1
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Lynch M, Wei W, Ye Z, Pfrender M. The genome-wide signature of short-term temporal selection. Proc Natl Acad Sci U S A 2024; 121:e2307107121. [PMID: 38959040 DOI: 10.1073/pnas.2307107121] [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: 05/01/2023] [Accepted: 06/03/2024] [Indexed: 07/04/2024] Open
Abstract
Despite evolutionary biology's obsession with natural selection, few studies have evaluated multigenerational series of patterns of selection on a genome-wide scale in natural populations. Here, we report on a 10-y population-genomic survey of the microcrustacean Daphnia pulex. The genome sequences of [Formula: see text]800 isolates provide insights into patterns of selection that cannot be obtained from long-term molecular-evolution studies, including the following: the pervasiveness of near quasi-neutrality across the genome (mean net selection coefficients near zero, but with significant temporal variance about the mean, and little evidence of positive covariance of selection across time intervals); the preponderance of weak positive selection operating on minor alleles; and a genome-wide distribution of numerous small linkage islands of observable selection influencing levels of nucleotide diversity. These results suggest that interannual fluctuating selection is a major determinant of standing levels of variation in natural populations, challenge the conventional paradigm for interpreting patterns of nucleotide diversity and divergence, and motivate the need for the further development of theoretical expressions for the interpretation of population-genomic data.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Wen Wei
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Zhiqiang Ye
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Michael Pfrender
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556
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2
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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.
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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
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3
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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.
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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
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4
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Chen HY, Krieg T, Mautz B, Jolly C, Scofield D, Maklakov AA, Immler S. Germline mutation rate is elevated in young and old parents in Caenorhabditis remanei. Evol Lett 2023; 7:478-489. [PMID: 38045724 PMCID: PMC10692996 DOI: 10.1093/evlett/qrad052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Revised: 09/19/2023] [Accepted: 10/06/2023] [Indexed: 12/05/2023] Open
Abstract
The effect of parental age on germline mutation rate across generations is not fully understood. While some studies report a positive linear relationship of mutation rate with increasing age, others suggest that mutation rate varies with age but not in a linear fashion. We investigated the effect of parental age on germline mutations by generating replicated mutation accumulation lines in Caenorhabditis remanei at three parental ages ("Young T1" [Day 1], "Peak T2" [Day 2], and "Old T5" [Day 5] parents). We conducted whole-genome resequencing and variant calling to compare differences in mutation rates after three generations of mutation accumulation. We found that Peak T2 lines had an overall reduced mutation rate compared to Young T1 and Old T5 lines, but this pattern of the effect varied depending on the variant impact. Specifically, we found no high-impact variants in Peak T2 lines, and modifiers and up- and downstream gene variants were less frequent in these lines. These results suggest that animals at the peak of reproduction have better DNA maintenance and repair compared to young and old animals. We propose that C. remanei start to reproduce before they optimize their DNA maintenance and repair, trading the benefits of earlier onset of reproduction against offspring mutation load. The increase in offspring mutation load with age likely represents germline senescence.
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Affiliation(s)
- Hwei-yen Chen
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
- Department of Biology, Lund University, Lund, Sweden
| | - Therese Krieg
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Brian Mautz
- Department of Medicine, Division of Epidemiology, Vanderbilt University, Nashville, United States
| | - Cécile Jolly
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden
| | - Douglas Scofield
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Alexei A Maklakov
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
| | - Simone Immler
- Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, United Kingdom
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5
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Ye Z, Wei W, Pfrender ME, Lynch M. Evolutionary Insights from a Large-Scale Survey of Population-Genomic Variation. Mol Biol Evol 2023; 40:msad233. [PMID: 37863047 PMCID: PMC10630549 DOI: 10.1093/molbev/msad233] [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: 05/03/2023] [Revised: 09/11/2023] [Accepted: 10/03/2023] [Indexed: 10/22/2023] Open
Abstract
The field of genomics has ushered in new methods for studying molecular-genetic variation in natural populations. However, most population-genomic studies still rely on small sample sizes (typically, <100 individuals) from single time points, leaving considerable uncertainties with respect to the behavior of relatively young (and rare) alleles and, owing to the large sampling variance of measures of variation, to the specific gene targets of unusually strong selection. Genomic sequences of ∼1,700 haplotypes distributed over a 10-year period from a natural population of the microcrustacean Daphnia pulex reveal evolutionary-genomic features at a refined scale, including previously hidden information on the behavior of rare alleles predicted by recent theory. Background selection, resulting from the recurrent introduction of deleterious alleles, appears to strongly influence the dynamics of neutral alleles, inducing indirect negative selection on rare variants and positive selection on common variants. Temporally fluctuating selection increases the persistence of nonsynonymous alleles with intermediate frequencies, while reducing standing levels of variation at linked silent sites. Combined with the results from an equally large metapopulation survey of the study species, classes of genes that are under strong positive selection can now be confidently identified in this key model organism. Most notable among rapidly evolving Daphnia genes are those associated with ribosomes, mitochondrial functions, sensory systems, and lifespan determination.
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Affiliation(s)
- Zhiqiang Ye
- Hubei Key Laboratory of Genetic Regulation & Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan 430079, China
| | - Wen Wei
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287, USA
| | - Michael E Pfrender
- Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA
| | - Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287, USA
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6
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Ye Z, Pfrender ME, Lynch M. Evolutionary Genomics of Sister Species Differing in Effective Population Sizes and Recombination Rates. Genome Biol Evol 2023; 15:evad202. [PMID: 37946625 PMCID: PMC10664402 DOI: 10.1093/gbe/evad202] [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: 05/31/2023] [Revised: 10/16/2023] [Accepted: 11/02/2023] [Indexed: 11/12/2023] Open
Abstract
Studies of closely related species with known ecological differences provide exceptional opportunities for understanding the genetic mechanisms of evolution. In this study, we compared population-genomics data between Daphnia pulex and Daphnia pulicaria, two reproductively compatible sister species experiencing ecological speciation, the first largely confined to intermittent ponds and the second to permanent lakes in the same geographic region. Daphnia pulicaria has lower genome-wide nucleotide diversity, a smaller effective population size, a higher incidence of private alleles, and a substantially more linkage disequilibrium than D. pulex. Positively selected genes in D. pulicaria are enriched in potentially aging-related categories such as cellular homeostasis, which may explain the extended life span in D. pulicaria. We also found that opsin-related genes, which may mediate photoperiodic responses, are under different selection pressures in these two species. Genes involved in mitochondrial functions, ribosomes, and responses to environmental stimuli are found to be under positive selection in both species. Additionally, we found that the two species have similar average evolutionary rates at the DNA-sequence level, although approximately 160 genes have significantly different rates in the two lineages. Our results provide insights into the physiological traits that differ within this regionally sympatric sister-species pair that occupies unique microhabitats.
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Affiliation(s)
- Zhiqiang Ye
- Hubei Key Laboratory of Genetic Regulation and Integrative Biology, School of Life Sciences, Central China Normal University, Wuhan, China
| | - Michael E Pfrender
- Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, Arizona, USA
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7
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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.
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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
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8
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Ye Z, Wei W, Pfrender M, Lynch M. Evolutionary Insights from a Large-scale Survey of Population-genomic Variation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.03.539276. [PMID: 37205430 PMCID: PMC10187179 DOI: 10.1101/2023.05.03.539276] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Results from data on > 1000 haplotypes distributed over a nine-year period from a natural population of the microcrustacean Daphnia pulex reveal evolutionary-genomic features at a refined scale, including key population-genetic properties that are obscured in studies with smaller sample sizes. Background selection, resulting from the recurrent introduction of deleterious alleles, appears to strongly influence the dynamics of neutral alleles, inducing indirect negative selection on rare variants and positive selection on common variants. Fluctuating selection increases the persistence of nonsynonymous alleles with intermediate frequencies, while reducing standing levels of variation at linked silent sites. Combined with the results from an equally large metapopulation survey of the study species, regions of gene structure that are under strong purifying selection and classes of genes that are under strong positive selection in this key species can be confidently identified. Most notable among rapidly evolving Daphnia genes are those associated with ribosomes, mitochondrial functions, sensory systems, and lifespan determination.
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Affiliation(s)
- Zhiqiang Ye
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Wen Wei
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Michael Pfrender
- Department of Biological Sciences, Notre Dame University, Notre Dame, IN 46556
| | - Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
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9
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Lynch M, Wei W, Ye Z, Pfrender M. The Genome-wide Signature of Short-term Temporal Selection. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.28.538790. [PMID: 37162919 PMCID: PMC10168312 DOI: 10.1101/2023.04.28.538790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Despite evolutionary biology's obsession with natural selection, few studies have evaluated multi-generational series of patterns of selection on a genome-wide scale in natural populations. Here, we report on a nine-year population-genomic survey of the microcrustacean Daphnia pulex. The genome-sequences of > 800 isolates provide insights into patterns of selection that cannot be obtained from long-term molecular-evolution studies, including the pervasiveness of near quasi-neutrality across the genome (mean net selection coefficients near zero, but with significant temporal variance about the mean, and little evidence of positive covariance of selection across time intervals), the preponderance of weak negative selection operating on minor alleles, and a genome-wide distribution of numerous small linkage islands of observable selection influencing levels of nucleotide diversity. These results suggest that fluctuating selection is a major determinant of standing levels of variation in natural populations, challenge the conventional paradigm for interpreting patterns of nucleotide diversity and divergence, and motivate the need for the development of new theoretical expressions for the interpretation of population-genomic data.
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Affiliation(s)
- Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Wen Wei
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Zhiqiang Ye
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ 85287
| | - Michael Pfrender
- Department of Biological Sciences, Notre Dame University, Notre Dame, IN 46556
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10
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Mutation Rate and Spectrum of the Silkworm in Normal and Temperature Stress Conditions. Genes (Basel) 2023; 14:genes14030649. [PMID: 36980921 PMCID: PMC10048334 DOI: 10.3390/genes14030649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 02/26/2023] [Accepted: 03/02/2023] [Indexed: 03/08/2023] Open
Abstract
Mutation rate is a crucial parameter in evolutionary genetics. However, the mutation rate of most species as well as the extent to which the environment can alter the genome of multicellular organisms remain poorly understood. Here, we used parents–progeny sequencing to investigate the mutation rate and spectrum of the domestic silkworm (Bombyx mori) among normal and two temperature stress conditions (32 °C and 0 °C). The rate of single-nucleotide mutations in the normal temperature rearing condition was 0.41 × 10−8 (95% confidence interval, 0.33 × 10−8–0.49 × 10−8) per site per generation, which was up to 1.5-fold higher than in four previously studied insects. Moreover, the mutation rates of the silkworm under the stresses are significantly higher than in normal conditions. Furthermore, the mutation rate varies less in gene regions under normal and temperature stresses. Together, these findings expand the known diversity of the mutation rate among eukaryotes but also have implications for evolutionary analysis that assumes a constant mutation rate among species and environments.
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11
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Wersebe MJ, Sherman RE, Jeyasingh PD, Weider LJ. The roles of recombination and selection in shaping genomic divergence in an incipient ecological species complex. Mol Ecol 2023; 32:1478-1496. [PMID: 35119153 DOI: 10.1111/mec.16383] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 01/16/2022] [Accepted: 01/28/2022] [Indexed: 11/24/2022]
Abstract
Speciation genomic studies have revealed that genomes of diverging lineages are shaped jointly by the actions of gene flow and selection. These evolutionary forces acting in concert with processes such as recombination and genome features such as gene density shape a mosaic landscape of divergence. We investigated the roles of recombination and gene density in shaping the patterns of differentiation and divergence between the cyclically parthenogenetic ecological sister-taxa, Daphnia pulicaria and Daphnia pulex. First, we assembled a phased chromosome-scale genome assembly using trio-binning for D. pulicaria and constructed a genetic map using an F2-intercross panel to understand sex-specific recombination rate heterogeneity. Finally, we used a ddRADseq data set with broad geographic sampling of D. pulicaria, D. pulex, and their hybrids to understand the patterns of genome-scale divergence and demographic parameters. Our study provides the first sex-specific estimates of recombination rates for a cyclical parthenogen, and unlike other eukaryotic species, we observed male-biased heterochiasmy in D. pulicaria, which may be related to this somewhat unique breeding mode. Additionally, regions of high gene density and recombination are generally more divergent than regions of suppressed recombination. Outlier analysis indicated that divergent genomic regions are probably driven by selection on D. pulicaria, the derived lineage colonizing a novel lake habitat. Together, our study supports a scenario of selection acting on genes related to local adaptation shaping genome-wide patterns of differentiation despite high local recombination rates in this species complex. Finally, we discuss the limitations of our data in light of demographic uncertainty.
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Affiliation(s)
- Matthew J Wersebe
- Department of Biology, Program in Ecology and Evolutionary Biology, University of Oklahoma, Norman, Oklahoma, USA
| | - Ryan E Sherman
- Department of Integrative Biology, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Punidan D Jeyasingh
- Department of Integrative Biology, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Lawrence J Weider
- Department of Biology, Program in Ecology and Evolutionary Biology, University of Oklahoma, Norman, Oklahoma, USA
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12
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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.
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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.
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13
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Patton DL, Cardenas T, Mele P, Navarro J, Sung W. CDMAP/CDVIS: context-dependent mutation analysis package and visualization software. G3 (BETHESDA, MD.) 2022; 13:6887836. [PMID: 36917690 PMCID: PMC10085751 DOI: 10.1093/g3journal/jkac299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2022] [Accepted: 10/17/2022] [Indexed: 12/15/2022]
Abstract
The Context-dependent Mutation Analysis Package and Visualization Software (CDMAP/CDVIS) is an automated, modular toolkit used for the analysis and visualization of context-dependent mutation patterns (site-specific variation in mutation rate from neighboring-nucleotide effects). The CDMAP computes context-dependent mutation rates using a Variant Call File (VCF), Genbank file, and reference genome and can generate high-resolution figures to analyze variation in mutation rate across spatiotemporal scales. This algorithm has been benchmarked against mutation accumulation data but can also be used to calculate context-dependent mutation rates for polymorphism or closely related species as long as the input requirements are met. Output from CDMAP can be integrated into CDVIS, an interactive database for visualizing mutation patterns across multiple taxa simultaneously.
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Affiliation(s)
- David L Patton
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC, 28223, USA
| | - Thomas Cardenas
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC, 28223, USA
| | - Perrin Mele
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC, 28223, USA
| | - Jon Navarro
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC, 28223, USA
| | - Way Sung
- Department of Bioinformatics and Genomics, University of North Carolina at Charlotte, 9201 University City Boulevard, Charlotte, NC, 28223, USA
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14
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Peres PA, Bracken-Grissom H, Timm LE, Mantelatto FL. Genomic Analyses Implicate the Amazon-Orinoco Plume as the Driver of Cryptic Speciation in a Swimming Crab. Genes (Basel) 2022; 13:genes13122263. [PMID: 36553531 PMCID: PMC9777557 DOI: 10.3390/genes13122263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 11/25/2022] [Accepted: 11/25/2022] [Indexed: 12/04/2022] Open
Abstract
The Amazon-Orinoco plume (AOP) is the world's largest freshwater and sediment discharge into the ocean. Previous studies limited to mtDNA suggest that the swimming crab Callinectes ornatus Ordway, 1863 exists as two distinct genetic clusters separated by the AOP. However, questions concerning migration, diversification time, and species delimitation are unresolved. Densely sampling markers across the genome (SNPs) could elucidate the evolutionary processes within this species. Here, we combined mtDNA data and ddRAD-seq to explore the diversification patterns and processes within the swimming crab C. ornatus. We show great genetic differentiation between groups on the north and south sides of the plume but also signs of hybridization. Demographic modeling indicates the divergence between groups starting around 8 Mya following the AOP's formation. After a period of isolation, we detect two incidences of secondary contact with stronger migration in concordance with the North Brazil Current flow. Our results suggest speciation with gene flow explained by the interplay among the AOP, oceanographic currents, and long larval dispersal. This work represents the first investigation employing ddRAD-seq in a marine invertebrate species with distribution encompassing the north and south Atlantic and sheds light on the role of the AOP in the diversification of a marine species.
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Affiliation(s)
- Pedro A. Peres
- Department of Biology, Institute of Environment, Florida International University (FIU), Miami, FL 33199, USA
- Laboratory of Bioecology and Systematics of Crustaceans (LBSC), Faculty of Philosophy, Sciences and Letters at Ribeirão Preto (FFCLRP), University of São Paulo (USP), Ribeirão Preto 14040-901, Brazil
- Correspondence:
| | - Heather Bracken-Grissom
- Department of Biology, Institute of Environment, Florida International University (FIU), Miami, FL 33199, USA
- Department of Invertebrate Zoology, National Museum of Natural History-Smithsonian, Washington, WA 20013-7012, USA
| | - Laura E. Timm
- College of Fisheries and Ocean Sciences, University of Alaska Fairbanks, Fairbanks, AK 99775, USA
- Auke Bay Laboratories, Alaska Fisheries Science Center, NOAA National Marine Fisheries Service, Juneau, AK 99801, USA
| | - Fernando L. Mantelatto
- Laboratory of Bioecology and Systematics of Crustaceans (LBSC), Faculty of Philosophy, Sciences and Letters at Ribeirão Preto (FFCLRP), University of São Paulo (USP), Ribeirão Preto 14040-901, Brazil
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15
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Ba Q, Zhou J, Li J, Cheng S, Zhang X, Wang H. Mutagenic Characteristics of Six Heavy Metals in Escherichia coli: The Commonality and Specificity. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2022; 56:13867-13877. [PMID: 36121417 PMCID: PMC9536316 DOI: 10.1021/acs.est.2c04785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2022] [Revised: 08/27/2022] [Accepted: 08/31/2022] [Indexed: 06/15/2023]
Abstract
The history of long-term environmental exposure to heavy metals can be recorded in the genome as sporadic and specific mutations. Variable environments introduce diverse and adaptive mutations to organisms. To reveal the information hidden in genomes about environmental exposure to heavy metals, we performed long-term mutation accumulation (MA) experiments with Escherichia coli, analyzed genomes from 36 populations across 1650 generations with 6 heavy metal exposure regimes (arsenic, cadmium, chromium, copper, nickel, and lead), and inferred metal-specific evolution modes at the genomic level. All heavy metals induced genetic mutations with a mean rate of 3.459 × 10-9 per nucleotide per generation. The mutational spectrum exhibited distinct signatures; however, heavy metals also shared common mutation signatures prominently associated with all cancer types. The mutated genes showed an average similarity of 54.4% within the same exposure regime, whereas only 38.8% between exposure regimes. In terms of biological insights, mutated genes were enriched to fundamental cellular processes such as metabolism, motility, and transport. Our study elucidates the mutagenic commonality and specificity of environmental heavy metals, which are highly specific at mutational features and locus, but conserved at gene and functional levels, and may play crucial roles in the convergence of adaptation to heavy metals.
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Affiliation(s)
- Qian Ba
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jingqi Zhou
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Jingquan Li
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Shujun Cheng
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
| | - Xiaokang Zhang
- School
of Public Health and Health Management, Gannan Medical University, Ganzhou 341000, China
| | - Hui Wang
- State
Key Laboratory of Oncogenes and Related Genes, Center for Single-Cell
Omics, School of Public Health, Shanghai
Jiao Tong University School of Medicine, Shanghai 200025, China
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16
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Abstract
The ways in which genetic variation is distributed within and among populations is a key determinant of the evolutionary features of a species. However, most comprehensive studies of these features have been restricted to studies of subdivision in settings known to have been driven by local adaptation, leaving our understanding of the natural dispersion of allelic variation less than ideal. Here, we present a geographic population-genomic analysis of 10 populations of the freshwater microcrustacean Daphnia pulex, an emerging model system in evolutionary genomics. These populations exhibit a pattern of moderate isolation-by-distance, with an average migration rate of 0.6 individuals per generation, and average effective population sizes of ∼650,000 individuals. Most populations contain numerous private alleles, and genomic scans highlight the presence of islands of excessively high population subdivision for more common alleles. A large fraction of such islands of population divergence likely reflect historical neutral changes, including rare stochastic migration and hybridization events. The data do point to local adaptive divergence, although the precise nature of the relevant variation is diffuse and cannot be associated with particular loci, despite the very large sample sizes involved in this study. In contrast, an analysis of between-species divergence highlights positive selection operating on a large set of genes with functions nearly nonoverlapping with those involved in local adaptation, in particular ribosome structure, mitochondrial bioenergetics, light reception and response, detoxification, and gene regulation. These results set the stage for using D. pulex as a model for understanding the relationship between molecular and cellular evolution in the context of natural environments.
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Affiliation(s)
- Takahiro Maruki
- Biodesign Center for Mechanisms of Evolution, Arizona State Univ., Tempe, AZ 85287USA
| | - Zhiqiang Ye
- Biodesign Center for Mechanisms of Evolution, Arizona State Univ., Tempe, AZ 85287USA
| | - Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State Univ., Tempe, AZ 85287USA
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17
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Ohtsuki H, Norimatsu H, Makino T, Urabe J. Invasions of an obligate asexual daphnid species support the nearly neutral theory. Sci Rep 2022; 12:7305. [PMID: 35508526 PMCID: PMC9068809 DOI: 10.1038/s41598-022-11218-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 04/20/2022] [Indexed: 11/09/2022] Open
Abstract
To verify the "nearly neutral theory (NNT)," the ratio of nonsynonymous to synonymous substitutions (dN/dS) was compared among populations of different species. To determine the validity of NNT, however, populations that are genetically isolated from each other but share the same selection agents and differ in size should be compared. Genetically different lineages of obligate asexual Daphnia pulex invading Japan from North America are an ideal example as they satisfy these prerequisites. Therefore, we analyzed the whole-genome sequences of 18 genotypes, including those of the two independently invaded D. pulex lineages (JPN1 and JPN2) and compared the dN/dS ratio between the lineages. The base substitution rate of each genotype demonstrated that the JPN1 lineage having a larger distribution range diverged earlier and thus was older than the JPN2 lineage. Comparisons of the genotypes within lineages revealed that changes in dN/dS occurred after the divergence and were larger in the younger lineage, JPN2. These results imply that the JPN1 lineage has been more effectively subjected to purification selections, while slightly deteriorating mutations are less purged in JPN2 with smaller population size. Altogether, the lineage-specific difference in the dN/dS ratio for the obligate asexual D. pulex was well explained by the NNT.
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Affiliation(s)
- Hajime Ohtsuki
- Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| | - Hirotomo Norimatsu
- Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| | - Takashi Makino
- Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan
| | - Jotaro Urabe
- Graduate School of Life Sciences, Tohoku University, 6-3 Aoba, Aramaki, Aoba-ku, Sendai, 980-8578, Japan.
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18
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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.
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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
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19
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Fields PD, McTaggart S, Reisser CMO, Haag C, Palmer WH, Little TJ, Ebert D, Obbard DJ. Population-genomic analysis identifies a low rate of global adaptive fixation in the proteins of the cyclical parthenogen Daphnia magna. Mol Biol Evol 2022; 39:6542319. [PMID: 35244177 PMCID: PMC8963301 DOI: 10.1093/molbev/msac048] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Daphnia are well-established ecological and evolutionary models, and the interaction between D. magna and its microparasites is widely considered a paragon of the host-parasite coevolutionary process. Like other well-studied arthropods such as Drosophila melanogaster and Anopheles gambiae, D. magna is a small, widespread, and abundant species that is therefore expected to display a large long-term population size and high rates of adaptive protein evolution. However, unlike these other species, D. magna is cyclically asexual and lives in a highly structured environment (ponds and lakes) with moderate levels of dispersal, both of which are predicted to impact upon long-term effective population size and adaptive protein evolution. To investigate patterns of adaptive protein fixation, we produced the complete coding genomes of 36 D. magna clones sampled from across the European range (Western Palaearctic), along with draft sequences for the close relatives D. similis and D. lumholtzi, used as outgroups. We analyzed genome-wide patterns of adaptive fixation, with a particular focus on genes that have an a priori expectation of high rates, such as those likely to mediate immune responses, RNA interference against viruses and transposable elements, and those with a strongly male-biased expression pattern. We find that, as expected, D. magna displays high levels of diversity and that this is highly structured among populations. However, compared with Drosophila, we find that D. magna proteins appear to have a high proportion of weakly deleterious variants and do not show evidence of pervasive adaptive fixation across its entire range. This is true of the genome as a whole, and also of putative ‘arms race’ genes that often show elevated levels of adaptive substitution in other species. In addition to the likely impact of extensive, and previously documented, local adaptation, we speculate that these findings may reflect reduced efficacy of selection associated with cyclical asexual reproduction.
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Affiliation(s)
- Peter D Fields
- University of Basel, Department of Environmental Sciences, Zoology, Vesalgasse 1, Basel, CH-4051, Switzerland
| | - Seanna McTaggart
- Institute of Evolutionary Biology; School of Biological Sciences University of Edinburgh, Edinburgh, EH9 3JT, United Kingdom
| | - Céline M O Reisser
- Centre d'Ecologie Fonctionnelle et Evolutive CEFE UMR 5175, Univ Montpellier, CNRS, EPHE, IRD, Univ Paul Valéry Montpellier 3, campus CNRS, 1919, route de Mende, 34293 Montpellier Cedex 5, France.,MARBEC, Univ Montpellier, CNRS, IFREMER, IRD, Montpellier, France
| | - Christoph Haag
- Centre d'Ecologie Fonctionnelle et Evolutive CEFE UMR 5175, Univ Montpellier, CNRS, EPHE, IRD, Univ Paul Valéry Montpellier 3, campus CNRS, 1919, route de Mende, 34293 Montpellier Cedex 5, France
| | - William H Palmer
- Institute of Evolutionary Biology; School of Biological Sciences University of Edinburgh, Edinburgh, EH9 3JT, United Kingdom
| | - Tom J Little
- Institute of Evolutionary Biology; School of Biological Sciences University of Edinburgh, Edinburgh, EH9 3JT, United Kingdom
| | - Dieter Ebert
- University of Basel, Department of Environmental Sciences, Zoology, Vesalgasse 1, Basel, CH-4051, Switzerland
| | - Darren J Obbard
- Institute of Evolutionary Biology; School of Biological Sciences University of Edinburgh, Edinburgh, EH9 3JT, United Kingdom
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20
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Kato K, Okamura K, Hiki K, Kintsu H, Nohara K, Yamagishi T, Nakajima N, Watanabe H, Yamamoto H. Potential differences in chitin synthesis ability cause different sensitivities to diflubenzuron among three strains of Daphnia magna. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2022; 243:106071. [PMID: 34995867 DOI: 10.1016/j.aquatox.2021.106071] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2021] [Revised: 12/24/2021] [Accepted: 12/26/2021] [Indexed: 06/14/2023]
Abstract
Ecotoxicity testing of crustaceans using Daphnia magna has been implemented in the chemical management systems of various countries. While the chemical sensitivity of D. magna varies depending on genetically different clonal lineages, the strain used in ecotoxicity tests, including the acute immobilization test (OECD TG202), has not been specified. We hypothesized that comprehensive gene expression profiles could provide useful information on phenotypic differences among strains, including chemical sensitivity. To test this hypothesis, we performed mRNA sequencing on three different strains (NIES, England, and Clone 5) of D. magna under culture conditions. The resulting expression profile of the NIES strain was clearly different compared to the profiles of the other two strains. Gene ontology (GO) enrichment analysis suggested that chitin metabolism was significantly enriched in the NIES strain compared to that in the England strain. Consistent with the GO analysis, evidence of high levels of chitin metabolism in the NIES strain were observed across multiple levels of biological organization, such as expression of chitin synthase genes, chitin content, and chitinase activity, which suggested that the different strains would exhibit different sensitivities to chemicals used to inhibit chitin synthesis. We found that among all strains, the NIES strain was more tolerant to diflubenzuron, a chitin synthesis inhibitor, with a 14-fold difference in the 48 h-EC50 value for the acute immobilization test compared to the England strain. The present study demonstrates that the differences among strains in chitin metabolism may lead to sensitivity difference to diflubenzuron, and serves as a case study of the usefulness of comprehensive gene expression profiles in finding sensitivity differences.
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Affiliation(s)
- Kota Kato
- Department of Natural Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8563, Japan; Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Kazuyuki Okamura
- Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Kyoshiro Hiki
- Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Hiroyuki Kintsu
- Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Keiko Nohara
- Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Takahiro Yamagishi
- Department of Natural Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8563, Japan; Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Nobuyoshi Nakajima
- Biodiversity Division, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Haruna Watanabe
- Department of Natural Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8563, Japan; Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan
| | - Hiroshi Yamamoto
- Department of Natural Environmental Studies, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba 277-8563, Japan; Health and Environmental Risk Division, National Institute for Environmental Studies (NIES), 16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japan.
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21
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Wang S, Li Y, Zhong L, Wu K, Zhang R, Kang T, Wu S, Wu Y. Efficient gene editing through an intronic selection marker in cells. Cell Mol Life Sci 2022; 79:111. [PMID: 35098362 PMCID: PMC8801403 DOI: 10.1007/s00018-022-04152-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 01/10/2022] [Accepted: 01/14/2022] [Indexed: 02/05/2023]
Abstract
BACKGROUND Gene editing technology has provided researchers with the ability to modify genome sequences in almost all eukaryotes. Gene-edited cell lines are being used with increasing frequency in both bench research and targeted therapy. However, despite the great importance and universality of gene editing, the efficiency of homology-directed DNA repair (HDR) is too low, and base editors (BEs) cannot accomplish desired indel editing tasks. RESULTS AND DISCUSSION Our group has improved HDR gene editing technology to indicate DNA variation with an independent selection marker using an HDR strategy, which we named Gene Editing through an Intronic Selection marker (GEIS). GEIS uses a simple process to avoid nonhomologous end joining (NHEJ)-mediated false-positive effects and achieves a DsRed positive rate as high as 87.5% after two rounds of fluorescence-activated cell sorter (FACS) selection without disturbing endogenous gene splicing and expression. We re-examined the correlation of the conversion tract and efficiency, and our data suggest that GEIS has the potential to edit approximately 97% of gene editing targets in human and mouse cells. The results of further comprehensive analysis suggest that the strategy may be useful for introducing multiple DNA variations in cells.
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Affiliation(s)
- Shang Wang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Department of Experimental Research, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, China
- Institute of Urology, The Third Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China
| | - Yuqing Li
- Institute of Urology, The Third Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China
- Teaching Center of Shenzhen Luohu Hospital, Shantou University Medical College, Shantou, 515000, China
| | - Li Zhong
- Center of Digestive Diseases, The Seventh Affiliated Hospital of Sun Yat-Sen University, Shenzhen, 518107, China
- Scientific Research Center, The Seventh Affiliated Hospital of Sun Yat-Sen University, Shenzhen, 518107, China
| | - Kai Wu
- Institute of Urology, The Third Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China
| | - Ruhua Zhang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Department of Experimental Research, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, China
| | - Tiebang Kang
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Department of Experimental Research, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, China
| | - Song Wu
- Institute of Urology, The Third Affiliated Hospital of Shenzhen University, Shenzhen, 518000, China.
- Teaching Center of Shenzhen Luohu Hospital, Shantou University Medical College, Shantou, 515000, China.
- Department of Urology, South China Hospital of Shenzhen University, Shenzhen, 518000, China.
| | - Yuanzhong Wu
- State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Department of Experimental Research, Sun Yat-Sen University Cancer Center, Guangzhou, 510060, China.
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22
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Tomanek I, Guet CC. Adaptation dynamics between copy-number and point mutations. eLife 2022; 11:82240. [PMID: 36546673 PMCID: PMC9833825 DOI: 10.7554/elife.82240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 12/20/2022] [Indexed: 12/24/2022] Open
Abstract
Together, copy-number and point mutations form the basis for most evolutionary novelty, through the process of gene duplication and divergence. While a plethora of genomic data reveals the long-term fate of diverging coding sequences and their cis-regulatory elements, little is known about the early dynamics around the duplication event itself. In microorganisms, selection for increased gene expression often drives the expansion of gene copy-number mutations, which serves as a crude adaptation, prior to divergence through refining point mutations. Using a simple synthetic genetic reporter system that can distinguish between copy-number and point mutations, we study their early and transient adaptive dynamics in real time in Escherichia coli. We find two qualitatively different routes of adaptation, depending on the level of functional improvement needed. In conditions of high gene expression demand, the two mutation types occur as a combination. However, under low gene expression demand, copy-number and point mutations are mutually exclusive; here, owing to their higher frequency, adaptation is dominated by copy-number mutations, in a process we term amplification hindrance. Ultimately, due to high reversal rates and pleiotropic cost, copy-number mutations may not only serve as a crude and transient adaptation, but also constrain sequence divergence over evolutionary time scales.
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Affiliation(s)
- Isabella Tomanek
- Institute of Science and Technology AustriaKlosterneuburgAustria
| | - Călin C Guet
- Institute of Science and Technology AustriaKlosterneuburgAustria
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23
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Ho EKH, Schaack S. Intraspecific Variation in the Rates of Mutations Causing Structural Variation in Daphnia magna. Genome Biol Evol 2021; 13:6444992. [PMID: 34849778 PMCID: PMC8691059 DOI: 10.1093/gbe/evab241] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2021] [Indexed: 12/17/2022] Open
Abstract
Mutations that cause structural variation are important sources of genetic variation upon which other evolutionary forces can act, however, they are difficult to observe and therefore few direct estimates of their rate and spectrum are available. Understanding mutation rate evolution, however, requires adding to the limited number of species for which direct estimates are available, quantifying levels of intraspecific variation in mutation rates, and assessing whether rate estimates co-vary across types of mutation. Here, we report structural variation-causing mutation rates (svcMRs) for six categories of mutations (short insertions and deletions, long deletions and duplications, and deletions and duplications at copy number variable sites) from nine genotypes of Daphnia magna collected from three populations in Finland, Germany, and Israel using a mutation accumulation approach. Based on whole-genome sequence data and validated using simulations, we find svcMRs are high (two orders of magnitude higher than base substitution mutation rates measured in the same lineages), highly variable among populations, and uncorrelated across categories of mutation. Furthermore, to assess the impact of scvMRs on the genome, we calculated rates while adjusting for the lengths of events and ran simulations to determine if the mutations occur in genic regions more or less frequently than expected by chance. Our results pose a challenge to most prevailing theories aimed at explaining the evolution of the mutation rate, underscoring the importance of obtaining additional mutation rate estimates in more genotypes, for more types of mutation, in more species, in order to improve our future understanding of mutation rates, their variation, and their evolution.
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Affiliation(s)
- Eddie K H Ho
- Department of Biology, Reed College, Portland, Oregon, USA
| | - Sarah Schaack
- Department of Biology, Reed College, Portland, Oregon, USA
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24
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Ye Z, Jiang X, Pfrender ME, Lynch M. Genome-Wide Allele-Specific Expression in Obligately Asexual Daphnia pulex and the Implications for the Genetic Basis of Asexuality. Genome Biol Evol 2021; 13:6415829. [PMID: 34726699 PMCID: PMC8598174 DOI: 10.1093/gbe/evab243] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2021] [Indexed: 01/17/2023] Open
Abstract
Although obligately asexual lineages are thought to experience selective disadvantages associated with reduced efficiency of fixing beneficial mutations and purging deleterious mutations, such lineages are phylogenetically and geographically widespread. However, despite several genome-wide association studies, little is known about the genetic elements underlying the origin of obligate asexuality and how they spread. Because many obligately asexual lineages have hybrid origins, it has been suggested that asexuality is caused by the unbalanced expression of alleles from the hybridizing species. Here, we investigate this idea by identifying genes with allele-specific expression (ASE) in a Daphnia pulex population, in which obligate parthenogens (OP) and cyclical parthenogens (CP) coexist, with the OP clones having been originally derived from hybridization between CP D. pulex and its sister species, Daphnia pulicaria. OP D. pulex have significantly more ASE genes (ASEGs) than do CP D. pulex. Whole-genomic comparison of OP and CP clones revealed ∼15,000 OP-specific markers and 42 consistent ASEGs enriched in marker-defined regions. Ten of the 42 ASEGs have alleles coding for different protein sequences, suggesting functional differences between the products of the two parental alleles. At least three of these ten genes appear to be directly involved in meiosis-related processes, for example, RanBP2 can cause abnormal chromosome segregation in anaphase I, and the presence of Wee1 in immature oocytes leads to failure to enter meiosis II. These results provide a guide for future molecular resolution of the genetic basis of the transition to ameiotic parthenogenesis.
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Affiliation(s)
- Zhiqiang Ye
- Center for Mechanisms of Evolution, Arizona State University, Tempe, Arizona
| | | | - Michael E Pfrender
- Department of Biological Sciences and Environmental Change Initiative, University of Notre Dame, Notre Dame, Indiana
| | - Michael Lynch
- Center for Mechanisms of Evolution, Arizona State University, Tempe, Arizona
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25
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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.
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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.
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26
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O'Grady CJ, Dhandapani V, Colbourne JK, Frisch D. Refining the evolutionary time machine: An assessment of whole genome amplification using single historical Daphnia eggs. Mol Ecol Resour 2021; 22:946-961. [PMID: 34672105 DOI: 10.1111/1755-0998.13524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 09/03/2021] [Accepted: 09/07/2021] [Indexed: 12/14/2022]
Abstract
Whole genome sequencing is instrumental for the study of genome variation in natural populations, delivering important knowledge on genomic modifications and potential targets of natural selection at the population level. Large dormant eggbanks of aquatic invertebrates such as the keystone herbivore Daphnia, a microcrustacean widespread in freshwater ecosystems, provide detailed sedimentary archives to study genomic processes over centuries. To overcome the problem of limited DNA amounts in single Daphnia dormant eggs, we developed an optimized workflow for whole genome amplification (WGA), yielding sufficient amounts of DNA for downstream whole genome sequencing of individual historical eggs, including polyploid lineages. We compare two WGA kits, applied to recently produced Daphnia magna dormant eggs from laboratory cultures, and to historical dormant eggs of Daphnia pulicaria collected from Arctic lake sediment between 10 and 300 years old. Resulting genome coverage breadth in most samples was ~70%, including those from >100-year-old isolates. Sequence read distribution was highly correlated among samples amplified with the same kit, but less correlated between kits. Despite this, a high percentage of genomic positions with single nucleotide polymorphisms in one or more samples (maximum of 74% between kits, and 97% within kits) were recovered at a depth required for genotyping. As a by-product of sequencing we obtained 100% coverage of the mitochondrial genomes even from the oldest isolates (~300 years). The mitochondrial DNA provides an additional source for evolutionary studies of these populations. We provide an optimized workflow for WGA followed by whole genome sequencing including steps to minimize exogenous DNA.
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Affiliation(s)
- Christopher James O'Grady
- School of Life Sciences, University of Warwick, Coventry, UK.,Cell and Gene Therapy Catapult, London, UK.,School of Biosciences, University of Birmingham, Birmingham, UK
| | | | | | - Dagmar Frisch
- School of Biosciences, University of Birmingham, Birmingham, UK.,Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
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27
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Keith N, Jackson CE, Glaholt SP, Young K, Lynch M, Shaw JR. Genome-Wide Analysis of Cadmium-Induced, Germline Mutations in a Long-Term Daphnia pulex Mutation-Accumulation Experiment. ENVIRONMENTAL HEALTH PERSPECTIVES 2021; 129:107003. [PMID: 34623885 PMCID: PMC8500294 DOI: 10.1289/ehp8932] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 09/15/2021] [Accepted: 09/21/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Germline mutations provide the raw material for all evolutionary processes and contribute to the occurrence of spontaneous human diseases and disorders. Yet despite the daily interaction of humans and other organisms with an increasing number of chemicals that are potentially mutagenic, precise measurements of chemically induced changes to the genome-wide rate and spectrum of germline mutation are lacking. OBJECTIVES A large-scale Daphnia pulex mutation-accumulation experiment was propagated in the presence and absence of an environmentally relevant cadmium concentration to quantify the influence of cadmium on germline mutation rates and spectra. RESULTS Cadmium exposure dramatically changed the genome-wide rates and regional spectra of germline mutations. In comparison with those in control conditions, Daphnia exposed to cadmium had a higher overall A:T→G:C mutation rates and a lower overall C:G→G:C mutation rate. Daphnia exposed to cadmium had a higher intergenic mutation rate and a lower exonic mutation rate. The higher intergenic mutation rate under cadmium exposure was the result of an elevated intergenic A:T→G:C rate, whereas the lower exon mutation rate in cadmium was the result of a complete loss of exonic C:G→G:C mutations-mutations that are known to be enriched at 5-hydroxymethylcytosine. We experimentally show that cadmium exposure significantly reduced 5-hydroxymethylcytosine levels. DISCUSSION These results provide evidence that cadmium changes regional mutation rates and can influence regional rates by interfering with an epigenetic process in the Daphnia pulex germline. We further suggest these observed cadmium-induced changes to the Daphnia germline mutation rate may be explained by cadmium's inhibition of zinc-containing domains. The cadmium-induced changes to germline mutation rates and spectra we report provide a comprehensive view of the mutagenic perils of cadmium and give insight into its potential impact on human population health. https://doi.org/10.1289/EHP8932.
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Affiliation(s)
- Nathan Keith
- O’Neill School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana, USA
| | - Craig E. Jackson
- O’Neill School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana, USA
| | - Stephen P. Glaholt
- O’Neill School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana, USA
| | - Kimberly Young
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Michael Lynch
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, Arizona, USA
| | - Joseph R. Shaw
- O’Neill School of Public and Environmental Affairs, Indiana University, Bloomington, Indiana, USA
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28
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Assis R. No Expression Divergence despite Transcriptional Interference between Nested Protein-Coding Genes in Mammals. Genes (Basel) 2021; 12:genes12091381. [PMID: 34573363 PMCID: PMC8467205 DOI: 10.3390/genes12091381] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 08/23/2021] [Accepted: 08/24/2021] [Indexed: 01/05/2023] Open
Abstract
Nested protein-coding genes accumulated throughout metazoan evolution, with early analyses of human and Drosophila microarray data indicating that this phenomenon was simply due to the presence of large introns. However, a recent study employing RNA-seq data uncovered evidence of transcriptional interference driving rapid expression divergence between Drosophila nested genes, illustrating that accurate expression estimation of overlapping genes can enhance detection of their relationships. Hence, here I apply an analogous approach to strand-specific RNA-seq data from human and mouse to revisit the role of transcriptional interference in the evolution of mammalian nested genes. A genomic survey reveals that whereas mammalian nested genes indeed accrued over evolutionary time, they are retained at lower frequencies than in Drosophila. Though several properties of mammalian nested genes align with observations in Drosophila and with expectations under transcriptional interference, contrary to both, their expression divergence is not statistically different from that between unnested genes, and also does not increase after nesting. Together, these results support the hypothesis that lower selection efficiencies limit rates of gene expression evolution in mammals, leading to their reliance on immediate eradication of deleterious nested genes to avoid transcriptional interference.
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Affiliation(s)
- Raquel Assis
- Department of Electrical Engineering and Computer Science, Institute for Human Health and Disease Intervention, Florida Atlantic University, Boca Raton, FL 33431, USA
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29
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Extensive standing genetic variation from a small number of founders enables rapid adaptation in Daphnia. Nat Commun 2021; 12:4306. [PMID: 34262034 PMCID: PMC8280168 DOI: 10.1038/s41467-021-24581-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Accepted: 06/24/2021] [Indexed: 02/06/2023] Open
Abstract
We lack a thorough understanding of the origin and maintenance of standing genetic variation that enables rapid evolutionary responses of natural populations. Whole genome sequencing of a resurrected Daphnia population shows that standing genetic variation in over 500 genes follows an evolutionary trajectory that parallels the pronounced and rapid adaptive evolution of multiple traits in response to predator-driven natural selection and its subsequent relaxation. Genetic variation carried by only five founding individuals from the regional genotype pool is shown to suffice at enabling the observed evolution. Our results provide insight on how natural populations can acquire the genomic variation, through colonization by a few regional genotypes, that fuels rapid evolution in response to strong selection pressures. While these evolutionary responses in our study population involved hundreds of genes, we observed no evidence of genetic erosion.
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30
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DeGiorgio M, Assis R. Learning Retention Mechanisms and Evolutionary Parameters of Duplicate Genes from Their Expression Data. Mol Biol Evol 2021; 38:1209-1224. [PMID: 33045078 PMCID: PMC7947822 DOI: 10.1093/molbev/msaa267] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Learning about the roles that duplicate genes play in the origins of novel phenotypes requires an understanding of how their functions evolve. A previous method for achieving this goal, CDROM, employs gene expression distances as proxies for functional divergence and then classifies the evolutionary mechanisms retaining duplicate genes from comparisons of these distances in a decision tree framework. However, CDROM does not account for stochastic shifts in gene expression or leverage advances in contemporary statistical learning for performing classification, nor is it capable of predicting the parameters driving duplicate gene evolution. Thus, here we develop CLOUD, a multi-layer neural network built on a model of gene expression evolution that can both classify duplicate gene retention mechanisms and predict their underlying evolutionary parameters. We show that not only is the CLOUD classifier substantially more powerful and accurate than CDROM, but that it also yields accurate parameter predictions, enabling a better understanding of the specific forces driving the evolution and long-term retention of duplicate genes. Further, application of the CLOUD classifier and predictor to empirical data from Drosophila recapitulates many previous findings about gene duplication in this lineage, showing that new functions often emerge rapidly and asymmetrically in younger duplicate gene copies, and that functional divergence is driven by strong natural selection. Hence, CLOUD represents a major advancement in classifying retention mechanisms and predicting evolutionary parameters of duplicate genes, thereby highlighting the utility of incorporating sophisticated statistical learning techniques to address long-standing questions about evolution after gene duplication.
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Affiliation(s)
- Michael DeGiorgio
- Department of Computer and Electrical Engineering and Computer Science, Florida Atlantic University, Boca Raton, FL 33431.,Institute for Human Health and Disease Intervention, Florida Atlantic University, Boca Raton, FL 33431
| | - Raquel Assis
- Department of Computer and Electrical Engineering and Computer Science, Florida Atlantic University, Boca Raton, FL 33431.,Institute for Human Health and Disease Intervention, Florida Atlantic University, Boca Raton, FL 33431
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31
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Silliman K, Indorf JL, Knowlton N, Browne WE, Hurt C. Base-substitution mutation rate across the nuclear genome of Alpheus snapping shrimp and the timing of isolation by the Isthmus of Panama. BMC Ecol Evol 2021; 21:104. [PMID: 34049492 PMCID: PMC8164322 DOI: 10.1186/s12862-021-01836-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 04/06/2021] [Indexed: 11/17/2022] Open
Abstract
Background The formation of the Isthmus of Panama and final closure of the Central American Seaway (CAS) provides an independent calibration point for examining the rate of DNA substitutions. This vicariant event has been widely used to estimate the substitution rate across mitochondrial genomes and to date evolutionary events in other taxonomic groups. Nuclear sequence data is increasingly being used to complement mitochondrial datasets for phylogenetic and evolutionary investigations; these studies would benefit from information regarding the rate and pattern of DNA substitutions derived from the nuclear genome. Results To estimate the genome-wide neutral mutation rate (µ), genotype-by-sequencing (GBS) datasets were generated for three transisthmian species pairs in Alpheus snapping shrimp. A range of bioinformatic filtering parameters were evaluated in order to minimize potential bias in mutation rate estimates that may result from SNP filtering. Using a Bayesian coalescent approach (G-PhoCS) applied to 44,960 GBS loci, we estimated µ to be 2.64E−9 substitutions/site/year, when calibrated with the closure of the CAS at 3 Ma. Post-divergence gene flow was detected in one species pair. Failure to account for this post-split migration inflates our substitution rate estimates, emphasizing the importance of demographic methods that can accommodate gene flow. Conclusions Results from our study, both parameter estimates and bioinformatic explorations, have broad-ranging implications for phylogeographic studies in other non-model taxa using reduced representation datasets. Our best estimate of µ that accounts for coalescent and demographic processes is remarkably similar to experimentally derived mutation rates in model arthropod systems. These results contradicted recent suggestions that the closure of the Isthmus was completed much earlier (around 10 Ma), as mutation rates based on an early calibration resulted in uncharacteristically low genomic mutation rates. Also, stricter filtering parameters resulted in biased datasets that generated lower mutation rate estimates and influenced demographic parameters, serving as a cautionary tale for the adherence to conservative bioinformatic strategies when generating reduced-representation datasets at the species level. To our knowledge this is the first use of transisthmian species pairs to calibrate the rate of molecular evolution from GBS data. Supplementary Information The online version contains supplementary material available at 10.1186/s12862-021-01836-3.
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Affiliation(s)
- Katherine Silliman
- School of Fisheries, Aquaculture, and Aquatic Sciences, Auburn University, Auburn, AL, 36849, USA. .,Committee on Evolutionary Biology, University of Chicago, Chicago, IL, 60637, USA.
| | - Jane L Indorf
- Department of Biology, University of Miami, Coral Gables, FL, 33146, USA
| | - Nancy Knowlton
- National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - William E Browne
- Department of Biology, University of Miami, Coral Gables, FL, 33146, USA
| | - Carla Hurt
- Department of Biology, University of Miami, Coral Gables, FL, 33146, USA.,Department of Biology, Tennessee Tech University, Cookeville, TN, 38505, USA
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32
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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.
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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
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33
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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.
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34
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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.
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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
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35
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Davenport ES, Agrelius TC, Harmon KB, Dudycha JL. Fitness effects of spontaneous mutations in a warming world. Evolution 2021; 75:1513-1524. [PMID: 33751559 PMCID: PMC8252619 DOI: 10.1111/evo.14208] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 02/09/2021] [Accepted: 02/16/2021] [Indexed: 12/14/2022]
Abstract
Spontaneous mutations fuel evolutionary processes and differ in consequence, but the consequences depend on the environment. Biophysical considerations of protein thermostability predict that warm temperatures may systematically increase the deleteriousness of mutation. We sought to test whether mutation reduced fitness more when measured in an environment that reflected climate change projections for temperature. We investigated the effects of spontaneous mutations on life history, size, and fitness in 21 mutation accumulation lines and 12 control lines of Daphnia pulex at standard and elevated (+4℃) temperatures. Warmer temperature accelerated life history and reduced body length and clutch sizes. Mutation led to reduced mean clutch sizes and fitness estimates at both temperatures. We found no evidence of a systematic temperature–mutation interaction on trait means, although some lines showed evidence of beneficial mutation at one temperature and deleterious mutation at the other. However, trait variances are also influenced by mutation, and we observed increased variances due to mutation for most traits. For variance of the intrinsic rate of increase and some reproductive traits, we found significant temperature–mutation interactions, with a larger increase due to mutation in the warmer environment. This suggests that selection on new mutations will be more efficient at elevated temperatures.
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Affiliation(s)
- Elizabeth S Davenport
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, 29208.,Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, 48109
| | - Trenton C Agrelius
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, 29208
| | - Krista B Harmon
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, 29208
| | - Jeffry L Dudycha
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina, 29208
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36
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Jaron KS, Bast J, Nowell RW, Ranallo-Benavidez TR, Robinson-Rechavi M, Schwander T. Genomic Features of Parthenogenetic Animals. J Hered 2021; 112:19-33. [PMID: 32985658 PMCID: PMC7953838 DOI: 10.1093/jhered/esaa031] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 08/17/2020] [Indexed: 12/21/2022] Open
Abstract
Evolution without sex is predicted to impact genomes in numerous ways. Case studies of individual parthenogenetic animals have reported peculiar genomic features that were suggested to be caused by their mode of reproduction, including high heterozygosity, a high abundance of horizontally acquired genes, a low transposable element load, or the presence of palindromes. We systematically characterized these genomic features in published genomes of 26 parthenogenetic animals representing at least 18 independent transitions to asexuality. Surprisingly, not a single feature was systematically replicated across a majority of these transitions, suggesting that previously reported patterns were lineage-specific rather than illustrating the general consequences of parthenogenesis. We found that only parthenogens of hybrid origin were characterized by high heterozygosity levels. Parthenogens that were not of hybrid origin appeared to be largely homozygous, independent of the cellular mechanism underlying parthenogenesis. Overall, despite the importance of recombination rate variation for the evolution of sexual animal genomes, the genome-wide absence of recombination does not appear to have had the dramatic effects which are expected from classical theoretical models. The reasons for this are probably a combination of lineage-specific patterns, the impact of the origin of parthenogenesis, and a survivorship bias of parthenogenetic lineages.
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Affiliation(s)
- Kamil S Jaron
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Jens Bast
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Reuben W Nowell
- Department of Life Sciences, Imperial College London, Ascot, Berkshire, UK
- Reuben W. Nowell is now at the Department of Zoology, University of Oxford, Oxford, UK
| | | | - Marc Robinson-Rechavi
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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37
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Belfield EJ, Brown C, Ding ZJ, Chapman L, Luo M, Hinde E, van Es SW, Johnson S, Ning Y, Zheng SJ, Mithani A, Harberd NP. Thermal stress accelerates Arabidopsis thaliana mutation rate. Genome Res 2020; 31:40-50. [PMID: 33334733 PMCID: PMC7849391 DOI: 10.1101/gr.259853.119] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 10/28/2020] [Indexed: 01/07/2023]
Abstract
Mutations are the source of both genetic diversity and mutational load. However, the effects of increasing environmental temperature on plant mutation rates and relative impact on specific mutational classes (e.g., insertion/deletion [indel] vs. single nucleotide variant [SNV]) are unknown. This topic is important because of the poorly defined effects of anthropogenic global temperature rise on biological systems. Here, we show the impact of temperature increase on Arabidopsis thaliana mutation, studying whole genome profiles of mutation accumulation (MA) lineages grown for 11 successive generations at 29°C. Whereas growth of A. thaliana at standard temperature (ST; 23°C) is associated with a mutation rate of 7 × 10−9 base substitutions per site per generation, growth at stressful high temperature (HT; 29°C) is highly mutagenic, increasing the mutation rate to 12 × 10−9. SNV frequency is approximately two- to threefold higher at HT than at ST, and HT-growth causes an ∼19- to 23-fold increase in indel frequency, resulting in a disproportionate increase in indels (vs. SNVs). Most HT-induced indels are 1–2 bp in size and particularly affect homopolymeric or dinucleotide A or T stretch regions of the genome. HT-induced indels occur disproportionately in nucleosome-free regions, suggesting that much HT-induced mutational damage occurs during cell-cycle phases when genomic DNA is packaged into nucleosomes. We conclude that stressful experimental temperature increases accelerate plant mutation rates and particularly accelerate the rate of indel mutation. Increasing environmental temperatures are thus likely to have significant mutagenic consequences for plants growing in the wild and may, in particular, add detrimentally to mutational load.
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Affiliation(s)
- Eric J Belfield
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Carly Brown
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Zhong Jie Ding
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Lottie Chapman
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Faculty of Sciences, University of Geneva, Geneva 1211, Switzerland
| | - Mengqian Luo
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Centre for Cell and Developmental Biology, State Key Laboratory of Agrobiotechnology, School of Life Sciences, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Eleanor Hinde
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Sam W van Es
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Department of Plant Physiology, Umeå Plant Science Centre, Umeå University, SE-901 87 Umeå, Sweden
| | - Sophie Johnson
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
| | - Youzheng Ning
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom.,Department of Plant Sciences, University of Cambridge, Cambridge CB2 3EA, United Kingdom
| | - Shao Jian Zheng
- State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Aziz Mithani
- Department of Biology, Syed Babar Ali School of Science and Engineering, Lahore University of Management Sciences (LUMS), DHA, Lahore 54792, Pakistan
| | - Nicholas P Harberd
- Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, United Kingdom
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38
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Sidorova A, Tverdislov V, Levashova N, Garaeva A. A model of autowave self-organization as a hierarchy of active media in the biological evolution. Biosystems 2020; 198:104234. [PMID: 32889101 DOI: 10.1016/j.biosystems.2020.104234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/23/2020] [Accepted: 08/24/2020] [Indexed: 11/28/2022]
Abstract
Within the framework of the active media concept, we develop a biophysical model of autowave self-organization which is treated as a hierarchy of active media in the evolution of the biosphere. We also propose a mathematical model of the autowave process of speciation in a flow of mutations for the three main taxonometric groups (prokaryotes, unicellular and multicellular eukaryotes) with a naturally determined lower boundary of living matter (the appearance of prokaryotes) and an open upper boundary for the formation of new species. It is shown that the fluctuation-bifurcation description of the evolution for the formation of new taxonometric groups as a trajectory of transformation of small fluctuations into giant ones adequately reflects the process of self-organization during the formation of taxa. The major concepts of biological evolution, conditions of hierarchy formation as a fundamental manifestation of self-organization and complexity in the evolution of biological systems are considered.
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Affiliation(s)
- Alla Sidorova
- Department of Biophysics, Faculty of Physics, Lomonosov Moscow State University, Moscow, 119991, Russia.
| | - Vsevolod Tverdislov
- Head of the Department of Biophysics, Faculty of Physics, Lomonosov Moscow State University, Moscow, 119991, Russia.
| | - Natalia Levashova
- Department of Mathematics, Faculty of Physics, Lomonosov Moscow State University, Moscow, 119991, Russia.
| | - Anastasia Garaeva
- Postgraduate Student of the Department of Biophysics, Faculty of Physics, Lomonosov Moscow State University, Moscow, 119991, Russia.
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39
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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.
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40
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Láruson ÁJ, Yeaman S, Lotterhos KE. The Importance of Genetic Redundancy in Evolution. Trends Ecol Evol 2020; 35:809-822. [DOI: 10.1016/j.tree.2020.04.009] [Citation(s) in RCA: 60] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2019] [Revised: 04/21/2020] [Accepted: 04/24/2020] [Indexed: 12/20/2022]
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41
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Beninde J, Möst M, Meyer A. Optimized and affordable high-throughput sequencing workflow for preserved and nonpreserved small zooplankton specimens. Mol Ecol Resour 2020; 20:1632-1646. [PMID: 32677266 DOI: 10.1111/1755-0998.13228] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Revised: 07/12/2020] [Accepted: 07/13/2020] [Indexed: 12/12/2022]
Abstract
Genomic analysis of hundreds of individuals is increasingly becoming standard in evolutionary and ecological research. Individual-based sequencing generates large amounts of valuable data from experimental and field studies, while using preserved samples is an invaluable resource for studying biodiversity in remote areas or across time. Yet, small-bodied individuals or specimens from collections are often of limited use for genomic analyses due to a lack of suitable extraction and library preparation protocols for preserved or small amounts of tissues. Currently, high-throughput sequencing in zooplankton is mostly restricted to clonal species, that can be maintained in live cultures to obtain sufficient amounts of tissue, or relies on a whole-genome amplification step that comes with several biases and high costs. Here, we present a workflow for high-throughput sequencing of single small individuals omitting the need for prior whole-genome amplification or live cultures. We establish and demonstrate this method using 27 species of the genus Daphnia, aquatic keystone organisms, and validate it with small-bodied ostracods. Our workflow is applicable to both live and preserved samples at low costs per sample. We first show that a silica-column based DNA extraction method resulted in the highest DNA yields for nonpreserved samples while a precipitation-based technique gave the highest yield for ethanol-preserved samples and provided the longest DNA fragments. We then successfully performed short-read whole genome sequencing from single Daphnia specimens and ostracods. Moreover, we assembled a draft reference genome from a single Daphnia individual (>50× coverage) highlighting the value of the workflow for non-model organisms.
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Affiliation(s)
- Jannik Beninde
- Department of Biology, University of Konstanz, Konstanz, Germany
| | - Markus Möst
- Department of Ecology, University of Innsbruck, Innsbruck, Austria
| | - Axel Meyer
- Department of Biology, University of Konstanz, Konstanz, Germany
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42
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Inference of Historical Population-Size Changes with Allele-Frequency Data. G3-GENES GENOMES GENETICS 2020; 10:211-223. [PMID: 31699776 PMCID: PMC6945023 DOI: 10.1534/g3.119.400854] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
With up to millions of nearly neutral polymorphisms now being routinely sampled in population-genomic surveys, it is possible to estimate the site-frequency spectrum of such sites with high precision. Each frequency class reflects a mixture of potentially unique demographic histories, which can be revealed using theory for the probability distributions of the starting and ending points of branch segments over all possible coalescence trees. Such distributions are completely independent of past population history, which only influences the segment lengths, providing the basis for estimating average population sizes separating tree-wide coalescence events. The history of population-size change experienced by a sample of polymorphisms can then be dissected in a model-flexible fashion, and extension of this theory allows estimation of the mean and full distribution of long-term effective population sizes and ages of alleles of specific frequencies. Here, we outline the basic theory underlying the conceptual approach, develop and test an efficient statistical procedure for parameter estimation, and apply this to multiple population-genomic datasets for the microcrustacean Daphnia pulex.
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43
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Shaw JR, Colbourne JK, Glaholt SP, Turner E, Folt CL, Chen CY. Dynamics of Cadmium Acclimation in Daphnia pulex: Linking Fitness Costs, Cross-Tolerance, and Hyper-Induction of Metallothionein. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2019; 53:14670-14678. [PMID: 31738529 DOI: 10.1021/acs.est.9b05006] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Acclimation increases tolerance to stress in individuals but is assumed to contribute fitness costs when the stressor is absent, though data supporting this widely held claim are sparse. Therefore, using clonal (i.e., genetically identical) cultures of Daphnia pulex, we isolated the contributions of acclimation to the regulation of the metal response gene, metallothionein 1 (MT1), and defined the reproductive benefits and costs of cadmium (Cd)-acclimation. Daphnia pulex were exposed for 50 parthenogenetic generations to environmentally realistic levels (1 μg Cd/L), and tolerance to Cd and other metals assessed during this period via standard toxicity tests. These tests revealed (1) increased tolerance to Cd compared to genetically identical nonacclimated cultures, (2) fitness costs in Cd-acclimated Daphnia when Cd was removed, and (3) cross-tolerance of Cd-acclimated Daphnia to zinc and silver, but not arsenic, thereby defining a functional role for metallothionein. Indeed, Cd-acclimated clones had significantly higher expression of MT1 mRNA than nonacclimated clones, when Cd exposed. Both the enhanced induction of MT1 and tolerant phenotype were rapidly lost when Cd was removed (1-2 generations), which is further evidence of acclimation costs. These findings provide evidence for the widely held view that acclimation is costly and are important for investigating evolutionary principles of genetic assimilation and the survival mechanisms of natural populations that face changing environments.
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Affiliation(s)
- Joseph R Shaw
- O'Neill School of Public and Environmental Affairs , Indiana University , Bloomington , Indiana 47405 , United States
- Department of Biology , Dartmouth College , Hanover , New Hampshire 03755 , United States
- Center for Environmental Health Sciences , Dartmouth Medical School , Hanover , New Hampshire 03755 , United States
| | - John K Colbourne
- School of Biosciences , University of Birmingham , Birmingham B15 2TT , U.K
| | - Stephen P Glaholt
- O'Neill School of Public and Environmental Affairs , Indiana University , Bloomington , Indiana 47405 , United States
- Department of Biology , Dartmouth College , Hanover , New Hampshire 03755 , United States
| | - Elizabeth Turner
- O'Neill School of Public and Environmental Affairs , Indiana University , Bloomington , Indiana 47405 , United States
| | - Carol L Folt
- Department of Biology , Dartmouth College , Hanover , New Hampshire 03755 , United States
- Center for Environmental Health Sciences , Dartmouth Medical School , Hanover , New Hampshire 03755 , United States
- USC Office of the President , University of Southern California , Los Angeles , California 90089 , United States
| | - Celia Y Chen
- Department of Biology , Dartmouth College , Hanover , New Hampshire 03755 , United States
- Center for Environmental Health Sciences , Dartmouth Medical School , Hanover , New Hampshire 03755 , United States
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44
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Cornetti L, Fields PD, Van Damme K, Ebert D. A fossil-calibrated phylogenomic analysis of Daphnia and the Daphniidae. Mol Phylogenet Evol 2019; 137:250-262. [DOI: 10.1016/j.ympev.2019.05.018] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2018] [Revised: 05/03/2019] [Accepted: 05/20/2019] [Indexed: 11/16/2022]
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45
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Abstract
Daphnia normally reproduce by cyclical parthenogenesis, with offspring sex being determined by environmental cues. However, some females have lost the ability to produce males. Our results demonstrate that this loss of male-producing ability is controlled by a dominant allele at a single locus. We identified the locus by comparing whole-genome sequences of 67 nonmale-producing (NMP) and 100 male-producing (MP) clones from 5 Daphnia pulex populations, revealing 132 NMP-linked SNPs and 59 NMP-linked indels within a single 1.1-Mb nonrecombining region on chromosome I. These markers include 7 nonsynonymous mutations, all of which are located within one unannotated protein-coding gene (gene 8960). Within this single gene, all of the marker-linked NMP haplotypes from different populations form a monophyletic clade, suggesting a single origin of the NMP phenotype, with the NMP haplotype originating by introgression from a sister species, Daphnia pulicaria Methyl farnesoate (MF) is the innate juvenile hormone in daphnids, which induces the production of males and whose inhibition results in female-only production. Gene 8960 is sensitive to treatment by MF in MP clones, but such responsiveness is greatly reduced in NMP clones. Thus, we hypothesize that gene 8960 is located downstream of the MF-signaling pathway in D. pulex, with the NMP phenotype being caused by expression change of gene 8960.
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46
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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.
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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
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47
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Fillinger RJ, Anderson MZ. Seasons of change: Mechanisms of genome evolution in human fungal pathogens. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2019; 70:165-174. [PMID: 30826447 DOI: 10.1016/j.meegid.2019.02.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/23/2019] [Accepted: 02/26/2019] [Indexed: 06/09/2023]
Abstract
Fungi are a diverse kingdom of organisms capable of thriving in various niches across the world including those in close association with multicellular eukaryotes. Fungal pathogens that contribute to human disease reside both within the host as commensal organisms of the microbiota and the environment. Their niche of origin dictates how infection initiates but also places specific selective pressures on the fungal pathogen that contributes to its genome organization and genetic repertoire. Recent efforts to catalogue genomic variation among major human fungal pathogens have unveiled evolutionary themes that shape the fungal genome. Mechanisms ranging from large scale changes such as aneuploidy and ploidy cycling as well as more targeted mutations like base substitutions and gene copy number variations contribute to the evolution of these species, which are often under multiple competing selective pressures with their host, environment, and other microbes. Here, we provide an overview of the major selective pressures and mechanisms acting to evolve the genome of clinically important fungal pathogens of humans.
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Affiliation(s)
- Robert J Fillinger
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210, USA
| | - Matthew Z Anderson
- Department of Microbial Infection and Immunity, The Ohio State University, Columbus, OH 43210, USA; Department of Microbiology, The Ohio State University, Columbus, OH 43210, USA.
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48
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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.
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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
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49
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Galtier N, Roux C, Rousselle M, Romiguier J, Figuet E, Glémin S, Bierne N, Duret L. Codon Usage Bias in Animals: Disentangling the Effects of Natural Selection, Effective Population Size, and GC-Biased Gene Conversion. Mol Biol Evol 2019; 35:1092-1103. [PMID: 29390090 DOI: 10.1093/molbev/msy015] [Citation(s) in RCA: 79] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Selection on codon usage bias is well documented in a number of microorganisms. Whether codon usage is also generally shaped by natural selection in large organisms, despite their relatively small effective population size (Ne), is unclear. In animals, the population genetics of codon usage bias has only been studied in a handful of model organisms so far, and can be affected by confounding, nonadaptive processes such as GC-biased gene conversion and experimental artefacts. Using population transcriptomics data, we analyzed the relationship between codon usage, gene expression, allele frequency distribution, and recombination rate in 30 nonmodel species of animals, each from a different family, covering a wide range of effective population sizes. We disentangled the effects of translational selection and GC-biased gene conversion on codon usage by separately analyzing GC-conservative and GC-changing mutations. We report evidence for effective translational selection on codon usage in large-Ne species of animals, but not in small-Ne ones, in agreement with the nearly neutral theory of molecular evolution. C- and T-ending codons tend to be preferred over synonymous G- and A-ending ones, for reasons that remain to be determined. In contrast, we uncovered a conspicuous effect of GC-biased gene conversion, which is widespread in animals and the main force determining the fate of AT↔GC mutations. Intriguingly, the strength of its effect was uncorrelated with Ne.
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Affiliation(s)
- Nicolas Galtier
- UMR5554, Institut des Sciences de l'Evolution, University Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Camille Roux
- UMR5554, Institut des Sciences de l'Evolution, University Montpellier, CNRS, IRD, EPHE, Montpellier, France.,Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,UMR 8198 - Evo-Eco-Paleo, CNRS, Université de Lille-Sciences et Technologies, Villeneuve d'Ascq, France
| | - Marjolaine Rousselle
- UMR5554, Institut des Sciences de l'Evolution, University Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Jonathan Romiguier
- UMR5554, Institut des Sciences de l'Evolution, University Montpellier, CNRS, IRD, EPHE, Montpellier, France.,Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Emeric Figuet
- UMR5554, Institut des Sciences de l'Evolution, University Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Sylvain Glémin
- UMR5554, Institut des Sciences de l'Evolution, University Montpellier, CNRS, IRD, EPHE, Montpellier, France.,Department of Ecology and Genetics, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden
| | - Nicolas Bierne
- UMR5554, Institut des Sciences de l'Evolution, University Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Laurent Duret
- Laboratoire de Biométrie et Biologie Evolutive, UMR 5558, CNRS, Université de Lyon, Université Lyon 1, Villeurbanne, France
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50
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Rousselle M, Laverré A, Figuet E, Nabholz B, Galtier N. Influence of Recombination and GC-biased Gene Conversion on the Adaptive and Nonadaptive Substitution Rate in Mammals versus Birds. Mol Biol Evol 2019; 36:458-471. [PMID: 30590692 PMCID: PMC6389324 DOI: 10.1093/molbev/msy243] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Recombination is expected to affect functional sequence evolution in several ways. On the one hand, recombination is thought to improve the efficiency of multilocus selection by dissipating linkage disequilibrium. On the other hand, natural selection can be counteracted by recombination-associated transmission distorters such as GC-biased gene conversion (gBGC), which tends to promote G and C alleles irrespective of their fitness effect in high-recombining regions. It has been suggested that gBGC might impact coding sequence evolution in vertebrates, and particularly the ratio of nonsynonymous to synonymous substitution rates (dN/dS). However, distinctive gBGC patterns have been reported in mammals and birds, maybe reflecting the documented contrasts in evolutionary dynamics of recombination rate between these two taxa. Here, we explore how recombination and gBGC affect coding sequence evolution in mammals and birds by analyzing proteome-wide data in six species of Galloanserae (fowls) and six species of catarrhine primates. We estimated the dN/dS ratio and rates of adaptive and nonadaptive evolution in bins of genes of increasing recombination rate, separately analyzing AT → GC, GC → AT, and G ↔ C/A ↔ T mutations. We show that in both taxa, recombination and gBGC entail a decrease in dN/dS. Our analysis indicates that recombination enhances the efficiency of purifying selection by lowering Hill-Robertson effects, whereas gBGC leads to an overestimation of the adaptive rate of AT → GC mutations. Finally, we report a mutagenic effect of recombination, which is independent of gBGC.
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Affiliation(s)
| | - Alexandre Laverré
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Emeric Figuet
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Benoit Nabholz
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
| | - Nicolas Galtier
- ISEM, Université de Montpellier, CNRS, IRD, EPHE, Montpellier, France
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