quite long (mean 4.3 kb). A single geometric distribution model for NCO tract lengths is incompatible with the data, suggesting that LD-based methods for estimating NCO recombination rates that make this assumption may need to be modified.
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Affiliation(s)
- Jeffrey D. Wall
- Institute for Human Genetics, University of California San Francisco, USA
| | | | - Laura A. Cox
- Center for Precision Medicine, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, USA
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22
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Versoza CJ, Rivera JA, Rosenblum EB, Vital-García C, Hews DK, Pfeifer SP. The recombination landscapes of spiny lizards (genus Sceloporus). G3 (BETHESDA, MD.) 2022; 12:jkab402. [PMID: 34878100 PMCID: PMC9210290 DOI: 10.1093/g3journal/jkab402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 11/14/2021] [Indexed: 11/16/2022]
Abstract
Despite playing a critical role in evolutionary processes and outcomes, relatively little is known about rates of recombination in the vast majority of species, including squamate reptiles-the second largest order of extant vertebrates, many species of which serve as important model organisms in evolutionary and ecological studies. This paucity of data has resulted in limited resolution on questions related to the causes and consequences of rate variation between species and populations, the determinants of within-genome rate variation, as well as the general tempo of recombination rate evolution on this branch of the tree of life. In order to address these questions, it is thus necessary to begin broadening our phylogenetic sampling. We here provide the first fine-scale recombination maps for two species of spiny lizards, Sceloporus jarrovii and Sceloporus megalepidurus, which diverged at least 12 Mya. As might be expected from similarities in karyotype, population-scaled recombination landscapes are largely conserved on the broad-scale. At the same time, considerable variation exists at the fine-scale, highlighting the importance of incorporating species-specific recombination maps in future population genomic studies.
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Affiliation(s)
- Cyril J Versoza
- School of Life Sciences, Arizona State University, Tempe, AZ 85281, USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ 85281, USA
| | - Julio A Rivera
- School of Life Sciences, Arizona State University, Tempe, AZ 85281, USA
| | - Erica Bree Rosenblum
- Department of Environmental Science, Policy and Management, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Cuauhcihuatl Vital-García
- Departamento de Ciencias Veterinarias, Programa de Maestría en Ciencia Animal, Universidad Autónoma de Ciudad Juárez México, Chihuahua 32315, Mexico
| | - Diana K Hews
- Department of Biology, Indiana State University, Terre Haute, IN 47809, USA
| | - Susanne P Pfeifer
- School of Life Sciences, Arizona State University, Tempe, AZ 85281, USA
- Center for Evolution and Medicine, Arizona State University, Tempe, AZ 85281, USA
- Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85281, USA
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23
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Datta S, Patel M, Kashyap S, Patel D, Singh U. Chimeric chromosome landscapes of human somatic cell cultures show dependence on stress and regulation of genomic repeats by CGGBP1. Oncotarget 2022; 13:136-155. [PMID: 35070079 PMCID: PMC8765472 DOI: 10.18632/oncotarget.28174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Accepted: 12/20/2021] [Indexed: 11/25/2022] Open
Abstract
Genomes of somatic cells in culture are prone to spontaneous mutations due to errors in replication and DNA repair. Some of these errors, such as chromosomal fusions, are not rectifiable and subject to selection or elimination in growing cultures. Somatic cell cultures are thus expected to generate background levels of potentially stable chromosomal chimeras. A description of the landscape of such spontaneously generated chromosomal chimeras in cultured cells will help understand the factors affecting somatic mosaicism. Here we show that short homology-associated non-homologous chromosomal chimeras occur in normal human fibroblasts and HEK293T cells at genomic repeats. The occurrence of chromosomal chimeras is enhanced by heat stress and depletion of a repeat regulatory protein CGGBP1. We also present evidence of homologous chromosomal chimeras between allelic copies in repeat-rich DNA obtained by methylcytosine immunoprecipitation. The formation of homologous chromosomal chimeras at Alu and L1 repeats increases upon depletion of CGGBP1. Our data are derived from de novo sequencing from three different cell lines under different experimental conditions and our chromosomal chimera detection pipeline is applicable to long as well as short read sequencing platforms. These findings present significant information about the generation, sensitivity and regulation of somatic mosaicism in human cell cultures.
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Affiliation(s)
- Subhamoy Datta
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
| | - Manthan Patel
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
- Centre for Genomics and Child Health, Blizard Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London E1 2AD, UK
| | - Sukesh Kashyap
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
| | - Divyesh Patel
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
- Current address: Research Programs Unit, Applied Tumor Genomics Program, Faculty of Medicine, University of Helsinki, Biomedicum, Helsinki 00290, Finland
| | - Umashankar Singh
- HoMeCell Lab, Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gandhinagar, Gujarat 382355, India
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24
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PRDM9-directed recombination hotspots depleted near meiotically transcribed genes. Gene 2021; 813:146123. [PMID: 34952174 DOI: 10.1016/j.gene.2021.146123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Revised: 11/22/2021] [Accepted: 12/10/2021] [Indexed: 11/24/2022]
Abstract
PRDM9 drives recombination hotspots in some mammals, including mice and apes. Non-functional orthologs of PRDM9 are present in a wide variety of vertebrates, but why it is functionally maintained in some lineages is not clear. One possible explanation is that PRDM9 plays a role in ensuring that meiosis is successful. During meiosis, available DNA may be a limiting resource given the tight packaging of chromosomes and could lead to competition between two key processes: meiotic transcription and recombination. Here we explore this potential competition and the role that PRDM9 might play in their interaction. Leveraging existing mouse genomic data, we use resampling schemes that simulate shuffled features along the genome and models that account for the rarity of features in the genome, to test if PRDM9 influences interactions between recombination hotspots and meiotic transcription in a whole genome framework. We also explored possible DNA sequence motifs associated to clusters of hotspots not tied to transcription or PRDM9. We find evidence of competition between meiotic transcription and recombination, with PRDM9 appearing to relocate recombination to avoid said conflict. We also find that retrotransposons may be playing a role in directing hotspots in the absence of other factors.
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25
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Alleva B, Brick K, Pratto F, Huang M, Camerini-Otero RD. Cataloging Human PRDM9 Allelic Variation Using Long-Read Sequencing Reveals PRDM9 Population Specificity and Two Distinct Groupings of Related Alleles. Front Cell Dev Biol 2021; 9:675286. [PMID: 34805134 PMCID: PMC8600002 DOI: 10.3389/fcell.2021.675286] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 10/11/2021] [Indexed: 11/29/2022] Open
Abstract
The PRDM9 protein determines sites of meiotic recombination in humans by directing meiotic DNA double-strand breaks to specific loci. Targeting specificity is encoded by a long array of C2H2 zinc fingers that bind to DNA. This zinc finger array is hypervariable, and the resulting alleles each have a potentially different DNA binding preference. The assessment of PRDM9 diversity is important for understanding the complexity of human population genetics, inheritance linkage patterns, and predisposition to genetic disease. Due to the repetitive nature of the PRDM9 zinc finger array, the large-scale sequencing of human PRDM9 is challenging. We, therefore, developed a long-read sequencing strategy to infer the diploid PRDM9 zinc finger array genotype in a high-throughput manner. From an unbiased study of PRDM9 allelic diversity in 720 individuals from seven human populations, we detected 69 PRDM9 alleles. Several alleles differ in frequency among human populations, and 32 alleles had not been identified by previous studies, which were heavily biased to European populations. PRDM9 alleles are distinguished by their DNA binding site preferences and fall into two major categories related to the most common PRDM9-A and PRDM9-C alleles. We also found that it is likely that inter-conversion between allele types is rare. By mapping meiotic double-strand breaks (DSBs) in the testis, we found that small variations in PRDM9 can substantially alter the meiotic recombination landscape, demonstrating that minor PRDM9 variants may play an under-appreciated role in shaping patterns of human recombination. In summary, our data greatly expands knowledge of PRDM9 diversity in humans.
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Affiliation(s)
- Benjamin Alleva
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Kevin Brick
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Florencia Pratto
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Mini Huang
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Rafael Daniel Camerini-Otero
- Genetics and Biochemistry Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
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26
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Turbek SP, Semenov GA, Enbody ED, Campagna L, Taylor SA. Variable Signatures of Selection Despite Conserved Recombination Landscapes Early in Speciation. J Hered 2021; 112:485-496. [PMID: 34499149 DOI: 10.1093/jhered/esab054] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 09/08/2021] [Indexed: 11/14/2022] Open
Abstract
Recently diverged taxa often exhibit heterogeneous landscapes of genomic differentiation, characterized by regions of elevated differentiation on an otherwise homogeneous background. While divergence peaks are generally interpreted as regions responsible for reproductive isolation, they can also arise due to background selection, selective sweeps unrelated to speciation, and variation in recombination and mutation rates. To investigate the association between patterns of recombination and landscapes of genomic differentiation during the early stages of speciation, we generated fine-scale recombination maps for six southern capuchino seedeaters (Sporophila) and two subspecies of White Wagtail (Motacilla alba), two recent avian radiations in which divergent selection on pigmentation genes has likely generated peaks of differentiation. We compared these recombination maps to those of Collared (Ficedula albicollis) and Pied Flycatchers (Ficedula hypoleuca), non-sister taxa characterized by moderate genomic divergence and a heterogenous landscape of genomic differentiation shaped in part by background selection. Although recombination landscapes were conserved within all three systems, we documented a weaker negative correlation between recombination rate and genomic differentiation in the recent radiations. All divergence peaks between capuchinos, wagtails, and flycatchers were located in regions with lower-than-average recombination rates, and most divergence peaks in capuchinos and flycatchers fell in regions of exceptionally reduced recombination. Thus, co-adapted allelic combinations in these regions may have been protected early in divergence, facilitating rapid diversification. Despite largely conserved recombination landscapes, divergence peaks are specific to each focal comparison in capuchinos, suggesting that regions of elevated differentiation have not been generated by variation in recombination rate alone.
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Affiliation(s)
- Sheela P Turbek
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Georgy A Semenov
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
| | - Erik D Enbody
- Department of Medical Biochemistry and Microbiology, Uppsala University, Uppsala, Sweden
| | - Leonardo Campagna
- Fuller Evolutionary Biology Program, Cornell Lab of Ornithology, Ithaca, NY, USA.,Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
| | - Scott A Taylor
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO, USA
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27
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Huang YF. Dissecting genomic determinants of positive selection with an evolution-guided regression model. Mol Biol Evol 2021; 39:6379733. [PMID: 34597406 PMCID: PMC8763110 DOI: 10.1093/molbev/msab291] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
In evolutionary genomics, it is fundamentally important to understand how characteristics of genomic sequences, such as gene expression level, determine the rate of adaptive evolution. While numerous statistical methods, such as the McDonald–Kreitman (MK) test, are available to examine the association between genomic features and the rate of adaptation, we currently lack a statistical approach to disentangle the independent effect of a genomic feature from the effects of other correlated genomic features. To address this problem, I present a novel statistical model, the MK regression, which augments the MK test with a generalized linear model. Analogous to the classical multiple regression model, the MK regression can analyze multiple genomic features simultaneously to infer the independent effect of a genomic feature, holding constant all other genomic features. Using the MK regression, I identify numerous genomic features driving positive selection in chimpanzees. These features include well-known ones, such as local mutation rate, residue exposure level, tissue specificity, and immune genes, as well as new features not previously reported, such as gene expression level and metabolic genes. In particular, I show that highly expressed genes may have a higher adaptation rate than their weakly expressed counterparts, even though a higher expression level may impose stronger negative selection. Also, I show that metabolic genes may have a higher adaptation rate than their nonmetabolic counterparts, possibly due to recent changes in diet in primate evolution. Overall, the MK regression is a powerful approach to elucidate the genomic basis of adaptation.
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Affiliation(s)
- Yi-Fei Huang
- Department of Biology, Pennsylvania State University, University Park, PA, 16802, USA.,Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, 16802, USA
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28
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FISH and Chimps: Insights into Frequency and Distribution of Sperm Aneuploidy in Chimpanzees ( Pan troglodytes). Int J Mol Sci 2021; 22:ijms221910383. [PMID: 34638739 PMCID: PMC8509033 DOI: 10.3390/ijms221910383] [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: 09/02/2021] [Revised: 09/23/2021] [Accepted: 09/24/2021] [Indexed: 12/03/2022] Open
Abstract
Numerical chromosomal aberrations in sperm are considered to be a major factor in infertility, early pregnancy loss and syndromes with developmental and cognitive disabilities in mammals, including primates. Despite numerous studies in human and farm animals, the incidence and importance of sperm aneuploidies in non-human primate remains mostly undetermined. Here we investigated the incidence and distribution of sperm aneuploidy in chimpanzees (Pan troglodytes), the species closest to human. We identify evolutionary conserved DNA sequences in human and chimpanzee and selected homologous sub-telomeric regions for all chromosomes to build custom probes and perform sperm-FISH analysis on more than 10,000 sperm nuclei per chromosome. Chimpanzee mean autosomal disomy rate was 0.057 ± 0.02%, gonosomes disomy rate was 0.198% and the total disomy rate was 1.497%. The proportion of X or Y gametes was respectively 49.94% and 50.06% for a ratio of 1.002 and diploidy rate was 0.053%. Our data provide for the first time an overview of aneuploidy in non-human primate sperm and shed new insights into the issues of aneuploidy origins and mechanisms.
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29
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Neupane S, Xu S. Adaptive Divergence of Meiotic Recombination Rate in Ecological Speciation. Genome Biol Evol 2021; 12:1869-1881. [PMID: 32857858 PMCID: PMC7594247 DOI: 10.1093/gbe/evaa182] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2020] [Indexed: 02/06/2023] Open
Abstract
Theories predict that directional selection during adaptation to a novel habitat results in elevated meiotic recombination rate. Yet the lack of population-level recombination rate data leaves this hypothesis untested in natural populations. Here, we examine the population-level recombination rate variation in two incipient ecological species, the microcrustacean Daphnia pulex (an ephemeral-pond species) and Daphnia pulicaria (a permanent-lake species). The divergence of D. pulicaria from D. pulex involved habitat shifts from pond to lake habitats as well as strong local adaptation due to directional selection. Using a novel single-sperm genotyping approach, we estimated the male-specific recombination rate of two linkage groups in multiple populations of each species in common garden experiments and identified a significantly elevated recombination rate in D. pulicaria. Most importantly, population genetic analyses show that the divergence in recombination rate between these two species is most likely due to divergent selection in distinct ecological habitats rather than neutral evolution.
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Affiliation(s)
| | - Sen Xu
- Department of Biology, University of Texas at Arlington
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30
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Natural variation identifies SNI1, the SMC5/6 component, as a modifier of meiotic crossover in Arabidopsis. Proc Natl Acad Sci U S A 2021; 118:2021970118. [PMID: 34385313 PMCID: PMC8379953 DOI: 10.1073/pnas.2021970118] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Meiotic recombination plays a fundamental role in shaping genetic diversity in eukaryotes. Extensive variation in crossover rate exists between populations and species. The identity of modifier loci and their roles in genome evolution remain incompletely understood. We explored natural variation in Arabidopsis crossover and identified SNI1 as the causal gene underlying a major modifier locus. To date, SNI1 had no known role in crossover. SNI1 is a component of the SMC5/6 complex that is closely related to cohesin and condensin. Arabidopsis sni1 and other SMC5/6 mutants show similar effects on the interference-independent crossover pathway. Hence, our findings demonstrate that the SMC5/6 complex, which is known for its role in DNA damage repair, is also important for control of meiotic crossover. The frequency and distribution of meiotic crossovers are tightly controlled; however, variation in this process can be observed both within and between species. Using crosses of two natural Arabidopsis thaliana accessions, Col and Ler, we mapped a crossover modifier locus to semidominant polymorphisms in SUPPRESSOR OF NPR1-1 INDUCIBLE 1 (SNI1), which encodes a component of the SMC5/6 complex. The sni1 mutant exhibits a modified pattern of recombination across the genome with crossovers elevated in chromosome distal regions but reduced in pericentromeres. Mutations in SNI1 result in reduced crossover interference and can partially restore the fertility of a Class I crossover pathway mutant, which suggests that the protein affects noninterfering crossover repair. Therefore, we tested genetic interactions between SNI1 and both RECQ4 and FANCM DNA helicases, which showed that additional Class II crossovers observed in the sni1 mutant are FANCM independent. Furthermore, genetic analysis of other SMC5/6 mutants confirms the observations of crossover redistribution made for SNI1. The study reveals the importance of the SMC5/6 complex in ensuring the proper progress of meiotic recombination in plants.
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31
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Moran BM, Payne C, Langdon Q, Powell DL, Brandvain Y, Schumer M. The genomic consequences of hybridization. eLife 2021; 10:e69016. [PMID: 34346866 PMCID: PMC8337078 DOI: 10.7554/elife.69016] [Citation(s) in RCA: 94] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Accepted: 07/09/2021] [Indexed: 12/29/2022] Open
Abstract
In the past decade, advances in genome sequencing have allowed researchers to uncover the history of hybridization in diverse groups of species, including our own. Although the field has made impressive progress in documenting the extent of natural hybridization, both historical and recent, there are still many unanswered questions about its genetic and evolutionary consequences. Recent work has suggested that the outcomes of hybridization in the genome may be in part predictable, but many open questions about the nature of selection on hybrids and the biological variables that shape such selection have hampered progress in this area. We synthesize what is known about the mechanisms that drive changes in ancestry in the genome after hybridization, highlight major unresolved questions, and discuss their implications for the predictability of genome evolution after hybridization.
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Affiliation(s)
- Benjamin M Moran
- Department of Biology, Stanford UniversityStanfordUnited States
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”HidalgoMexico
| | - Cheyenne Payne
- Department of Biology, Stanford UniversityStanfordUnited States
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”HidalgoMexico
| | - Quinn Langdon
- Department of Biology, Stanford UniversityStanfordUnited States
| | - Daniel L Powell
- Department of Biology, Stanford UniversityStanfordUnited States
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”HidalgoMexico
| | - Yaniv Brandvain
- Department of Ecology, Evolution & Behavior and Plant and Microbial Biology, University of MinnesotaMinneapolisUnited States
| | - Molly Schumer
- Department of Biology, Stanford UniversityStanfordUnited States
- Centro de Investigaciones Científicas de las Huastecas “Aguazarca”HidalgoMexico
- Hanna H. Gray Fellow, Howard Hughes Medical InstituteStanfordUnited States
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32
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Bergman J, Schierup MH. Population dynamics of GC-changing mutations in humans and great apes. Genetics 2021; 218:6291657. [PMID: 34081117 DOI: 10.1093/genetics/iyab083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 05/27/2021] [Indexed: 11/14/2022] Open
Abstract
The nucleotide composition of the genome is a balance between origin and fixation rates of different mutations. For example, it is well-known that transitions occur more frequently than transversions, particularly at CpG sites. Differences in fixation rates of mutation types are less explored. Specifically, recombination-associated GC-biased gene conversion (gBGC) may differentially impact GC-changing mutations, due to differences in their genomic distributions and efficiency of mismatch repair mechanisms. Given that recombination evolves rapidly across species, we explore gBGC of different mutation types across human populations and great ape species. We report a stronger correlation between segregating GC frequency and recombination for transitions than for transversions. Notably, CpG transitions are most strongly affected by gBGC in humans and chimpanzees. We show that the overall strength of gBGC is generally correlated with effective population sizes in humans, with some notable exceptions, such as a stronger effect of gBGC on non-CpG transitions in populations of European descent. Furthermore, species of the Gorilla and Pongo genus have a greatly reduced gBGC effect on CpG sites. We also study the dependence of gBGC dynamics on flanking nucleotides and show that some mutation types evolve in opposition to the gBGC expectation, likely due to hypermutability of specific nucleotide contexts. Our results highlight the importance of different gBGC dynamics experienced by GC-changing mutations and their impact on nucleotide composition evolution.
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Affiliation(s)
- Juraj Bergman
- Bioinformatics Research Institute, Aarhus University, DK-8000 Aarhus C, Denmark
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33
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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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34
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Abstract
Despite its important biological role, the evolution of recombination rates remains relatively poorly characterized. This owes, in part, to the lack of high-quality genomic resources to address this question across diverse species. Humans and our closest evolutionary relatives, anthropoid apes, have remained a major focus of large-scale sequencing efforts, and thus recombination rate variation has been comparatively well studied in this group-with earlier work revealing a conservation at the broad- but not the fine-scale. However, in order to better understand the nature of this variation, and the time scales on which substantial modifications occur, it is necessary to take a broader phylogenetic perspective. I here present the first fine-scale genetic map for vervet monkeys based on whole-genome population genetic data from ten individuals and perform a series of comparative analyses with the great apes. The results reveal a number of striking features. First, owing to strong positive correlations with diversity and weak negative correlations with divergence, analyses suggest a dominant role for purifying and background selection in shaping patterns of variation in this species. Second, results support a generally reduced broad-scale recombination rate compared with the great apes, as well as a narrower fraction of the genome in which the majority of recombination events are observed to occur. Taken together, this data set highlights the great necessity of future research to identify genomic features and quantify evolutionary processes that are driving these rate changes across primates.
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Affiliation(s)
- Susanne P Pfeifer
- Center for Evolution and Medicine, School of Life Sciences, Arizona State University, Tempe, AZ
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35
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Heerschop S, Fagrouch Z, Verschoor EJ, Zischler H. Pinpointing the PRDM9-PRDM7 Gene Duplication Event During Primate Divergence. Front Genet 2021; 12:593725. [PMID: 33719332 PMCID: PMC7943923 DOI: 10.3389/fgene.2021.593725] [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: 08/11/2020] [Accepted: 02/01/2021] [Indexed: 12/03/2022] Open
Abstract
Studies on the function of PRDM9 in model systems and its evolution during vertebrate divergence shed light on the basic molecular mechanisms of hybrid sterility and its evolutionary consequences. However, information regarding PRDM9-homolog, PRDM7, whose origin is placed in the primate evolutionary tree, as well as information about the fast-evolving DNA-binding zinc finger array of strepsirrhine PRDM9 are scarce. Thus, we aimed to narrow down the date of the duplication event leading to the emergence of PRDM7 during primate evolution by comparing the phylogenetic tree reconstructions of representative primate samples of PRDM orthologs and paralogs. To confirm our PRDM7 paralogization pattern, database-deposited sequences were used to test the presence/absence patterns expected from the paralogization timing. In addition, we extended the existing phylogenetic tree of haplorrhine PRDM9 zinc fingers with their strepsirrhine counterparts. The inclusion of strepsirrhine zinc fingers completes the PRDM9 primate phylogeny. Moreover, the updated phylogeny of PRDM9 zinc fingers showed distinct clusters of strepsirrhine, tarsier, and anthropoid degenerated zinc fingers. Here, we show that PRDM7 emerged on the branch leading to the most recent common ancestor of catarrhines; therefore, its origin is more recent than previously expected. A more detailed character evolutionary study suggests that PRDM7 may have evolved differently in Cercopithecoidea as compared to Hominoidea: it lacks the first four exons in Old World monkeys orthologs and exon 10 in Papionini orthologs. Dating the origin of PRDM7 is essential for further studies investigating why Hominoidea representatives need another putative histone methyltransferase in the testis.
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Affiliation(s)
- Sacha Heerschop
- Division of Anthropology, Institute of Organismic and Molecular Evolution, Faculty of Biology, Johannes Gutenberg University Mainz, Mainz, Germany
| | - Zahra Fagrouch
- Department of Virology, Biomedical Primate Research Centre, Rijswijk, Netherlands
| | - Ernst J Verschoor
- Department of Virology, Biomedical Primate Research Centre, Rijswijk, Netherlands
| | - Hans Zischler
- Division of Anthropology, Institute of Organismic and Molecular Evolution, Faculty of Biology, Johannes Gutenberg University Mainz, Mainz, Germany
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36
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Petty LE, Phillippi-Falkenstein K, Kubisch HM, Raveendran M, Harris RA, Vallender EJ, Huff CD, Bohm RP, Rogers J, Below JE. Pedigree reconstruction and distant pairwise relatedness estimation from genome sequence data: A demonstration in a population of rhesus macaques (Macaca mulatta). Mol Ecol Resour 2021; 21:1333-1346. [PMID: 33386679 PMCID: PMC8247968 DOI: 10.1111/1755-0998.13317] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 11/13/2020] [Accepted: 12/07/2020] [Indexed: 12/30/2022]
Abstract
A primary challenge in the analysis of free‐ranging animal populations is the accurate estimation of relatedness among individuals. Many aspects of population analysis rely on knowledge of relatedness patterns, including socioecology, demography, heritability and gene mapping analyses, wildlife conservation and the management of breeding colonies. Methods for determining relatedness using genome‐wide data have improved our ability to determine kinship and reconstruct pedigrees in humans. However, methods for reconstructing complex pedigree structures and estimating distant relatedness (beyond third‐degree) have not been widely applied to other species. We sequenced the genomes of 150 male rhesus macaques from the Tulane National Primate Research Center colony to estimate pairwise relatedness, reconstruct closely related pedigrees, estimate more distant relationships and augment colony records. Methods for determining relatedness developed for human genetic data were applied and evaluated in the analysis of nonhuman primates, including identity‐by‐descent‐based methods for pedigree reconstruction and shared segment‐based inference of more distant relatedness. We compared the genotype‐based pedigrees and estimated relationships to available colony pedigree records and found high concordance (95.5% agreement) between expected and identified relationships for close relatives. In addition, we detected distant relationships not captured in colony records, including some as distant as twelfth‐degree. Furthermore, while deep sequence coverage is preferable, we show that this approach can also provide valuable information when only low‐coverage (5×) sequence data is available. Our findings demonstrate the value of these methods for determination of relatedness in various animal populations, with diverse applications to conservation biology, evolutionary and ecological research and biomedical studies.
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Affiliation(s)
- Lauren E Petty
- Vanderbilt Genetics Institute and Department of Genetic Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | | | - H Michael Kubisch
- Division of Veterinary Medicine, Tulane National Primate Research Center, Covington, LA, USA
| | - Muthuswamy Raveendran
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - R Alan Harris
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Eric J Vallender
- Division of Veterinary Medicine, Tulane National Primate Research Center, Covington, LA, USA.,Department of Psychiatry and Human Behavior, University of Mississippi Medical Center, Jackson, MS, USA
| | - Chad D Huff
- Department of Epidemiology, University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Rudolf P Bohm
- Division of Veterinary Medicine, Tulane National Primate Research Center, Covington, LA, USA
| | - Jeffrey Rogers
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Jennifer E Below
- Vanderbilt Genetics Institute and Department of Genetic Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
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37
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Abstract
The great apes play an important role as model organisms. They are our closest living relatives, allowing us to identify the genetic basis of phenotypic traits that we think of as characteristically human. However, the most significant asset of great apes as model organisms is that they share with humans most of their genetic makeup. This means that we can extend our vast knowledge of the human genome, its genes, and the associated phenotypes to these species. Comparative genomic studies of humans and apes thus reveal how very similar genomes react when exposed to different population genetic regimes. In this way, each species represents a natural experiment, where a genome highly similar to the human one, is differently exposed to the evolutionary forces of demography, population structure, selection, recombination, and admixture/hybridization. The initial sequencing of reference genomes for chimpanzee, orangutan, gorilla, the bonobo, each provided new insights and a second generation of sequencing projects has provided diversity data for all the great apes. In this chapter, we will outline some of the findings that population genomic analysis of great apes has provided, and how comparative studies have helped us understand how the fundamental forces in evolution have contributed to shaping the genomes and the genetic diversity of the great apes.
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Affiliation(s)
- David Castellano
- Bioinformatics and Genomics, Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology (BIST), Barcelona, Spain
| | - Kasper Munch
- Bioinformatics Research Centre, Aarhus University, Aarhus C, Denmark
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38
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Hassan S, Surakka I, Taskinen MR, Salomaa V, Palotie A, Wessman M, Tukiainen T, Pirinen M, Palta P, Ripatti S. High-resolution population-specific recombination rates and their effect on phasing and genotype imputation. Eur J Hum Genet 2020; 29:615-624. [PMID: 33249422 PMCID: PMC8114909 DOI: 10.1038/s41431-020-00768-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Revised: 10/01/2020] [Accepted: 10/20/2020] [Indexed: 11/24/2022] Open
Abstract
Previous research has shown that using population-specific reference panels has a significant effect on downstream population genomic analyses like haplotype phasing, genotype imputation, and association, especially in the context of population isolates. Here, we developed a high-resolution recombination rate mapping at 10 and 50 kb scale using high-coverage (20–30×) whole-genome sequenced data of 55 family trios from Finland and compared it to recombination rates of non-Finnish Europeans (NFE). We tested the downstream effects of the population-specific recombination rates in statistical phasing and genotype imputation in Finns as compared to the same analyses performed by using the NFE-based recombination rates. We found that Finnish recombination rates have a moderately high correlation (Spearman’s ρ = 0.67–0.79) with NFE, although on average (across all autosomal chromosomes), Finnish rates (2.268 ± 0.4209 cM/Mb) are 12–14% lower than NFE (2.641 ± 0.5032 cM/Mb). Finnish recombination map was found to have no significant effect in haplotype phasing accuracy (switch error rates ~2%) and average imputation concordance rates (97–98% for common, 92–96% for low frequency and 78–90% for rare variants). Our results suggest that haplotype phasing and genotype imputation mostly depend on population-specific contexts like appropriate reference panels and their sample size, but not on population-specific recombination maps. Even though recombination rate estimates had some differences between the Finnish and NFE populations, haplotyping and imputation had not been noticeably affected by the recombination map used. Therefore, the currently available HapMap recombination maps seem robust for population-specific phasing and imputation pipelines, even in the context of relatively isolated populations like Finland.
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Affiliation(s)
- Shabbeer Hassan
- Institute for Molecular Medicine Finland, FIMM, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Ida Surakka
- Institute for Molecular Medicine Finland, FIMM, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Marja-Riitta Taskinen
- Clinical and molecular metabolism, Research program unit, University of Helsinki, Helsinki, Finland
| | - Veikko Salomaa
- Finnish Institute for Health and Welfare, Helsinki, Finland
| | - Aarno Palotie
- Institute for Molecular Medicine Finland, FIMM, HiLIFE, University of Helsinki, Helsinki, Finland.,Massachusetts General Hospital & Harvard Medical School, Boston, MA, USA.,Broad Institute of the Massachusetts Institute of Technology and Harvard University, Cambridge, MA, USA
| | - Maija Wessman
- Institute for Molecular Medicine Finland, FIMM, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Taru Tukiainen
- Institute for Molecular Medicine Finland, FIMM, HiLIFE, University of Helsinki, Helsinki, Finland
| | - Matti Pirinen
- Institute for Molecular Medicine Finland, FIMM, HiLIFE, University of Helsinki, Helsinki, Finland.,Department of Public Health, Faculty of Medicine, Clinicum, University of Helsinki, Helsinki, Finland.,Department of Mathematics and Statistics, University of Helsinki, Helsinki, Finland
| | - Priit Palta
- Institute for Molecular Medicine Finland, FIMM, HiLIFE, University of Helsinki, Helsinki, Finland.,Estonian Genome Center, Institute of Genomics, University of Tartu, Tartu, Estonia
| | - Samuli Ripatti
- Institute for Molecular Medicine Finland, FIMM, HiLIFE, University of Helsinki, Helsinki, Finland. .,Broad Institute of the Massachusetts Institute of Technology and Harvard University, Cambridge, MA, USA. .,Department of Public Health, Faculty of Medicine, Clinicum, University of Helsinki, Helsinki, Finland.
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39
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Murphy WJ, Foley NM, Bredemeyer KR, Gatesy J, Springer MS. Phylogenomics and the Genetic Architecture of the Placental Mammal Radiation. Annu Rev Anim Biosci 2020; 9:29-53. [PMID: 33228377 DOI: 10.1146/annurev-animal-061220-023149] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The genomes of placental mammals are being sequenced at an unprecedented rate. Alignments of hundreds, and one day thousands, of genomes spanning the rich living and extinct diversity of species offer unparalleled power to resolve phylogenetic controversies, identify genomic innovations of adaptation, and dissect the genetic architecture of reproductive isolation. We highlight outstanding questions about the earliest phases of placental mammal diversification and the promise of newer methods, as well as remaining challenges, toward using whole genome data to resolve placental mammal phylogeny. The next phase of mammalian comparative genomics will see the completion and application of finished-quality, gapless genome assemblies from many ordinal lineages and closely related species. Interspecific comparisons between the most hypervariable genomic loci will likely reveal large, but heretofore mostly underappreciated, effects on population divergence, morphological innovation, and the origin of new species.
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Affiliation(s)
- William J Murphy
- Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA;
| | - Nicole M Foley
- Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA;
| | - Kevin R Bredemeyer
- Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77843, USA;
| | - John Gatesy
- Division of Vertebrate Zoology, American Museum of Natural History, New York, NY 10024, USA
| | - Mark S Springer
- Department of Evolution, Ecology and Organismal Biology, University of California, Riverside, California 92521, USA
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40
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Xue C, Rustagi N, Liu X, Raveendran M, Harris RA, Venkata MG, Rogers J, Yu F. Reduced meiotic recombination in rhesus macaques and the origin of the human recombination landscape. PLoS One 2020; 15:e0236285. [PMID: 32841250 PMCID: PMC7447010 DOI: 10.1371/journal.pone.0236285] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Accepted: 07/01/2020] [Indexed: 11/18/2022] Open
Abstract
Characterizing meiotic recombination rates across the genomes of nonhuman primates is important for understanding the genetics of primate populations, performing genetic analyses of phenotypic variation and reconstructing the evolution of human recombination. Rhesus macaques (Macaca mulatta) are the most widely used nonhuman primates in biomedical research. We constructed a high-resolution genetic map of the rhesus genome based on whole genome sequence data from Indian-origin rhesus macaques. The genetic markers used were approximately 18 million SNPs, with marker density 6.93 per kb across the autosomes. We report that the genome-wide recombination rate in rhesus macaques is significantly lower than rates observed in apes or humans, while the distribution of recombination across the macaque genome is more uniform. These observations provide new comparative information regarding the evolution of recombination in primates.
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Affiliation(s)
- Cheng Xue
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail: (FY); (JR); (CX)
| | - Navin Rustagi
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Xiaoming Liu
- USF Genomics & College of Public Health, University of South Florida, Tampa, Florida, United States of America
| | - Muthuswamy Raveendran
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - R. Alan Harris
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | | | - Jeffrey Rogers
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail: (FY); (JR); (CX)
| | - Fuli Yu
- Human Genome Sequencing Center and Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail: (FY); (JR); (CX)
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41
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Schwarzkopf EJ, Motamayor JC, Cornejo OE. Genetic differentiation and intrinsic genomic features explain variation in recombination hotspots among cocoa tree populations. BMC Genomics 2020; 21:332. [PMID: 32349675 PMCID: PMC7191684 DOI: 10.1186/s12864-020-6746-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 04/21/2020] [Indexed: 12/16/2022] Open
Abstract
Background Recombination plays an important evolutionary role by breaking up haplotypes and shuffling genetic variation. This process impacts the ability of selection to eliminate deleterious mutations or increase the frequency of beneficial mutations in a population. To understand the role of recombination generating and maintaining haplotypic variation in a population, we can construct fine-scale recombination maps. Such maps have been used to study a variety of model organisms and proven to be informative of how selection and demographics shape species-wide variation. Here we present a fine-scale recombination map for ten populations of Theobroma cacao – a non-model, long-lived, woody crop. We use this map to elucidate the dynamics of recombination rates in distinct populations of the same species, one of which is domesticated. Results Mean recombination rates in range between 2.5 and 8.6 cM/Mb for most populations of T. cacao with the exception of the domesticated Criollo (525 cM/Mb) and Guianna, a more recently established population (46.5 cM/Mb). We found little overlap in the location of hotspots of recombination across populations. We also found that hotspot regions contained fewer known retroelement sequences than expected and were overrepresented near transcription start and termination sites. We find mutations in FIGL-1, a protein shown to downregulate cross-over frequency in Arabidopsis, statistically associated to higher recombination rates in domesticated Criollo. Conclusions We generated fine-scale recombination maps for ten populations of Theobroma cacao and used them to understand what processes are associated with population-level variation in this species. Our results provide support to the hypothesis of increased recombination rates in domesticated plants (Criollo population). We propose a testable mechanistic hypothesis for the change in recombination rate in domesticated populations in the form of mutations to a previously identified recombination-suppressing protein. Finally, we establish a number of possible correlates of recombination hotspots that help explain general patterns of recombination in this species.
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Affiliation(s)
| | | | - Omar E Cornejo
- School of Biological Sciences, Washington State University, Pullman, WA, USA.
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42
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A High-Quality Genome Assembly from Short and Long Reads for the Non-biting Midge Chironomus riparius (Diptera). G3-GENES GENOMES GENETICS 2020; 10:1151-1157. [PMID: 32060047 PMCID: PMC7144091 DOI: 10.1534/g3.119.400710] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Chironomus riparius is of great importance as a study species in various fields like ecotoxicology, molecular genetics, developmental biology and ecology. However, only a fragmented draft genome exists to date, hindering the recent rush of population genomic studies in this species. Making use of 50 NGS datasets, we present a hybrid genome assembly from short and long sequence reads that make C. riparius’ genome one of the most contiguous Dipteran genomes published, the first complete mitochondrial genome of the species, and the respective recombination rate among the first insect recombination rates at all. The genome assembly and associated resources will be highly valuable to the broad community working with dipterans in general and chironomids in particular. The estimated recombination rate will help evolutionary biologists gaining a better understanding of commonalities and differences of genomic patterns in insects.
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43
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Fawcett JA, Innan H. The Role of Gene Conversion between Transposable Elements in Rewiring Regulatory Networks. Genome Biol Evol 2020; 11:1723-1729. [PMID: 31209488 PMCID: PMC6598467 DOI: 10.1093/gbe/evz124] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/11/2019] [Indexed: 12/23/2022] Open
Abstract
Nature has found many ways to utilize transposable elements (TEs) throughout evolution. Many molecular and cellular processes depend on DNA-binding proteins recognizing hundreds or thousands of similar DNA motifs dispersed throughout the genome that are often provided by TEs. It has been suggested that TEs play an important role in the evolution of such systems, in particular, the rewiring of gene regulatory networks. One mechanism that can further enhance the rewiring of regulatory networks is nonallelic gene conversion between copies of TEs. Here, we will first review evidence for nonallelic gene conversion in TEs. Then, we will illustrate the benefits nonallelic gene conversion provides in rewiring regulatory networks. For instance, nonallelic gene conversion between TE copies offers an alternative mechanism to spread beneficial mutations that improve the network, it allows multiple mutations to be combined and transferred together, and it allows natural selection to work efficiently in spreading beneficial mutations and removing disadvantageous mutations. Future studies examining the role of nonallelic gene conversion in the evolution of TEs should help us to better understand how TEs have contributed to evolution.
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44
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Albers PK, McVean G. Dating genomic variants and shared ancestry in population-scale sequencing data. PLoS Biol 2020; 18:e3000586. [PMID: 31951611 PMCID: PMC6992231 DOI: 10.1371/journal.pbio.3000586] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 01/30/2020] [Accepted: 01/02/2020] [Indexed: 12/31/2022] Open
Abstract
The origin and fate of new mutations within species is the fundamental process underlying evolution. However, while much attention has been focused on characterizing the presence, frequency, and phenotypic impact of genetic variation, the evolutionary histories of most variants are largely unexplored. We have developed a nonparametric approach for estimating the date of origin of genetic variants in large-scale sequencing data sets. The accuracy and robustness of the approach is demonstrated through simulation. Using data from two publicly available human genomic diversity resources, we estimated the age of more than 45 million single-nucleotide polymorphisms (SNPs) in the human genome and release the Atlas of Variant Age as a public online database. We characterize the relationship between variant age and frequency in different geographical regions and demonstrate the value of age information in interpreting variants of functional and selective importance. Finally, we use allele age estimates to power a rapid approach for inferring the ancestry shared between individual genomes and to quantify genealogical relationships at different points in the past, as well as to describe and explore the evolutionary history of modern human populations.
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Affiliation(s)
- Patrick K. Albers
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
- * E-mail:
| | - Gil McVean
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, United Kingdom
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45
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Dreissig S, Mascher M, Heckmann S. Variation in Recombination Rate Is Shaped by Domestication and Environmental Conditions in Barley. Mol Biol Evol 2020; 36:2029-2039. [PMID: 31209472 PMCID: PMC6736446 DOI: 10.1093/molbev/msz141] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Meiotic recombination generates genetic diversity upon which selection can act. Recombination rates are highly variable between species, populations, individuals, sexes, chromosomes, and chromosomal regions. The underlying mechanisms are controlled at the genetic and epigenetic level and show plasticity toward the environment. Environmental plasticity may be divided into short- and long-term responses. We estimated recombination rates in natural populations of wild barley and domesticated landraces using a population genetics approach. We analyzed recombination landscapes in wild barley and domesticated landraces at high resolution. In wild barley, high recombination rates are found in more interstitial chromosome regions in contrast to distal chromosome regions in domesticated barley. Among subpopulations of wild barley, natural variation in effective recombination rate is correlated with temperature, isothermality, and solar radiation in a nonlinear manner. A positive linear correlation was found between effective recombination rate and annual precipitation. We discuss our findings with respect to how the environment might shape effective recombination rates in natural populations. Higher recombination rates in wild barley populations subjected to specific environmental conditions could be a means to maintain fitness in a strictly inbreeding species.
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Affiliation(s)
- Steven Dreissig
- Meiosis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) OT Gatersleben, Seeland, Germany
| | - Martin Mascher
- Domestication Genomics Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) OT Gatersleben, Seeland, Germany.,German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Leipzig, Germany
| | - Stefan Heckmann
- Meiosis Research Group, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK) OT Gatersleben, Seeland, Germany
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46
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Li G, Figueiró HV, Eizirik E, Murphy WJ. Recombination-Aware Phylogenomics Reveals the Structured Genomic Landscape of Hybridizing Cat Species. Mol Biol Evol 2020; 36:2111-2126. [PMID: 31198971 PMCID: PMC6759079 DOI: 10.1093/molbev/msz139] [Citation(s) in RCA: 71] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Current phylogenomic approaches implicitly assume that the predominant phylogenetic signal within a genome reflects the true evolutionary history of organisms, without assessing the confounding effects of postspeciation gene flow that can produce a mosaic of phylogenetic signals that interact with recombinational variation. Here, we tested the validity of this assumption with a phylogenomic analysis of 27 species of the cat family, assessing local effects of recombination rate on species tree inference and divergence time estimation across their genomes. We found that the prevailing phylogenetic signal within the autosomes is not always representative of the most probable speciation history, due to ancient hybridization throughout felid evolution. Instead, phylogenetic signal was concentrated within regions of low recombination, and notably enriched within large X chromosome recombination cold spots that exhibited recurrent patterns of strong genetic differentiation and selective sweeps across mammalian orders. By contrast, regions of high recombination were enriched for signatures of ancient gene flow, and these sequences inflated crown-lineage divergence times by ∼40%. We conclude that existing phylogenomic approaches to infer the Tree of Life may be highly misleading without considering the genomic architecture of phylogenetic signal relative to recombination rate and its interplay with historical hybridization.
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Affiliation(s)
- Gang Li
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
| | - Henrique V Figueiró
- PUCRS, Escola de Ciências, Laboratory of Genomics and Molecular Biology, Porto Alegre, Brazil.,INCT-EECBio, Brazil
| | - Eduardo Eizirik
- PUCRS, Escola de Ciências, Laboratory of Genomics and Molecular Biology, Porto Alegre, Brazil.,INCT-EECBio, Brazil
| | - William J Murphy
- Veterinary Integrative Biosciences, Texas A&M University, College Station, TX
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47
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Castellano D, Eyre-Walker A, Munch K. Impact of Mutation Rate and Selection at Linked Sites on DNA Variation across the Genomes of Humans and Other Homininae. Genome Biol Evol 2020; 12:3550-3561. [PMID: 31596481 PMCID: PMC6944223 DOI: 10.1093/gbe/evz215] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/03/2019] [Indexed: 12/23/2022] Open
Abstract
DNA diversity varies across the genome of many species. Variation in diversity across a genome might arise from regional variation in the mutation rate, variation in the intensity and mode of natural selection, and regional variation in the recombination rate. We show that both noncoding and nonsynonymous diversity are positively correlated to a measure of the mutation rate and the recombination rate and negatively correlated to the density of conserved sequences in 50 kb windows across the genomes of humans and nonhuman homininae. Interestingly, we find that although noncoding diversity is equally affected by these three genomic variables, nonsynonymous diversity is mostly dominated by the density of conserved sequences. The positive correlation between diversity and our measure of the mutation rate seems to be largely a direct consequence of regions with higher mutation rates having more diversity. However, the positive correlation with recombination rate and the negative correlation with the density of conserved sequences suggest that selection at linked sites also affect levels of diversity. This is supported by the observation that the ratio of the number of nonsynonymous to noncoding polymorphisms is negatively correlated to a measure of the effective population size across the genome. We show these patterns persist even when we restrict our analysis to GC-conservative mutations, demonstrating that the patterns are not driven by GC biased gene conversion. In conclusion, our comparative analyses describe how recombination rate, gene density, and mutation rate interact to produce the patterns of DNA diversity that we observe along the hominine genomes.
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Affiliation(s)
- David Castellano
- Bioinformatics Research Centre, Aarhus University, Denmark
- Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Dr Aiguader 88, Barcelona, Spain
| | - Adam Eyre-Walker
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Kasper Munch
- Bioinformatics Research Centre, Aarhus University, Denmark
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48
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Luo X, Xu L, Wang Y, Dong J, Chen Y, Tang M, Fan L, Zhu Y, Liu L. An ultra-high-density genetic map provides insights into genome synteny, recombination landscape and taproot skin colour in radish (Raphanus sativus L.). PLANT BIOTECHNOLOGY JOURNAL 2020; 18:274-286. [PMID: 31218798 PMCID: PMC6920339 DOI: 10.1111/pbi.13195] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Revised: 05/30/2019] [Accepted: 06/11/2019] [Indexed: 05/19/2023]
Abstract
High-density genetic map is a valuable tool for exploring novel genomic information, quantitative trait locus (QTL) mapping and gene discovery of economically agronomic traits in plant species. However, high-resolution genetic map applied to tag QTLs associated with important traits and to investigate genomic features underlying recombination landscape in radish (Raphanus sativus) remains largely unexplored. In this study, an ultra-high-density genetic map with 378 738 SNPs covering 1306.8 cM in nine radish linkage groups (LGs) was developed by a whole-genome sequencing-based approach. A total of 18 QTLs for 11 horticulture traits were detected. The map-based cloning data indicated that the R2R3-MYB transcription factor RsMYB90 was a crucial candidate gene determining the taproot skin colour. Comparative genomics analysis among radish, Brassica rapa and B. oleracea genome revealed several genomic rearrangements existed in the radish genome. The highly uneven distribution of recombination was observed across the nine radish chromosomes. Totally, 504 recombination hot regions (RHRs) were enriched near gene promoters and terminators. The recombination rate in RHRs was positively correlated with the density of SNPs and gene, and GC content, respectively. Functional annotation indicated that genes within RHRs were mainly involved in metabolic process and binding. Three QTLs for three traits were found in the RHRs. The results provide novel insights into the radish genome evolution and recombination landscape, and facilitate the development of effective strategies for molecular breeding by targeting and dissecting important traits in radish.
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Affiliation(s)
- Xiaobo Luo
- National Key Laboratory of Crop Genetics and Germplasm EnhancementKey Laboratory of Horticultural Crop Biology and Genetic Improvement (East China) of MOA, College of HorticultureNanjing Agricultural UniversityNanjingChina
- Guizhou Institute of BiotechnologyGuizhou Academy of Agricultural SciencesGuiyangChina
| | | | - Yan Wang
- National Key Laboratory of Crop Genetics and Germplasm EnhancementKey Laboratory of Horticultural Crop Biology and Genetic Improvement (East China) of MOA, College of HorticultureNanjing Agricultural UniversityNanjingChina
| | - Junhui Dong
- National Key Laboratory of Crop Genetics and Germplasm EnhancementKey Laboratory of Horticultural Crop Biology and Genetic Improvement (East China) of MOA, College of HorticultureNanjing Agricultural UniversityNanjingChina
| | - Yinglong Chen
- The UWA Institute of Agriculture, and School of Agriculture and EnvironmentThe University of Western AustraliaPerthWAAustralia
| | - Mingjia Tang
- National Key Laboratory of Crop Genetics and Germplasm EnhancementKey Laboratory of Horticultural Crop Biology and Genetic Improvement (East China) of MOA, College of HorticultureNanjing Agricultural UniversityNanjingChina
| | - Lianxue Fan
- National Key Laboratory of Crop Genetics and Germplasm EnhancementKey Laboratory of Horticultural Crop Biology and Genetic Improvement (East China) of MOA, College of HorticultureNanjing Agricultural UniversityNanjingChina
| | - Yuelin Zhu
- National Key Laboratory of Crop Genetics and Germplasm EnhancementKey Laboratory of Horticultural Crop Biology and Genetic Improvement (East China) of MOA, College of HorticultureNanjing Agricultural UniversityNanjingChina
| | - Liwang Liu
- National Key Laboratory of Crop Genetics and Germplasm EnhancementKey Laboratory of Horticultural Crop Biology and Genetic Improvement (East China) of MOA, College of HorticultureNanjing Agricultural UniversityNanjingChina
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49
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Schmidt JM, de Manuel M, Marques-Bonet T, Castellano S, Andrés AM. The impact of genetic adaptation on chimpanzee subspecies differentiation. PLoS Genet 2019; 15:e1008485. [PMID: 31765391 PMCID: PMC6901233 DOI: 10.1371/journal.pgen.1008485] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2019] [Revised: 12/09/2019] [Accepted: 10/17/2019] [Indexed: 12/25/2022] Open
Abstract
Chimpanzees, humans' closest relatives, are in danger of extinction. Aside from direct human impacts such as hunting and habitat destruction, a key threat is transmissible disease. As humans continue to encroach upon their habitats, which shrink in size and grow in density, the risk of inter-population and cross-species viral transmission increases, a point dramatically made in the reverse with the global HIV/AIDS pandemic. Inhabiting central Africa, the four subspecies of chimpanzees differ in demographic history and geographical range, and are likely differentially adapted to their particular local environments. To quantitatively explore genetic adaptation, we investigated the genic enrichment for SNPs highly differentiated between chimpanzee subspecies. Previous analyses of such patterns in human populations exhibited limited evidence of adaptation. In contrast, chimpanzees show evidence of recent positive selection, with differences among subspecies. Specifically, we observe strong evidence of recent selection in eastern chimpanzees, with highly differentiated SNPs being uniquely enriched in genic sites in a way that is expected under recent adaptation but not under neutral evolution or background selection. These sites are enriched for genes involved in immune responses to pathogens, and for genes inferred to differentiate the immune response to infection by simian immunodeficiency virus (SIV) in natural vs. non-natural host species. Conversely, central chimpanzees exhibit an enrichment of signatures of positive selection only at cytokine receptors, due to selective sweeps in CCR3, CCR9 and CXCR6 -paralogs of CCR5 and CXCR4, the two major receptors utilized by HIV to enter human cells. Thus, our results suggest that positive selection has contributed to the genetic and phenotypic differentiation of chimpanzee subspecies, and that viruses likely play a predominate role in this differentiation, with SIV being a likely selective agent. Interestingly, our results suggest that SIV has elicited distinctive adaptive responses in these two chimpanzee subspecies.
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MESH Headings
- Adaptation, Physiological/genetics
- Adaptation, Physiological/immunology
- Animals
- Demography
- Genetic Drift
- Genetic Speciation
- HIV/genetics
- HIV/immunology
- HIV/pathogenicity
- Humans
- Immunity, Innate/genetics
- Pan troglodytes/genetics
- Pan troglodytes/immunology
- Pan troglodytes/virology
- Polymorphism, Single Nucleotide/genetics
- Receptors, CCR/genetics
- Receptors, CCR3/genetics
- Receptors, CCR5/genetics
- Receptors, CXCR4/genetics
- Receptors, CXCR6/immunology
- Selection, Genetic/genetics
- Simian Immunodeficiency Virus/genetics
- Simian Immunodeficiency Virus/immunology
- Simian Immunodeficiency Virus/pathogenicity
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Affiliation(s)
- Joshua M. Schmidt
- UCL Genetics Institute, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- Max Planck Institute for Evolutionary Anthropology, Department of Evolutionary Genetics, Leipzig, Germany
- * E-mail: (JMS); (AMA)
| | - Marc de Manuel
- Institut de Biologia Evolutiva (Consejo Superior de Investigaciones Científicas–Universitat Pompeu Fabra), Barcelona, Spain
| | - Tomas Marques-Bonet
- Institut de Biologia Evolutiva (Consejo Superior de Investigaciones Científicas–Universitat Pompeu Fabra), Barcelona, Spain
- National Centre for Genomic Analysis–Centre for Genomic Regulation, Barcelona Institute of Science and Technology, Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Sergi Castellano
- Max Planck Institute for Evolutionary Anthropology, Department of Evolutionary Genetics, Leipzig, Germany
- Genetics and Genomic Medicine Programme, Great Ormond Street Institute of Child Health, University College London (UCL), London, United Kingdom
- UCL Genomics, London, United Kingdom
| | - Aida M. Andrés
- UCL Genetics Institute, Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
- Max Planck Institute for Evolutionary Anthropology, Department of Evolutionary Genetics, Leipzig, Germany
- * E-mail: (JMS); (AMA)
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Mouresan EF, González-Rodríguez A, Cañas-Álvarez JJ, Munilla S, Altarriba J, Díaz C, Baró JA, Molina A, Lopez-Buesa P, Piedrafita J, Varona L. Mapping Recombination Rate on the Autosomal Chromosomes Based on the Persistency of Linkage Disequilibrium Phase Among Autochthonous Beef Cattle Populations in Spain. Front Genet 2019; 10:1170. [PMID: 31824571 PMCID: PMC6880760 DOI: 10.3389/fgene.2019.01170] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 10/23/2019] [Indexed: 01/14/2023] Open
Abstract
In organisms with sexual reproduction, genetic diversity, and genome evolution are governed by meiotic recombination caused by crossing-over, which is known to vary within the genome. In this study, we propose a simple method to estimate the recombination rate that makes use of the persistency of linkage disequilibrium (LD) phase among closely related populations. The biological material comprised 171 triplets (sire/dam/offspring) from seven populations of autochthonous beef cattle in Spain (Asturiana de los Valles, Avileña-Negra Ibérica, Bruna dels Pirineus, Morucha, Pirenaica, Retinta, and Rubia Gallega), which were genotyped for 777,962 SNPs with the BovineHD BeadChip. After standard quality filtering, we reconstructed the haplotype phases in the parental individuals and calculated the LD by the correlation -r- between each pair of markers that had a genetic distance < 1 Mb. Subsequently, these correlations were used to calculate the persistency of LD phase between each pair of populations along the autosomal genome. Therefore, the distribution of the recombination rate along the genome can be inferred since the effect of the number of generations of divergence should be equivalent throughout the genome. In our study, the recombination rate was highest in the largest chromosomes and at the distal portion of the chromosomes. In addition, the persistency of LD phase was highly heterogeneous throughout the genome, with a ratio of 25.4 times between the estimates of the recombination rates from the genomic regions that had the highest (BTA18-7.1 Mb) and the lowest (BTA12-42.4 Mb) estimates. Finally, an overrepresentation enrichment analysis (ORA) showed differences in the enriched gene ontology (GO) terms between the genes located in the genomic regions with estimates of the recombination rate over (or below) the 95th (or 5th) percentile throughout the autosomal genome.
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Affiliation(s)
- Elena Flavia Mouresan
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain
| | | | | | - Sebastián Munilla
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain.,Departamento de Producción Animal, Facultad de Agronomía, Universidad de Buenos Aires, CONICET, Buenos Aires, Argentina
| | - Juan Altarriba
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain
| | - Clara Díaz
- Departamento de Mejora Genética Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Madrid, Spain
| | - Jesús A Baró
- Instituto Agroalimentario de Aragón (IA2), Zaragoza, Spain
| | - Antonio Molina
- Departamento de Ciencias Agroforestales, Universidad de Valladolid, Valladolid, Spain
| | - Pascual Lopez-Buesa
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain
| | - Jesús Piedrafita
- Departament de Ciència Animal i dels Aliments, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Luis Varona
- Departamento de Anatomía, Embriología y Genética Animal, Universidad de Zaragoza, Zaragoza, Spain
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