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Kalhor R, Beslon G, Lafond M, Scornavacca C. A Rigorous Framework to Classify the Postduplication Fate of Paralogous Genes. J Comput Biol 2024. [PMID: 39088355 DOI: 10.1089/cmb.2023.0331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2024] Open
Abstract
Gene duplication has a central role in evolution; still, little is known on the fates of the duplicated copies, their relative frequency, and on how environmental conditions affect them. Moreover, the lack of rigorous definitions concerning the fate of duplicated genes hinders the development of a global vision of this process. In this paper, we present a new framework aiming at characterizing and formally differentiating the fate of duplicated genes. Our framework has been tested via simulations, where the evolution of populations has been simulated using aevol, an in silico experimental evolution platform. Our results show several patterns that confirm some of the conclusions from previous studies, while also exhibiting new tendencies; this may open up new avenues to better understand the role of duplications as a driver of evolution.
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Affiliation(s)
- Reza Kalhor
- Department of Computer Science, Université de Sherbrooke, Sherbrooke, Canada
| | | | - Manuel Lafond
- Department of Computer Science, Université de Sherbrooke, Sherbrooke, Canada
| | - Celine Scornavacca
- Institut des Sciences de l'Evolution de Montpellier (Université de Montpellier, CNRS, IRD, EPHE), Montpellier, France
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2
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Shvartzman B, Ram Y. Self-replicating artificial neural networks give rise to universal evolutionary dynamics. PLoS Comput Biol 2024; 20:e1012004. [PMID: 38547320 PMCID: PMC11003675 DOI: 10.1371/journal.pcbi.1012004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2023] [Revised: 04/09/2024] [Accepted: 03/17/2024] [Indexed: 04/11/2024] Open
Abstract
In evolutionary models, mutations are exogenously introduced by the modeler, rather than endogenously introduced by the replicator itself. We present a new deep-learning based computational model, the self-replicating artificial neural network (SeRANN). We train it to (i) copy its own genotype, like a biological organism, which introduces endogenous spontaneous mutations; and (ii) simultaneously perform a classification task that determines its fertility. Evolving 1,000 SeRANNs for 6,000 generations, we observed various evolutionary phenomena such as adaptation, clonal interference, epistasis, and evolution of both the mutation rate and the distribution of fitness effects of new mutations. Our results demonstrate that universal evolutionary phenomena can naturally emerge in a self-replicator model when both selection and mutation are implicit and endogenous. We therefore suggest that SeRANN can be applied to explore and test various evolutionary dynamics and hypotheses.
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Affiliation(s)
- Boaz Shvartzman
- School of Zoology, Faculty of Life Sciences, Tel Aviv University; Tel Aviv, Israel
- School of Computer Science, Reichman University; Herzliya, Israel
| | - Yoav Ram
- School of Zoology, Faculty of Life Sciences, Tel Aviv University; Tel Aviv, Israel
- Sagol School of Neuroscience, Tel Aviv University; Tel Aviv, Israel
- Edmond J. Safra Center for Bioinformatics, Tel Aviv University; Tel Aviv, Israel
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3
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Ortega R, Fortuna MA. avidaR: an R library to perform complex queries on an ontology-based database of digital organisms. PeerJ Comput Sci 2023; 9:e1568. [PMID: 37810343 PMCID: PMC10557521 DOI: 10.7717/peerj-cs.1568] [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: 12/15/2022] [Accepted: 08/14/2023] [Indexed: 10/10/2023]
Abstract
Digital evolution is a branch of artificial life in which self-replicating computer programs-digital organisms-mutate and evolve within a user-defined computational environment. In spite of its value in biology, we still lack an up-to-date and comprehensive database on digital organisms resulting from evolution experiments. Therefore, we have developed an ontology-based semantic database-avidaDB-and an R package-avidaR-that provides users of the R programming language with an easy-to-use tool for performing complex queries without specific knowledge of SPARQL or RDF. avidaR can be used to do research on robustness, evolvability, complexity, phenotypic plasticity, gene regulatory networks, and genomic architecture by retrieving the genomes, phenotypes, and transcriptomes of more than a million digital organisms available on avidaDB. avidaR is already accepted on CRAN (i.e., a comprehensive collection of R packages contributed by the R community) and will make biologists better equipped to embrace the field of digital evolution.
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Affiliation(s)
- Raúl Ortega
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas, Seville, Spain
| | - Miguel Angel Fortuna
- Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas, Seville, Spain
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4
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Grandchamp A, Kühl L, Lebherz M, Brüggemann K, Parsch J, Bornberg-Bauer E. Population genomics reveals mechanisms and dynamics of de novo expressed open reading frame emergence in Drosophila melanogaster. Genome Res 2023; 33:872-890. [PMID: 37442576 PMCID: PMC10519401 DOI: 10.1101/gr.277482.122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 06/06/2023] [Indexed: 07/15/2023]
Abstract
Novel genes are essential for evolutionary innovations and differ substantially even between closely related species. Recently, multiple studies across many taxa showed that some novel genes arise de novo, that is, from previously noncoding DNA. To characterize the underlying mutations that allowed de novo gene emergence and their order of occurrence, homologous regions must be detected within noncoding sequences in closely related sister genomes. So far, most studies do not detect noncoding homologs of de novo genes because of incomplete assemblies and annotations, and long evolutionary distances separating genomes. Here, we overcome these issues by searching for de novo expressed open reading frames (neORFs), the not-yet fixed precursors of de novo genes that emerged within a single species. We sequenced and assembled genomes with long-read technology and the corresponding transcriptomes from inbred lines of Drosophila melanogaster, derived from seven geographically diverse populations. We found line-specific neORFs in abundance but few neORFs shared by lines, suggesting a rapid turnover. Gain and loss of transcription is more frequent than the creation of ORFs, for example, by forming new start and stop codons. Consequently, the gain of ORFs becomes rate limiting and is frequently the initial step in neORFs emergence. Furthermore, transposable elements (TEs) are major drivers for intragenomic duplications of neORFs, yet TE insertions are less important for the emergence of neORFs. However, highly mutable genomic regions around TEs provide new features that enable gene birth. In conclusion, neORFs have a high birth-death rate, are rapidly purged, but surviving neORFs spread neutrally through populations and within genomes.
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Affiliation(s)
- Anna Grandchamp
- Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany;
| | - Lucas Kühl
- Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
| | - Marie Lebherz
- Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
| | - Kathrin Brüggemann
- Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
| | - John Parsch
- Division of Evolutionary Biology, Faculty of Biology, Ludwig-Maximilians-Universität München, 82152 Munich, Germany
| | - Erich Bornberg-Bauer
- Institute for Evolution and Biodiversity, University of Münster, 48149 Münster, Germany
- Max Planck Institute for Biology Tübingen, Department of Protein Evolution, 72076 Tübingen, Germany
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5
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Fortuna MA, Beslon G, Ofria C. Editorial: Digital evolution: Insights for biologists. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.1037040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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6
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Abstract
In digital evolution, populations of computational organisms evolve via the same principles that govern natural selection in nature. These platforms have been used to great effect as a controlled system in which to conduct evolutionary experiments and develop novel evolutionary theory. In addition to their complex evolutionary dynamics, many digital evolution systems also produce rich ecological communities. As a result, digital evolution is also a powerful tool for research on eco-evolutionary dynamics. Here, we review the research to date in which digital evolution platforms have been used to address eco-evolutionary (and in some cases purely ecological) questions. This work has spanned a wide range of topics, including competition, facilitation, parasitism, predation, and macroecological scaling laws. We argue for the value of further ecological research in digital evolution systems and present some particularly promising directions for further research.
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7
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Decrulle AL, Frénoy A, Meiller-Legrand TA, Bernheim A, Lotton C, Gutierrez A, Lindner AB. Engineering gene overlaps to sustain genetic constructs in vivo. PLoS Comput Biol 2021; 17:e1009475. [PMID: 34624014 PMCID: PMC8528312 DOI: 10.1371/journal.pcbi.1009475] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 10/20/2021] [Accepted: 09/23/2021] [Indexed: 11/20/2022] Open
Abstract
Evolution is often an obstacle to the engineering of stable biological systems due to the selection of mutations inactivating costly gene circuits. Gene overlaps induce important constraints on sequences and their evolution. We show that these constraints can be harnessed to increase the stability of costly genes by purging loss-of-function mutations. We combine computational and synthetic biology approaches to rationally design an overlapping reading frame expressing an essential gene within an existing gene to protect. Our algorithm succeeded in creating overlapping reading frames in 80% of E. coli genes. Experimentally, scoring mutations in both genes of such overlapping construct, we found that a significant fraction of mutations impacting the gene to protect have a deleterious effect on the essential gene. Such an overlap thus protects a costly gene from removal by natural selection by associating the benefit of this removal with a larger or even lethal cost. In our synthetic constructs, the overlap converts many of the possible mutants into evolutionary dead-ends, reducing the evolutionary potential of the system and thus increasing its stability over time. Genomes are translated by triplets of nucleotides on two different strands, allowing for six different reading frames. This permits the existence of gene overlaps, often observed in microbial genomes, where two different proteins are encoded on the same piece of DNA, but in different reading frames. Gene overlaps are classically considered an obstacle for both evolution and genetic engineering, as mutations in overlapping regions likely have pleitrotropic effects on several genes. In 2013, we identified specific evolutionary scenarios where the decrease in evolutionary potential caused by gene overlaps could instead be advantageous and selected for. In this work, we demonstrate the use of gene overlaps in another context where reducing evolutionary potential can be useful: preventing evolution from inactivating synthetic circuits. We show that gene overlaps can be engineered to increase the evolutionary stability of genes that are costly to their hosts, by entangling these costly genes with essential genes.
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Affiliation(s)
| | - Antoine Frénoy
- Université de Paris, INSERM U1001, Paris, France
- Université Grenoble Alpes, CNRS UMR5525, Grenoble, France
- * E-mail: (AF); (ABL)
| | | | | | | | | | - Ariel B. Lindner
- Université de Paris, INSERM U1001, Paris, France
- Université de Paris, INSERM U1284, Center for Research and Interdisciplinarity (CRI), Paris, France
- * E-mail: (AF); (ABL)
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8
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Torres DE, Thomma BPHJ, Seidl MF. Transposable Elements Contribute to Genome Dynamics and Gene Expression Variation in the Fungal Plant Pathogen Verticillium dahliae. Genome Biol Evol 2021; 13:evab135. [PMID: 34100895 PMCID: PMC8290119 DOI: 10.1093/gbe/evab135] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2021] [Indexed: 12/12/2022] Open
Abstract
Transposable elements (TEs) are a major source of genetic and regulatory variation in their host genome and are consequently thought to play important roles in evolution. Many fungal and oomycete plant pathogens have evolved dynamic and TE-rich genomic regions containing genes that are implicated in host colonization and adaptation. TEs embedded in these regions have typically been thought to accelerate the evolution of these genomic compartments, but little is known about their dynamics in strains that harbor them. Here, we used whole-genome sequencing data of 42 strains of the fungal plant pathogen Verticillium dahliae to systematically identify polymorphic TEs that may be implicated in genomic as well as in gene expression variation. We identified 2,523 TE polymorphisms and characterize a subset of 8% of the TEs as polymorphic elements that are evolutionary younger, less methylated, and more highly expressed when compared with the remaining 92% of the total TE complement. As expected, the polyrmorphic TEs are enriched in the adaptive genomic regions. Besides, we observed an association of polymorphic TEs with pathogenicity-related genes that localize nearby and that display high expression levels. Collectively, our analyses demonstrate that TE dynamics in V. dahliae contributes to genomic variation, correlates with expression of pathogenicity-related genes, and potentially impacts the evolution of adaptive genomic regions.
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Affiliation(s)
- David E Torres
- Theoretical Biology and Bioinformatics Group, Department of Biology, Utrecht University, The Netherlands
- Laboratory of Phytopathology, Wageningen University and Research, The Netherlands
| | - Bart P H J Thomma
- Laboratory of Phytopathology, Wageningen University and Research, The Netherlands
- Cluster of Excellence on Plant Sciences (CEPLAS), Institute for Plant Sciences, University of Cologne, Germany
| | - Michael F Seidl
- Theoretical Biology and Bioinformatics Group, Department of Biology, Utrecht University, The Netherlands
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9
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Paul D, Saha S, Kumar A, mathew J. Evolutionary multi-objective optimization based overlapping subspace clustering. Pattern Recognit Lett 2021. [DOI: 10.1016/j.patrec.2021.02.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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10
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Guerra-Almeida D, Nunes-da-Fonseca R. Small Open Reading Frames: How Important Are They for Molecular Evolution? Front Genet 2020; 11:574737. [PMID: 33193682 PMCID: PMC7606980 DOI: 10.3389/fgene.2020.574737] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2020] [Accepted: 08/25/2020] [Indexed: 11/13/2022] Open
Affiliation(s)
- Diego Guerra-Almeida
- Institute of Biodiversity and Sustainability, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
| | - Rodrigo Nunes-da-Fonseca
- Institute of Biodiversity and Sustainability, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.,National Institute of Science and Technology in Molecular Entomology, Rio de Janeiro, Brazil
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11
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Peignier S, Rigotti C, Beslon G. Evolutionary subspace clustering using variable genome length. Comput Intell 2020. [DOI: 10.1111/coin.12254] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Sergio Peignier
- INSA‐Lyon, INRA, BF2I, UMR0203, F‐69621, University of Lyon Villeurbanne France
| | - Christophe Rigotti
- INSA‐Lyon, CNRS, INRIA, LIRIS, UMR5205, F‐69621, University of Lyon Villeurbanne France
| | - Guillaume Beslon
- INSA‐Lyon, CNRS, INRIA, LIRIS, UMR5205, F‐69621, University of Lyon Villeurbanne France
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12
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Liard V, Parsons DP, Rouzaud-Cornabas J, Beslon G. The Complexity Ratchet: Stronger than Selection, Stronger than Evolvability, Weaker than Robustness. ARTIFICIAL LIFE 2020; 26:38-57. [PMID: 32027534 DOI: 10.1162/artl_a_00312] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Using the in silico experimental evolution platform Aevol, we have tested the existence of a complexity ratchet by evolving populations of digital organisms under environmental conditions in which simple organisms can very well thrive and reproduce. We observed that in most simulations, organisms become complex although such organisms are a lot less fit than simple ones and have no robustness or evolvability advantage. This excludes selection from the set of possible explanations for the evolution of complexity. However, complementary experiments showed that selection is nevertheless necessary for complexity to evolve, also excluding non-selective effects. Analyzing the long-term fate of complex organisms, we showed that complex organisms almost never switch back to simplicity despite the potential fitness benefit. On the contrary, they consistently accumulate complexity in the long term, meanwhile slowly increasing their fitness but never overtaking that of simple organisms. This suggests the existence of a complexity ratchet powered by negative epistasis: Mutations leading to simple solutions, which are favorable at the beginning of the simulation, become deleterious after other mutations-leading to complex solutions-have been fixed. This also suggests that this complexity ratchet cannot be beaten by selection, but that it can be overthrown by robustness because of the constraints it imposes on the coding capacity of the genome.
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Affiliation(s)
- Vincent Liard
- Inria Beagle Team
- Université de Lyon
- INSA-Lyon
- CNRS
- LIRIS
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13
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Lehman J, Clune J, Misevic D, Adami C, Altenberg L, Beaulieu J, Bentley PJ, Bernard S, Beslon G, Bryson DM, Cheney N, Chrabaszcz P, Cully A, Doncieux S, Dyer FC, Ellefsen KO, Feldt R, Fischer S, Forrest S, Fŕenoy A, Gagńe C, Le Goff L, Grabowski LM, Hodjat B, Hutter F, Keller L, Knibbe C, Krcah P, Lenski RE, Lipson H, MacCurdy R, Maestre C, Miikkulainen R, Mitri S, Moriarty DE, Mouret JB, Nguyen A, Ofria C, Parizeau M, Parsons D, Pennock RT, Punch WF, Ray TS, Schoenauer M, Schulte E, Sims K, Stanley KO, Taddei F, Tarapore D, Thibault S, Watson R, Weimer W, Yosinski J. The Surprising Creativity of Digital Evolution: A Collection of Anecdotes from the Evolutionary Computation and Artificial Life Research Communities. ARTIFICIAL LIFE 2020; 26:274-306. [PMID: 32271631 DOI: 10.1162/artl_a_00319] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Evolution provides a creative fount of complex and subtle adaptations that often surprise the scientists who discover them. However, the creativity of evolution is not limited to the natural world: Artificial organisms evolving in computational environments have also elicited surprise and wonder from the researchers studying them. The process of evolution is an algorithmic process that transcends the substrate in which it occurs. Indeed, many researchers in the field of digital evolution can provide examples of how their evolving algorithms and organisms have creatively subverted their expectations or intentions, exposed unrecognized bugs in their code, produced unexpectedly adaptations, or engaged in behaviors and outcomes, uncannily convergent with ones found in nature. Such stories routinely reveal surprise and creativity by evolution in these digital worlds, but they rarely fit into the standard scientific narrative. Instead they are often treated as mere obstacles to be overcome, rather than results that warrant study in their own right. Bugs are fixed, experiments are refocused, and one-off surprises are collapsed into a single data point. The stories themselves are traded among researchers through oral tradition, but that mode of information transmission is inefficient and prone to error and outright loss. Moreover, the fact that these stories tend to be shared only among practitioners means that many natural scientists do not realize how interesting and lifelike digital organisms are and how natural their evolution can be. To our knowledge, no collection of such anecdotes has been published before. This article is the crowd-sourced product of researchers in the fields of artificial life and evolutionary computation who have provided first-hand accounts of such cases. It thus serves as a written, fact-checked collection of scientifically important and even entertaining stories. In doing so we also present here substantial evidence that the existence and importance of evolutionary surprises extends beyond the natural world, and may indeed be a universal property of all complex evolving systems.
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Affiliation(s)
| | | | - Dusan Misevic
- Université de Paris, INSERM U1284, Center for Research and Interdisciplinarity.
| | | | | | | | | | | | | | | | | | | | | | - Stephane Doncieux
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Institute of Intelligent Systems and Robotics (ISIR)
| | | | | | | | | | | | | | | | - Leni Le Goff
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Institute of Intelligent Systems and Robotics (ISIR)
| | | | | | | | - Laurent Keller
- Department of Fundamental Microbiology, University of Lausanne
| | | | | | | | | | | | - Carlos Maestre
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Institute of Intelligent Systems and Robotics (ISIR)
| | | | - Sara Mitri
- Department of Fundamental Microbiology, University of Lausanne
| | | | | | | | | | | | | | | | | | | | | | | | | | | | - François Taddei
- Center for Research and Interdisciplinarity, INSERM U1284, Université de Paris
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14
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Colizzi ES, Hogeweg P. Transcriptional Mutagenesis Prevents Ribosomal DNA Deterioration: The Role of Duplications and Deletions. Genome Biol Evol 2019; 11:3207-3217. [PMID: 31651950 PMCID: PMC6855279 DOI: 10.1093/gbe/evz235] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2019] [Indexed: 11/13/2022] Open
Abstract
Clashes between transcription and replication complexes can cause point mutations and chromosome rearrangements on heavily transcribed genes. In eukaryotic ribosomal RNA genes, the system that prevents transcription-replication conflicts also causes frequent copy number variation. Such fast mutational dynamics do not alter growth rates in yeast and are thus selectively near neutral. It was recently found that yeast regulates these mutations by means of a signaling cascade that depends on the availability of nutrients. Here, we investigate the long-term evolutionary effect of the mutational dynamics observed in yeast. We developed an in silico model of single-cell organisms whose genomes mutate more frequently when transcriptional load is larger. We show that mutations induced by high transcriptional load are beneficial when biased toward gene duplications and deletions: they decrease mutational load even though they increase the overall mutation rates. In contrast, genome stability is compromised when mutations are not biased toward gene duplications and deletions, even when mutations occur much less frequently. Taken together, our results show that the mutational dynamics observed in yeast are beneficial for the long-term stability of the genome and pave the way for a theory of evolution where genetic operators are themselves cause and outcome of the evolutionary dynamics.
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Affiliation(s)
- Enrico Sandro Colizzi
- Origins Center, 9747AG, Groningen, the Netherlands.,Mathematical Institute, Leiden University, the Netherlands
| | - Paulien Hogeweg
- Theoretical Biology and Bioinformatics, Utrecht University, The Netherlands
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15
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Rutten JP, Hogeweg P, Beslon G. Adapting the engine to the fuel: mutator populations can reduce the mutational load by reorganizing their genome structure. BMC Evol Biol 2019; 19:191. [PMID: 31627727 PMCID: PMC6800497 DOI: 10.1186/s12862-019-1507-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 09/02/2019] [Indexed: 11/24/2022] Open
Abstract
Background Mutators are common in bacterial populations, both in natural isolates and in the lab. The fate of these lineages, which mutation rate is increased up to 100 ×, has long been studied using population genetics models, showing that they can spread in a population following an environmental change. However in stable conditions, they suffer from the increased mutational load, hence being overcome by non-mutators. However, these results don’t take into account the fact that an elevated mutation rate can impact the genetic structure, hence changing the sensitivity of the population to mutations. Here we used Aevol, an in silico experimental evolution platform in which genomic structures are free to evolve, in order to study the fate of mutator populations evolving for a long time in constant conditions. Results Starting from wild-types that were pre-evolved for 300,000 generations, we let 100 mutator populations (point mutation rate ×100) evolve for 100,000 further generations in constant conditions. As expected all populations initially undergo a fitness loss. However, after that the mutator populations started to recover. Most populations ultimately recovered their ancestors fitness, and a significant fraction became even fitter than the non-mutator control clones that evolved in parallel. By analyzing the genomes of the mutators, we show that the fitness recovery is due to two mechanisms: i. an increase in robustness through compaction of the coding part of the mutator genomes, ii. an increase of the selection coefficient that decreases the mean-fitness of the population. Strikingly the latter is due to the accumulation of non-coding sequences in the mutators genomes. Conclusion Our results show that the mutational burden that is classically thought to be associated with mutator phenotype is escapable. On the long run mutators adapted their genomes and reshaped the distribution of mutation effects. Therewith the lineage is able to recover fitness even though the population still suffers the elevated mutation rate. Overall these results change our view of mutator dynamics: by being able to reduce the deleterious effect of the elevated mutation rate, mutator populations may be able to last for a very long time; A situation commonly observed in nature.
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Affiliation(s)
- Jacob Pieter Rutten
- Theoretical Biology and Bioinformatics group,Utrecht University, Padualaan 8, Utrecht, Netherlands.,Université de Lyon, INRIA, CNRS, INSA-Lyon, Beagle Team, LIRIS, UMR5205, Villeurbanne, 69601, France
| | - Paulien Hogeweg
- Theoretical Biology and Bioinformatics group,Utrecht University, Padualaan 8, Utrecht, Netherlands
| | - Guillaume Beslon
- Université de Lyon, INRIA, CNRS, INSA-Lyon, Beagle Team, LIRIS, UMR5205, Villeurbanne, 69601, France.
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16
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Gesto-Borroto R, Cardoso-Taketa A, Yactayo-Chang JP, Medina-Jiménez K, Hornung-Leoni C, Lorence A, Villarreal ML. DNA barcoding and TLC as tools to properly identify natural populations of the Mexican medicinal species Galphimia glauca Cav. PLoS One 2019; 14:e0217313. [PMID: 31136619 PMCID: PMC6538163 DOI: 10.1371/journal.pone.0217313] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/08/2019] [Indexed: 01/30/2023] Open
Abstract
Galphimia glauca is a plant that is endemic to Mexico and has been commonly used since pre-Hispanic times to treat various illnesses, including central nervous system disorders and inflammation. The first studies investigating a natural population of G. glauca in Mexico showed that the plant has anxiolytic and sedative activities in mice and humans. The plant's bioactive compounds were isolated and identified, and they belong to a family of nor-secofriedelanes called galphimines. The integration of DNA barcoding and thin-layer chromatography analysis was performed to clarify whether the botanical classification of the populations in the study, which were collected in different regions of Mexico, as G. glauca was correct or if the populations consist of more than one species of the genus Galphimia. We employed six DNA barcodes (matK, rbcL, rpoC1, psbA-trnH, ITS1 and ITS2) that were analyzed individually and in combination and then compared each other, to indicate differences among the studied populations. In the phylogenetic analysis, ITS1 and ITS2 markers as well as the combination of all DNA regions were the most efficient for discriminating the population studied. The thin-layer chromatography analysis exhibited four principal chemical profiles, one of which corresponded to the populations that produced galphimines. DNA barcoding was consistent and enabled us to differentiate the populations that produce galphimines from those that do not. The results of this investigation suggest that the studied populations belong to at least four different species of the genus Galphimia. The phylogenetic analysis and the thin-layer chromatography chemical profiles were convenient tools for establishing a strong relationship between the genotype and phenotype of the studied populations and could be used for quality control purposes to prepare herbal medicines from plants of the genus Galphimia.
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Affiliation(s)
- Reinier Gesto-Borroto
- Doctorado en Ciencias, Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Morelos, México
- Laboratorio de Investigación en Plantas Medicinales, Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Morelos, México
| | - Alexandre Cardoso-Taketa
- Laboratorio de Investigación en Plantas Medicinales, Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Morelos, México
| | - Jessica P. Yactayo-Chang
- Arkansas Biosciences Institute, Arkansas State University, Jonesboro, Arkansas, United States of America
| | - Karina Medina-Jiménez
- Arkansas Biosciences Institute, Arkansas State University, Jonesboro, Arkansas, United States of America
| | - Claudia Hornung-Leoni
- Centro de Investigaciones Biológicas, Instituto de Ciencias Básicas e Ingeniería Universidad Autónoma del Estado de Hidalgo, Hidalgo, México
| | - Argelia Lorence
- Arkansas Biosciences Institute, Arkansas State University, Jonesboro, Arkansas, United States of America
| | - Maria Luisa Villarreal
- Laboratorio de Investigación en Plantas Medicinales, Centro de Investigación en Biotecnología, Universidad Autónoma del Estado de Morelos, Morelos, México
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17
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Biller P, Guéguen L, Knibbe C, Tannier E. Breaking Good: Accounting for Fragility of Genomic Regions in Rearrangement Distance Estimation. Genome Biol Evol 2016; 8:1427-39. [PMID: 27190002 PMCID: PMC4898800 DOI: 10.1093/gbe/evw083] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Models of evolution by genome rearrangements are prone to two types of flaws: One is to ignore the diversity of susceptibility to breakage across genomic regions, and the other is to suppose that susceptibility values are given. Without necessarily supposing their precise localization, we call "solid" the regions that are improbably broken by rearrangements and "fragile" the regions outside solid ones. We propose a model of evolution by inversions where breakage probabilities vary across fragile regions and over time. It contains as a particular case the uniform breakage model on the nucleotidic sequence, where breakage probabilities are proportional to fragile region lengths. This is very different from the frequently used pseudouniform model where all fragile regions have the same probability to break. Estimations of rearrangement distances based on the pseudouniform model completely fail on simulations with the truly uniform model. On pairs of amniote genomes, we show that identifying coding genes with solid regions yields incoherent distance estimations, especially with the pseudouniform model, and to a lesser extent with the truly uniform model. This incoherence is solved when we coestimate the number of fragile regions with the rearrangement distance. The estimated number of fragile regions is surprisingly small, suggesting that a minority of regions are recurrently used by rearrangements. Estimations for several pairs of genomes at different divergence times are in agreement with a slowly evolvable colocalization of active genomic regions in the cell.
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Affiliation(s)
- Priscila Biller
- INRIA Grenoble Rhône-Alpes, Montbonnot, France University of Campinas, São Paulo, Brazil
| | | | - Carole Knibbe
- INRIA Grenoble Rhône-Alpes, Montbonnot, France Université Lyon 1, LIRIS, UMR5205, Villeurbanne, France
| | - Eric Tannier
- INRIA Grenoble Rhône-Alpes, Montbonnot, France Université Lyon 1, LBBE, UMR5558, Villeurbanne, France
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18
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Defining and simulating open-ended novelty: requirements, guidelines, and challenges. Theory Biosci 2016; 135:131-61. [PMID: 27194550 DOI: 10.1007/s12064-016-0229-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 04/29/2016] [Indexed: 01/31/2023]
Abstract
The open-endedness of a system is often defined as a continual production of novelty. Here we pin down this concept more fully by defining several types of novelty that a system may exhibit, classified as variation, innovation, and emergence. We then provide a meta-model for including levels of structure in a system's model. From there, we define an architecture suitable for building simulations of open-ended novelty-generating systems and discuss how previously proposed systems fit into this framework. We discuss the design principles applicable to those systems and close with some challenges for the community.
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19
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Gupta A, LaBar T, Miyagi M, Adami C. Evolution of Genome Size in Asexual Digital Organisms. Sci Rep 2016; 6:25786. [PMID: 27181837 PMCID: PMC4867773 DOI: 10.1038/srep25786] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 04/22/2016] [Indexed: 12/21/2022] Open
Abstract
Genome sizes have evolved to vary widely, from 250 bases in viroids to 670 billion bases in some amoebas. This remarkable variation in genome size is the outcome of complex interactions between various evolutionary factors such as mutation rate and population size. While comparative genomics has uncovered how some of these evolutionary factors influence genome size, we still do not understand what drives genome size evolution. Specifically, it is not clear how the primordial mutational processes of base substitutions, insertions, and deletions influence genome size evolution in asexual organisms. Here, we use digital evolution to investigate genome size evolution by tracking genome edits and their fitness effects in real time. In agreement with empirical data, we find that mutation rate is inversely correlated with genome size in asexual populations. We show that at low point mutation rate, insertions are significantly more beneficial than deletions, driving genome expansion and the acquisition of phenotypic complexity. Conversely, the high mutational load experienced at high mutation rates inhibits genome growth, forcing the genomes to compress their genetic information. Our analyses suggest that the inverse relationship between mutation rate and genome size is a result of the tradeoff between evolving phenotypic innovation and limiting the mutational load.
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Affiliation(s)
- Aditi Gupta
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
| | - Thomas LaBar
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.,Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, MI 48824, USA
| | - Michael Miyagi
- Department of Integrative Biology, University of Texas at Austin, Austin, TX 78712, USA
| | - Christoph Adami
- BEACON Center for the Study of Evolution in Action, Michigan State University, East Lansing, MI 48824, USA.,Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA.,Program in Ecology, Evolutionary Biology, and Behavior, Michigan State University, East Lansing, MI 48824, USA.,Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA
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20
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21
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Misevic D, Frénoy A, Lindner AB, Taddei F. Shape matters: lifecycle of cooperative patches promotes cooperation in bulky populations. Evolution 2015; 69:788-802. [PMID: 25639379 PMCID: PMC4409860 DOI: 10.1111/evo.12616] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2014] [Accepted: 01/02/2015] [Indexed: 11/29/2022]
Abstract
Natural cooperative systems take many forms, ranging from one-dimensional cyanobacteria arrays to fractal-like biofilms. We use in silico experimental systems to study a previously overlooked factor in the evolution of cooperation, physical shape of the population. We compare the emergence and maintenance of cooperation in populations of digital organisms that inhabit bulky (100 × 100 cells) or slender (4 × 2500) toroidal grids. Although more isolated subpopulations of secretors in a slender population could be expected to favor cooperation, we find the opposite: secretion evolves to higher levels in bulky populations. We identify the mechanistic explanation for the shape effect by analyzing the lifecycle and dynamics of cooperator patches, from their emergence and growth, to invasion by noncooperators and extinction. Because they are constrained by the population shape, the cooperator patches expand less in slender than in bulky populations, leading to fewer cooperators, less public good secretion, and generally lower cooperation. The patch dynamics and mechanisms of shape effect are robust across several digital cooperation systems and independent of the underlying basis for cooperation (public good secretion or a cooperation game). Our results urge for a greater consideration of population shape in the study of the evolution of cooperation across experimental and modeling systems.
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Affiliation(s)
- Dusan Misevic
- Center for Research and Interdisciplinarity, INSERM U1001, Medicine Faculty, site Cochin Port-Royal, University Paris Descartes, Sorbonne Paris Cité, 24, rue du Faubourg Saint Jacques, 75014, Paris, France.
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22
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de Boer FK, Hogeweg P. Mutation rates and evolution of multiple coding in RNA-based protocells. J Mol Evol 2014; 79:193-203. [PMID: 25280530 PMCID: PMC4247474 DOI: 10.1007/s00239-014-9648-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2013] [Accepted: 09/18/2014] [Indexed: 11/28/2022]
Abstract
RNA has a myriad of biological roles in contemporary life. We use the RNA paradigm for genotype-phenotype mappings to study the evolution of multiple coding in dependence to mutation rates. We study three different one-to-many genotype-phenotype mappings which have the potential to encode the information for multiple functions on a single sequence. These three different maps are (i) cofolding, where two sequences can bind and “cofold,” (ii) suboptimal folding, where the alternative foldings within a certain range of the native state of sequences are considered, and (iii) adapter-based folding, in which protocells can evolve adapter-mediated alternative foldings. We study how protocells with a set of sequences can code for a set of predefined functional structures, while avoiding all other structures, which are considered to be misfoldings. Note that such misfolded structures are far more prevalent than functional ones. Our results highlight the flexibility of the RNA sequence to secondary structure mapping and the power of evolution to shape the genotype-phenotype mapping. We show that high fitness can be achieved even at high mutation rates. Mutation rates affect genome size, but differently depending on which folding method is used. We observe that cofolding limits the possibility to avoid misfolded structures and that adapters are always beneficial for fitness, but even more beneficial at low mutation rates. In all cases, the evolution procedure selects for molecules that can form additional structures. Our results indicate that inherent properties of RNA molecules and their interactions allow the evolution of complexity even at high mutation rates.
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Affiliation(s)
- Folkert K de Boer
- Theoretical Biology and Bioinformatics, Universiteit Utrecht, Utrecht, The Netherlands,
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23
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Reductive genome evolution at both ends of the bacterial population size spectrum. Nat Rev Microbiol 2014; 12:841-50. [DOI: 10.1038/nrmicro3331] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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24
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Mitchener WG. Evolution of communication protocols using an artificial regulatory network. ARTIFICIAL LIFE 2014; 20:491-530. [PMID: 25148549 DOI: 10.1162/artl_a_00146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
I describe the Utrecht Machine (UM), a discrete artificial regulatory network designed for studying how evolution discovers biochemical computation mechanisms. The corresponding binary genome format is compatible with gene deletion, duplication, and recombination. In the simulation presented here, an agent consisting of two UMs, a sender and a receiver, must encode, transmit, and decode a binary word over time using the narrow communication channel between them. This communication problem has chicken-and-egg structure in that a sending mechanism is useless without a corresponding receiving mechanism. An in-depth case study reveals that a coincidence creates a minimal partial solution, from which a sequence of partial sending and receiving mechanisms evolve. Gene duplications contribute by enlarging the regulatory network. Analysis of 60,000 sample runs under a variety of parameter settings confirms that crossover accelerates evolution, that stronger selection tends to find clumsier solutions and finds them more slowly, and that there is implicit selection for robust mechanisms and genomes at the codon level. Typical solutions associate each input bit with an activation speed and combine them almost additively. The parents of breakthrough organisms sometimes have lower fitness scores than others in the population, indicating that populations can cross valleys in the fitness landscape via outlying members. The simulation exhibits back mutations and population-level memory effects not accounted for in traditional population genetics models. All together, these phenomena suggest that new evolutionary models are needed that incorporate regulatory network structure.
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25
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Fischer S, Bernard S, Beslon G, Knibbe C. A model for genome size evolution. Bull Math Biol 2014; 76:2249-91. [PMID: 25142746 PMCID: PMC4153982 DOI: 10.1007/s11538-014-9997-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 07/15/2014] [Indexed: 01/27/2023]
Abstract
We present a model for genome size evolution that takes into account both local mutations such as small insertions and small deletions, and large chromosomal rearrangements such as duplications and large deletions. We introduce the possibility of undergoing several mutations within one generation. The model, albeit minimalist, reveals a non-trivial spontaneous dynamics of genome size: in the absence of selection, an arbitrary large part of genomes remains beneath a finite size, even for a duplication rate 2.6-fold higher than the rate of large deletions, and even if there is also a systematic bias toward small insertions compared to small deletions. Specifically, we show that the condition of existence of an asymptotic stationary distribution for genome size non-trivially depends on the rates and mean sizes of the different mutation types. We also give upper bounds for the median and other quantiles of the genome size distribution, and argue that these bounds cannot be overcome by selection. Taken together, our results show that the spontaneous dynamics of genome size naturally prevents it from growing infinitely, even in cases where intuition would suggest an infinite growth. Using quantitative numerical examples, we show that, in practice, a shrinkage bias appears very quickly in genomes undergoing mutation accumulation, even though DNA gains and losses appear to be perfectly symmetrical at first sight. We discuss this spontaneous dynamics in the light of the other evolutionary forces proposed in the literature and argue that it provides them a stability-related size limit below which they can act.
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Affiliation(s)
- Stephan Fischer
- INSA-Lyon, Inria, CNRS, LIRIS, UMR5205, 69621, Villeurbanne, France,
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26
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Resistant traits in digital organisms do not revert preselection status despite extended deselection: implications to microbial antibiotics resistance. BIOMED RESEARCH INTERNATIONAL 2014; 2014:648389. [PMID: 24977157 PMCID: PMC4054778 DOI: 10.1155/2014/648389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Revised: 04/29/2014] [Accepted: 05/07/2014] [Indexed: 11/25/2022]
Abstract
Antibiotics resistance is a serious biomedical issue as formally susceptible organisms gain resistance under its selective pressure. There have been contradictory results regarding the prevalence of resistance following withdrawal and disuse of the specific antibiotics. Here, we use experimental evolution in “digital organisms” to examine the rate of gain and loss of resistance under the assumption that there is no fitness cost for maintaining resistance. Our results show that selective pressure is likely to result in maximum resistance with respect to the selective pressure. During deselection as a result of disuse of the specific antibiotics, a large initial loss and prolonged stabilization of resistance are observed, but resistance is not lost to the stage of preselection. This suggests that a pool of partial persists organisms persist long after withdrawal of selective pressure at a relatively constant proportion. Hence, contradictory results regarding the prevalence of resistance following withdrawal and disuse of the specific antibiotics may be a statistical variation about constant proportion. Our results also show that subsequent reintroduction of the same selective pressure results in rapid regain of maximal resistance. Thus, our simulation results suggest that complete elimination of specific antibiotics resistance is unlikely after the disuse of antibiotics once a resistant pool of microorganisms has been established.
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27
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Frénoy A, Taddei F, Misevic D. Genetic architecture promotes the evolution and maintenance of cooperation. PLoS Comput Biol 2013; 9:e1003339. [PMID: 24278000 PMCID: PMC3836702 DOI: 10.1371/journal.pcbi.1003339] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2013] [Accepted: 09/30/2013] [Indexed: 12/19/2022] Open
Abstract
When cooperation has a direct cost and an indirect benefit, a selfish behavior is more likely to be selected for than an altruistic one. Kin and group selection do provide evolutionary explanations for the stability of cooperation in nature, but we still lack the full understanding of the genomic mechanisms that can prevent cheater invasion. In our study we used Aevol, an agent-based, in silico genomic platform to evolve populations of digital organisms that compete, reproduce, and cooperate by secreting a public good for tens of thousands of generations. We found that cooperating individuals may share a phenotype, defined as the amount of public good produced, but have very different abilities to resist cheater invasion. To understand the underlying genetic differences between cooperator types, we performed bio-inspired genomics analyses of our digital organisms by recording and comparing the locations of metabolic and secretion genes, as well as the relevant promoters and terminators. Association between metabolic and secretion genes (promoter sharing, overlap via frame shift or sense-antisense encoding) was characteristic for populations with robust cooperation and was more likely to evolve when secretion was costly. In mutational analysis experiments, we demonstrated the potential evolutionary consequences of the genetic association by performing a large number of mutations and measuring their phenotypic and fitness effects. The non-cooperating mutants arising from the individuals with genetic association were more likely to have metabolic deleterious mutations that eventually lead to selection eliminating such mutants from the population due to the accompanying fitness decrease. Effectively, cooperation evolved to be protected and robust to mutations through entangled genetic architecture. Our results confirm the importance of second-order selection on evolutionary outcomes, uncover an important genetic mechanism for the evolution and maintenance of cooperation, and suggest promising methods for preventing gene loss in synthetically engineered organisms.
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Affiliation(s)
- Antoine Frénoy
- INSERM U1001, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris Descartes, Paris, France
- * E-mail:
| | - François Taddei
- INSERM U1001, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris Descartes, Paris, France
| | - Dusan Misevic
- INSERM U1001, Université Paris Descartes, Sorbonne Paris Cité, Faculté de Médecine Paris Descartes, Paris, France
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28
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Batut B, Parsons DP, Fischer S, Beslon G, Knibbe C. In silico experimental evolution: a tool to test evolutionary scenarios. BMC Bioinformatics 2013; 14 Suppl 15:S11. [PMID: 24564457 PMCID: PMC3851946 DOI: 10.1186/1471-2105-14-s15-s11] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Comparative genomics has revealed that some species have exceptional genomes, compared to their closest relatives. For instance, some species have undergone a strong reduction of their genome with a drastic reduction of their genic repertoire. Deciphering the causes of these atypical trajectories can be very difficult because of the many phenomena that are intertwined during their evolution (e.g. changes of population size, environment structure and dynamics, selection strength, mutation rates...). Here we propose a methodology based on synthetic experiments to test the individual effect of these phenomena on a population of simulated organisms. We developed an evolutionary model--aevol--in which evolutionary conditions can be changed one at a time to test their effects on genome size and organization (e.g. coding ratio). To illustrate the proposed approach, we used aevol to test the effects of a strong reduction in the selection strength on a population of (simulated) bacteria. Our results show that this reduction of selection strength leads to a genome reduction of ~35% with a slight loss of coding sequences (~15% of the genes are lost--mainly those for which the contribution to fitness is the lowest). More surprisingly, under a low selection strength, genomes undergo a strong reduction of the noncoding compartment (~55% of the noncoding sequences being lost). These results are consistent with what is observed in reduced Prochlorococcus strains (marine cyanobacteria) when compared to close relatives.
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29
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Takeuchi N, Hogeweg P. Evolutionary dynamics of RNA-like replicator systems: A bioinformatic approach to the origin of life. Phys Life Rev 2012; 9:219-63. [PMID: 22727399 PMCID: PMC3466355 DOI: 10.1016/j.plrev.2012.06.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2012] [Accepted: 06/04/2012] [Indexed: 11/29/2022]
Abstract
We review computational studies on prebiotic evolution, focusing on informatic processes in RNA-like replicator systems. In particular, we consider the following processes: the maintenance of information by replicators with and without interactions, the acquisition of information by replicators having a complex genotype-phenotype map, the generation of information by replicators having a complex genotype-phenotype-interaction map, and the storage of information by replicators serving as dedicated templates. Focusing on these informatic aspects, we review studies on quasi-species, error threshold, RNA-folding genotype-phenotype map, hypercycle, multilevel selection (including spatial self-organization, classical group selection, and compartmentalization), and the origin of DNA-like replicators. In conclusion, we pose a future question for theoretical studies on the origin of life.
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Affiliation(s)
- Nobuto Takeuchi
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, 8600 Rockville Pike, Bethesda, MD 20894, USA.
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30
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Hindré T, Knibbe C, Beslon G, Schneider D. New insights into bacterial adaptation through in vivo and in silico experimental evolution. Nat Rev Microbiol 2012; 10:352-65. [PMID: 22450379 DOI: 10.1038/nrmicro2750] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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31
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Cuypers TD, Hogeweg P. Virtual genomes in flux: an interplay of neutrality and adaptability explains genome expansion and streamlining. Genome Biol Evol 2012; 4:212-29. [PMID: 22234601 PMCID: PMC3318439 DOI: 10.1093/gbe/evr141] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The picture that emerges from phylogenetic gene content reconstructions is that genomes evolve in a dynamic pattern of rapid expansion and gradual streamlining. Ancestral organisms have been estimated to possess remarkably rich gene complements, although gene loss is a driving force in subsequent lineage adaptation and diversification. Here, we study genome dynamics in a model of virtual cells evolving to maintain homeostasis. We observe a pattern of an initial rapid expansion of the genome and a prolonged phase of mutational load reduction. Generally, load reduction is achieved by the deletion of redundant genes, generating a streamlining pattern. Load reduction can also occur as a result of the generation of highly neutral genomic regions. These regions can expand and contract in a neutral fashion. Our study suggests that genome expansion and streamlining are generic patterns of evolving systems. We propose that the complex genotype to phenotype mapping in virtual cells as well as in their biological counterparts drives genome size dynamics, due to an emerging interplay between adaptation, neutrality, and evolvability.
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Affiliation(s)
- Thomas D Cuypers
- Department of Theoretical Biology and Bioinformatics, Utrecht University, Utrecht, The Netherlands.
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32
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Mutation–selection dynamics and error threshold in an evolutionary model for Turing machines. Biosystems 2012; 107:18-33. [DOI: 10.1016/j.biosystems.2011.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/13/2011] [Accepted: 08/14/2011] [Indexed: 11/18/2022]
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33
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Beslon G, Parsons D, Sanchez-Dehesa Y, Peña JM, Knibbe C. Scaling laws in bacterial genomes: A side-effect of selection of mutational robustness? Biosystems 2010; 102:32-40. [DOI: 10.1016/j.biosystems.2010.07.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2010] [Accepted: 07/15/2010] [Indexed: 11/25/2022]
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