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Yıldırım B, Vogl C. The influence of GC-biased gene conversion on non-adaptive sequence evolution in short introns of Drosophila melanogaster. J Evol Biol 2024; 37:383-400. [PMID: 38367009 DOI: 10.1093/jeb/voae015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 11/06/2023] [Accepted: 02/09/2024] [Indexed: 02/19/2024]
Abstract
Population genetic inference of selection on the nucleotide sequence level often proceeds by comparison to a reference sequence evolving only under mutation and population demography. Among the few candidates for such a reference sequence is the 5' part of short introns (5SI) in Drosophila. In addition to mutation and population demography, however, there is evidence for a weak force favouring GC bases, likely due to GC-biased gene conversion (gBGC), and for the effect of linked selection. Here, we use polymorphism and divergence data of Drosophila melanogaster to detect and describe the forces affecting the evolution of the 5SI. We separately analyse mutation classes, compare them between chromosomes, and relate them to recombination rate frequencies. GC-conservative mutations seem to be mainly influenced by mutation and drift, with linked selection mostly causing differences between the central and the peripheral (i.e., telomeric and centromeric) regions of the chromosome arms. Comparing GC-conservative mutation patterns between autosomes and the X chromosome showed differences in mutation rates, rather than linked selection, in the central chromosomal regions after accounting for differences in effective population sizes. On the other hand, GC-changing mutations show asymmetric site frequency spectra, indicating the presence of gBGC, varying among mutation classes and in intensity along chromosomes, but approximately equal in strength in autosomes and the X chromosome.
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Affiliation(s)
- Burçin Yıldırım
- Department of Biomedical Sciences, Vetmeduni, Vienna, Wien, Austria
- Vienna Graduate School of Population Genetics, Wien, Austria
| | - Claus Vogl
- Department of Biomedical Sciences, Vetmeduni, Vienna, Wien, Austria
- Vienna Graduate School of Population Genetics, Wien, Austria
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2
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Caizergues AE, Santangelo JS, Ness RW, Angeoletto F, Anstett DN, Anstett J, Baena-Diaz F, Carlen EJ, Chaves JA, Comerford MS, Dyson K, Falahati-Anbaran M, Fellowes MDE, Hodgins KA, Hood GR, Iñiguez-Armijos C, Kooyers NJ, Lázaro-Lobo A, Moles AT, Munshi-South J, Paule J, Porth IM, Santiago-Rosario LY, Whitney KS, Tack AJM, Johnson MTJ. Does urbanisation lead to parallel demographic shifts across the world in a cosmopolitan plant? Mol Ecol 2024; 33:e17311. [PMID: 38468155 DOI: 10.1111/mec.17311] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2023] [Revised: 12/08/2023] [Accepted: 01/30/2024] [Indexed: 03/13/2024]
Abstract
Urbanisation is occurring globally, leading to dramatic environmental changes that are altering the ecology and evolution of species. In particular, the expansion of human infrastructure and the loss and fragmentation of natural habitats in cities is predicted to increase genetic drift and reduce gene flow by reducing the size and connectivity of populations. Alternatively, the 'urban facilitation model' suggests that some species will have greater gene flow into and within cities leading to higher diversity and lower differentiation in urban populations. These alternative hypotheses have not been contrasted across multiple cities. Here, we used the genomic data from the GLobal Urban Evolution project (GLUE), to study the effects of urbanisation on non-adaptive evolutionary processes of white clover (Trifolium repens) at a global scale. We found that white clover populations presented high genetic diversity and no evidence of reduced Ne linked to urbanisation. On the contrary, we found that urban populations were less likely to experience a recent decrease in effective population size than rural ones. In addition, we found little genetic structure among populations both globally and between urban and rural populations, which showed extensive gene flow between habitats. Interestingly, white clover displayed overall higher gene flow within urban areas than within rural habitats. Our study provides the largest comprehensive test of the demographic effects of urbanisation. Our results contrast with the common perception that heavily altered and fragmented urban environments will reduce the effective population size and genetic diversity of populations and contribute to their isolation.
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Affiliation(s)
- Aude E Caizergues
- Centre for Urban Environments, University of Toronto Mississauga, Mississauga, Ontario, Canada
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - James S Santangelo
- Department of Integrative Biology, University of California Berkeley, Berkeley, California, USA
| | - Rob W Ness
- Centre for Urban Environments, University of Toronto Mississauga, Mississauga, Ontario, Canada
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
| | - Fabio Angeoletto
- Programa de Pós-Graduação em Gestão e Tecnologia Ambiental da Universidade Federal de Rondonópolis, Rondonópolis, Brasil
| | - Daniel N Anstett
- Department of Plant Biology, Department of Entomology, Plant Resilience Institute, Michigan State University, East Lansing, Michigan, USA
| | - Julia Anstett
- Genomic Sciences and Technology Program, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada
| | | | - Elizabeth J Carlen
- Living Earth Collaborative, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Jaime A Chaves
- Universidad San Francisco de Quito, Ecuador, Quito
- San Francisco State University, San Francisco, California, USA
| | - Mattheau S Comerford
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | | | | | | | - Kathryn A Hodgins
- School of Biological Sciences, Monash University, Melbourne, Victoria, Australia
| | - Glen Ray Hood
- Department of Biological Sciences, Wayne State University, Detroit, Michigan, USA
| | - Carlos Iñiguez-Armijos
- Laboratorio de Ecología Tropical y Servicios Ecosistémicos (EcoSs-Lab), Universidad Técnica Particular de Loja, Loja, Ecuador
| | | | - Adrián Lázaro-Lobo
- Biodiversity Research Institute (IMIB), CSIC-University of Oviedo-Principality of Asturias, Mieres, Spain
| | - Angela T Moles
- Evolution & Ecology Research Centre, UNSW-University of New South Wales, Sydney, New South Wales, Australia
| | - Jason Munshi-South
- Department of Biology and Louis Calder Center, Fordham University, New York City, New York, USA
| | - Juraj Paule
- Botanischer Garten und Botanisches Museum Berlin, Freie Universität Berlin, Berlin, Germany
| | - Ilga M Porth
- Institut de biologie intégrative et des systèmes, Université Laval, Quebec City, Quebec, Canada
| | - Luis Y Santiago-Rosario
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota, USA
| | - Kaitlin Stack Whitney
- Science, Technology & Society Department, Rochester Institute of Technology, Rochester, New York, USA
| | - Ayko J M Tack
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Marc T J Johnson
- Centre for Urban Environments, University of Toronto Mississauga, Mississauga, Ontario, Canada
- Department of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada
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3
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Yang LP, Jiang TJ, He MM, Ling YH, Wang ZX, Wu HX, Zhang Z, Xu RH, Wang F, Yuan SQ, Zhao Q. Comprehensive genomic characterization of sporadic synchronous colorectal cancer: Implications for treatment optimization and clinical outcome. Cell Rep Med 2023; 4:101222. [PMID: 37794586 PMCID: PMC10591049 DOI: 10.1016/j.xcrm.2023.101222] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 07/12/2023] [Accepted: 09/11/2023] [Indexed: 10/06/2023]
Abstract
Sporadic synchronous colorectal cancer (SCRC) refers to multiple primary CRC tumors detected simultaneously in an individual without predisposing hereditary conditions, which accounts for the majority of multiple CRCs while lacking a profound understanding of the genomic landscape and evolutionary dynamics to optimize its treatment. In this study, 103 primary tumor samples from 51 patients with SCRC undergo whole-exome sequencing. The germline and somatic mutations and evolutionary and clinical features are comprehensively investigated. Somatic genetic events are largely inconsistent between paired tumors. Compared with solitary CRC, SCRCs have higher prevalence of tumor mutation burden high (TMB-H; 33.3%) and microsatellite-instability high (MSI-H; 29.4%) and different mutation frequencies in oncogenic signaling pathways. Moreover, neutrally evolving SCRC tumors are associated with higher intratumoral heterogeneity and better prognosis. These findings unveil special molecular features, carcinogenesis, and prognosis of sporadic SCRC. Strategies for targeted therapy and immunotherapy should be optimized accordingly.
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Affiliation(s)
- Lu-Ping Yang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China
| | - Teng-Jia Jiang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China
| | - Ming-Ming He
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China; Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, P.R. China
| | - Yi-Hong Ling
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China
| | - Zi-Xian Wang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China; Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, P.R. China
| | - Hao-Xiang Wu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China; Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, P.R. China
| | - Zhen Zhang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China
| | - Rui-Hua Xu
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China; Research Unit of Precision Diagnosis and Treatment for Gastrointestinal Cancer, Chinese Academy of Medical Sciences, Guangzhou 510060, P.R. China
| | - Feng Wang
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China
| | - Shu-Qiang Yuan
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China.
| | - Qi Zhao
- Sun Yat-sen University Cancer Center, State Key Laboratory of Oncology in South China, Collaborative Innovation Center for Cancer Medicine, Guangzhou 510060, P.R. China.
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4
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Warrener A. The multifactor pelvis: An alternative to the adaptationist approach of the obstetrical dilemma. Evol Anthropol 2023; 32:260-274. [PMID: 37527355 DOI: 10.1002/evan.21997] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 02/23/2023] [Accepted: 07/08/2023] [Indexed: 08/03/2023]
Abstract
The obstetrical dilemma describes the competing demands that a bipedally adapted pelvis and a large-brained neonate place on human childbirth and is the predominant model within which hypotheses about the evolution of the pelvis are framed. I argue the obstetrical dilemma follows the adaptationist program outlined by Gould and Lewontin in 1979 and should be replaced with a new model, the multifactor pelvis. This change will allow thorough consideration of nonadaptive explanations for the evolution of the human pelvis and avoid negative social impacts from considering human childbirth inherently dangerous. First, the atomization of the pelvis into discrete traits is discussed, after which current evidence for both adaptive and nonadaptive hypotheses is evaluated, including childbirth, locomotion, shared genetics with other traits under selection, evolutionary history, genetic drift, and environmental and epigenetic influences on the pelvis.
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Affiliation(s)
- Anna Warrener
- Department of Anthropology, University of Colorado Denver, Denver, Colorado, USA
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5
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Liska O, Boross G, Rocabert C, Szappanos B, Tengölics R, Papp B. Principles of metabolome conservation in animals. Proc Natl Acad Sci U S A 2023; 120:e2302147120. [PMID: 37603743 PMCID: PMC10468614 DOI: 10.1073/pnas.2302147120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Accepted: 07/16/2023] [Indexed: 08/23/2023] Open
Abstract
Metabolite levels shape cellular physiology and disease susceptibility, yet the general principles governing metabolome evolution are largely unknown. Here, we introduce a measure of conservation of individual metabolite levels among related species. By analyzing multispecies tissue metabolome datasets in phylogenetically diverse mammals and fruit flies, we show that conservation varies extensively across metabolites. Three major functional properties, metabolite abundance, essentiality, and association with human diseases predict conservation, highlighting a striking parallel between the evolutionary forces driving metabolome and protein sequence conservation. Metabolic network simulations recapitulated these general patterns and revealed that abundant metabolites are highly conserved due to their strong coupling to key metabolic fluxes in the network. Finally, we show that biomarkers of metabolic diseases can be distinguished from other metabolites simply based on evolutionary conservation, without requiring any prior clinical knowledge. Overall, this study uncovers simple rules that govern metabolic evolution in animals and implies that most tissue metabolome differences between species are permitted, rather than favored by natural selection. More broadly, our work paves the way toward using evolutionary information to identify biomarkers, as well as to detect pathogenic metabolome alterations in individual patients.
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Affiliation(s)
- Orsolya Liska
- Hungarian Centre of Excellence for Molecular Medicine - Biological Research Centre Metabolic Systems Biology Lab, 6728Szeged, Hungary
- National Laboratory of Biotechnology, Synthetic and System Biology Unit, Institute of Biochemistry, Biological Research Centre, Eötvös Loránd Research Network, 6726Szeged, Hungary
- Doctoral School of Biology, University of Szeged, 6726Szeged, Hungary
| | - Gábor Boross
- National Laboratory of Biotechnology, Synthetic and System Biology Unit, Institute of Biochemistry, Biological Research Centre, Eötvös Loránd Research Network, 6726Szeged, Hungary
- Department of Biology, Stanford University, Stanford, City of Palo Alto, CA94305-5020
| | - Charles Rocabert
- National Laboratory of Biotechnology, Synthetic and System Biology Unit, Institute of Biochemistry, Biological Research Centre, Eötvös Loránd Research Network, 6726Szeged, Hungary
- Inria, 78150Rocquencourt, 69100Villeurbanne, France
- Organismal and Evolutionary Biology Research Programme, University of Helsinki, 00014Helsinki, Finland
- Institute for Computational Cell Biology, Heinrich-Heine Universität, 40225Düsseldorf, Germany
| | - Balázs Szappanos
- Hungarian Centre of Excellence for Molecular Medicine - Biological Research Centre Metabolic Systems Biology Lab, 6728Szeged, Hungary
- National Laboratory of Biotechnology, Synthetic and System Biology Unit, Institute of Biochemistry, Biological Research Centre, Eötvös Loránd Research Network, 6726Szeged, Hungary
- Department of Biotechnology, University of Szeged, 6726Szeged, Hungary
| | - Roland Tengölics
- Hungarian Centre of Excellence for Molecular Medicine - Biological Research Centre Metabolic Systems Biology Lab, 6728Szeged, Hungary
- National Laboratory of Biotechnology, Synthetic and System Biology Unit, Institute of Biochemistry, Biological Research Centre, Eötvös Loránd Research Network, 6726Szeged, Hungary
- Metabolomics Lab, Core facilities, Biological Research Centre, Eötvös Loránd Research Network, 6726Szeged, Hungary
| | - Balázs Papp
- Hungarian Centre of Excellence for Molecular Medicine - Biological Research Centre Metabolic Systems Biology Lab, 6728Szeged, Hungary
- National Laboratory of Biotechnology, Synthetic and System Biology Unit, Institute of Biochemistry, Biological Research Centre, Eötvös Loránd Research Network, 6726Szeged, Hungary
- National Laboratory for Health Security, Biological Research Centre, Eötvös Loránd Research Network, 6726Szeged, Hungary
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6
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Rathmann H, Perretti S, Porcu V, Hanihara T, Scott GR, Irish JD, Reyes-Centeno H, Ghirotto S, Harvati K. Inferring human neutral genetic variation from craniodental phenotypes. PNAS Nexus 2023; 2:pgad217. [PMID: 37457893 PMCID: PMC10338903 DOI: 10.1093/pnasnexus/pgad217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/14/2023] [Accepted: 06/20/2023] [Indexed: 07/18/2023]
Abstract
There is a growing consensus that global patterns of modern human cranial and dental variation are shaped largely by neutral evolutionary processes, suggesting that craniodental features can be used as reliable proxies for inferring population structure and history in bioarchaeological, forensic, and paleoanthropological contexts. However, there is disagreement on whether certain types of data preserve a neutral signature to a greater degree than others. Here, we address this unresolved question and systematically test the relative neutrality of four standard metric and nonmetric craniodental data types employing an extensive computational genotype-phenotype comparison across modern populations from around the world. Our computation draws on the largest existing data sets currently available, while accounting for geographically structured environmental variation, population sampling uncertainty, disparate numbers of phenotypic variables, and stochastic variation inherent to a neutral model of evolution. Our results reveal that the four data types differentially capture neutral genomic variation, with highest signals preserved in dental nonmetric and cranial metric data, followed by cranial nonmetric and dental metric data. Importantly, we demonstrate that combining all four data types together maximizes the neutral genetic signal compared with using them separately, even with a limited number of phenotypic variables. We hypothesize that this reflects a lower level of genetic integration through pleiotropy between, compared to within, the four data types, effectively forming four different modules associated with relatively independent sets of loci. Therefore, we recommend that future craniodental investigations adopt holistic combined data approaches, allowing for more robust inferences about underlying neutral genetic variation.
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Affiliation(s)
| | - Silvia Perretti
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara 44121, Italy
| | - Valentina Porcu
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara 44121, Italy
| | - Tsunehiko Hanihara
- Department of Anatomy, Kitasato University School of Medicine, Sagamihara 252-0374, Japan
| | - G Richard Scott
- Department of Anthropology, University of Nevada, Reno, NV 89557, USA
| | - Joel D Irish
- Research Centre in Evolutionary Anthropology and Palaeoecology, School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool L3 3AF, UK
- The Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg WITS 2050, South Africa
| | - Hugo Reyes-Centeno
- Department of Anthropology, University of Kentucky, Lexington, KY 40506, USA
- William S. Webb Museum of Anthropology, University of Kentucky, Lexington, KY 40504, USA
- DFG Center for Advanced Studies ‘Words, Bones, Genes, Tools’, University of Tübingen, Tübingen 72070, Germany
| | - Silvia Ghirotto
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara 44121, Italy
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7
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Kokate PP, Bales E, Joyner D, Hazen TC, Techtmann SM. Biogeographic patterns in populations of marine Pseudoalteromonas atlantica isolates. FEMS Microbiol Lett 2023; 370:fnad081. [PMID: 37573136 DOI: 10.1093/femsle/fnad081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 07/14/2023] [Accepted: 08/11/2023] [Indexed: 08/14/2023] Open
Abstract
Intra-specific genomic diversity is well documented in microbes. The question, however, remains whether natural selection or neutral evolution is the major contributor to this diversity. We undertook this study to estimate genomic diversity in Pseudoalteromonas atlantica populations and whether the diversity, if present, could be attributed to environmental factors or distance effects. We isolated and sequenced twenty-three strains of P. atlantica from three geographically distant deep marine basins and performed comparative genomic analyses to study the genomic diversity of populations among these basins. Average nucleotide identity followed a strictly geographical pattern. In two out of three locations, the strains within the location exhibited >99.5% identity, whereas, among locations, the strains showed <98.11% identity. Phylogenetic and pan-genome analysis also reflected the biogeographical separation of the strains. Strains from the same location shared many accessory genes and clustered closely on the phylogenetic tree. Phenotypic diversity between populations was studied in ten out of twenty-three strains testing carbon and nitrogen source utilization and osmotolerance. A genetic basis for phenotypic diversity could be established in most cases but was apparently not influenced by local environmental conditions. Our study suggests that neutral evolution may have a substantial role in the biodiversity of P. atlantica.
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Affiliation(s)
- Prajakta P Kokate
- Department of Biological Sciences, Michigan Technological University, Houghton, MI 49931, United States
| | - Erika Bales
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, TN 37996, United States
| | - Dominique Joyner
- Department of Civil and Environmental Engineering, University of Tennessee Knoxville, Knoxville, TN 37996, United States
| | - Terry C Hazen
- Department of Microbiology, University of Tennessee Knoxville, Knoxville, TN 37996, United States
- Department of Civil and Environmental Engineering, University of Tennessee Knoxville, Knoxville, TN 37996, United States
| | - Stephen M Techtmann
- Department of Biological Sciences, Michigan Technological University, Houghton, MI 49931, United States
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8
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Mutumi GL, Jacobs DS, Bam L. Geographic variation in the skulls of the horseshoe bats, Rhinolophus simulator and R. cf. simulator: Determining the relative contributions of adaptation and drift using geometric morphometrics. Ecol Evol 2021; 11:15916-15935. [PMID: 34824800 PMCID: PMC8601903 DOI: 10.1002/ece3.8262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Revised: 09/21/2021] [Accepted: 09/21/2021] [Indexed: 11/07/2022] Open
Abstract
The relative contributions of adaptation and genetic drift to morphological diversification of the skulls of echolocating mammals were investigated using two horseshoe bat species, Rhinolophus simulator and R. cf. simulator, as test cases. We used 3D geometric morphometrics to compare the shapes of skulls of the two lineages collected at various localities in southern Africa. Size and shape variation was predominantly attributed to selective forces; the between-population variance (B) was not proportional to the within-population variance (W). Modularity was evident in the crania of R. simulator but absent in the crania of R. cf. simulator and the mandibles of both species. The skulls of the two lineages thus appeared to be under different selection pressures, despite the overlap in their distributions. Difference in the crania of R. cf. simulator was centered largely on the nasal dome region of R. cf. simulator but on the cranium and mandibles of R. simulator. It is likely that the size and shape of the nasal dome, which acts as a frequency-dependent acoustic horn, is more crucial in R. cf. simulator than in R. simulator because of the higher echolocation frequencies used by R. cf. simulator. A larger nasal dome in R. cf. simulator would allow the emission of higher intensity pulses, resulting in comparable detection distances to that of R. simulator. In contrast, selection pressure is probably more pronounced on the mandibles and cranium of R. simulator to compensate for the loss in bite force because of its elongated rostrum. The predominance of selection probably reflects the stringent association between environment and the optimal functioning of phenotypic characters associated with echolocation and feeding in bats.
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Affiliation(s)
- Gregory L. Mutumi
- Animal Evolution and Systematics Group (AES)Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
- Life and Environmental Sciences DepartmentUniversity of California–MercedMercedCaliforniaUSA
| | - David S. Jacobs
- Animal Evolution and Systematics Group (AES)Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
| | - Lunga Bam
- Radiation Science DepartmentSouth Africa Nuclear Energy CorporationPretoriaSouth Africa
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9
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Bányai L, Trexler M, Kerekes K, Csuka O, Patthy L. Use of signals of positive and negative selection to distinguish cancer genes and passenger genes. eLife 2021; 10:e59629. [PMID: 33427197 PMCID: PMC7877913 DOI: 10.7554/elife.59629] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 01/10/2021] [Indexed: 12/14/2022] Open
Abstract
A major goal of cancer genomics is to identify all genes that play critical roles in carcinogenesis. Most approaches focused on genes positively selected for mutations that drive carcinogenesis and neglected the role of negative selection. Some studies have actually concluded that negative selection has no role in cancer evolution. We have re-examined the role of negative selection in tumor evolution through the analysis of the patterns of somatic mutations affecting the coding sequences of human genes. Our analyses have confirmed that tumor suppressor genes are positively selected for inactivating mutations, oncogenes, however, were found to display signals of both negative selection for inactivating mutations and positive selection for activating mutations. Significantly, we have identified numerous human genes that show signs of strong negative selection during tumor evolution, suggesting that their functional integrity is essential for the growth and survival of tumor cells.
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Affiliation(s)
- László Bányai
- Institute of Enzymology, Research Centre for Natural SciencesBudapestHungary
| | - Maria Trexler
- Institute of Enzymology, Research Centre for Natural SciencesBudapestHungary
| | - Krisztina Kerekes
- Institute of Enzymology, Research Centre for Natural SciencesBudapestHungary
| | - Orsolya Csuka
- Department of Pathogenetics, National Institute of OncologyBudapestHungary
| | - László Patthy
- Institute of Enzymology, Research Centre for Natural SciencesBudapestHungary
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10
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Melo WA, Vieira LD, Novaes E, Bacon CD, Collevatti RG. Selective Sweeps Lead to Evolutionary Success in an Amazonian Hyperdominant Palm. Front Genet 2020; 11:596662. [PMID: 33424928 PMCID: PMC7786001 DOI: 10.3389/fgene.2020.596662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Accepted: 11/18/2020] [Indexed: 01/21/2023] Open
Abstract
Despite the global importance of tropical ecosystems, few studies have identified how natural selection has shaped their megadiversity. Here, we test for the role of adaptation in the evolutionary success of the widespread, highly abundant Neotropical palm Mauritia flexuosa. We used a genome scan framework, sampling 16,262 single-nucleotide polymorphisms (SNPs) with target sequence capture in 264 individuals from 22 populations in rainforest and savanna ecosystems. We identified outlier loci as well as signal of adaptation using Bayesian correlations of allele frequency with environmental variables and detected both selective sweeps and genetic hitchhiking events. Functional annotation of SNPs with selection footprints identified loci affecting genes related to adaptation to environmental stress, plant development, and primary metabolic processes. The strong differences in climatic and soil variables between ecosystems matched the high differentiation and low admixture in population Bayesian clustering. Further, we found only small differences in allele frequency distribution in loci putatively under selection among widespread populations from different ecosystems, with fixation of a single allele in most populations. Taken together, our results indicate that adaptive selective sweeps related to environmental stress shaped the spatial pattern of genetic diversity in M. flexuosa, leading to high similarity in allele frequency among populations from different ecosystems.
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Affiliation(s)
- Warita A Melo
- Laboratório de Genética & Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
| | - Lucas D Vieira
- Laboratório de Genética & Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
| | - Evandro Novaes
- Departamento de Biologia, Universidade Federal de Lavras, Lavras, Brazil
| | - Christine D Bacon
- Department of Biological and Environmental Sciences, University of Gothenburg, Gothenburg, Sweden.,Gothenburg Global Biodiversity Centre, Gothenburg, Sweden
| | - Rosane G Collevatti
- Laboratório de Genética & Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal de Goiás, Goiânia, Brazil
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11
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Abstract
Following the advent of cancer immunotherapy, increasing insight has been gained on the role of mutational load and neoantigens as key ingredients in T cell recognition of malignancies. However, not all highly mutational tumours react to immune therapies, and initial success is often followed by eventual relapse. Heterogeneity in the neoantigen landscape of a tumour might be key in the failure of immune surveillance. In this work, we present a mathematical framework to describe how neoantigen distributions shape the immune response. The model predicts the existence of an antigen diversity threshold level beyond which T cells fail at controlling heterogeneous tumours. Incorporating this diversity marker adds predictive value to antigen load for two cohorts of anti-CTLA-4 treated melanoma patients. Furthermore, our analytical approach indicates rapid increases in epitope heterogeneity in early malignancy growth following immune escape. We propose a combination therapy scheme that takes advantage of preexisting resistance to a targeted agent. The model indicates that the selective sweep for a resistant subclone reduces neoantigen heterogeneity, and we postulate the existence of a time window before tumour relapse where checkpoint blockade immunotherapy can become more effective.
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Affiliation(s)
- Guim Aguadé-Gorgorió
- ICREA-Complex Systems Lab, Universitat Pompeu Fabra, 08003 Barcelona, Spain.,Institut de Biologia Evolutiva (CSIC-UPF), Psg Maritim Barceloneta, 37, 08003 Barcelona, Spain
| | - Ricard Solé
- ICREA-Complex Systems Lab, Universitat Pompeu Fabra, 08003 Barcelona, Spain.,Institut de Biologia Evolutiva (CSIC-UPF), Psg Maritim Barceloneta, 37, 08003 Barcelona, Spain.,Santa Fe Institute, 399 Hyde Park Road, Santa Fe NM 87501, USA
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12
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Abstract
Teeth have been studied for decades and continue to reveal information relevant to human evolution. Studies have shown that many traits of the outer enamel surface evolve neutrally and can be used to infer human population structure. However, many of these traits are unavailable in archaeological and fossil individuals due to processes of wear and taphonomy. Enamel-dentine junction (EDJ) morphology, the shape of the junction between the enamel and the dentine within a tooth, captures important information about tooth development and vertebrate evolution and is informative because it is subject to less wear and thus preserves more anatomy in worn or damaged specimens, particularly in mammals with relatively thick enamel like hominids. This study looks at the molar EDJ across a large sample of human populations. We assessed EDJ morphological variation in a sample of late Holocene modern humans (n = 161) from archaeological populations using μ-CT biomedical imaging and geometric morphometric analyses. Global variation in human EDJ morphology was compared to the statistical expectations of neutral evolution and "Out of Africa" dispersal modeling of trait evolution. Significant correlations between phenetic variation and neutral genetic variation indicate that EDJ morphology has evolved neutrally in humans. While EDJ morphology reflects population history, its global distribution does not follow expectations of the Out of Africa dispersal model. This study increases our knowledge of human dental variation and contributes to our understanding of dental development more broadly, with important applications to the investigation of population history and human genetic structure.
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13
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Marchi N, Excoffier L. Gene flow as a simple cause for an excess of high-frequency-derived alleles. Evol Appl 2020; 13:2254-2263. [PMID: 33005222 PMCID: PMC7513730 DOI: 10.1111/eva.12998] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2020] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 01/19/2023] Open
Abstract
Most human populations exhibit an excess of high-frequency variants, leading to a U-shaped site-frequency spectrum (uSFS). This pattern has been generally interpreted as a signature of ongoing episodes of positive selection, or as evidence for a mis-assignment of ancestral/derived allelic states, but uSFS has also been observed in populations receiving gene flow from a ghost population, in structured populations, or after range expansions. In order to better explain the prevalence of high-frequency variants in humans and other populations, we describe here which patterns of gene flow and population demography can lead to uSFS by using extensive coalescent simulations. We find that uSFS can often be observed in a population if gene flow brings a few ancestral alleles from a well-differentiated population. Gene flow can either consist in single pulses of admixture or continuous immigration, but different demographic conditions are necessary to observe uSFS in these two scenarios. Indeed, an extremely low and recent gene flow is required in the case of single admixture events, while with continuous immigration, uSFS occurs only if gene flow started recently at a high rate or if it lasted for a long time at a low rate. Overall, we find that a neutral uSFS occurs under more restrictive conditions in populations having received single pulses of gene flow than in populations exposed to continuous gene flow. We also show that the uSFS observed in human populations from the 1000 Genomes Project can easily be explained by gene flow from surrounding populations without requiring past episodes of positive selection. These results imply that uSFS should be common in non-isolated populations, such as most wild or domesticated plants and animals.
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Affiliation(s)
- Nina Marchi
- CMPGInstitute of Ecology and EvolutionUniversity of BerneBerneSwitzerland
- Swiss Institute of BioinformaticsLausanneSwitzerland
| | - Laurent Excoffier
- CMPGInstitute of Ecology and EvolutionUniversity of BerneBerneSwitzerland
- Swiss Institute of BioinformaticsLausanneSwitzerland
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14
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Haag KL, Pombert JF, Sun Y, de Albuquerque NRM, Batliner B, Fields P, Lopes TF, Ebert D. Microsporidia with Vertical Transmission Were Likely Shaped by Nonadaptive Processes. Genome Biol Evol 2020; 12:3599-3614. [PMID: 31825473 PMCID: PMC6944219 DOI: 10.1093/gbe/evz270] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/05/2019] [Indexed: 12/14/2022] Open
Abstract
Microsporidia have the leanest genomes among eukaryotes, and their physiological and genomic simplicity has been attributed to their intracellular, obligate parasitic life-style. However, not all microsporidia genomes are small or lean, with the largest dwarfing the smallest ones by at least an order of magnitude. To better understand the evolutionary mechanisms behind this genomic diversification, we explore here two clades of microsporidia with distinct life histories, Ordospora and Hamiltosporidium, parasitizing the same host species, Daphnia magna. Based on seven newly assembled genomes, we show that mixed-mode transmission (the combination of horizontal and vertical transmission), which occurs in Hamiltosporidium, is found to be associated with larger and AT-biased genomes, more genes, and longer intergenic regions, as compared with the exclusively horizontally transmitted Ordospora. Furthermore, the Hamiltosporidium genome assemblies contain a variety of repetitive elements and long segmental duplications. We show that there is an excess of nonsynonymous substitutions in the microsporidia with mixed-mode transmission, which cannot be solely attributed to the lack of recombination, suggesting that bursts of genome size in these microsporidia result primarily from genetic drift. Overall, these findings suggest that the switch from a horizontal-only to a mixed mode of transmission likely produces population bottlenecks in Hamiltosporidium species, therefore reducing the effectiveness of natural selection, and allowing their genomic features to be largely shaped by nonadaptive processes.
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Affiliation(s)
- Karen L Haag
- Department of Genetics and Post-Graduation Program of Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | | | - Yukun Sun
- Department of Biology, Illinois Institute of Technology
| | - Nathalia Rammé M de Albuquerque
- Department of Genetics and Post-Graduation Program of Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | | | - Peter Fields
- Department of Environmental Sciences, Zoology, Basel University, Switzerland
| | - Tiago Falcon Lopes
- Department of Genetics and Post-Graduation Program of Genetics and Molecular Biology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, Basel University, Switzerland
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15
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Abstract
In the absence of both positive and negative selections, coding sequences evolve at a neutral rate (R = 1). Such a high genomic rate is generally not achievable due to the prevalence of negative selection against codon substitutions. Remarkably, somatic evolution exhibits the seemingly neutral rate R ∼ 1 across normal and cancerous tissues. Nevertheless, R ∼ 1 may also mean that positive and negative selections are both strong, but equal in intensity. We refer to this regime as quasi-neutral. Indeed, individual genes in cancer cells often evolve at a much higher, or lower, rate than R ∼ 1. Here, we show that 1) quasi-neutrality is much more likely when populations are small (N < 50); 2) stem-cell populations in single normal tissue niches, from which tumors likely emerge, have a small N (usually <50) but selection at this stage is measurable and strong; 3) when N dips below 50, selection efficacy decreases precipitously; and 4) notably, N is smaller in the stem-cell niche of the small intestine than in the colon. Hence, the ∼70-fold higher rate of phenotypic evolution (observed as cancer risk) in the latter can be explained by the greater efficacy of selection, which then leads to the fixation of more advantageous and fewer deleterious mutations in colon cancers. In conclusion, quasi-neutral evolution sheds a new light on a general evolutionary principle that helps to explain aspects of cancer evolution.
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Affiliation(s)
- Bingjie Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Zongkun Shi
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Qingjian Chen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Xu Shen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Darryl Shibata
- Department of Pathology, Keck School of Medicine of the University of Southern California, Los Angeles, CA
| | - Haijun Wen
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China
| | - Chung-I Wu
- State Key Laboratory of Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, China.,CAS Key Laboratory of Genomic and Precision Medicine, Beijing Institute of Genomics, Chinese Academy of Sciences, Beijing, China.,Department of Ecology and Evolution, University of Chicago, Chicago, IL
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16
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Cabalzar AP, Fields PD, Kato Y, Watanabe H, Ebert D. Parasite-mediated selection in a natural metapopulation of Daphnia magna. Mol Ecol 2019; 28:4770-4785. [PMID: 31591747 DOI: 10.1111/mec.15260] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/17/2019] [Accepted: 09/27/2019] [Indexed: 01/03/2023]
Abstract
Parasite-mediated selection varying across time and space in metapopulations is expected to result in host local adaptation and the maintenance of genetic diversity in disease-related traits. However, nonadaptive processes like migration and extinction-(re)colonization dynamics might interfere with adaptive evolution. Understanding how adaptive and nonadaptive processes interact to shape genetic variability in life-history and disease-related traits can provide important insights into their evolution in subdivided populations. Here we investigate signatures of spatially fluctuating, parasite-mediated selection in a natural metapopulation of Daphnia magna. Host genotypes from infected and uninfected populations were genotyped at microsatellite markers, and phenotyped for life-history and disease traits in common garden experiments. Combining phenotypic and genotypic data a QST -FST -like analysis was conducted to test for signatures of parasite mediated selection. We observed high variation within and among populations for phenotypic traits, but neither an indication of host local adaptation nor a cost of resistance. Infected populations have a higher gene diversity (Hs) than uninfected populations and Hs is strongly positively correlated with fitness. These results suggest a strong parasite effect on reducing population level inbreeding. We discuss how stochastic processes related to frequent extinction-(re)colonization dynamics as well as host and parasite migration impede the evolution of resistance in the infected populations. We suggest that the genetic and phenotypic patterns of variation are a product of dynamic changes in the host gene pool caused by the interaction of colonization bottlenecks, inbreeding, immigration, hybrid vigor, rare host genotype advantage and parasitism. Our study highlights the effect of the parasite in ameliorating the negative fitness consequences caused by the high drift load in this metapopulation.
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Affiliation(s)
- Andrea P Cabalzar
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Peter D Fields
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Yasuhiko Kato
- Department of Biotechnology, Division of Advance Science and Biotechnology, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Hajime Watanabe
- Department of Biotechnology, Division of Advance Science and Biotechnology, Graduate School of Engineering, Osaka University, Suita, Japan
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland.,Tvärminne Zoological Station, Tvärminne, Finland
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17
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Nanjundiah V. Many roads lead to Rome: Neutral phenotypes in microorganisms. J Exp Zool B Mol Dev Evol 2019; 332:339-348. [PMID: 31617664 DOI: 10.1002/jez.b.22909] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Revised: 09/10/2019] [Accepted: 09/14/2019] [Indexed: 11/09/2022]
Abstract
John Bonner pointed out that microorganisms differ in several ways, some of which may reflect neutral phenotypic evolution. For making his case, Bonner referred to interspecies differences and morphological traits. Here we consider intraspecies differences and physiological traits. As a case-study, we examine the production of an extracellular cyclic 3 ' ,5 ' monophosphate phosphodiesterase in the cellular slime mold Dictyostelium discoideum. Temporal profiles of phosphodiesterase activity differ significantly between wild-type strains. From that we argue that the inference drawn initially from studies on a single wild-type, namely that the profile displayed by it pointed to an adaptive role, was mistaken. We generalize the conclusion to suggest that physiological differences exhibited by microorganisms of the same species may, but need not, reflect adaptations to different environments. Rather, the differences could be related to the fact that microorganisms live in groups whose composition can vary between homogeneous (clonal) and heterogeneous (polyclonal). More than one physiological profile is consistent with the normal development of the group in a given environment; the alternatives are neutral. When studying microbial physiology and behavior, it is expected that the observations are made on a clonal population; genetic (and so phenotypic) heterogeneity is carefully guarded against. As the example from D. discoideum shows, an unintended consequence of overlooking phenotypic heterogeneity is that one can fall into the trap of accepting a seemingly plausible, but possibly erroneous, adaptive explanation for a "normal" wild-type phenotype.
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Affiliation(s)
- Vidyanand Nanjundiah
- Centre for Human Genetics, BioTech Park, Bangalore, India.,Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Research Centre at Stellenbosch University, Stellenbosch, South Africa
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18
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Abrusán G, Marsh JA. Ligand Binding Site Structure Influences the Evolution of Protein Complex Function and Topology. Cell Rep 2019; 22:3265-3276. [PMID: 29562182 PMCID: PMC5873459 DOI: 10.1016/j.celrep.2018.02.085] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Revised: 01/17/2018] [Accepted: 02/22/2018] [Indexed: 02/06/2023] Open
Abstract
It has been suggested that the evolution of protein complexes is significantly influenced by stochastic, non-adaptive processes. Using ligand binding as a proxy of function, we show that the structure of ligand-binding sites significantly influences the evolution of protein complexes. We show that homomers with multi-chain binding sites (MBSs) evolve new functions slower than monomers or other homomers, and those binding cofactors and metals have more conserved quaternary structure than other homomers. Moreover, the ligands and ligand-binding pockets of homologous MBS homomers are more similar than monomers and other homomers. Our results suggest strong evolutionary selection for quaternary structure in cofactor-binding MBS homomers, whereas neutral processes are more important in complexes with single-chain binding sites. They also have pharmacological implications, suggesting that complexes with single-chain binding sites are better targets for selective drugs, whereas MBS homomers are good candidates for broad-spectrum antibiotic and multitarget drug design. Ligand binding site structure significantly influences protein function evolution MBS homomers have more similar ligand binding pockets than monomers and other homomers Cofactor and metal-binding MBS homomers have more conserved QS than other homomers MBS homomers are promising targets for developing antibiotics and multitarget drugs
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Affiliation(s)
- György Abrusán
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK.
| | - Joseph A Marsh
- MRC Human Genetics Unit, Institute of Genetics and Molecular Medicine, University of Edinburgh, Crewe Road, Edinburgh EH4 2XU, UK
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19
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Nielly-Thibault L, Landry CR. Differences Between the Raw Material and the Products of de Novo Gene Birth Can Result from Mutational Biases. Genetics 2019; 212:1353-1366. [PMID: 31227545 PMCID: PMC6707459 DOI: 10.1534/genetics.119.302187] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Accepted: 06/14/2019] [Indexed: 12/03/2022] Open
Abstract
Proteins are among the most important constituents of biological systems. Because all protein-coding genes have a noncoding ancestral form, the properties of noncoding sequences and how they shape the birth of novel proteins may influence the structure and function of all proteins. Differences between the properties of young proteins and random expectations from noncoding sequences have previously been interpreted as the result of natural selection. However, interpreting such deviations requires a yet-unattained understanding of the raw material of de novo gene birth and its relation to novel functional proteins. We mathematically show that the average properties and selective filtering of the "junk" polypeptides of which this raw material is composed are not the only factors influencing the properties of novel functional proteins. We find that in some biological scenarios, they also depend on the variance of the properties of junk polypeptides and their correlation with the rate of allelic turnover, which may itself depend on mutational biases. This suggests for instance that any property of polypeptides that accelerates their exploration of the sequence space could be overrepresented in novel functional proteins, even if it has a limited effect on adaptive value. To exemplify the use of our general theoretical results, we build a simple model that predicts the mean length and mean intrinsic disorder of novel functional proteins from the genomic GC content and a single evolutionary parameter. This work provides a theoretical framework that can guide the prediction and interpretation of results when studying the de novo emergence of protein-coding genes.
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Affiliation(s)
- Lou Nielly-Thibault
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Quebec, Quebec G1V 0A6, Canada
- Département de Biologie, Université Laval, Quebec, Quebec G1V 0A6, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Université Laval, Quebec, Quebec G1V 0A6, Canada
- PROTEO, Quebec, Quebec G1V 0A6, Canada
| | - Christian R Landry
- Institut de Biologie Intégrative et des Systèmes, Université Laval, Quebec, Quebec G1V 0A6, Canada
- Département de Biologie, Université Laval, Quebec, Quebec G1V 0A6, Canada
- Département de Biochimie, de Microbiologie et de Bio-Informatique, Université Laval, Quebec, Quebec G1V 0A6, Canada
- PROTEO, Quebec, Quebec G1V 0A6, Canada
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20
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Abstract
A long-standing question in evolutionary biology is the relative contribution of large and small effect mutations to the adaptive process. We have investigated this question in proteins by estimating the rate of adaptive evolution between all pairs of amino acids separated by one mutational step using a McDonald-Kreitman type approach and genome-wide data from several Drosophila species. We find that the rate of adaptive evolution is highest among amino acids that are more similar. This is partly due to the fact that the proportion of mutations that are adaptive is higher among more similar amino acids. We also find that the rate of neutral evolution between amino acids is higher among more similar amino acids. Overall our results suggest that both the adaptive and nonadaptive evolution of proteins are dominated by substitutions between similar amino acids.
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Affiliation(s)
- Juraj Bergman
- Institut für Populationsgenetik, Vetmeduni Vienna, Wien, Austria.,Vienna Graduate School of Population Genetics, Wien, Austria
| | - Adam Eyre-Walker
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
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21
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Abstract
Changes in gene regulation have long been thought to play an important role in primate evolution. However, although a number of studies have compared genome-wide gene expression patterns across primate species, fewer have investigated the gene regulatory mechanisms that underlie such patterns, or the relative contribution of drift versus selection. Here, we profiled genome-scale DNA methylation levels in blood samples from five of the six extant species of the baboon genus Papio (4-14 individuals per species). This radiation presents the opportunity to investigate DNA methylation divergence at both shallow and deeper timescales (0.380-1.4 My). In contrast to studies in human populations, but similar to studies in great apes, DNA methylation profiles clearly mirror genetic and geographic structure. Divergence in DNA methylation proceeds fastest in unannotated regions of the genome and slowest in regions of the genome that are likely more constrained at the sequence level (e.g., gene exons). Both heuristic approaches and Ornstein-Uhlenbeck models suggest that DNA methylation levels at a small set of sites have been affected by positive selection, and that this class is enriched in functionally relevant contexts, including promoters, enhancers, and CpG islands. Our results thus indicate that the rate and distribution of DNA methylation changes across the genome largely mirror genetic structure. However, at some CpG sites, DNA methylation levels themselves may have been a target of positive selection, pointing to loci that could be important in connecting sequence variation to fitness-related traits.
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Affiliation(s)
- Tauras P Vilgalys
- Department of Evolutionary Anthropology, Duke University, Durham, NC
| | - Jeffrey Rogers
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX
| | - Clifford J Jolly
- Department of Anthropology, New York University, New York, NY
- Center for the Study of Human Origins, New York University, New York, NY
- New York Consortium for Evolutionary Primatology, New York, NY
| | | | - Sayan Mukherjee
- Department of Statistical Science, Duke University, Durham, NC
- Department of Mathematics, Duke University, Durham, NC
- Department of Computer Science, Duke University, Durham, NC
| | - Jenny Tung
- Department of Evolutionary Anthropology, Duke University, Durham, NC
- Department of Biology, Duke University, Durham, NC
- Duke University Population Research Institute, Duke University, Durham, NC
- Institute of Primate Research, National Museums of Kenya, Karen, Nairobi, Kenya
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22
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Abstract
Purpose of review Recent studies demonstrate that normal human tissues accumulate substantial numbers of somatic mutations with aging, to levels comparable to their corresponding cancers. If mutations cause cancer, how do tissues avoid cancer when mutations are unavoidable? Recent findings The small intestines (SI) and colon accumulate similar numbers of replication errors, but SI adenocarcinoma is much rarer than colorectal cancer. Both the small and large intestines are subdivided into millions of small neighborhoods (crypts) that are maintained by small numbers of stem cells. To explain the SI cancer paradox, four fundamental evolution parameters (mutation, drift, selection, and population size) are translated to crypts. Summary The accumulations of driver mutations in a single stem cell may be analogous to an evolutionary poker game. The rarity of SI cancer may reflect that SI crypts are smaller and have fewer stem cells than the colon, which reduces the numbers of cells at risk for mutation and perhaps selection efficiency. Tissue microarchitecture may physically modulate cancer evolution by controlling the numbers of directly competing neighboring cells. A better understanding of the SI cancer paradox may illuminate how tissues naturally avoid cancers when mutations are unavoidable.
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Affiliation(s)
- Darryl Shibata
- Department of Pathology, University of Southern California Keck School of Medicine,
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23
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Abstract
There exists a positive correlation between the pH of subcellular compartments and the median isoelectric point (pI) for the associated proteomes. Proteins in the human lysosome-a highly acidic compartment in the cell-have a median pI of ∼6.5, whereas proteins in the more basic mitochondria have a median pI of ∼8.0. Proposed mechanisms reflect potential adaptations to pH. For example, enzyme active site general acid/base residue pKs are likely evolved to match environmental pH. However, such effects would be limited to a few residues on specific proteins, and might not affect the proteome at large. A protein model that considers residue burial upon folding recapitulates the correlation between proteome pI and environmental pH. This correlation can be fully described by a neutral evolution process; no functional selection is included in the model. Proteins in acidic environments incur a lower energetic penalty for burying acidic residues than basic residues, resulting in a net accumulation of acidic residues in the protein core. The inverse is true under alkaline conditions. The pI distributions of subcellular proteomes are likely not a direct result of functional adaptations to pH, but a molecular spandrel stemming from marginal stability.
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24
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da Silva Alcântara Castro KM, do Santos MP, Brito MFG, Bidau CJ, Martinez PA. Ontogenetic allometry conservatism across five teleost orders. J Fish Biol 2018; 93:745-749. [PMID: 30066331 DOI: 10.1111/jfb.13767] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 07/25/2018] [Indexed: 06/08/2023]
Abstract
Geometric morphometrics were used to analyse ontogenetic trajectories in representatives of the Characiformes, Cichliformes, Cyprinodontiformes, Siluriformes, and Tetraodontiformes. It was not possible to differentiate any allometric growth patterns across groups, indicating that a phylogenetically conserved developmental pattern is widespread throughout Teleostei.
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Affiliation(s)
| | - Maiara P do Santos
- Laboratório de Pesquisas Integrativas em Biodiversidade, Departamento de Biologia, Universidade Federal de Sergipe, São Cristóvão, Brasil
| | - Marcelo F G Brito
- Laboratório de Ictiologia, Departamento de Biologia, Universidade Federal de Sergipe, São Cristóvão, Brasil
| | - Claudio J Bidau
- Laboratorio de Genética Evolutiva, Facultad de Ciencias Exactas, Químicas y Naturales, Universidad Nacional de Misiones, Posadas, and Consejo Nacional de Investigaciones Científicas y Técnicas, Buenos Aires, Argentina
| | - Pablo A Martinez
- Laboratório de Pesquisas Integrativas em Biodiversidade, Departamento de Biologia, Universidade Federal de Sergipe, São Cristóvão, Brasil
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25
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Abstract
Mutation is one of the most fundamental evolutionary forces. Studying variation in the mutation rate within and among closely-related species can help reveal mechanisms of genome divergence, but such variation is unstudied in the vast majority of organisms. Previous studies on ciliated protozoa have found extremely low mutation rates. In this study, using mutation-accumulation techniques combined with deep whole-genome sequencing, we explore the germline base-substitution mutation-rate variation of three cryptic species in the Paramecium aurelia species complex—P. biaurelia, P. sexaurelia, and P. tetraurelia. We find that there is extremely limited variation of the mutation rate and spectrum in the three species and confirm the extremely low mutation rate of ciliates.
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26
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Weaver TD, Gunz P. Using geometric morphometric visualizations of directional selection gradients to investigate morphological differentiation. Evolution 2018; 72:838-850. [PMID: 29510468 DOI: 10.1111/evo.13460] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Accepted: 01/29/2018] [Indexed: 01/03/2023]
Abstract
Researchers studying extant and extinct taxa are often interested in identifying the evolutionary processes that have lead to the morphological differences among the taxa. Ideally, one could distinguish the influences of neutral evolutionary processes (genetic drift, mutation) from natural selection, and in situations for which selection is implicated, identify the targets of selection. The directional selection gradient is an effective tool for investigating evolutionary process, because it can relate form (size and shape) differences between taxa to the variation and covariation found within taxa. However, although most modern morphometric analyses use the tools of geometric morphometrics (GM) to analyze landmark data, to date, selection gradients have mainly been calculated from linear measurements. To address this methodological gap, here we present a GM approach for visualizing and comparing between-taxon selection gradients with each other, associated difference vectors, and "selection" gradients from neutral simulations. To exemplify our approach, we use a dataset of 347 three-dimensional landmarks and semilandmarks recorded on the crania of 260 primate specimens (112 humans, 67 common chimpanzees, 36 bonobos, 45 gorillas). Results on this example dataset show how incorporating geometric information can provide important insights into the evolution of the human braincase, and serve to demonstrate the utility of our approach for understanding morphological evolution.
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Affiliation(s)
- Timothy D Weaver
- Department of Anthropology, University of California, Davis, California 95616.,Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany
| | - Philipp Gunz
- Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, 04103 Leipzig, Germany
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27
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Ghalayini M, Launay A, Bridier-Nahmias A, Clermont O, Denamur E, Lescat M, Tenaillon O. Evolution of a Dominant Natural Isolate of Escherichia coli in the Human Gut over the Course of a Year Suggests a Neutral Evolution with Reduced Effective Population Size. Appl Environ Microbiol 2018; 84:e02377-17. [PMID: 29305507 DOI: 10.1128/AEM.02377-17] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2017] [Accepted: 12/22/2017] [Indexed: 11/20/2022] Open
Abstract
In vitro and in vivo evolution experiments on Escherichia coli revealed several principles of bacterial adaptation. However, few data are available in the literature describing the behavior of E. coli in its natural environment. We attempted here to study the evolution in the human gut of a commensal dominant E. coli clone, ED1a belonging to the B2 phylogroup, through a longitudinal genomic study. We sequenced 24 isolates sampled at three different time points within a healthy individual over almost a year. We computed a mutation rate of 6.90 × 10-7 mutations per base per year of the chromosome for E. coli ED1a in healthy human gut. We observed very limited genomic diversity and could not detect any evidence of selection, in contrast to what is observed in experimental evolution over a similar length of time. We therefore suggest that ED1a, being well adapted to the healthy human gut, evolves mostly neutrally with a low effective population size (Ne of ≈500 to 1,700).IMPORTANCE In this study, we follow the genomic fate of a dominant clone of Escherichia coli in the human gut of a healthy individual over about a year. We could compute a low annual mutation rate that supports low diversity, and we could not retrieve any clear signature of selection. These observations support a neutral evolution of E. coli in the human gut, compatible with a very limited effective population size that deviates drastically with the observations made previously in experimental evolution.
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Abstract
The map between genotype and phenotype is fundamental to biology. Biological information is stored and passed on in the form of genotypes, and expressed in the form of phenotypes. A growing body of literature has examined a wide range of genotype-phenotype (GP) maps and has established a number of properties that appear to be shared by many GP maps. These properties are 'structural' in the sense that they are properties of the distribution of phenotypes across the point-mutation network of genotypes. They include: a redundancy of genotypes, meaning that many genotypes map to the same phenotypes, a highly non-uniform distribution of the number of genotypes per phenotype, a high robustness of phenotypes and the ability to reach a large number of new phenotypes within a small number of mutational steps. A further important property is that the robustness and evolvability of phenotypes are positively correlated. In this review, I give an overview of the study of GP maps with particular emphasis on these structural properties, and discuss a model that attempts to explain why these properties arise, as well as some of the fundamental ways in which the structure of GP maps can affect evolutionary outcomes.
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Affiliation(s)
- S E Ahnert
- Sainsbury Laboratory, University of Cambridge, Bateman Street, Cambridge CB2 1LR, UK .,Theory of Condensed Matter Group, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK
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Meng JW, He DC, Zhu W, Yang LN, Wu EJ, Xie JH, Shang LP, Zhan J. Human-Mediated Gene Flow Contributes to Metapopulation Genetic Structure of the Pathogenic Fungus Alternaria alternata from Potato. Front Plant Sci 2018; 9:198. [PMID: 29497439 PMCID: PMC5818430 DOI: 10.3389/fpls.2018.00198] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2017] [Accepted: 02/01/2018] [Indexed: 06/01/2023]
Abstract
Metapopulation structure generated by recurrent extinctions and recolonizations plays an important role in the evolution of species but is rarely considered in agricultural systems. In this study, generation and mechanism of metapopulation structure were investigated by microsatellite assaying 725 isolates of Alternaria alternata sampled from potato hosts at 16 locations across China. We found a single major cluster, no isolate-geography associations and no bottlenecks in the A. alternata isolates, suggesting a metapopulation genetic structure of the pathogen. We also found weak isolation-by-distance, lower among than within cropping region population differentiation, concordant moving directions of potato products and net gene flow and the highest gene diversity in the region with the most potato imports. These results indicate that in addition to natural dispersal, human-mediated gene flow also contributes to the generation and dynamics of the metapopulation genetic structure of A. alternata in China. Metapopulation structure increases the adaptive capacity of the plant pathogen as a result of enhanced genetic variation and reduced population fragmentation. Consequently, rigid quarantine regulations may be required to reduce population connectivity and the evolutionary potential of A. alternata and other pathogens with a similar population dynamics for a sustainable plant disease management.
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Affiliation(s)
- Jing-Wen Meng
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Dun-Chun He
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Wen Zhu
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Li-Na Yang
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - E-Jiao Wu
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jia-Hui Xie
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Li-Ping Shang
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Jiasui Zhan
- Fujian Key Laboratory of Plant Virology, Institute of Plant Virology, Fujian Agriculture and Forestry University, Fuzhou, China
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Fujian Agriculture and Forestry University, Fuzhou, China
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30
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Muscat AM, Wong NC, Drummond KJ, Algar EM, Khasraw M, Verhaak R, Field K, Rosenthal MA, Ashley DM. The evolutionary pattern of mutations in glioblastoma reveals therapy-mediated selection. Oncotarget 2017; 9:7844-7858. [PMID: 29487696 PMCID: PMC5814263 DOI: 10.18632/oncotarget.23541] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2017] [Accepted: 10/05/2017] [Indexed: 01/08/2023] Open
Abstract
Glioblastoma presents as a heterogeneous disease with poor prognosis despite the use of multimodal therapy. Analysis of genomic DNA changes between initial diagnosis and recurrence in response to standard treatment protocols would enhance understanding of disease progression and better inform new treatment strategies. A cohort of 21 patients with primary glioblastoma were examined between diagnosis and first recurrence. This study presented a rare opportunity to characterize molecular alterations in tumors observed in three patients who received no therapeutic intervention, other than surgery, offering a unique control. We focused this study by comparing the dynamic mutation profiles between the primary tumors and their matched recurrent counterparts. Molecular profiling of tumors was performed using multiplexed targeted deep sequencing of 409 well characterized cancer-associated genes, achieving a mean read depth of 1272 x. Three levels of evidence suggested an evolutionary pattern consistent with a response to therapy-mediated selection pressures exists in treated patients: 1) variant burden was reduced in recurrent tumors, 2) neutral evolutionary dynamics apparent in untreated tumors shifted toward a non-neutral mode of evolution in treated patients at recurrence, and 3) the recurrent tumor of one patient displayed an increased mutation rate attributable to a temozolomide-associated hypermutator phenotype. Our observations suggest that current treatment modalities are likely to fail in achieving long term remission with the majority of relapse samples containing distinct mutations when compared to primary diagnostic samples.
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Affiliation(s)
- Andrea M Muscat
- School of Medicine, Deakin University, Geelong, Victoria, Australia.,Cancer Services, Barwon Health, Geelong, Victoria, Australia
| | - Nicholas C Wong
- Department of Pediatrics, The University of Melbourne, Parkville, Victoria, Australia.,Monash Bioinformatics Platform, Monash University, Clayton, Victoria, Australia
| | - Katharine J Drummond
- Department of Neurosurgery, The Royal Melbourne Hospital, Parkville, Victoria, Australia.,Department of Surgery, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
| | - Elizabeth M Algar
- Center for Cancer Research, Hudson Institute of Medical Research, Clayton, Victoria, Australia.,Department of Molecular and Translational Science, Monash University, Clayton, Victoria, Australia
| | - Mustafa Khasraw
- School of Medicine, Deakin University, Geelong, Victoria, Australia.,Cancer Services, Barwon Health, Geelong, Victoria, Australia.,NHMRC Clinical Trials Center, University of Sydney, Sydney, New South Wales, Australia
| | - Roel Verhaak
- The Jackson Laboratory for Genomic Medicine, Farmington, Connecticut, USA
| | - Kathryn Field
- Department of Neurosurgery, The Royal Melbourne Hospital, Parkville, Victoria, Australia.,Department of Surgery, The Royal Melbourne Hospital, The University of Melbourne, Parkville, Victoria, Australia
| | - Mark A Rosenthal
- Department of Medical Oncology, Peter MacCallum Cancer Center, Melbourne, Victoria, Australia
| | - David M Ashley
- School of Medicine, Deakin University, Geelong, Victoria, Australia.,Cancer Services, Barwon Health, Geelong, Victoria, Australia
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O'Dwyer JP, Kandler A. Inferring processes of cultural transmission: the critical role of rare variants in distinguishing neutrality from novelty biases. Philos Trans R Soc Lond B Biol Sci 2017; 372:20160426. [PMID: 29061898 PMCID: PMC5665813 DOI: 10.1098/rstb.2016.0426] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/24/2017] [Indexed: 11/12/2022] Open
Abstract
Neutral evolution assumes that there are no selective forces distinguishing different variants in a population. Despite this striking assumption, many recent studies have sought to assess whether neutrality can provide a good description of different episodes of cultural change. One approach has been to test whether neutral predictions are consistent with observed progeny distributions, recording the number of variants that have produced a given number of new instances within a specified time interval: a classic example is the distribution of baby names. Using an overlapping generations model, we show that these distributions consist of two phases: a power-law phase with a constant exponent of [Formula: see text], followed by an exponential cut-off for variants with very large numbers of progeny. Maximum-likelihood estimations of the model parameters provide a direct way to establish whether observed empirical patterns are consistent with neutral evolution. We apply our approach to a complete dataset of baby names from Australia. Crucially, we show that analyses based on only the most popular variants, as is often the case in studies of cultural evolution, can provide misleading evidence for underlying transmission hypotheses. While neutrality provides a plausible description of progeny distributions of abundant variants, rare variants deviate from neutrality. Further, we develop a simulation framework that allows the detection of alternative cultural transmission processes. We show that anti-novelty bias is able to replicate the complete progeny distribution of the Australian dataset.This article is part of the themed issue 'Process and pattern in innovations from cells to societies'.
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Affiliation(s)
- James P O'Dwyer
- Department of Plant Biology, University of Illinois, Urbana IL 61801, USA
| | - Anne Kandler
- Department of Human Behavior, Ecology and Culture, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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32
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Strauss C, Long H, Patterson CE, Te R, Lynch M. Genome-Wide Mutation Rate Response to pH Change in the Coral Reef Pathogen Vibrio shilonii AK1. mBio 2017; 8:e01021-17. [PMID: 28830944 DOI: 10.1128/mBio.01021-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Recent application of mutation accumulation techniques combined with whole-genome sequencing (MA/WGS) has greatly promoted studies of spontaneous mutation. However, such explorations have rarely been conducted on marine organisms, and it is unclear how marine habitats have influenced genome stability. This report resolves the mutation rate and spectrum of the coral reef pathogen Vibrio shilonii, which causes coral bleaching and endangers the biodiversity maintained by coral reefs. We found that its mutation rate and spectrum are highly similar to those of other studied bacteria from various habitats, despite the saline environment. The mutational properties of this marine bacterium are thus controlled by other general evolutionary forces such as natural selection and genetic drift. We also found that as pH drops, the mutation rate decreases and the mutation spectrum is biased in the direction of generating G/C nucleotides. This implies that evolutionary features of this organism and perhaps other marine microbes might be altered by the increasingly acidic ocean water caused by excess CO2 emission. Nonetheless, further exploration is needed as the pH range tested in this study was rather narrow and many other possible mutation determinants, such as carbonate increase, are associated with ocean acidification. This study explored the pH dependence of a bacterial genome-wide mutation rate. We discovered that the genome-wide rates of appearance of most mutation types decrease linearly and that the mutation spectrum is biased in generating more G/C nucleotides with pH drop in the coral reef pathogen V. shilonii.
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Abstract
Whether prokaryotes (Bacteria and Archaea) are naturally organized into phenotypically and genetically cohesive units comparable to animal or plant species remains contested, frustrating attempts to estimate how many such units there might be, or to identify the ecological roles they play. Analyses of gene sequences in various closely related prokaryotic groups reveal that sequence diversity is typically organized into distinct clusters, and processes such as periodic selection and extensive recombination are understood to be drivers of cluster formation ("speciation"). However, observed patterns are rarely compared with those obtainable with simple null models of diversification under stochastic lineage birth and death and random genetic drift. Via a combination of simulations and analyses of core and phylogenetic marker genes, we show that patterns of diversity for the genera Escherichia, Neisseria, and Borrelia are generally indistinguishable from patterns arising under a null model. We suggest that caution should thus be taken in interpreting observed clustering as a result of selective evolutionary forces. Unknown forces do, however, appear to play a role in Helicobacter pylori, and some individual genes in all groups fail to conform to the null model. Taken together, we recommend the presented birth-death model as a null hypothesis in prokaryotic speciation studies. It is only when the real data are statistically different from the expectations under the null model that some speciation process should be invoked.
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34
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Mutumi GL, Jacobs DS, Winker H. The relative contribution of drift and selection to phenotypic divergence: A test case using the horseshoe bats Rhinolophus simulator and Rhinolophus swinnyi. Ecol Evol 2017; 7:4299-4311. [PMID: 28649342 PMCID: PMC5478076 DOI: 10.1002/ece3.2966] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Revised: 03/13/2017] [Accepted: 03/14/2017] [Indexed: 11/17/2022] Open
Abstract
Natural selection and drift can act on populations individually, simultaneously or in tandem and our understanding of phenotypic divergence depends on our ability to recognize the contribution of each. According to the quantitative theory of evolution, if an organism has diversified through neutral evolutionary processes (mutation and drift), variation of phenotypic characteristics between different geographic localities (B) should be directly proportional to the variation within localities (W), that is, B ∝ W. Significant deviations from this null model imply that non-neutral forces such as natural selection are acting on a phenotype. We investigated the relative contributions of drift and selection to intraspecific diversity using southern African horseshoe bats as a test case. We characterized phenotypic diversity across the distributional range of Rhinolophus simulator (n = 101) and Rhinolophus swinnyi (n = 125) using several traits associated with flight and echolocation. Our results suggest that geographic variation in both species was predominantly caused by disruptive natural selection (B was not directly proportional to W). Evidence for correlated selection (co-selection) among traits further confirmed that our results were not compatible with drift. Selection rather than drift is likely the predominant evolutionary process shaping intraspecific variation in traits that strongly impact fitness.
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Affiliation(s)
- Gregory L. Mutumi
- Animal Evolution and Systematics Group (AES)Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
- Department of BiologyUniversity of Massachusetts Amherst221 Morrill Science CenterAmherstMA01003USA
| | - David S. Jacobs
- Animal Evolution and Systematics Group (AES)Department of Biological SciencesUniversity of Cape TownCape TownSouth Africa
| | - Henning Winker
- Centre for Statistics in Ecology, Environment and Conservation (SEEC)Department of Statistical SciencesUniversity of Cape TownCape TownSouth Africa
- South African National Biodiversity Institute (SANBI)Cape TownSouth Africa
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35
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Mazel F, Wüest RO, Gueguen M, Renaud J, Ficetola GF, Lavergne S, Thuiller W. The Geography of Ecological Niche Evolution in Mammals. Curr Biol 2017; 27:1369-1374. [PMID: 28457870 DOI: 10.1016/j.cub.2017.03.046] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 02/02/2017] [Accepted: 03/21/2017] [Indexed: 11/19/2022]
Abstract
Convergent adaptive evolution of species' ecological niches-i.e., the appearance of similar niches in independent lineages-is the result of natural selection acting on niche-related species traits ("traits" hereafter) and contrasts with neutral evolution [1-4]. Although trait convergences are recognized as being of importance at the species scale, we still know little about the impact of species convergence on the overall trait and niche structure of entire biotas at large spatial scales [5]. Here, we map the convergent evolution of four traits (diet, body mass, activity cycle, and foraging strata) for mammal species and assemblages (defined at 200 × 200 km resolution) at a global scale. Using data on the geographic distributions, traits, and phylogenetic relationships of species and by comparing observed patterns of trait β-diversity to evolutionary neutral expectations, we show that trait convergence is not restricted to particular lineages but scales up to entire assemblages (i.e., whole species communities). We find region-wide biota convergence in traits between regions with similar climates, particularly between Australia and other continents. Pairs of assemblages that show trait divergence often involves Arctic regions where rapid evolutionary changes occurred in response to extreme climatic constraints. By integrating both macroecological and macroevolutionary approaches into a single framework, our study quantifies the crucial role of evolutionary processes such as natural selection in the spatial distribution and structure of large-scale species assemblages.
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Affiliation(s)
- Florent Mazel
- Université Grenoble Alpes, CNRS, Laboratoire d'Écologie Alpine (LECA), 38000 Grenoble, France.
| | - Rafael O Wüest
- Université Grenoble Alpes, CNRS, Laboratoire d'Écologie Alpine (LECA), 38000 Grenoble, France; Swiss Federal Research Institute WSL, Landscape Dynamics, 8903 Birmensdorf, Switzerland
| | - Maya Gueguen
- Université Grenoble Alpes, CNRS, Laboratoire d'Écologie Alpine (LECA), 38000 Grenoble, France
| | - Julien Renaud
- Université Grenoble Alpes, CNRS, Laboratoire d'Écologie Alpine (LECA), 38000 Grenoble, France
| | - Gentile Francesco Ficetola
- Université Grenoble Alpes, CNRS, Laboratoire d'Écologie Alpine (LECA), 38000 Grenoble, France; Department of Biosciences, Università degli Studi di Milano, Via Celoria 26, 20133 Milano, Italy
| | - Sébastien Lavergne
- Université Grenoble Alpes, CNRS, Laboratoire d'Écologie Alpine (LECA), 38000 Grenoble, France
| | - Wilfried Thuiller
- Université Grenoble Alpes, CNRS, Laboratoire d'Écologie Alpine (LECA), 38000 Grenoble, France
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Abstract
A complete and compelling evolutionary explanation for the origin of human menopause is wanting. Menopause onset is defined clinically as the final menses, confirmed after 1 year without menstruation. The theory proposed herein explains at multiple levels - ultimately genetic but involving (1) behavioral, (2) life history, and (3) social changes - the origin and evolution of menopause in women. Individuals in Lower Paleolithic human populations were characterized by short lifespans with diminished late-age survival and fertility, similar to contemporary chimpanzees, and thence were subject to three changes. (1) A mating behavior change was established in which only young women reproduced, thereby rendering as effectively neutral female-specific late-onset fertility-diminishing mutations, which accumulated subsequently. (2) A lifespan increase was manifested adaptively, revealing the reproductive senescence phenotype encoded in late-onset fertility-diminishing mutation genotypes, which, heretofore, had been unexpressed in the shorter lifespan. (3) A social interaction change emerged exaptively, when older non-reproductive women exclusively started assisting in rearing grandchildren rather than giving birth to and caring for their own children, ultimately leading to menstrual cycle cessation. The changes associate in a one-to-one manner with existing, non-mutually exclusive hypotheses for the origin of human menopause. Evidence for each hypothesis and its associated change having occurred are reviewed, and the hypotheses are combined in a synthetic theory for the origin of human menopause. The new theory simultaneously addresses the main theoretical problem with each hypothesis and yields predictions for future testing.
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Affiliation(s)
| | - Rama S. Singh
- Department of Biology, Origins Institute, McMaster University, HamiltonON, Canada
| | - John Stone
- Department of Biology, Origins Institute, McMaster University, HamiltonON, Canada
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Abstract
The temporal dynamics of cancer evolution remain elusive, because it is impractical to longitudinally observe cancers unperturbed by treatment. Consequently, our knowledge of how cancers grow largely derives from inferences made from a single point in time - the endpoint in the cancer's evolution, when it is removed from the body and studied in the laboratory. Fortuitously however, the cancer genome, by virtue of ongoing mutations that uniquely mark clonal lineages within the tumour, provides a rich, yet surreptitious, record of cancer development. In this review, we describe how a cancer's genome can be analysed to reveal the temporal history of mutation and selection, and discuss why both selective and neutral evolution feature prominently in carcinogenesis. We argue that selection in cancer can only be properly studied once we have some understanding of what the absence of selection looks like. We review the data describing punctuated evolution in cancer, and reason that punctuated phenotype evolution is consistent with both gradual and punctuated genome evolution. We conclude that, to map and predict evolutionary trajectories during carcinogenesis, it is critical to better understand the relationship between genotype change and phenotype change. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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Affiliation(s)
- Trevor A Graham
- Evolution and Cancer Laboratory, Barts Cancer Institute, Queen Mary University of London, London, UK
| | - Andrea Sottoriva
- Cancer Evolutionary Genomics and Modelling Laboratory, Centre for Evolution and Cancer, The Institute of Cancer Research, Sutton, UK
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Oppold AM, Pedrosa JAM, Bálint M, Diogo JB, Ilkova J, Pestana JLT, Pfenninger M. Support for the evolutionary speed hypothesis from intraspecific population genetic data in the non-biting midge Chironomus riparius. Proc Biol Sci 2016; 283:20152413. [PMID: 26888029 DOI: 10.1098/rspb.2015.2413] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The evolutionary speed hypothesis (ESH) proposes a causal mechanism for the latitudinal diversity gradient. The central idea of the ESH is that warmer temperatures lead to shorter generation times and increased mutation rates. On an absolute time scale, both should lead to an acceleration of selection and drift. Based on the ESH, we developed predictions regarding the distribution of intraspecific genetic diversity: populations of ectothermic species with more generations per year owing to warmer ambient temperatures should be more differentiated from each other, accumulate more mutations and show evidence for increased mutation rates compared with populations in colder regions. We used the multivoltine insect species Chironomus riparius to test these predictions with cytochrome oxidase I (COI) sequence data and found that populations from warmer regions are indeed significantly more differentiated and have significantly more derived haplotypes than populations from colder regions. We also found a significant correlation of the annual mean temperature with the population mutation parameter θ that serves as a proxy for the per generation mutation rate under certain assumptions. This pattern could be corroborated with two nuclear loci. Overall, our results support the ESH and indicate that the thermal regime experienced may be crucially driving the evolution of ectotherms and may thus ultimately govern their speciation rate.
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Affiliation(s)
- Ann-Marie Oppold
- Molecular Ecology Group, Institute for Ecology, Evolution and Diversity, Goethe-University Frankfurt am Main, Hessen, Germany Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Hessen, Germany
| | - João A M Pedrosa
- Departamento de Biologia and CESAM, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal Conservation Genetics Group, Senckenberg Research Institute, Gelnhausen, Hessen, Germany
| | - Miklós Bálint
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Hessen, Germany
| | - João B Diogo
- Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Hessen, Germany
| | - Julia Ilkova
- Institute of Biodiversity and Ecosystem research, Bulgarian Academy of Sciences, Sofia, Bulgaria
| | - João L T Pestana
- Departamento de Biologia and CESAM, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal
| | - Markus Pfenninger
- Molecular Ecology Group, Institute for Ecology, Evolution and Diversity, Goethe-University Frankfurt am Main, Hessen, Germany Senckenberg Biodiversity and Climate Research Centre, Frankfurt am Main, Hessen, Germany
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Abstract
Comparisons of QST to FST can provide insights into the evolutionary processes that lead to differentiation, or lack thereof, among the phenotypes of different groups (e.g., populations, species), and these comparisons have been performed on a variety of taxa, including humans. Here, I show that for neutrally evolving (i.e., by genetic drift, mutation, and gene flow alone) quantitative characters, the two commonly used QST estimators have somewhat different interpretations in terms of coalescence times, particularly when the number of groups that have been sampled is small. A similar situation occurs for FST estimators. Consequently, when observations come from only a small number of groups, which is not an unusual situation, it is important to match estimators appropriately when comparing QST to FST.
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Affiliation(s)
- Timothy D Weaver
- Department of Anthropology University of California Davis CA USA
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40
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Schiffer PH, Gravemeyer J, Rauscher M, Wiehe T. Ultra Large Gene Families: A Matter of Adaptation or Genomic Parasites? Life (Basel) 2016; 6:E32. [PMID: 27509525 DOI: 10.3390/life6030032] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2016] [Revised: 06/27/2016] [Accepted: 07/20/2016] [Indexed: 01/17/2023] Open
Abstract
Gene duplication is an important mechanism of molecular evolution. It offers a fast track to modification, diversification, redundancy or rescue of gene function. However, duplication may also be neutral or (slightly) deleterious, and often ends in pseudo-geneisation. Here, we investigate the phylogenetic distribution of ultra large gene families on long and short evolutionary time scales. In particular, we focus on a family of NACHT-domain and leucine-rich-repeat-containing (NLR)-genes, which we previously found in large numbers to occupy one chromosome arm of the zebrafish genome. We were interested to see whether such a tight clustering is characteristic for ultra large gene families. Our data reconfirm that most gene family inflations are lineage-specific, but we can only identify very few gene clusters. Based on our observations we hypothesise that, beyond a certain size threshold, ultra large gene families continue to proliferate in a mechanism we term “run-away evolution”. This process might ultimately lead to the failure of genomic integrity and drive species to extinction.
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Abstract
Despite extraordinary efforts to profile cancer genomes, interpreting the vast amount of genomic data in the light of cancer evolution remains challenging. Here we demonstrate that neutral tumor evolution results in a power-law distribution of the mutant allele frequencies reported by next-generation sequencing of tumor bulk samples. We find that the neutral power law fits with high precision 323 of 904 cancers from 14 types and from different cohorts. In malignancies identified as evolving neutrally, all clonal selection seemingly occurred before the onset of cancer growth and not in later-arising subclones, resulting in numerous passenger mutations that are responsible for intratumoral heterogeneity. Reanalyzing cancer sequencing data within the neutral framework allowed the measurement, in each patient, of both the in vivo mutation rate and the order and timing of mutations. This result provides a new way to interpret existing cancer genomic data and to discriminate between functional and non-functional intratumoral heterogeneity.
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Affiliation(s)
- Marc J Williams
- Evolution and Cancer Laboratory, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
- Centre for Mathematics and Physics in the Life Sciences and Experimental Biology (CoMPLEX), University College London, London, WC1E 6BT, UK
| | - Benjamin Werner
- Centre for Evolution and Cancer, The Institute of Cancer Research, London, SM2 5NG, UK
| | - Chris P Barnes
- Department of Cell and Developmental Biology, University College London, London WC1E 6BT, UK
- Department of Genetics, Evolution and Environment, University College London, London, WC1E 6BT, UK
| | - Trevor A Graham
- Evolution and Cancer Laboratory, Barts Cancer Institute, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
| | - Andrea Sottoriva
- Centre for Evolution and Cancer, The Institute of Cancer Research, London, SM2 5NG, UK
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42
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Abstract
Characteristics of pseudogene degeneration at the coding level are well-known, such as a shift toward neutral rates of nonsynonymous substitutions and gain of frameshift mutations. In contrast, degeneration of pseudogene transcriptional regulation is not well understood. Here, we test two predictions of regulatory degeneration along a pseudogenized lineage: 1) Decreased transcription factor (TF) binding and 2) accelerated evolution in putative cis-regulatory regions.We find evidence for decreased TF binding levels nearby two primate pseudogenes compared with functional liver genes. However, the majority of TF-bound sequences nearby pseudogenes do not show evidence for lineage-specific accelerated rates of evolution. We conclude that decreases in TF binding level could be a marker for regulatory degeneration, while sequence degeneration in primate cis-regulatory modules may be obscured by background rates of TF binding site turnover.
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Affiliation(s)
- Gavin M Douglas
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Michael D Wilson
- Genetics and Genome Biology Program, SickKids Research Institute, Toronto, ON, Canada Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Alan M Moses
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
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43
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Chi PB, Liberles DA. Selection on protein structure, interaction, and sequence. Protein Sci 2016; 25:1168-78. [PMID: 26808055 DOI: 10.1002/pro.2886] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 01/18/2016] [Accepted: 01/19/2016] [Indexed: 11/10/2022]
Abstract
Characterizing the probabilities of observing amino acid substitutions at specific sites in a protein over evolutionary time is a major goal in the field of molecular evolution. While purely statistical approaches at different levels of complexity exist, approaches rooted in underlying biological processes are necessary to characterize both the context-dependence of sequence changes (epistasis) and to extrapolate to sequences not observed in biological databases. To develop such approaches, an understanding of the different selective forces that act on amino acid substitution is necessary. Here, an overview of selection on and corresponding modeling of folding stability, folding specificity, binding affinity and specificity for ligands, the evolution of new binding sites on protein surfaces, protein dynamics, intrinsic disorder, and protein aggregation as well as the interplay with protein expression level (concentration) and biased mutational processes are presented.
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Affiliation(s)
- Peter B Chi
- Department of Biology and Center for Computational Genetics and Genomics, Temple University, Philadelphia, Pennsylvania, 19122.,Department of Mathematics and Computer Science, Ursinus College, Collegeville, Pennsylvania, 19426
| | - David A Liberles
- Department of Biology and Center for Computational Genetics and Genomics, Temple University, Philadelphia, Pennsylvania, 19122
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44
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Metzger BPH, Duveau F, Yuan DC, Tryban S, Yang B, Wittkopp PJ. Contrasting Frequencies and Effects of cis- and trans-Regulatory Mutations Affecting Gene Expression. Mol Biol Evol 2016; 33:1131-46. [PMID: 26782996 DOI: 10.1093/molbev/msw011] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Heritable differences in gene expression are caused by mutations in DNA sequences encoding cis-regulatory elements and trans-regulatory factors. These two classes of regulatory change differ in their relative contributions to expression differences in natural populations because of the combined effects of mutation and natural selection. Here, we investigate how new mutations create the regulatory variation upon which natural selection acts by quantifying the frequencies and effects of hundreds of new cis- and trans-acting mutations altering activity of the TDH3 promoter in the yeast Saccharomyces cerevisiae in the absence of natural selection. We find that cis-regulatory mutations have larger effects on expression than trans-regulatory mutations and that while trans-regulatory mutations are more common overall, cis- and trans-regulatory changes in expression are equally abundant when only the largest changes in expression are considered. In addition, we find that cis-regulatory mutations are skewed toward decreased expression while trans-regulatory mutations are skewed toward increased expression. We also measure the effects of cis- and trans-regulatory mutations on the variability in gene expression among genetically identical cells, a property of gene expression known as expression noise, finding that trans-regulatory mutations are much more likely to decrease expression noise than cis-regulatory mutations. Because new mutations are the raw material upon which natural selection acts, these differences in the frequencies and effects of cis- and trans-regulatory mutations should be considered in models of regulatory evolution.
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Affiliation(s)
- Brian P H Metzger
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor
| | - Fabien Duveau
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor
| | - David C Yuan
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor Department of Biology, Stanford University
| | - Stephen Tryban
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor
| | - Bing Yang
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor
| | - Patricia J Wittkopp
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor
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45
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Kandler A, Shennan S. A generative inference framework for analysing patterns of cultural change in sparse population data with evidence for fashion trends in LBK culture. J R Soc Interface 2015; 12:20150905. [PMID: 26674195 PMCID: PMC4707864 DOI: 10.1098/rsif.2015.0905] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Accepted: 11/20/2015] [Indexed: 11/12/2022] Open
Abstract
Cultural change can be quantified by temporal changes in frequency of different cultural artefacts and it is a central question to identify what underlying cultural transmission processes could have caused the observed frequency changes. Observed changes, however, often describe the dynamics in samples of the population of artefacts, whereas transmission processes act on the whole population. Here we develop a modelling framework aimed at addressing this inference problem. To do so, we firstly generate population structures from which the observed sample could have been drawn randomly and then determine theoretical samples at a later time t2 produced under the assumption that changes in frequencies are caused by a specific transmission process. Thereby we also account for the potential effect of time-averaging processes in the generation of the observed sample. Subsequent statistical comparisons (e.g. using Bayesian inference) of the theoretical and observed samples at t2 can establish which processes could have produced the observed frequency data. In this way, we infer underlying transmission processes directly from available data without any equilibrium assumption. We apply this framework to a dataset describing pottery from settlements of some of the first farmers in Europe (the LBK culture) and conclude that the observed frequency dynamic of different types of decorated pottery is consistent with age-dependent selection, a preference for 'young' pottery types which is potentially indicative of fashion trends.
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Affiliation(s)
- Anne Kandler
- Department of Mathematics, City University London, Northampton Square, London EC1V 0HB, UK Santa Fe Institute, 1599 Hyde Park Road, Santa Fe, NM 87501, USA
| | - Stephen Shennan
- Institute of Archaeology, University College London, 31-34 Gordon Square, London WC1H 0PY, UK
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46
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Schilling S, Gramzow L, Lobbes D, Kirbis A, Weilandt L, Hoffmeier A, Junker A, Weigelt-Fischer K, Klukas C, Wu F, Meng Z, Altmann T, Theißen G. Non-canonical structure, function and phylogeny of the Bsister MADS-box gene OsMADS30 of rice (Oryza sativa). Plant J 2015; 84:1059-1072. [PMID: 26473514 DOI: 10.1111/tpj.13055] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 10/02/2015] [Accepted: 10/06/2015] [Indexed: 06/05/2023]
Abstract
Bsister MADS-box genes play key roles in female reproductive organ and seed development throughout seed plants. This view is supported by their high conservation in terms of sequence, expression and function. In grasses, there are three subclades of Bsister genes: the OsMADS29-, the OsMADS30- and the OsMADS31-like genes. Here, we report on the evolution of the OsMADS30-like genes. Our analyses indicate that these genes evolved under relaxed purifying selection and are rather weakly expressed. OsMADS30, the representative of the OsMADS30-like genes from rice (Oryza sativa), shows strong sequence deviations in its 3' region when compared to orthologues from other grass species. We show that this is due to a 2.4-kbp insertion, possibly of a hitherto unknown helitron, which confers a heterologous C-terminal domain to OsMADS30. This putative helitron is not present in the OsMADS30 orthologues from closely related wild rice species, pointing to a relatively recent insertion event. Unlike other Bsister mutants O. sativa plants carrying a T-DNA insertion in the OsMADS30 gene do not show aberrant seed phenotypes, indicating that OsMADS30 likely does not have a canonical 'Bsister function'. However, imaging-based phenotyping of the T-DNA carrying plants revealed alterations in shoot size and architecture. We hypothesize that sequence deviations that accumulated during a period of relaxed selection in the gene lineage that led to OsMADS30 and the alteration of the C-terminal domain might have been a precondition for a potential neo-functionalization of OsMADS30 in O. sativa.
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Affiliation(s)
- Susanne Schilling
- Department of Genetics, Friedrich Schiller University Jena, Jena, D-07743, Germany
| | - Lydia Gramzow
- Department of Genetics, Friedrich Schiller University Jena, Jena, D-07743, Germany
| | - Dajana Lobbes
- Department of Genetics, Friedrich Schiller University Jena, Jena, D-07743, Germany
| | - Alexander Kirbis
- Department of Genetics, Friedrich Schiller University Jena, Jena, D-07743, Germany
| | - Lisa Weilandt
- Department of Genetics, Friedrich Schiller University Jena, Jena, D-07743, Germany
| | - Andrea Hoffmeier
- Department of Genetics, Friedrich Schiller University Jena, Jena, D-07743, Germany
| | - Astrid Junker
- Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, D-06466, Germany
| | - Kathleen Weigelt-Fischer
- Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, D-06466, Germany
| | - Christian Klukas
- Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, D-06466, Germany
| | - Feng Wu
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Zheng Meng
- Key Laboratory of Plant Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing, 100093, China
| | - Thomas Altmann
- Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, D-06466, Germany
| | - Günter Theißen
- Department of Genetics, Friedrich Schiller University Jena, Jena, D-07743, Germany
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47
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Simón M, Montiel R, Smerling A, Solórzano E, Díaz N, Álvarez-Sandoval BA, Jiménez-Marín AR, Malgosa A. Molecular analysis of ancient caries. Proc Biol Sci 2015; 281:rspb.2014.0586. [PMID: 25056622 DOI: 10.1098/rspb.2014.0586] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An 84 base pair sequence of the Streptococcus mutans virulence factor, known as dextranase, has been obtained from 10 individuals from the Bronze Age to the Modern Era in Europe and from before and after the colonization in America. Modern samples show four polymorphic sites that have not been found in the ancient samples studied so far. The nucleotide and haplotype diversity of this region have increased over time, which could be reflecting the footprint of a population expansion. While this segment has apparently evolved according to neutral evolution, we have been able to detect one site that is under positive selection pressure both in present and past populations. This study is a first step to study the evolution of this microorganism, analysed using direct evidence obtained from ancient remains.
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Affiliation(s)
- Marc Simón
- Unitat d'Antropologia Biològica, Department of Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona, Spain
| | - Rafael Montiel
- Laboratorio Nacional de Genómica para la Biodiversidad, Unidad de Genómica Avanzada, CINVESTAV-IPN. Km. 9.6 Libramiento Norte Carretera Irapuato - León, Irapuato, Guanajuato, Mexico
| | - Andrea Smerling
- Unitat d'Antropologia Biològica, Department of Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona, Spain
| | - Eduvigis Solórzano
- Unitat d'Antropologia Biològica, Department of Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona, Spain
| | - Nancy Díaz
- Unitat d'Antropologia Biològica, Department of Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona, Spain
| | - Brenda A Álvarez-Sandoval
- Laboratorio Nacional de Genómica para la Biodiversidad, Unidad de Genómica Avanzada, CINVESTAV-IPN. Km. 9.6 Libramiento Norte Carretera Irapuato - León, Irapuato, Guanajuato, Mexico
| | - Andrea R Jiménez-Marín
- Laboratorio Nacional de Genómica para la Biodiversidad, Unidad de Genómica Avanzada, CINVESTAV-IPN. Km. 9.6 Libramiento Norte Carretera Irapuato - León, Irapuato, Guanajuato, Mexico
| | - Assumpció Malgosa
- Unitat d'Antropologia Biològica, Department of Biologia Animal, Biologia Vegetal i Ecologia, Universitat Autònoma de Barcelona, Spain
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48
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Ling S, Hu Z, Yang Z, Yang F, Li Y, Lin P, Chen K, Dong L, Cao L, Tao Y, Hao L, Chen Q, Gong Q, Wu D, Li W, Zhao W, Tian X, Hao C, Hungate EA, Catenacci DV, Hudson RR, Li WH, Lu X, Wu CI. Extremely high genetic diversity in a single tumor points to prevalence of non-Darwinian cell evolution. Proc Natl Acad Sci U S A. 2015;112:E6496-E6505. [PMID: 26561581 DOI: 10.1073/pnas.1519556112] [Citation(s) in RCA: 226] [Impact Index Per Article: 25.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The prevailing view that the evolution of cells in a tumor is driven by Darwinian selection has never been rigorously tested. Because selection greatly affects the level of intratumor genetic diversity, it is important to assess whether intratumor evolution follows the Darwinian or the non-Darwinian mode of evolution. To provide the statistical power, many regions in a single tumor need to be sampled and analyzed much more extensively than has been attempted in previous intratumor studies. Here, from a hepatocellular carcinoma (HCC) tumor, we evaluated multiregional samples from the tumor, using either whole-exome sequencing (WES) (n = 23 samples) or genotyping (n = 286) under both the infinite-site and infinite-allele models of population genetics. In addition to the many single-nucleotide variations (SNVs) present in all samples, there were 35 "polymorphic" SNVs among samples. High genetic diversity was evident as the 23 WES samples defined 20 unique cell clones. With all 286 samples genotyped, clonal diversity agreed well with the non-Darwinian model with no evidence of positive Darwinian selection. Under the non-Darwinian model, MALL (the number of coding region mutations in the entire tumor) was estimated to be greater than 100 million in this tumor. DNA sequences reveal local diversities in small patches of cells and validate the estimation. In contrast, the genetic diversity under a Darwinian model would generally be orders of magnitude smaller. Because the level of genetic diversity will have implications on therapeutic resistance, non-Darwinian evolution should be heeded in cancer treatments even for microscopic tumors.
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49
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Klopfstein S, Vilhelmsen L, Ronquist F. A Nonstationary Markov Model Detects Directional Evolution in Hymenopteran Morphology. Syst Biol 2015; 64:1089-103. [PMID: 26272507 PMCID: PMC4604834 DOI: 10.1093/sysbio/syv052] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Accepted: 07/17/2015] [Indexed: 11/13/2022] Open
Abstract
Directional evolution has played an important role in shaping the morphological, ecological, and molecular diversity of life. However, standard substitution models assume stationarity of the evolutionary process over the time scale examined, thus impeding the study of directionality. Here we explore a simple, nonstationary model of evolution for discrete data, which assumes that the state frequencies at the root differ from the equilibrium frequencies of the homogeneous evolutionary process along the rest of the tree (i.e., the process is nonstationary, nonreversible, but homogeneous). Within this framework, we develop a Bayesian approach for testing directional versus stationary evolution using a reversible-jump algorithm. Simulations show that when only data from extant taxa are available, the success in inferring directionality is strongly dependent on the evolutionary rate, the shape of the tree, the relative branch lengths, and the number of taxa. Given suitable evolutionary rates (0.1-0.5 expected substitutions between root and tips), accounting for directionality improves tree inference and often allows correct rooting of the tree without the use of an outgroup. As an empirical test, we apply our method to study directional evolution in hymenopteran morphology. We focus on three character systems: wing veins, muscles, and sclerites. We find strong support for a trend toward loss of wing veins and muscles, while stationarity cannot be ruled out for sclerites. Adding fossil and time information in a total-evidence dating approach, we show that accounting for directionality results in more precise estimates not only of the ancestral state at the root of the tree, but also of the divergence times. Our model relaxes the assumption of stationarity and reversibility by adding a minimum of additional parameters, and is thus well suited to studying the nature of the evolutionary process in data sets of limited size, such as morphology and ecology.
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Affiliation(s)
- Seraina Klopfstein
- Department of Bioinformatics and Genetics, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden; The University of Adelaide, ACEBB, Adelaide SA 5005, Australia; Natural History Museum, Department of Invertebrates, CH-3005 Bern, Switzerland;
| | - Lars Vilhelmsen
- Biosystematics, Natural History Museum of Denmark, DK-2100 Copenhagen Ø, Denmark
| | - Fredrik Ronquist
- Department of Bioinformatics and Genetics, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden
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50
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Abstract
Large sets of genotypes give rise to the same phenotype, because phenotypic expression is highly redundant. Accordingly, a population can accept mutations without altering its phenotype, as long as the genotype mutates into another one on the same set. By linking every pair of genotypes that are mutually accessible through mutation, genotypes organize themselves into neutral networks (NNs). These networks are known to be heterogeneous and assortative, and these properties affect the evolutionary dynamics of the population. By studying the dynamics of populations on NNs with arbitrary topology, we analyse the effect of assortativity, of NN (phenotype) fitness and of network size. We find that the probability that the population leaves the network is smaller the longer the time spent on it. This progressive 'phenotypic entrapment' entails a systematic increase in the overdispersion of the process with time and an acceleration in the fixation rate of neutral mutations. We also quantify the variation of these effects with the size of the phenotype and with its fitness relative to that of neighbouring alternatives.
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Affiliation(s)
- Susanna Manrubia
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain Systems Biology Programme, National Centre for Biotechnology (CSIC), c/ Darwin 3, 28049 Madrid, Spain
| | - José A Cuesta
- Grupo Interdisciplinar de Sistemas Complejos (GISC), Madrid, Spain Department of Mathematics, Universidad Carlos III de Madrid, 28911 Leganés, Madrid, Spain Instituto de Biocomputación y Física de Sistemas Complejos (BIFI), Universidad de Zaragoza, 50009 Zaragoza, Spain
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