1
|
Murray CS, Karram M, Bass DJ, Doceti M, Becker D, Nunez JCB, Ratan A, Bergland AO. Balancing selection and the functional effects of shared polymorphism in cryptic Daphnia species. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.16.589693. [PMID: 38659826 PMCID: PMC11042267 DOI: 10.1101/2024.04.16.589693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
The patterns of genetic variation within and between related taxa represent the genetic history of a species. Shared polymorphisms, loci with identical alleles across species, are of unique interest as they may represent cases of ancient selection maintaining functional variation post-speciation. In this study, we investigate the abundance of shared polymorphism in the Daphnia pulex species complex. We test whether shared mutations are consistent with the action of balancing selection or alternative hypotheses such as hybridization, incomplete lineage sorting, or convergent evolution. We analyzed over 2,000 genomes from North American and European D. pulex and several outgroup species to examine the prevalence and distribution of shared alleles between the focal species pair, North American and European D. pulex. We show that while North American and European D. pulex diverged over ten million years ago, they retained tens of thousands of shared alleles. We found that the number of shared polymorphisms between North American and European D. pulex cannot be explained by hybridization or incomplete lineage sorting alone. Instead, we show that most shared polymorphisms could be the product of convergent evolution, that a limited number appear to be old trans-specific polymorphisms, and that balancing selection is affecting young and ancient mutations alike. Finally, we provide evidence that a blue wavelength opsin gene with trans-specific polymorphisms has functional effects on behavior and fitness in the wild. Ultimately, our findings provide insights into the genetic basis of adaptation and the maintenance of genetic diversity between species.
Collapse
Affiliation(s)
- Connor S. Murray
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Madison Karram
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - David J. Bass
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Madison Doceti
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Dörthe Becker
- Department of Biology, University of Virginia, Charlottesville, VA, USA
- School of Biosciences, Ecology and Evolutionary Biology, University of Sheffield, Sheffield, UK
| | | | - Aakrosh Ratan
- Center of Public Health Genomics, University of Virginia, Charlottesville, VA, USA
- Department of Public Health Sciences, University of Virginia, Charlottesville, VA, USA
| | - Alan O. Bergland
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| |
Collapse
|
2
|
Flynn JM, Yamashita YM. The implications of satellite DNA instability on cellular function and evolution. Semin Cell Dev Biol 2024; 156:152-159. [PMID: 37852904 DOI: 10.1016/j.semcdb.2023.10.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 09/21/2023] [Accepted: 10/11/2023] [Indexed: 10/20/2023]
Abstract
Abundant tandemly repeated satellite DNA is present in most eukaryotic genomes. Previous limitations including a pervasive view that it was uninteresting junk DNA, combined with challenges in studying it, are starting to dissolve - and recent studies have found important functions for satellite DNAs. The observed rapid evolution and implied instability of satellite DNA now has important significance for their functions and maintenance within the genome. In this review, we discuss the processes that lead to satellite DNA copy number instability, and the importance of mechanisms to manage the potential negative effects of instability. Satellite DNA is vulnerable to challenges during replication and repair, since it forms difficult-to-process secondary structures and its homology within tandem arrays can result in various types of recombination. Satellite DNA instability may be managed by DNA or chromatin-binding proteins ensuring proper nuclear localization and repair, or by proteins that process aberrant structures that satellite DNAs tend to form. We also discuss the pattern of satellite DNA mutations from recent mutation accumulation (MA) studies that have tracked changes in satellite DNA for up to 1000 generations with minimal selection. Finally, we highlight examples of satellite evolution from studies that have characterized satellites across millions of years of Drosophila fruit fly evolution, and discuss possible ways that selection might act on the satellite DNA composition.
Collapse
Affiliation(s)
- Jullien M Flynn
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA; Howard Hughes Medical Institute, Cambridge, MA, USA.
| | - Yukiko M Yamashita
- Whitehead Institute for Biomedical Research, Cambridge, MA, USA; Howard Hughes Medical Institute, Cambridge, MA, USA; Massachusetts Institute of Technology, Cambridge, MA, USA.
| |
Collapse
|
3
|
Xu S, Neupane S, Wang H, Pham TP, Snyman M, Huynh TV, Wang L. Efficient CRISPR genome editing and integrative genomic analyses reveal the mosaicism of Cas-induced mutations and pleiotropic effects of scarlet gene in an emerging model system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.29.577787. [PMID: 38352317 PMCID: PMC10862705 DOI: 10.1101/2024.01.29.577787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/22/2024]
Abstract
Despite the revolutionary impacts of CRISPR-Cas gene editing systems, the effective and widespread use of CRISPR technologies in emerging model organisms still faces significant challenges. These include the inefficiency in generating heritable mutations at the organismal level, limited knowledge about the genomic consequences of gene editing, and an inadequate understanding of the inheritance patterns of CRISPR-Cas-induced mutations. This study addresses these issues by 1) developing an efficient microinjection delivery method for CRISPR editing in the microcrustacean Daphnia pulex; 2) assessing the editing efficiency of Cas9 and Cas12a nucleases, examining mutation inheritance patterns, and analyzing the local and global mutation spectrum in the scarlet mutants; and 3) investigating the transcriptomes of scarlet mutants to understand the pleiotropic effects of scarlet underlying their swimming behavior changes. Our reengineered CRISPR microinjection method results in efficient biallelic editing with both nucleases. While indels are dominant in Cas-induced mutations, a few on-site large deletions (>1kb) are observed, most likely caused by microhomology-mediated end joining repair. Knock-in of a stop codon cassette to the scarlet locus was successful, despite complex induced mutations surrounding the target site. Moreover, extensive germline mosaicism exists in some mutants, which unexpectedly produce different phenotypes/genotypes in their asexual progenies. Lastly, our transcriptomic analyses unveil significant gene expression changes associated with scarlet knock-out and altered swimming behavior in mutants, including several genes (e.g., NMDA1, ABAT, CNTNAP2) involved in human neurodegenerative diseases. This study expands our understanding of the dynamics of gene editing in the tractable model organism Daphnia and highlights its promising potential as a neurological disease model.
Collapse
Affiliation(s)
- Sen Xu
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, 65211, USA
| | - Swatantra Neupane
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, 65211, USA
| | - Hongjun Wang
- Department of Biology, University of Texas at Arlington, Arlington, Texas, 76019, USA
| | - Thinh Phu Pham
- Department of Biology, University of Texas at Arlington, Arlington, Texas, 76019, USA
| | - Marelize Snyman
- Department of Biology, University of Texas at Arlington, Arlington, Texas, 76019, USA
| | - Trung V. Huynh
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, 65211, USA
| | - Li Wang
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, 65211, USA
| |
Collapse
|
4
|
Legrand C, Andriantsoa R, Lichter P, Raddatz G, Lyko F. Time-resolved, integrated analysis of clonally evolving genomes. PLoS Genet 2023; 19:e1011085. [PMID: 38096267 PMCID: PMC10754456 DOI: 10.1371/journal.pgen.1011085] [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: 03/27/2023] [Revised: 12/28/2023] [Accepted: 11/27/2023] [Indexed: 12/29/2023] Open
Abstract
Clonal genome evolution is a key feature of asexually reproducing species and human cancer development. While many studies have described the landscapes of clonal genome evolution in cancer, few determine the underlying evolutionary parameters from molecular data, and even fewer integrate theory with data. We derived theoretical results linking mutation rate, time, expansion dynamics, and biological/clinical parameters. Subsequently, we inferred time-resolved estimates of evolutionary parameters from mutation accumulation, mutational signatures and selection. We then applied this framework to predict the time of speciation of the marbled crayfish, an enigmatic, globally invasive parthenogenetic freshwater crayfish. The results predict that speciation occurred between 1986 and 1990, which is consistent with biological records. We also used our framework to analyze whole-genome sequencing datasets from primary and relapsed glioblastoma, an aggressive brain tumor. The results identified evolutionary subgroups and showed that tumor cell survival could be inferred from genomic data that was generated during the resection of the primary tumor. In conclusion, our framework allowed a time-resolved, integrated analysis of key parameters in clonally evolving genomes, and provided novel insights into the evolutionary age of marbled crayfish and the progression of glioblastoma.
Collapse
Affiliation(s)
- Carine Legrand
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Heidelberg, Germany
- Université Paris Cité, Génomes, biologie cellulaire et thérapeutique U944, INSERM, CNRS, Paris, France
| | - Ranja Andriantsoa
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Heidelberg, Germany
| | - Peter Lichter
- Division of Molecular Genetics, German Cancer Research Consortium (DKTK), German Cancer Research Center (DKFZ), Heidelberg, Germany
- Molecular Precision Oncology, National Center for Tumor Diseases, Heidelberg, Germany
| | - Günter Raddatz
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Heidelberg, Germany
| | - Frank Lyko
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Heidelberg, Germany
| |
Collapse
|
5
|
Miller CL, Sun D, Thornton LH, McGuigan K. The Contribution of Mutation to Variation in Temperature-Dependent Sprint Speed in Zebrafish, Danio rerio. Am Nat 2023; 202:519-533. [PMID: 37792923 DOI: 10.1086/726011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/06/2023]
Abstract
AbstractThe contribution of new mutations to phenotypic variation and the consequences of this variation for individual fitness are fundamental concepts for understanding genetic variation and adaptation. Here, we investigated how mutation influenced variation in a complex trait in zebrafish, Danio rerio. Typical of many ecologically relevant traits in ectotherms, swimming speed in fish is temperature dependent, with evidence of adaptive evolution of thermal performance. We chemically induced novel germline point mutations in males and measured sprint speed in their sons at six temperatures (between 16°C and 34°C). Heterozygous mutational effects on speed were strongly positively correlated among temperatures, resulting in statistical support for only a single axis of mutational variation, reflecting temperature-independent variation in speed (faster-slower mode). These results suggest pleiotropic effects on speed across different temperatures; however, spurious correlations arise via linkage or heterogeneity in mutation number when mutations have consistent directional effects on each trait. Here, mutation did not change mean speed, indicating no directional bias in mutational effects. The results contribute to emerging evidence that mutations may predominantly have synergistic cross-environment effects, in contrast to conditionally neutral or antagonistic effects that underpin thermal adaptation. We discuss several aspects of experimental design that may affect resolution of mutations with nonsynergistic effects.
Collapse
|
6
|
Molinier C, Lenormand T, Haag CR. No recombination suppression in asexually produced males of Daphnia pulex. Evolution 2023; 77:1987-1999. [PMID: 37345677 DOI: 10.1093/evolut/qpad114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 05/26/2023] [Accepted: 06/20/2023] [Indexed: 06/23/2023]
Abstract
Obligate parthenogenesis (OP) is often thought to evolve by disruption of reductional meiosis and suppression of crossover recombination. In the crustacean Daphnia pulex, OP lineages, which have evolved from cyclical parthenogenetic (CP) ancestors, occasionally produce males that are capable of reductional meiosis. Here, by constructing high-density linkage maps, we find that these males show only slightly and nonsignificantly reduced recombination rates compared to CP males and females. Both meiosis disruption and recombination suppression are therefore sex-limited (or partly so), which speaks against the evolution of OP by disruption of a gene that is essential for meiosis or recombination in both sexes. The findings may be explained by female-limited action of genes that suppress recombination, but previously identified candidate genes are known to be expressed in both sexes. Alternatively, and equally consistent with the data, OP might have evolved through a reuse of the parthenogenesis pathways already present in CP and through their extension to all events of oogenesis. The causal mutations for the CP to OP transition may therefore include mutations in genes involved in oogenesis regulation and may not necessarily be restricted to genes of the "meiosis toolkit." More generally, our study emphasizes that there are many ways to achieve asexuality, and elucidating the possible mechanisms is key to ultimately identify the genes and traits involved.
Collapse
Affiliation(s)
- Cécile Molinier
- CEFE, Univ Montpellier, CNRS, EPHE, IRD, Montpellier, France
- Department of Algal Development and Evolution, Max Planck Institute for Biology, Tuebingen, Germany
| | | | | |
Collapse
|
7
|
Sato DX, Matsuda Y, Usio N, Funayama R, Nakayama K, Makino T. Genomic adaptive potential to cold environments in the invasive red swamp crayfish. iScience 2023; 26:107267. [PMID: 37520695 PMCID: PMC10371857 DOI: 10.1016/j.isci.2023.107267] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 05/31/2023] [Accepted: 06/28/2023] [Indexed: 08/01/2023] Open
Abstract
Biological invasion refers to the introduction, spread, and establishment of non-native species in a novel habitat. The ways in which invasive species successfully colonize new and different environments remain a fundamental topic of research in ecology and evolutionary biology. Here, we investigated the genomic and transcriptomic characteristics of the red swamp crayfish (Procambarus clarkii), a widespread invader in freshwater environments. Targeting a recently colonized population in Sapporo, Japan that appears to have acquired a high degree of cold tolerance, RNA-seq analysis revealed differentially expressed genes in response to cold exposure, and those involved in protease inhibitors and cuticle development were considered top candidates. We also found remarkable duplications for these gene families during evolution and their concerted expression patterns, suggesting functional amplification against low temperatures. Our study thus provides clues to the unique genetic characteristics of P. clarkii, possibly related to cold adaptation.
Collapse
Affiliation(s)
- Daiki X. Sato
- Institute for Advanced Academic Research, Chiba University, Chiba 263-8522, Japan
- Graduate School of Science, Chiba University, Chiba 263-8522, Japan
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Yuki Matsuda
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| | - Nisikawa Usio
- Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa 920-1192, Japan
| | - Ryo Funayama
- Department of Cell Proliferation, United Center for Advanced Research and Translational Medicine, Graduate School of Medicine, Tohoku University, Aoba-ku, Sendai 980-8575, Japan
| | - Keiko Nakayama
- Department of Cell Proliferation, United Center for Advanced Research and Translational Medicine, Graduate School of Medicine, Tohoku University, Aoba-ku, Sendai 980-8575, Japan
| | - Takashi Makino
- Graduate School of Life Sciences, Tohoku University, Aoba-ku, Sendai 980-8578, Japan
| |
Collapse
|
8
|
Pflughaupt P, Sahakyan AB. Generalised interrelations among mutation rates drive the genomic compliance of Chargaff's second parity rule. Nucleic Acids Res 2023; 51:7409-7423. [PMID: 37293966 PMCID: PMC10415130 DOI: 10.1093/nar/gkad477] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2022] [Revised: 05/05/2023] [Accepted: 05/17/2023] [Indexed: 06/10/2023] Open
Abstract
Chargaff's second parity rule (PR-2), where the complementary base and k-mer contents are matching within the same strand of a double stranded DNA (dsDNA), is a phenomenon that invited many explanations. The strict compliance of nearly all nuclear dsDNA to PR-2 implies that the explanation should also be similarly adamant. In this work, we revisited the possibility of mutation rates driving PR-2 compliance. Starting from the assumption-free approach, we constructed kinetic equations for unconstrained simulations. The results were analysed for their PR-2 compliance by employing symbolic regression and machine learning techniques. We arrived to a generalised set of mutation rate interrelations in place in most species that allow for their full PR-2 compliance. Importantly, our constraints explain PR-2 in genomes out of the scope of the prior explanations based on the equilibration under mutation rates with simpler no-strand-bias constraints. We thus reinstate the role of mutation rates in PR-2 through its molecular core, now shown, under our formulation, to be tolerant to previously noted strand biases and incomplete compositional equilibration. We further investigate the time for any genome to reach PR-2, showing that it is generally earlier than the compositional equilibrium, and well within the age of life on Earth.
Collapse
Affiliation(s)
- Patrick Pflughaupt
- MRC WIMM Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Aleksandr B Sahakyan
- MRC WIMM Centre for Computational Biology, MRC Weatherall Institute of Molecular Medicine, Radcliffe Department of Medicine, University of Oxford, Oxford, OX3 9DS, UK
| |
Collapse
|
9
|
Snyman M, Xu S. The effects of mutations on gene expression and alternative splicing. Proc Biol Sci 2023; 290:20230565. [PMID: 37403507 PMCID: PMC10320348 DOI: 10.1098/rspb.2023.0565] [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: 03/09/2023] [Accepted: 06/12/2023] [Indexed: 07/06/2023] Open
Abstract
Understanding the relationship between mutations and their genomic and phenotypic consequences has been a longstanding goal of evolutionary biology. However, few studies have investigated the impact of mutations on gene expression and alternative splicing on the genome-wide scale. In this study, we aim to bridge this knowledge gap by utilizing whole-genome sequencing data and RNA sequencing data from 16 obligately parthenogenetic Daphnia mutant lines to investigate the effects of ethyl methanesulfonate-induced mutations on gene expression and alternative splicing. Using rigorous analyses of mutations, expression changes and alternative splicing, we show that trans-effects are the major contributor to the variance in gene expression and alternative splicing between the wild-type and mutant lines, whereas cis mutations only affected a limited number of genes and do not always alter gene expression. Moreover, we show that there is a significant association between differentially expressed genes and exonic mutations, indicating that exonic mutations are an important driver of altered gene expression.
Collapse
Affiliation(s)
- Marelize Snyman
- Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA
| | - Sen Xu
- Department of Biology, University of Texas at Arlington, Arlington, TX 76019, USA
| |
Collapse
|
10
|
Smukowski Heil C. Loss of Heterozygosity and Its Importance in Evolution. J Mol Evol 2023; 91:369-377. [PMID: 36752826 PMCID: PMC10276065 DOI: 10.1007/s00239-022-10088-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 12/23/2022] [Indexed: 02/09/2023]
Abstract
Loss of heterozygosity (LOH) is a mitotic recombination event that converts heterozygous loci to homozygous loci. This mutation event is widespread in organisms that have asexual reproduction like budding yeasts, and is also an important and frequent mutation event in tumorigenesis. Mutation accumulation studies have demonstrated that LOH occurs at a rate higher than the point mutation rate, and can impact large portions of the genome. Laboratory evolution experiments of heterozygous yeasts have revealed that LOH often unmasks beneficial recessive alleles that can confer large fitness advantages. Here, I highlight advances in understanding dominance, fitness, and phenotypes in laboratory evolved heterozygous yeast strains. I discuss best practices for detecting LOH in intraspecific and interspecific evolved clones and populations. Utilizing heterozygous strain backgrounds in laboratory evolution experiments offers an opportunity to advance our understanding of this important mutation type in shaping adaptation and genome evolution in wild, domesticated, and clinical populations.
Collapse
Affiliation(s)
- Caiti Smukowski Heil
- Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA.
| |
Collapse
|
11
|
Gill SE, Chain FJJ. Very Low Rates of Spontaneous Gene Deletions and Gene Duplications in Dictyostelium discoideum. J Mol Evol 2023; 91:24-32. [PMID: 36484794 PMCID: PMC9849192 DOI: 10.1007/s00239-022-10081-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022]
Abstract
The study of spontaneous mutation rates has revealed a wide range of heritable point mutation rates across species, but there are comparatively few estimates for large-scale deletion and duplication rates. The handful of studies that have directly calculated spontaneous rates of deletion and duplication using mutation accumulation lines have estimated that genes are duplicated and deleted at orders of magnitude greater rates than the spontaneous point mutation rate. In our study, we tested whether spontaneous gene deletion and gene duplication rates are also high in Dictyostelium discoideum, a eukaryote with among the lowest point mutation rates (2.5 × 10-11 per site per generation) and an AT-rich genome (GC content of 22%). We calculated mutation rates of gene deletions and duplications using whole-genome sequencing data originating from a mutation accumulation experiment and determined the association between the copy number mutations and GC content. Overall, we estimated an average of 3.93 × 10-8 gene deletions and 1.18 × 10-8 gene duplications per gene per generation. While orders of magnitude greater than their point mutation rate, these rates are much lower compared to gene deletion and duplication rates estimated from mutation accumulation lines in other organisms (that are on the order of ~ 10-6 per gene/generation). The deletions and duplications were enriched in regions that were AT-rich even compared to the genomic background, in contrast to our expectations if low GC content was contributing to low mutation rates. The low deletion and duplication mutation rates in D. discoideum compared to other eukaryotes mirror their low point mutation rates, supporting previous work suggesting that this organism has high replication fidelity and effective molecular machinery to avoid the accumulation of mutations in their genome.
Collapse
Affiliation(s)
- Shelbi E Gill
- Department of Biology, University of Massachusetts Lowell, Lowell, MA, 01854-2874, USA.
| | - Frédéric J J Chain
- Department of Biology, University of Massachusetts Lowell, Lowell, MA, 01854-2874, USA.
| |
Collapse
|
12
|
Barnard-Kubow KB, Becker D, Murray CS, Porter R, Gutierrez G, Erickson P, Nunez JCB, Voss E, Suryamohan K, Ratan A, Beckerman A, Bergland AO. Genetic Variation in Reproductive Investment Across an Ephemerality Gradient in Daphnia pulex. Mol Biol Evol 2022; 39:msac121. [PMID: 35642301 PMCID: PMC9198359 DOI: 10.1093/molbev/msac121] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Species across the tree of life can switch between asexual and sexual reproduction. In facultatively sexual species, the ability to switch between reproductive modes is often environmentally dependent and subject to local adaptation. However, the ecological and evolutionary factors that influence the maintenance and turnover of polymorphism associated with facultative sex remain unclear. We studied the ecological and evolutionary dynamics of reproductive investment in the facultatively sexual model species, Daphnia pulex. We found that patterns of clonal diversity, but not genetic diversity varied among ponds consistent with the predicted relationship between ephemerality and clonal structure. Reconstruction of a multi-year pedigree demonstrated the coexistence of clones that differ in their investment into male production. Mapping of quantitative variation in male production using lab-generated and field-collected individuals identified multiple putative quantitative trait loci (QTL) underlying this trait, and we identified a plausible candidate gene. The evolutionary history of these QTL suggests that they are relatively young, and male limitation in this system is a rapidly evolving trait. Our work highlights the dynamic nature of the genetic structure and composition of facultative sex across space and time and suggests that quantitative genetic variation in reproductive strategy can undergo rapid evolutionary turnover.
Collapse
Affiliation(s)
- Karen B Barnard-Kubow
- Department of Biology, University of Virginia, Charlottesville, VA, USA
- Department of Biology, James Madison University, Harrisonburg, VA, USA
| | - Dörthe Becker
- Department of Biology, University of Virginia, Charlottesville, VA, USA
- School of Biosciences, Ecology and Evolutionary Biology, University of Sheffield, Sheffield, UK
- Department of Biology, University of Marburg, Marburg, Germany
| | - Connor S Murray
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Robert Porter
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Grace Gutierrez
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | | | - Joaquin C B Nunez
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| | - Erin Voss
- Department of Biology, University of Virginia, Charlottesville, VA, USA
- Department of Integrative Biology, UC Berkeley, Berkeley, CA, USA
| | | | - Aakrosh Ratan
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA
- Department of Public Health Sciences, University of Virginia, Charlottesville, VA, USA
| | - Andrew Beckerman
- School of Biosciences, Ecology and Evolutionary Biology, University of Sheffield, Sheffield, UK
| | - Alan O Bergland
- Department of Biology, University of Virginia, Charlottesville, VA, USA
| |
Collapse
|
13
|
Pfenninger M, Doria HB, Nickel J, Thielsch A, Schwenk K, Cordellier M. Spontaneous rate of clonal single nucleotide mutations in Daphnia galeata. PLoS One 2022; 17:e0265632. [PMID: 35363773 PMCID: PMC8975155 DOI: 10.1371/journal.pone.0265632] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 03/05/2022] [Indexed: 11/30/2022] Open
Abstract
Mutations are the ultimate source of heritable variation and therefore the fuel for evolution, but direct estimates of mutation rates exist only for few species. We estimated the spontaneous single nucleotide mutation rate among clonal generations in the waterflea Daphnia galeata with a short-term mutation accumulation approach. Individuals from eighteen mutation accumulation lines over five generations were deep sequenced to count de novo mutations that were not present in a pool of F1 individuals, representing the parental genotype. We identified 12 new nucleotide mutations in 90 clonal generational passages. This resulted in an estimated single nucleotide mutation rate of 0.745 x 10-9 (95% c.f. 0.39 x 10-9-1.26 x 10-9), which is slightly lower than recent estimates for other Daphnia species. We discuss the implications for the population genetics of Cladocerans.
Collapse
Affiliation(s)
- Markus Pfenninger
- Department Molecular Ecology, Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
- Institute for Molecular and Organismic Evolution, Johannes Gutenberg University, Mainz, Germany
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
| | - Halina Binde Doria
- Department Molecular Ecology, Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Germany
| | - Jana Nickel
- Institut für Zoologie, Fakultät für Mathematik, Informatik und Naturwissenschaften, Universität Hamburg, Hamburg, Germany
| | - Anne Thielsch
- Institute for Environmental Sciences, Universität Koblenz-Landau, Landau, Germany
| | - Klaus Schwenk
- Institute for Environmental Sciences, Universität Koblenz-Landau, Landau, Germany
| | - Mathilde Cordellier
- Institut für Zoologie, Fakultät für Mathematik, Informatik und Naturwissenschaften, Universität Hamburg, Hamburg, Germany
| |
Collapse
|
14
|
Abstract
Non-random usage of synonymous codons, known as “codon bias”, has been described in many organisms, from bacteria to Drosophila, but little is known about it in phytoplankton. This phenomenon is thought to be driven by selection for translational efficiency. As the efficacy of selection is proportional to the effective population size, species with large population sizes, such as phytoplankton, are expected to have strong codon bias. To test this, we measured codon bias in 215 strains from Haptophyta, Chlorophyta, Ochrophyta (except diatoms that were studied previously), Dinophyta, Cryptophyta, Ciliophora, unicellular Rhodophyta and Chlorarachniophyta. Codon bias is modest in most groups, despite the astronomically large population sizes of marine phytoplankton. The strength of the codon bias, measured with the effective number of codons, is the strongest in Haptophyta and the weakest in Chlorarachniophyta. The optimal codons are GC-ending in most cases, but several shifts to AT-ending codons were observed (mainly in Ochrophyta and Ciliophora). As it takes a long time to reach a new equilibrium after such shifts, species having AT-ending codons show a lower frequency of optimal codons compared to other species. Genetic diversity, calculated for species with more than three strains sequenced, is modest, indicating that the effective population sizes are many orders of magnitude lower than the astronomically large census population sizes, which helps to explain the modest codon bias in marine phytoplankton. This study represents the first comparative analysis of codon bias across multiple major phytoplankton groups.
Collapse
|
15
|
Laine VN, Sackton T, Meselson M. Genomic Signature of Sexual Reproduction in the Bdelloid Rotifer Macrotrachella quadricornifera. Genetics 2021; 220:6458333. [PMID: 34888647 DOI: 10.1093/genetics/iyab221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022] Open
Abstract
Bdelloid rotifers, common freshwater invertebrates of ancient origin and worldwide distribution have long been thought to be entirely asexual, being the principal exception to the view that in eukaryotes the loss of sex leads to early extinction. That bdelloids are facultatively sexual is shown by a study of allele sharing within a group of closely related bdelloids of the species Macrotrachella quadricornifera, supporting the view that sexual reproduction is essential for long-term success in all eukaryotes.
Collapse
Affiliation(s)
- Veronika N Laine
- Department of Animal Ecology, Finnish Museum of Natural History, University of Helsinki, Helsinki 00100, Finland
| | - Timothy Sackton
- Informatics Group, Faculty of Arts and Sciences, Harvard University, Cambridge, MA 02138; USA
| | - Matthew Meselson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
| |
Collapse
|
16
|
Lemmen KD, Verhoeven KJF, Declerck SAJ. Experimental evidence of rapid heritable adaptation in the absence of initial standing genetic variation. Funct Ecol 2021. [DOI: 10.1111/1365-2435.13943] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Kimberley D. Lemmen
- Department of Aquatic Ecology Netherlands Institute of Ecology (NIOO‐KNAW) Wageningen The Netherlands
- Department of Evolutionary Biology and Environmental Studies University of Zurich Zurich Switzerland
| | - Koen J. F. Verhoeven
- Department of Terrestrial Ecology Netherlands Institute of Ecology (NIOO‐KNAW) Wageningen The Netherlands
| | - Steven A. J. Declerck
- Department of Aquatic Ecology Netherlands Institute of Ecology (NIOO‐KNAW) Wageningen The Netherlands
- Department of Biology Laboratory of Aquatic Ecology, Evolution and Conservation KULeuven Leuven Belgium
| |
Collapse
|
17
|
Snyman M, Huynh TV, Smith MT, Xu S. The genome-wide rate and spectrum of EMS-induced heritable mutations in the microcrustacean Daphnia: on the prospect of forward genetics. Heredity (Edinb) 2021; 127:535-545. [PMID: 34667306 DOI: 10.1038/s41437-021-00478-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 10/04/2021] [Accepted: 10/05/2021] [Indexed: 02/03/2023] Open
Abstract
Forward genetic screening using the alkylating mutagen ethyl methanesulfonate (EMS) is an effective method for identifying phenotypic mutants of interest, which can be further genetically dissected to pinpoint the causal genetic mutations. An accurate estimate of the rate of EMS-induced heritable mutations is fundamental for determining the mutant sample size of a screening experiment that aims to saturate all the genes in a genome with mutations. This study examines the genome-wide EMS-induced heritable base-substitutions in three species of the freshwater microcrustacean Daphnia to help guide screening experiments. Our results show that the 10 mM EMS treatment induces base substitutions at an average rate of 1.17 × 10-6/site/generation across the three species, whereas a significantly higher average mutation rate of 1.75 × 10-6 occurs at 25 mM. The mutation spectrum of EMS-induced base substitutions at both concentration is dominated by G:C to A:T transitions. Furthermore, we find that female Daphnia exposed to EMS (F0 individuals) can asexually produce unique mutant offspring (F1) for at least 3 consecutive broods, suggestive of multiple broods as F1 mutants. Lastly, we estimate that about 750 F1s are needed for all genes in the Daphnia genome to be mutated at least once with a 95% probability. We also recommend 4-5 F2s should be collected from each F1 mutant through sibling crossing so that all induced mutations could appear in the homozygous state in the F2 population at 70-80% probability.
Collapse
Affiliation(s)
- Marelize Snyman
- Department of Biology, University of Texas at Arlington, Arlington, TX, 76019, USA
| | - Trung V Huynh
- Department of Biology, University of Texas at Arlington, Arlington, TX, 76019, USA
| | - Matthew T Smith
- Department of Biology, University of Texas at Arlington, Arlington, TX, 76019, USA
| | - Sen Xu
- Department of Biology, University of Texas at Arlington, Arlington, TX, 76019, USA.
| |
Collapse
|
18
|
Waldvogel AM, Pfenninger M. Temperature dependence of spontaneous mutation rates. Genome Res 2021; 31:1582-1589. [PMID: 34301628 PMCID: PMC8415371 DOI: 10.1101/gr.275168.120] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Accepted: 07/21/2021] [Indexed: 11/29/2022]
Abstract
Mutation is the source of genetic variation and the fundament of evolution. Temperature has long been suggested to have a direct impact on realized spontaneous mutation rates. If mutation rates vary in response to environmental conditions, such as the variation of the ambient temperature through space and time, they should no longer be described as species-specific constants. By combining mutation accumulation with whole-genome sequencing in a multicellular organism, we provide empirical support to reject the null hypothesis of a constant, temperature-independent mutation rate. Instead, mutation rates depended on temperature in a U-shaped manner with increasing rates toward both temperature extremes. This relation has important implications for mutation-dependent processes in molecular evolution, processes shaping the evolution of mutation rates, and even the evolution of biodiversity as such.
Collapse
Affiliation(s)
- Ann-Marie Waldvogel
- Senckenberg Biodiversity and Climate Research Centre, 60325 Frankfurt am Main, Germany
- Institute of Zoology, University of Cologne, 50674 Cologne, Germany
| | - Markus Pfenninger
- Senckenberg Biodiversity and Climate Research Centre, 60325 Frankfurt am Main, Germany
- LOEWE Centre for Translational Biodiversity Genomics, Senckenberg Biodiversity and Climate Research Centre, 60325 Frankfurt am Main, Germany
- Institute for Organismic and Molecular Evolution, Johannes Gutenberg University, 55128 Mainz, Germany
| |
Collapse
|
19
|
López-Cortegano E, Craig RJ, Chebib J, Samuels T, Morgan AD, Kraemer SA, Böndel KB, Ness RW, Colegrave N, Keightley PD. De Novo Mutation Rate Variation and Its Determinants in Chlamydomonas. Mol Biol Evol 2021; 38:3709-3723. [PMID: 33950243 PMCID: PMC8383909 DOI: 10.1093/molbev/msab140] [Citation(s) in RCA: 9] [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] [Indexed: 12/12/2022] Open
Abstract
De novo mutations are central for evolution, since they provide the raw material for natural selection by regenerating genetic variation. However, studying de novo mutations is challenging and is generally restricted to model species, so we have a limited understanding of the evolution of the mutation rate and spectrum between closely related species. Here, we present a mutation accumulation (MA) experiment to study de novo mutation in the unicellular green alga Chlamydomonas incerta and perform comparative analyses with its closest known relative, Chlamydomonas reinhardtii. Using whole-genome sequencing data, we estimate that the median single nucleotide mutation (SNM) rate in C. incerta is μ = 7.6 × 10-10, and is highly variable between MA lines, ranging from μ = 0.35 × 10-10 to μ = 131.7 × 10-10. The SNM rate is strongly positively correlated with the mutation rate for insertions and deletions between lines (r > 0.97). We infer that the genomic factors associated with variation in the mutation rate are similar to those in C. reinhardtii, allowing for cross-prediction between species. Among these genomic factors, sequence context and complexity are more important than GC content. With the exception of a remarkably high C→T bias, the SNM spectrum differs markedly between the two Chlamydomonas species. Our results suggest that similar genomic and biological characteristics may result in a similar mutation rate in the two species, whereas the SNM spectrum has more freedom to diverge.
Collapse
Affiliation(s)
- Eugenio López-Cortegano
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Rory J Craig
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Jobran Chebib
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Toby Samuels
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Andrew D Morgan
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | | | - Katharina B Böndel
- Institute of Plant Breeding, Seed Science and Population Genetics, University of Hohenheim, Stuttgart, Germany
| | - Rob W Ness
- Department of Biology, University of Toronto Mississauga, Mississauga, ON, Canada
| | - Nick Colegrave
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Peter D Keightley
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
20
|
Xu Z, Gao T, Xu Y, Li X, Li J, Lin H, Yan W, Pan J, Tang J. A chromosome-level reference genome of red swamp crayfish Procambarus clarkii provides insights into the gene families regarding growth or development in crustaceans. Genomics 2021; 113:3274-3284. [PMID: 34303807 DOI: 10.1016/j.ygeno.2021.07.017] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 05/28/2021] [Accepted: 07/14/2021] [Indexed: 11/27/2022]
Abstract
Red swamp crayfish Procambarus clarkii is an ecologically and economically important crustacean species. Here, based on a de novo assembly strategy combining PacBio with Hi-C sequencing, we presented a high quality chromosome-level P. clarkii genome. The assembled genome is 2.75 Gb in size with a contig N50 of 216.75 kb. Transposable elements (TEs) make up the largest fraction of the genome (~79.61%), and LINEs comprise the majority of the TEs. Frequent molting and rapid growth of the red swamp crayfish may be explained by the expansion of multiple gene families regarding growth or development. Phylogenetic analysis revealed that P. clarkii diverged from Portunus trituberculatus at 278-407 million years ago (Mya). PSMC analysis identified multiple bottleneck events of the P. clarkii population between 2 kaBP to 14 kaBP. The obtained P. clarkii genome should not only facilitate us understanding the development and evolution of the crayfish species, but also contribute to the genetic improvement in future breeding selections.
Collapse
Affiliation(s)
- Zhiqiang Xu
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China; Institute of Marine Biology, College of Oceanography, Hohai University, Nanjing 210098, China; Jiangsu Key laboratory for Conservation and Utilization of freshwater Fisheries Germplasm Resources, Nanjing 210017, China.
| | - Tianheng Gao
- Institute of Marine Biology, College of Oceanography, Hohai University, Nanjing 210098, China; Jiangsu Key laboratory for Conservation and Utilization of freshwater Fisheries Germplasm Resources, Nanjing 210017, China
| | - Yu Xu
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China; Jiangsu Key laboratory for Conservation and Utilization of freshwater Fisheries Germplasm Resources, Nanjing 210017, China
| | - Xuguang Li
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China; Jiangsu Key laboratory for Conservation and Utilization of freshwater Fisheries Germplasm Resources, Nanjing 210017, China
| | - Jiajia Li
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China
| | - Hai Lin
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China
| | - Weihui Yan
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China
| | - Jianlin Pan
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China; Institute of Marine Biology, College of Oceanography, Hohai University, Nanjing 210098, China; Jiangsu Key laboratory for Conservation and Utilization of freshwater Fisheries Germplasm Resources, Nanjing 210017, China
| | - Jianqing Tang
- Freshwater Fisheries Research Institute of Jiangsu Province, Nanjing 210017, China; Jiangsu Key laboratory for Conservation and Utilization of freshwater Fisheries Germplasm Resources, Nanjing 210017, China.
| |
Collapse
|
21
|
Krasovec M. The spontaneous mutation rate of Drosophila pseudoobscura. G3 GENES|GENOMES|GENETICS 2021; 11:6265464. [PMID: 33950174 PMCID: PMC8495931 DOI: 10.1093/g3journal/jkab151] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Accepted: 04/26/2021] [Indexed: 02/05/2023]
Abstract
Abstract
The spontaneous mutation rate is a very variable trait that is subject to drift, selection and is sometimes highly plastic. Consequently, its variation between close species, or even between populations from the same species, can be very large. Here, I estimated the spontaneous mutation rate of Drosophila pseudoobscura and Drosophila persimilis crosses to explore the mutation rate variation within the Drosophila genus. All mutation rate estimations in Drosophila varied fourfold, probably explained by the sensitivity of the mutation rate to environmental and experimental conditions. Moreover, I found a very high mutation rate in the hybrid cross between D. pseudoobscura and D. persimilis, in agreement with known elevated mutation rate in hybrids. This mutation rate increase can be explained by heterozygosity and fitness decrease effects in hybrids.
Collapse
Affiliation(s)
- Marc Krasovec
- CNRS, Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls-sur-Mer 66650, France
| |
Collapse
|
22
|
Lu Z, Cui J, Wang L, Teng N, Zhang S, Lam HM, Zhu Y, Xiao S, Ke W, Lin J, Xu C, Jin B. Genome-wide DNA mutations in Arabidopsis plants after multigenerational exposure to high temperatures. Genome Biol 2021; 22:160. [PMID: 34034794 PMCID: PMC8145854 DOI: 10.1186/s13059-021-02381-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 05/13/2021] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Elevated temperatures can cause physiological, biochemical, and molecular responses in plants that can greatly affect their growth and development. Mutations are the most fundamental force driving biological evolution. However, how long-term elevations in temperature influence the accumulation of mutations in plants remains unknown. RESULTS Multigenerational exposure of Arabidopsis MA (mutation accumulation) lines and MA populations to extreme heat and moderate warming results in significantly increased mutation rates in single-nucleotide variants (SNVs) and small indels. We observe distinctive mutational spectra under extreme and moderately elevated temperatures, with significant increases in transition and transversion frequencies. Mutation occurs more frequently in intergenic regions, coding regions, and transposable elements in plants grown under elevated temperatures. At elevated temperatures, more mutations accumulate in genes associated with defense responses, DNA repair, and signaling. Notably, the distribution patterns of mutations among all progeny differ between MA populations and MA lines, suggesting that stronger selection effects occurred in populations. Methylation is observed more frequently at mutation sites, indicating its contribution to the mutation process at elevated temperatures. Mutations occurring within the same genome under elevated temperatures are significantly biased toward low gene density regions, special trinucleotides, tandem repeats, and adjacent simple repeats. Additionally, mutations found in all progeny overlap significantly with genetic variations reported in 1001 Genomes, suggesting non-uniform distribution of de novo mutations through the genome. CONCLUSION Collectively, our results suggest that elevated temperatures can accelerate the accumulation, and alter the molecular profiles, of DNA mutations in plants, thus providing significant insight into how environmental temperatures fuel plant evolution.
Collapse
Affiliation(s)
- Zhaogeng Lu
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China
- Key Laboratory of Plant Functional Genomics of the Ministry of Education, Agricultural College of Yangzhou University, Yangzhou, China
| | - Jiawen Cui
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China
| | - Li Wang
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China
| | - Nianjun Teng
- College of Horticulture, Nanjing Agricultural University, Nanjing, China
| | - Shoudong Zhang
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region China
| | - Hon-Ming Lam
- Center for Soybean Research of the State Key Laboratory of Agrobiotechnology and School of Life Sciences, The Chinese University of Hong Kong, Shatin, Hong Kong Special Administrative Region China
| | - Yingfang Zhu
- Institute of Plant Stress Biology, State Key Laboratory of Cotton Biology, Department of Biology, Henan University, Kaifeng, China
| | - Siwei Xiao
- Wuhan Frasergen Bioinformatics Co, Wuhan, China
| | - Wensi Ke
- Wuhan Frasergen Bioinformatics Co, Wuhan, China
| | - Jinxing Lin
- College of Biological Sciences and Technology, Beijing Forestry University, Beijing, China
| | - Chenwu Xu
- Key Laboratory of Plant Functional Genomics of the Ministry of Education, Agricultural College of Yangzhou University, Yangzhou, China
| | - Biao Jin
- College of Horticulture and Plant Protection, Yangzhou University, Yangzhou, China
| |
Collapse
|
23
|
Stability across the Whole Nuclear Genome in the Presence and Absence of DNA Mismatch Repair. Cells 2021; 10:cells10051224. [PMID: 34067668 PMCID: PMC8156620 DOI: 10.3390/cells10051224] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/13/2021] [Accepted: 05/14/2021] [Indexed: 01/06/2023] Open
Abstract
We describe the contribution of DNA mismatch repair (MMR) to the stability of the eukaryotic nuclear genome as determined by whole-genome sequencing. To date, wild-type nuclear genome mutation rates are known for over 40 eukaryotic species, while measurements in mismatch repair-defective organisms are fewer in number and are concentrated on Saccharomyces cerevisiae and human tumors. Well-studied organisms include Drosophila melanogaster and Mus musculus, while less genetically tractable species include great apes and long-lived trees. A variety of techniques have been developed to gather mutation rates, either per generation or per cell division. Generational rates are described through whole-organism mutation accumulation experiments and through offspring–parent sequencing, or they have been identified by descent. Rates per somatic cell division have been estimated from cell line mutation accumulation experiments, from systemic variant allele frequencies, and from widely spaced samples with known cell divisions per unit of tissue growth. The latter methods are also used to estimate generational mutation rates for large organisms that lack dedicated germlines, such as trees and hyphal fungi. Mechanistic studies involving genetic manipulation of MMR genes prior to mutation rate determination are thus far confined to yeast, Arabidopsis thaliana, Caenorhabditis elegans, and one chicken cell line. A great deal of work in wild-type organisms has begun to establish a sound baseline, but far more work is needed to uncover the variety of MMR across eukaryotes. Nonetheless, the few MMR studies reported to date indicate that MMR contributes 100-fold or more to genome stability, and they have uncovered insights that would have been impossible to obtain using reporter gene assays.
Collapse
|
24
|
Ho EKH, Macrae F, Latta LC, McIlroy P, Ebert D, Fields PD, Benner MJ, Schaack S. High and Highly Variable Spontaneous Mutation Rates in Daphnia. Mol Biol Evol 2021; 37:3258-3266. [PMID: 32520985 PMCID: PMC7820357 DOI: 10.1093/molbev/msaa142] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The rate and spectrum of spontaneous mutations are critical parameters in basic and applied biology because they dictate the pace and character of genetic variation introduced into populations, which is a prerequisite for evolution. We use a mutation–accumulation approach to estimate mutation parameters from whole-genome sequence data from multiple genotypes from multiple populations of Daphnia magna, an ecological and evolutionary model system. We report extremely high base substitution mutation rates (µ-n,bs = 8.96 × 10−9/bp/generation [95% CI: 6.66–11.97 × 10−9/bp/generation] in the nuclear genome and µ-m,bs = 8.7 × 10−7/bp/generation [95% CI: 4.40–15.12 × 10−7/bp/generation] in the mtDNA), the highest of any eukaryote examined using this approach. Levels of intraspecific variation based on the range of estimates from the nine genotypes collected from three populations (Finland, Germany, and Israel) span 1 and 3 orders of magnitude, respectively, resulting in up to a ∼300-fold difference in rates among genomic partitions within the same lineage. In contrast, mutation spectra exhibit very consistent patterns across genotypes and populations, suggesting the mechanisms underlying the mutational process may be similar, even when the rates at which they occur differ. We discuss the implications of high levels of intraspecific variation in rates, the importance of estimating gene conversion rates using a mutation–accumulation approach, and the interacting factors influencing the evolution of mutation parameters. Our findings deepen our knowledge about mutation and provide both challenges to and support for current theories aimed at explaining the evolution of the mutation rate, as a trait, across taxa.
Collapse
Affiliation(s)
- Eddie K H Ho
- Department of Biology, Reed College, Portland, OR
| | | | - Leigh C Latta
- Department of Biology, Reed College, Portland, OR.,Division of Natural Sciences and Mathematics, Lewis-Clark State College, Lewiston, ID
| | | | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | | | | |
Collapse
|
25
|
Nguyen DT, Wu B, Long H, Zhang N, Patterson C, Simpson S, Morris K, Thomas WK, Lynch M, Hao W. Variable Spontaneous Mutation and Loss of Heterozygosity among Heterozygous Genomes in Yeast. Mol Biol Evol 2021; 37:3118-3130. [PMID: 33219379 DOI: 10.1093/molbev/msaa150] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Mutation and recombination are the primary sources of genetic variation. To better understand the evolution of genetic variation, it is crucial to comprehensively investigate the processes involving mutation accumulation and recombination. In this study, we performed mutation accumulation experiments on four heterozygous diploid yeast species in the Saccharomycodaceae family to determine spontaneous mutation rates, mutation spectra, and losses of heterozygosity (LOH). We observed substantial variation in mutation rates and mutation spectra. We also observed high LOH rates (1.65-11.07×10-6 events per heterozygous site per cell division). Biases in spontaneous mutation and LOH together with selection ultimately shape the variable genome-wide nucleotide landscape in yeast species.
Collapse
Affiliation(s)
- Duong T Nguyen
- Department of Biological Sciences, Wayne State University, Detroit, MI
| | - Baojun Wu
- Department of Biological Sciences, Wayne State University, Detroit, MI
| | - Hongan Long
- Institute of Evolution and Marine Biodiversity, KLMME, Ocean University of China, Qingdao, Shandong Province, China
| | - Nan Zhang
- Department of Biological Sciences, Wayne State University, Detroit, MI
| | | | | | | | | | - Michael Lynch
- Center for Mechanisms of Evolution, The Biodesign Institute, Arizona State University, Tempe, AZ
| | - Weilong Hao
- Department of Biological Sciences, Wayne State University, Detroit, MI
| |
Collapse
|
26
|
Silva CNS, Young EF, Murphy NP, Bell JJ, Green BS, Morley SA, Duhamel G, Cockcroft AC, Strugnell JM. Climatic change drives dynamic source-sink relationships in marine species with high dispersal potential. Ecol Evol 2021; 11:2535-2550. [PMID: 33767820 PMCID: PMC7981208 DOI: 10.1002/ece3.7204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/17/2020] [Accepted: 12/23/2020] [Indexed: 12/14/2022] Open
Abstract
While there is now strong evidence that many factors can shape dispersal, the mechanisms influencing connectivity patterns are species-specific and remain largely unknown for many species with a high dispersal potential. The rock lobsters Jasus tristani and Jasus paulensis have a long pelagic larval duration (up to 20 months) and inhabit seamounts and islands in the southern Atlantic and Indian Oceans, respectively. We used a multidisciplinary approach to assess the genetic relationships between J. tristani and J. paulensis, investigate historic and contemporary gene flow, and inform fisheries management. Using 17,256 neutral single nucleotide polymorphisms we found low but significant genetic differentiation. We show that patterns of connectivity changed over time in accordance with climatic fluctuations. Historic migration estimates showed stronger connectivity from the Indian to the Atlantic Ocean (influenced by the Agulhas Leakage). In contrast, the individual-based model coupled with contemporary migration estimates inferred from genetic data showed stronger inter-ocean connectivity in the opposite direction from the Atlantic to the Indian Ocean driven by the Subtropical Front. We suggest that the J. tristani and J. paulensis historical distribution might have extended further north (when water temperatures were lower) resulting in larval dispersal between the ocean basis being more influenced by the Agulhas Leakage than the Subtropical Front. As water temperatures in the region increase in accordance with anthropogenic climate change, a southern shift in the distribution range of J. tristani and J. paulensis could further reduce larval transport from the Indian to the Atlantic Ocean, adding complexity to fisheries management.
Collapse
Affiliation(s)
- Catarina N. S. Silva
- Centre for Sustainable Tropical Fisheries and AquacultureJames Cook UniversityTownsvilleQldAustralia
| | | | | | - James J. Bell
- School of Biological SciencesVictoria University of WellingtonWellingtonNew Zealand
| | - Bridget S. Green
- Institute for Marine and Antarctic StudiesUniversity of TasmaniaHobartTASAustralia
| | | | - Guy Duhamel
- Département Adaptations du VivantBOREAMNHNParisFrance
| | - Andrew C. Cockcroft
- Department of Agriculture, Forestry and FisheriesSouth African GovernmentCape TownSouth Africa
| | - Jan M. Strugnell
- Centre for Sustainable Tropical Fisheries and AquacultureJames Cook UniversityTownsvilleQldAustralia
- Department of EcologyLa Trobe UniversityMelbourneVic.Australia
| |
Collapse
|
27
|
Maiakovska O, Andriantsoa R, Tönges S, Legrand C, Gutekunst J, Hanna K, Pârvulescu L, Novitsky R, Weiperth A, Sciberras A, Deidun A, Ercoli F, Kouba A, Lyko F. Genome analysis of the monoclonal marbled crayfish reveals genetic separation over a short evolutionary timescale. Commun Biol 2021; 4:74. [PMID: 33462402 PMCID: PMC7814009 DOI: 10.1038/s42003-020-01588-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 12/10/2020] [Indexed: 12/20/2022] Open
Abstract
The marbled crayfish (Procambarus virginalis) represents a very recently evolved parthenogenetic freshwater crayfish species that has invaded diverse habitats in Europe and in Madagascar. However, population genetic analyses have been hindered by the homogeneous genetic structure of the population and the lack of suitable tools for data analysis. We have used whole-genome sequencing to characterize reference specimens from various known wild populations. In parallel, we established a whole-genome sequencing data analysis pipeline for the population genetic analysis of nearly monoclonal genomes. Our results provide evidence for systematic genetic differences between geographically separated populations and illustrate the emerging differentiation of the marbled crayfish genome. We also used mark-recapture population size estimation in combination with genetic data to model the growth pattern of marbled crayfish populations. Our findings uncover evolutionary dynamics in the marbled crayfish genome over a very short evolutionary timescale and identify the rapid growth of marbled crayfish populations as an important factor for ecological monitoring. Olena Maiakovska et al. provide whole-genome sequencing of the parthenogenetic and invasive marbled crayfish and develop a computational framework for data analysis of monoclonal genomes. These data and methodology allow the authors to demonstrate genetic separation between two populations and provide the first size estimate for a marbled crayfish colony, which they used to model population growth patterns.
Collapse
Affiliation(s)
- Olena Maiakovska
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Ranja Andriantsoa
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Sina Tönges
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Carine Legrand
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Julian Gutekunst
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Katharina Hanna
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Im Neuenheimer Feld 580, 69120, Heidelberg, Germany
| | - Lucian Pârvulescu
- Department of Biology-Chemistry, West University of Timisoara, 16A Pestalozzi St., 300115, Timisoara, Romania
| | - Roman Novitsky
- Department of Water Bioresources and Aquaculture, Dnipro State Agrarian and Economic University, 25 Serhii Efremov St., Dnipro, 49600, Ukraine
| | - András Weiperth
- Department of Aquaculture, Institute for Natural Resources Conservation, Faculty of Agriculture and Environmental Sciences, Szent István University, Páter Károly utca 1, 2100, Gödöllő, Hungary
| | - Arnold Sciberras
- Physical Oceanography Research Group, Department of Geosciences, University of Malta, Msida, MSD 2080, Malta
| | - Alan Deidun
- Physical Oceanography Research Group, Department of Geosciences, University of Malta, Msida, MSD 2080, Malta
| | - Fabio Ercoli
- Chair of Hydrobiology and Fisheries, Institute of Agricultural and Environment Sciences, Estonian University of Life Sciences, Kreutzwaldi 5D, 51006, Tartu, Estonia.,Natural Resources and Environment, Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland
| | - Antonin Kouba
- Faculty of Fisheries and Protection of Waters, CENAKVA, University of South Bohemia in České Budějovice, Zátiší 728/II, 38925, Vodňany, Czech Republic
| | - Frank Lyko
- Division of Epigenetics, DKFZ-ZMBH Alliance, German Cancer Research Center, Im Neuenheimer Feld 580, 69120, Heidelberg, Germany.
| |
Collapse
|
28
|
Sui Y, Qi L, Wu JK, Wen XP, Tang XX, Ma ZJ, Wu XC, Zhang K, Kokoska RJ, Zheng DQ, Petes TD. Genome-wide mapping of spontaneous genetic alterations in diploid yeast cells. Proc Natl Acad Sci U S A 2020; 117:28191-28200. [PMID: 33106417 PMCID: PMC7668089 DOI: 10.1073/pnas.2018633117] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Genomic alterations including single-base mutations, deletions and duplications, translocations, mitotic recombination events, and chromosome aneuploidy generate genetic diversity. We examined the rates of all of these genetic changes in a diploid strain of Saccharomyces cerevisiae by whole-genome sequencing of many independent isolates (n = 93) subcloned about 100 times in unstressed growth conditions. The most common alterations were point mutations and small (<100 bp) insertion/deletions (n = 1,337) and mitotic recombination events (n = 1,215). The diploid cells of most eukaryotes are heterozygous for many single-nucleotide polymorphisms (SNPs). During mitotic cell divisions, recombination can produce derivatives of these cells that have become homozygous for the polymorphisms, termed loss-of-heterozygosity (LOH) events. LOH events can change the phenotype of the cells and contribute to tumor formation in humans. We observed two types of LOH events: interstitial events (conversions) resulting in a short LOH tract (usually less than 15 kb) and terminal events (mostly cross-overs) in which the LOH tract extends to the end of the chromosome. These two types of LOH events had different distributions, suggesting that they may have initiated by different mechanisms. Based on our results, we present a method of calculating the probability of an LOH event for individual SNPs located throughout the genome. We also identified several hotspots for chromosomal rearrangements (large deletions and duplications). Our results provide insights into the relative importance of different types of genetic alterations produced during vegetative growth.
Collapse
Affiliation(s)
- Yang Sui
- Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, 316021 Zhoushan, China
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27705
| | - Lei Qi
- Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, 316021 Zhoushan, China
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27705
| | - Jian-Kun Wu
- Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, 316021 Zhoushan, China
| | - Xue-Ping Wen
- Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, 316021 Zhoushan, China
| | - Xing-Xing Tang
- Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, 316021 Zhoushan, China
| | - Zhong-Jun Ma
- Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, 316021 Zhoushan, China
| | - Xue-Chang Wu
- Institute of Microbiology, College of Life Science, Zhejiang University, 310058 Hangzhou, China
| | - Ke Zhang
- Institute of Microbiology, College of Life Science, Zhejiang University, 310058 Hangzhou, China;
| | - Robert J Kokoska
- Physical Sciences Directorate, United States Army Research Office, Research Triangle Park, NC 27709
| | - Dao-Qiong Zheng
- Institute of Marine Biology and Pharmacology, Ocean College, Zhejiang University, 316021 Zhoushan, China;
| | - Thomas D Petes
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27705;
| |
Collapse
|
29
|
Estimation of the SNP Mutation Rate in Two Vegetatively Propagating Species of Duckweed. G3-GENES GENOMES GENETICS 2020; 10:4191-4200. [PMID: 32973000 PMCID: PMC7642947 DOI: 10.1534/g3.120.401704] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Mutation rate estimates for vegetatively reproducing organisms are rare, despite their frequent occurrence across the tree of life. Here we report mutation rate estimates in two vegetatively reproducing duckweed species, Lemna minor and Spirodela polyrhiza We use a modified approach to estimating mutation rates by taking into account the reduction in mutation detection power that occurs when new individuals are produced from multiple cell lineages. We estimate an extremely low per generation mutation rate in both species of duckweed and note that allelic coverage at de novo mutation sites is very skewed. We also find no substantial difference in mutation rate between mutation accumulation lines propagated under benign conditions and those grown under salt stress. Finally, we discuss the implications of interpreting mutation rate estimates in vegetatively propagating organisms.
Collapse
|
30
|
Loss of Heterozygosity and Base Mutation Rates Vary Among Saccharomyces cerevisiae Hybrid Strains. G3-GENES GENOMES GENETICS 2020; 10:3309-3319. [PMID: 32727920 PMCID: PMC7466981 DOI: 10.1534/g3.120.401551] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A growing body of evidence suggests that mutation rates exhibit intra-species specific variation. We estimated genome-wide loss of heterozygosity (LOH), gross chromosomal changes, and single nucleotide mutation rates to determine intra-species specific differences in hybrid and homozygous strains of Saccharomyces cerevisiae. The mutation accumulation lines of the S. cerevisiae hybrid backgrounds - S288c/YJM789 (S/Y) and S288c/RM11-1a (S/R) were analyzed along with the homozygous diploids RM11, S288c, and YJM145. LOH was extensive in both S/Y and S/R hybrid backgrounds. The S/Y background also showed longer LOH tracts, gross chromosomal changes, and aneuploidy. Short copy number aberrations were observed in the S/R background. LOH data from the S/Y and S/R hybrids were used to construct a LOH map for S288c to identify hotspots. Further, we observe up to a sixfold difference in single nucleotide mutation rates among the S. cerevisiae S/Y and S/R genetic backgrounds. Our results demonstrate LOH is common during mitotic divisions in S. cerevisiae hybrids and also highlight genome-wide differences in LOH patterns and rates of single nucleotide mutations between commonly used S. cerevisiae hybrid genetic backgrounds.
Collapse
|
31
|
Harvey EF, Cristescu ME, Dale J, Hunter H, Randall C, Crease TJ. Metal exposure causes rDNA copy number to fluctuate in mutation accumulation lines of Daphnia pulex. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2020; 226:105556. [PMID: 32652413 DOI: 10.1016/j.aquatox.2020.105556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Revised: 05/29/2020] [Accepted: 06/26/2020] [Indexed: 06/11/2023]
Abstract
Ribosomal (r)DNA is a highly dynamic, conserved, multigene family whose sequence homogeneity is thought to be maintained by intra- and interchromosomal recombination, which are capable of changing rDNA copy number. It is generally not known how environmental stress such as sublethal exposure to environmentally relevant concentrations of metals impacts rDNA copy number. To determine how chronic metal exposure affects rDNA, we measured copy number of the 18S rRNA gene in 355 copper and nickel-exposed samples and 132 metal-free samples derived from 325 mutation accumulation (MA) lines of two genetically distinct Daphnia pulex lineages. The MA lines were sampled at four time points over 100+ generations of clonal propagation. The copy number of rDNA was also measured in 15 individuals sampled from a metal-free non-MA control population established from the same progenitor as one of the MA lineages. We found that mean rDNA copy number fluctuated across lines exposed to metals with a tendency to decrease over time. In contrast, mean rDNA copy number in the metal-free control lines and the non-MA population remained stable over time. It is generally accepted that extreme rDNA loss results in the loss of organism fitness. Thus, fluctuations in rDNA copy number, including losses, could affect the long-term viability of natural populations of Daphnia in metal-contaminated habitats.
Collapse
Affiliation(s)
- Eleanor F Harvey
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada
| | - Melania E Cristescu
- Biology Department, McGill University, Stewart Biology Building, 1205 Dr Penfield Ave, Montreal, QC, H3A 1B1, Canada
| | - Jenna Dale
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada
| | - Hailey Hunter
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada
| | - Connor Randall
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada
| | - Teresa J Crease
- Department of Integrative Biology, University of Guelph, 50 Stone Road West, Guelph, ON, N1G 2W1, Canada.
| |
Collapse
|
32
|
Dead or alive: sediment DNA archives as tools for tracking aquatic evolution and adaptation. Commun Biol 2020; 3:169. [PMID: 32265485 PMCID: PMC7138834 DOI: 10.1038/s42003-020-0899-z] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 03/10/2020] [Indexed: 12/18/2022] Open
Abstract
DNA can be preserved in marine and freshwater sediments both in bulk sediment and in intact, viable resting stages. Here, we assess the potential for combined use of ancient, environmental, DNA and timeseries of resurrected long-term dormant organisms, to reconstruct trophic interactions and evolutionary adaptation to changing environments. These new methods, coupled with independent evidence of biotic and abiotic forcing factors, can provide a holistic view of past ecosystems beyond that offered by standard palaeoecology, help us assess implications of ecological and molecular change for contemporary ecosystem functioning and services, and improve our ability to predict adaptation to environmental stress. Ellegaard et al. discuss the potential for using ancient environmental DNA (eDNA), combined with resurrection ecology, to analyse trophic interactions and evolutionary adaptation to changing environments. Their Review suggests that these techniques will improve our ability to predict genetic and phenotypic adaptation to environmental stress.
Collapse
|
33
|
Sellinger TPP, Abu Awad D, Moest M, Tellier A. Inference of past demography, dormancy and self-fertilization rates from whole genome sequence data. PLoS Genet 2020; 16:e1008698. [PMID: 32251472 PMCID: PMC7173940 DOI: 10.1371/journal.pgen.1008698] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 04/21/2020] [Accepted: 02/24/2020] [Indexed: 02/04/2023] Open
Abstract
Several methods based on the Sequential Markovian coalescence (SMC) have been developed that make use of genome sequence data to uncover population demographic history, which is of interest in its own right and is a key requirement to generate a null model for selection tests. While these methods can be applied to all possible kind of species, the underlying assumptions are sexual reproduction in each generation and non-overlapping generations. However, in many plants, invertebrates, fungi and other taxa, those assumptions are often violated due to different ecological and life history traits, such as self-fertilization or long term dormant structures (seed or egg-banking). We develop a novel SMC-based method to infer 1) the rates/parameters of dormancy and of self-fertilization, and 2) the populations' past demographic history. Using simulated data sets, we demonstrate the accuracy of our method for a wide range of demographic scenarios and for sequence lengths from one to 30 Mb using four sampled genomes. Finally, we apply our method to a Swedish and a German population of Arabidopsis thaliana demonstrating a selfing rate of ca. 0.87 and the absence of any detectable seed-bank. In contrast, we show that the water flea Daphnia pulex exhibits a long lived egg-bank of three to 18 generations. In conclusion, we here present a novel method to infer accurate demographies and life-history traits for species with selfing and/or seed/egg-banks. Finally, we provide recommendations for the use of SMC-based methods for non-model organisms, highlighting the importance of the per site and the effective ratios of recombination over mutation.
Collapse
Affiliation(s)
| | - Diala Abu Awad
- Department of Population Genetics, Technische Universitaet Muenchen, Freising, Germany
| | - Markus Moest
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Aurélien Tellier
- Department of Population Genetics, Technische Universitaet Muenchen, Freising, Germany
| |
Collapse
|
34
|
Fazalova V, Nevado B. Low Spontaneous Mutation Rate and Pleistocene Radiation of Pea Aphids. Mol Biol Evol 2020; 37:2045-2051. [DOI: 10.1093/molbev/msaa066] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Abstract
Accurate estimates of divergence times are essential to understand the evolutionary history of species. It allows linking evolutionary histories of the diverging lineages with past geological, climatic, and other changes in environment and shed light on the processes involved in speciation. The pea aphid radiation includes multiple host races adapted to different legume host plants. It is thought that diversification in this system occurred very recently, over the past 8,000–16,000 years. This young age estimate was used to link diversification in pea aphids to the onset of human agriculture, and led to the establishment of the pea aphid radiation as a model system in the study of speciation with gene flow. Here, we re-examine the age of the pea aphid radiation, by combining a mutation accumulation experiment with a genome-wide estimate of divergence between distantly related pea aphid host races. We estimate the spontaneous mutation rate for pea aphids as 2.7×10-10 per haploid genome per parthenogenic generation. Using this estimate of mutation rate and the genome-wide genetic differentiation observed between pea aphid host races, we show that the pea aphid radiation is much more ancient than assumed previously, predating Neolithic agriculture by several hundreds of thousands of years. Our results rule out human agriculture as the driver of diversification of the pea aphid radiation, and call for re-assessment of the role of allopatric isolation during Pleistocene climatic oscillations in divergence of the pea aphid complex.
Collapse
Affiliation(s)
- Varvara Fazalova
- Department of Zoology, University of Oxford, Oxford, United Kingdom
| | - Bruno Nevado
- Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
35
|
Krasovec M, Sanchez-Brosseau S, Piganeau G. First Estimation of the Spontaneous Mutation Rate in Diatoms. Genome Biol Evol 2020; 11:1829-1837. [PMID: 31218358 PMCID: PMC6604790 DOI: 10.1093/gbe/evz130] [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] [Accepted: 06/17/2019] [Indexed: 12/25/2022] Open
Abstract
Mutations are the origin of genetic diversity, and the mutation rate is a fundamental parameter to understand all aspects of molecular evolution. The combination of mutation-accumulation experiments and high-throughput sequencing enabled the estimation of mutation rates in most model organisms, but several major eukaryotic lineages remain unexplored. Here, we report the first estimation of the spontaneous mutation rate in a model unicellular eukaryote from the Stramenopile kingdom, the diatom Phaeodactylum tricornutum (strain RCC2967). We sequenced 36 mutation accumulation lines for an average of 181 generations per line and identified 156 de novo mutations. The base substitution mutation rate per site per generation is μbs = 4.77 × 10-10 and the insertion-deletion mutation rate is μid = 1.58 × 10-11. The mutation rate varies as a function of the nucleotide context and is biased toward an excess of mutations from GC to AT, consistent with previous observations in other species. Interestingly, the mutation rates between the genomes of organelles and the nucleus differ, with a significantly higher mutation rate in the mitochondria. This confirms previous claims based on indirect estimations of the mutation rate in mitochondria of photosynthetic eukaryotes that acquired their plastid through a secondary endosymbiosis. This novel estimate enables us to infer the effective population size of P. tricornutum to be Ne∼8.72 × 106.
Collapse
Affiliation(s)
- Marc Krasovec
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls/Mer, France
| | - Sophie Sanchez-Brosseau
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls/Mer, France
| | - Gwenael Piganeau
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Biologie Intégrative des Organismes Marins (BIOM), Observatoire Océanologique, Banyuls/Mer, France.,Department of Plant Sciences, University of Oxford, Oxford, United Kingdom
| |
Collapse
|
36
|
Konrad A, Brady MJ, Bergthorsson U, Katju V. Mutational Landscape of Spontaneous Base Substitutions and Small Indels in Experimental Caenorhabditis elegans Populations of Differing Size. Genetics 2019; 212:837-854. [PMID: 31110155 PMCID: PMC6614903 DOI: 10.1534/genetics.119.302054] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2019] [Accepted: 05/16/2019] [Indexed: 02/08/2023] Open
Abstract
Experimental investigations into the rates and fitness effects of spontaneous mutations are fundamental to our understanding of the evolutionary process. To gain insights into the molecular and fitness consequences of spontaneous mutations, we conducted a mutation accumulation (MA) experiment at varying population sizes in the nematode Caenorhabditis elegans, evolving 35 lines in parallel for 409 generations at three population sizes (N = 1, 10, and 100 individuals). Here, we focus on nuclear SNPs and small insertion/deletions (indels) under minimal influence of selection, as well as their accrual rates in larger populations under greater selection efficacy. The spontaneous rates of base substitutions and small indels are 1.84 (95% C.I. ± 0.14) × 10-9 substitutions and 6.84 (95% C.I. ± 0.97) × 10-10 changes/site/generation, respectively. Small indels exhibit a deletion bias with deletions exceeding insertions by threefold. Notably, there was no correlation between the frequency of base substitutions, nonsynonymous substitutions, or small indels with population size. These results contrast with our previous analysis of mitochondrial DNA mutations and nuclear copy-number changes in these MA lines, and suggest that nuclear base substitutions and small indels are under less stringent purifying selection compared to the former mutational classes. A transition bias was observed in exons as was a near universal base substitution bias toward A/T. Strongly context-dependent base substitutions, where 5'-Ts and 3'-As increase the frequency of A/T → T/A transversions, especially at the boundaries of A or T homopolymeric runs, manifest as higher mutation rates in (i) introns and intergenic regions relative to exons, (ii) chromosomal cores vs. arms and tips, and (iii) germline-expressed genes.
Collapse
Affiliation(s)
- Anke Konrad
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77845
| | - Meghan J Brady
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77845
| | - Ulfar Bergthorsson
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77845
| | - Vaishali Katju
- Department of Veterinary Integrative Biosciences, Texas A&M University, College Station, Texas 77845
| |
Collapse
|
37
|
Dukić M, Berner D, Haag CR, Ebert D. How clonal are clones? A quest for loss of heterozygosity during asexual reproduction in Daphnia magna. J Evol Biol 2019; 32:619-628. [PMID: 30888725 PMCID: PMC6850383 DOI: 10.1111/jeb.13443] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 03/04/2019] [Indexed: 12/25/2022]
Abstract
Due to the lack of recombination, asexual organisms are predicted to accumulate mutations and show high levels of within‐individual allelic divergence (heterozygosity); however, empirical evidence for this prediction is largely missing. Instead, evidence of genome homogenization during asexual reproduction is accumulating. Ameiotic crossover recombination is a mechanism that could lead to long genomic stretches of loss of heterozygosity (LOH) and unmasking of mutations that have little or no effect in heterozygous state. Therefore, LOH might be an important force for inducing variation among asexual offspring and may contribute to the limited longevity of asexual lineages. To investigate the genetic consequences of asexuality, here we used high‐throughput sequencing of Daphnia magna for assessing the rate of LOH over a single generation of asexual reproduction. Comparing parthenogenetic daughters with their mothers at several thousand genetic markers generated by restriction site‐associated DNA (RAD) sequencing resulted in high LOH rate estimation that largely overlapped with our estimates for the error rate. To distinguish these two, we Sanger re‐sequenced the top 17 candidate RAD‐loci for LOH, and all of them proved to be false positives. Hence, even though we cannot exclude the possibility that short stretches of LOH occur in genomic regions not covered by our markers, we conclude that LOH does not occur frequently during asexual reproduction in D. magna and ameiotic crossovers are very rare or absent. This finding suggests that clonal lineages of D. magna will remain genetically homogeneous at least over time periods typically relevant for experimental work.
Collapse
Affiliation(s)
- Marinela Dukić
- Zoological Institute, University of Basel, Basel, Switzerland.,Department of Cell and Developmental Biology, John Innes Centre, Norwich Research Park, Norwich, UK
| | - Daniel Berner
- Zoological Institute, University of Basel, Basel, Switzerland
| | - Christoph R Haag
- Centre d'Ecologie Fonctionnelle et Evolutive-CEFE UMR 5175, CNRS-Université de Montpellier-Université Paul-Valéry Montpellier-EPHE, campus CNRS, Montpellier, France.,Department of Biology, Ecology and Evolution, University of Fribourg, Fribourg, Switzerland
| | - Dieter Ebert
- Zoological Institute, University of Basel, Basel, Switzerland
| |
Collapse
|
38
|
Xu S, Stapley J, Gablenz S, Boyer J, Appenroth KJ, Sree KS, Gershenzon J, Widmer A, Huber M. Low genetic variation is associated with low mutation rate in the giant duckweed. Nat Commun 2019; 10:1243. [PMID: 30886148 PMCID: PMC6423293 DOI: 10.1038/s41467-019-09235-5] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Accepted: 02/27/2019] [Indexed: 12/30/2022] Open
Abstract
Mutation rate and effective population size (Ne) jointly determine intraspecific genetic diversity, but the role of mutation rate is often ignored. Here we investigate genetic diversity, spontaneous mutation rate and Ne in the giant duckweed (Spirodela polyrhiza). Despite its large census population size, whole-genome sequencing of 68 globally sampled individuals reveals extremely low intraspecific genetic diversity. Assessed under natural conditions, the genome-wide spontaneous mutation rate is at least seven times lower than estimates made for other multicellular eukaryotes, whereas Ne is large. These results demonstrate that low genetic diversity can be associated with large-Ne species, where selection can reduce mutation rates to very low levels. This study also highlights that accurate estimates of mutation rate can help to explain seemingly unexpected patterns of genome-wide variation.
Collapse
Affiliation(s)
- Shuqing Xu
- Institute for Evolution and Biodiversity, University of Münster, Hüfferstrasse 1, 48149, Münster, Germany.
| | - Jessica Stapley
- Center for Adaptation to a Changing Environment, ETH Zurich, Universitätstrasse 16, 8092, Zürich, Switzerland
| | - Saskia Gablenz
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, 07745, Jena, Germany
| | - Justin Boyer
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, 07745, Jena, Germany
| | - Klaus J Appenroth
- Matthias-Schleiden-Institute, Plant Physiology, Friedrich Schiller University of Jena, Dornburgerstraße 159, 07743, Jena, Germany
| | - K Sowjanya Sree
- Department of Environmental Science, Central University of Kerala, Periye, 671316, India
| | - Jonathan Gershenzon
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, 07745, Jena, Germany
| | - Alex Widmer
- Institute of Integrative Biology, ETH Zurich, Universitätstrasse 16, 8092, Zürich, Switzerland
| | - Meret Huber
- Department of Biochemistry, Max Planck Institute for Chemical Ecology, Hans-Knöll-Strasse 8, 07745, Jena, Germany.
- Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 7, 48143, Münster, Germany.
| |
Collapse
|
39
|
Fitness and Genomic Consequences of Chronic Exposure to Low Levels of Copper and Nickel in Daphnia pulex Mutation Accumulation Lines. G3-GENES GENOMES GENETICS 2019; 9:61-71. [PMID: 30389796 PMCID: PMC6325897 DOI: 10.1534/g3.118.200797] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In at least some unicellular organisms, mutation rates are temporarily raised upon exposure to environmental stress, potentially contributing to the evolutionary response to stress. Whether this is true for multicellular organisms, however, has received little attention. This study investigated the effects of chronic mild stress, in the form of low-level copper and nickel exposure, on mutational processes in Daphnia pulex using a combination of mutation accumulation, whole genome sequencing and life-history assays. After over 100 generations of mutation accumulation, we found no effects of metal exposure on the rates of single nucleotide mutations and of loss of heterozygosity events, the two mutation classes that occurred in sufficient numbers to allow statistical analysis. Similarly, rates of decline in fitness, as measured by intrinsic rate of population increase and of body size at first reproduction, were negligibly affected by metal exposure. We can reject the possibility that Daphnia were insufficiently stressed to invoke genetic responses as we have previously shown rates of large-scale deletions and duplications are elevated under metal exposure in this experiment. Overall, the mutation accumulation lines did not significantly depart from initial values for phenotypic traits measured, indicating the lineage used was broadly mutationally robust. Taken together, these results indicate that the mutagenic effects of chronic low-level exposure to these metals are restricted to certain mutation classes and that fitness consequences are likely minor and therefore unlikely to be relevant in determining the evolutionary responses of populations exposed to these stressors.
Collapse
|
40
|
Chain FJJ, Flynn JM, Bull JK, Cristescu ME. Accelerated rates of large-scale mutations in the presence of copper and nickel. Genome Res 2019; 29:64-73. [PMID: 30487211 PMCID: PMC6314161 DOI: 10.1101/gr.234724.118] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 11/22/2018] [Indexed: 12/13/2022]
Abstract
Mutation rate variation has been under intense investigation for decades. Despite these efforts, little is known about the extent to which environmental stressors accelerate mutation rates and influence the genetic load of populations. Moreover, most studies on stressors have focused on unicellular organisms and point mutations rather than large-scale deletions and duplications (copy number variations [CNVs]). We estimated mutation rates in Daphnia pulex exposed to low levels of environmental stressors as well as the effect of selection on de novo mutations. We conducted a mutation accumulation (MA) experiment in which selection was minimized, coupled with an experiment in which a population was propagated under competitive conditions in a benign environment. After an average of 103 generations of MA propagation, we sequenced 60 genomes and found significantly accelerated rates of deletions and duplications in MA lines exposed to ecologically relevant concentrations of metals. Whereas control lines had gene deletion and duplication rates comparable to other multicellular eukaryotes (1.8 × 10-6 per gene per generation), the presence of nickel and copper increased these rates fourfold. The realized mutation rate under selection was reduced to 0.4× that of control MA lines, providing evidence that CNVs contribute to mutational load. Our CNV breakpoint analysis revealed that nonhomologous recombination associated with regions of DNA fragility is the primary source of CNVs, plausibly linking metal-induced DNA strand breaks with higher CNV rates. Our findings suggest that environmental stress, in particular multiple stressors, can have profound effects on large-scale mutation rates and mutational load of multicellular organisms.
Collapse
Affiliation(s)
- Frédéric J J Chain
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
| | - Jullien M Flynn
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
| | - James K Bull
- Department of Biology, McGill University, Montréal, Québec H3A 1B1, Canada
| | | |
Collapse
|
41
|
Katju V, Bergthorsson U. Old Trade, New Tricks: Insights into the Spontaneous Mutation Process from the Partnering of Classical Mutation Accumulation Experiments with High-Throughput Genomic Approaches. Genome Biol Evol 2019; 11:136-165. [PMID: 30476040 PMCID: PMC6330053 DOI: 10.1093/gbe/evy252] [Citation(s) in RCA: 70] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/22/2018] [Indexed: 12/17/2022] Open
Abstract
Mutations spawn genetic variation which, in turn, fuels evolution. Hence, experimental investigations into the rate and fitness effects of spontaneous mutations are central to the study of evolution. Mutation accumulation (MA) experiments have served as a cornerstone for furthering our understanding of spontaneous mutations for four decades. In the pregenomic era, phenotypic measurements of fitness-related traits in MA lines were used to indirectly estimate key mutational parameters, such as the genomic mutation rate, new mutational variance per generation, and the average fitness effect of mutations. Rapidly emerging next-generating sequencing technology has supplanted this phenotype-dependent approach, enabling direct empirical estimates of the mutation rate and a more nuanced understanding of the relative contributions of different classes of mutations to the standing genetic variation. Whole-genome sequencing of MA lines bears immense potential to provide a unified account of the evolutionary process at multiple levels-the genetic basis of variation, and the evolutionary dynamics of mutations under the forces of selection and drift. In this review, we have attempted to synthesize key insights into the spontaneous mutation process that are rapidly emerging from the partnering of classical MA experiments with high-throughput sequencing, with particular emphasis on the spontaneous rates and molecular properties of different mutational classes in nuclear and mitochondrial genomes of diverse taxa, the contribution of mutations to the evolution of gene expression, and the rate and stability of transgenerational epigenetic modifications. Future advances in sequencing technologies will enable greater species representation to further refine our understanding of mutational parameters and their functional consequences.
Collapse
Affiliation(s)
- Vaishali Katju
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4458
| | - Ulfar Bergthorsson
- Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4458
| |
Collapse
|
42
|
Charlesworth B. Mutational load, inbreeding depression and heterosis in subdivided populations. Mol Ecol 2018; 27:4991-5003. [DOI: 10.1111/mec.14933] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 10/05/2018] [Accepted: 10/08/2018] [Indexed: 01/02/2023]
Affiliation(s)
- Brian Charlesworth
- Institute of Evolutionary Biology School of Biological Sciences University of Edinburgh Edinburgh UK
| |
Collapse
|
43
|
Flynn JM, Lower SE, Barbash DA, Clark AG. Rates and Patterns of Mutation in Tandem Repetitive DNA in Six Independent Lineages of Chlamydomonas reinhardtii. Genome Biol Evol 2018; 10:1673-1686. [PMID: 29931069 PMCID: PMC6041958 DOI: 10.1093/gbe/evy123] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/18/2018] [Indexed: 12/15/2022] Open
Abstract
The mutational patterns of large tandem arrays of short sequence repeats remain largely unknown, despite observations of their high levels of variation in sequence and genomic abundance within and between species. Many factors can influence the dynamics of tandem repeat evolution; however, their evolution has only been examined over a limited phylogenetic sample of taxa. Here, we use publicly available whole-genome sequencing data of 85 haploid mutation accumulation lines derived from six geographically diverse Chlamydomonas reinhardtii isolates to investigate genome-wide mutation rates and patterns in tandem repeats in this species. We find that tandem repeat composition differs among ancestral strains, both in genome-wide abundance and presence/absence of individual repeats. Estimated mutation rates (repeat copy number expansion and contraction) were high, averaging 4.3×10−4 per generation per single unit copy. Although orders of magnitude higher than other types of mutation previously reported in C. reinhardtii, these tandem repeat mutation rates were one order of magnitude lower than what has recently been found in Daphnia pulex, even after correcting for lower overall genome-wide satellite abundance in C. reinhardtii. Most high-abundance repeats were related to others by a single mutational step. Correlations of repeat copy number changes within genomes revealed clusters of closely related repeats that were strongly correlated positively or negatively, and similar patterns of correlation arose independently in two different mutation accumulation experiments. Together, these results paint a dynamic picture of tandem repeat evolution in this unicellular alga.
Collapse
Affiliation(s)
- Jullien M Flynn
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
| | - Sarah E Lower
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
| | - Daniel A Barbash
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York
| |
Collapse
|
44
|
Abstract
Understanding the context-dependence of spontaneous mutations is crucial to predicting evolutionary trajectories. In this experiment, the impact of genetic background and trait-type on mutational susceptibility was investigated. Mutant and non-mutant lines of six unique genotypes from two populations of Daphnia magna were phenotypically assayed using a common-garden experiment. Morphological, life-history, and behavioral traits were measured and estimates of the mutation parameters were generated. The mutation parameters varied between the populations and among genotypes, suggesting differential susceptibility to mutation depending upon genomic background. Traits also varied in their susceptibility to mutation with behavioral traits evolving more rapidly than life-history and morphological traits. These results may reflect the unique selection histories of these populations.
Collapse
|
45
|
Steevensz A, Gombar R, Vergilino R, Cristescu ME, Vacratsis PO. Proteomic Profile of Daphnia pulex using Data-Independent Acquisition Mass Spectrometry and Ion Mobility Separation. Proteomics 2018; 18:e1700460. [PMID: 29972280 DOI: 10.1002/pmic.201700460] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 06/14/2018] [Indexed: 11/09/2022]
Abstract
Daphnia pulex is a keystone species for aquatic habitats and an ecological/evolution model organism. Although significant progress has been made on characterizing its genome, the D. pulex proteome remains largely uncharacterized partially due to abnormally high protein degradation during homogenization and emphasis on genomic analysis. In this study, various sample preparation and mass spectrometry acquisition methods are performed for the purpose of improving D. pulex proteome exploration. Benefits for employing both in-gel and in-solution methods of trypsin digestion are observed. Furthermore, acquisition methods employing ion mobility separation greatly increase peptide identification and more than doubled the proteome coverage. Bioinformatic analysis suggests that mitochondrial and hydrolytic activities are enriched in D. pulex compared to closely related invertebrates or Homo sapiens. Also, novel D. pulex proteins possessing putative genome modifying functional domains are identified. Data are available via ProteomeXchange with identifier PXD008455.
Collapse
Affiliation(s)
- Aaron Steevensz
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, N9B 3P4, Canada
| | - Robert Gombar
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, N9B 3P4, Canada
| | - Roland Vergilino
- Great Lakes Institute of Environmental Research, University of Windsor, Windsor, ON, N9B 3P4, Canada
| | | | - Panayiotis O Vacratsis
- Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, N9B 3P4, Canada
| |
Collapse
|
46
|
Krasovec M, Chester M, Ridout K, Filatov DA. The Mutation Rate and the Age of the Sex Chromosomes in Silene latifolia. Curr Biol 2018; 28:1832-1838.e4. [PMID: 29804812 DOI: 10.1016/j.cub.2018.04.069] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Revised: 04/12/2018] [Accepted: 04/19/2018] [Indexed: 12/15/2022]
Abstract
Many aspects of sex chromosome evolution are common to both plants and animals [1], but the process of Y chromosome degeneration, where genes on the Y become non-functional over time, may be much slower in plants due to purifying selection against deleterious mutations in the haploid gametophyte [2, 3]. Testing for differences in Y degeneration between the kingdoms has been hindered by the absence of accurate age estimates for plant sex chromosomes. Here, we used genome resequencing to estimate the spontaneous mutation rate and the age of the sex chromosomes in white campion (Silene latifolia). Screening of single nucleotide polymorphisms (SNPs) in parents and 10 F1 progeny identified 39 de novo mutations and yielded a rate of 7.31 × 10-9 (95% confidence interval: 5.20 × 10-9 - 8.00 × 10-9) mutations per site per haploid genome per generation. Applying this mutation rate to the synonymous divergence between homologous X- and Y-linked genes (gametologs) gave age estimates of 11.00 and 6.32 million years for the old and young strata, respectively. Based on SNP segregation patterns, we inferred which genes were Y-linked and found that at least 47% are already dysfunctional. Applying our new estimates for the age of the sex chromosomes indicates that the rate of Y degeneration in S. latifolia is nearly 2-fold slower when compared to animal sex chromosomes of a similar age. Our revised estimates support Y degeneration taking place more slowly in plants, a discrepancy that may be explained by differences in the life cycles of animals and plants.
Collapse
Affiliation(s)
- Marc Krasovec
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Michael Chester
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Kate Ridout
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK
| | - Dmitry A Filatov
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK.
| |
Collapse
|
47
|
Burkholder AB, Lujan SA, Lavender CA, Grimm SA, Kunkel TA, Fargo DC. Muver, a computational framework for accurately calling accumulated mutations. BMC Genomics 2018; 19:345. [PMID: 29743009 PMCID: PMC5944071 DOI: 10.1186/s12864-018-4753-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2018] [Accepted: 05/02/2018] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Identification of mutations from next-generation sequencing data typically requires a balance between sensitivity and accuracy. This is particularly true of DNA insertions and deletions (indels), that can impart significant phenotypic consequences on cells but are harder to call than substitution mutations from whole genome mutation accumulation experiments. To overcome these difficulties, we present muver, a computational framework that integrates established bioinformatics tools with novel analytical methods to generate mutation calls with the extremely low false positive rates and high sensitivity required for accurate mutation rate determination and comparison. RESULTS Muver uses statistical comparison of ancestral and descendant allelic frequencies to identify variant loci and assigns genotypes with models that include per-sample assessments of sequencing errors by mutation type and repeat context. Muver identifies maximally parsimonious mutation pathways that connect these genotypes, differentiating potential allelic conversion events and delineating ambiguities in mutation location, type, and size. Benchmarking with a human gold standard father-son pair demonstrates muver's sensitivity and low false positive rates. In DNA mismatch repair (MMR) deficient Saccharomyces cerevisiae, muver detects multi-base deletions in homopolymers longer than the replicative polymerase footprint at rates greater than predicted for sequential single-base deletions, implying a novel multi-repeat-unit slippage mechanism. CONCLUSIONS Benchmarking results demonstrate the high accuracy and sensitivity achieved with muver, particularly for indels, relative to available tools. Applied to an MMR-deficient Saccharomyces cerevisiae system, muver mutation calls facilitate mechanistic insights into DNA replication fidelity.
Collapse
Affiliation(s)
- Adam B Burkholder
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, Durham, NC, 27709, USA
| | - Scott A Lujan
- Laboratory of Genomic Integrity and Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, Durham, NC, 27709, USA
| | - Christopher A Lavender
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, Durham, NC, 27709, USA
| | - Sara A Grimm
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, Durham, NC, 27709, USA
| | - Thomas A Kunkel
- Laboratory of Genomic Integrity and Structural Biology, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, Durham, NC, 27709, USA
| | - David C Fargo
- Integrative Bioinformatics, National Institute of Environmental Health Sciences, NIH, DHHS, Research Triangle Park, Durham, NC, 27709, USA.
| |
Collapse
|
48
|
Genome Dynamics of Hybrid Saccharomyces cerevisiae During Vegetative and Meiotic Divisions. G3-GENES GENOMES GENETICS 2017; 7:3669-3679. [PMID: 28916648 PMCID: PMC5677154 DOI: 10.1534/g3.117.1135] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mutation and recombination are the major sources of genetic diversity in all organisms. In the baker’s yeast, all mutation rate estimates are in homozygous background. We determined the extent of genetic change through mutation and loss of heterozygosity (LOH) in a heterozygous Saccharomyces cerevisiae genome during successive vegetative and meiotic divisions. We measured genome-wide LOH and base mutation rates during vegetative and meiotic divisions in a hybrid (S288c/YJM789) S. cerevisiae strain. The S288c/YJM789 hybrid showed nearly complete reduction in heterozygosity within 31 generations of meioses and improved spore viability. LOH in the meiotic lines was driven primarily by the mating of spores within the tetrad. The S288c/YJM789 hybrid lines propagated vegetatively for the same duration as the meiotic lines, showed variable LOH (from 2 to 3% and up to 35%). Two of the vegetative lines with extensive LOH showed frequent and large internal LOH tracts that suggest a high frequency of recombination repair. These results suggest significant LOH can occur in the S288c/YJM789 hybrid during vegetative propagation presumably due to return to growth events. The average base substitution rates for the vegetative lines (1.82 × 10−10 per base per division) and the meiotic lines (1.22 × 10−10 per base per division) are the first genome-wide mutation rate estimates for a hybrid yeast. This study therefore provides a novel context for the analysis of mutation rates (especially in the context of detecting LOH during vegetative divisions), compared to previous mutation accumulation studies in yeast that used homozygous backgrounds.
Collapse
|
49
|
Selection Constrains High Rates of Tandem Repetitive DNA Mutation in Daphnia pulex. Genetics 2017; 207:697-710. [PMID: 28811387 DOI: 10.1534/genetics.117.300146] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 08/11/2017] [Indexed: 12/26/2022] Open
Abstract
A long-standing evolutionary puzzle is that all eukaryotic genomes contain large amounts of tandemly-repeated DNA whose sequence motifs and abundance vary greatly among even closely related species. To elucidate the evolutionary forces governing tandem repeat dynamics, quantification of the rates and patterns of mutations in repeat copy number and tests of its selective neutrality are necessary. Here, we used whole-genome sequences of 28 mutation accumulation (MA) lines of Daphnia pulex, in addition to six isolates from a non-MA population originating from the same progenitor, to both estimate mutation rates of abundances of repeat sequences and evaluate the selective regime acting upon them. We found that mutation rates of individual repeats were both high and highly variable, ranging from additions/deletions of 0.29-105 copies per generation (reflecting changes of 0.12-0.80% per generation). Our results also provide evidence that new repeat sequences are often formed from existing ones. The non-MA population isolates showed a signal of either purifying or stabilizing selection, with 33% lower variation in repeat copy number on average than the MA lines, although the level of selective constraint was not evenly distributed across all repeats. The changes between many pairs of repeats were correlated, and the pattern of correlations was significantly different between the MA lines and the non-MA population. Our study demonstrates that tandem repeats can experience extremely rapid evolution in copy number, which can lead to high levels of divergence in genome-wide repeat composition between closely related species.
Collapse
|