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Barros KO, Batista TM, Soares RCC, Lopes MR, Alvarenga FBM, Souza GFL, Abegg MA, Santos ARO, Góes-Neto A, Hilário HO, Moreira RG, Franco GR, Lachance MA, Rosa CA. Spathaspora marinasilvae sp. nov., a xylose-fermenting yeast isolated from galleries of passalid beetles and rotting wood in the Amazonian rainforest biome. Yeast 2024; 41:437-447. [PMID: 38850070 DOI: 10.1002/yea.3966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Revised: 05/03/2024] [Accepted: 05/23/2024] [Indexed: 06/09/2024] Open
Abstract
Four yeast isolates were obtained from rotting wood and galleries of passalid beetles collected in different sites of the Brazilian Amazonian Rainforest in Brazil. This yeast produces unconjugated allantoid asci each with a single elongated ascospore with curved ends. Sequence analysis of the internal transcribed spacer-5.8 S region and the D1/D2 domains of the large subunit ribosomal RNA (rRNA) gene showed that the isolates represent a novel species of the genus Spathaspora. The novel species is phylogenetically related to a subclade containing Spathaspora arborariae and Spathaspora suhii. Phylogenomic analysis based on 1884 single-copy orthologs for a set of Spathaspora species whose whole genome sequences are available confirmed that the novel species represented by strain UFMG-CM-Y285 is phylogenetically close to Sp. arborariae. The name Spathaspora marinasilvae sp. nov. is proposed to accommodate the novel species. The holotype of Sp. marinasilvae is CBS 13467 T (MycoBank 852799). The novel species was able to accumulate xylitol and produce ethanol from d-xylose, a trait of biotechnological interest common to several species of the genus Spathaspora.
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Affiliation(s)
- Katharina O Barros
- Departamento de Microbiologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Thiago M Batista
- Centro de Formação em Ciências Ambientais, C.P. 108, Universidade Federal do Sul da Bahia, Porto Seguro, Bahia, Brazil
| | - Rafaela C C Soares
- Departamento de Microbiologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Mariana R Lopes
- Departamento de Microbiologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Flávia B M Alvarenga
- Departamento de Microbiologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Gisele F L Souza
- Departamento de Microbiologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Maxwel A Abegg
- Institute of Exact Sciences and Technology (ICET), Federal University of Amazonas (UFAM), Itacoatiara, Brazil
| | - Ana Raquel O Santos
- Departamento de Microbiologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Aristóteles Góes-Neto
- Departamento de Microbiologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Heron O Hilário
- Laboratório de Genética da Conservação, PPG Biologia dos Vertebrados, Pontifícia Universidade Católica de Minas Gerais, Contagem, Minas Gerais, Brazil
| | - Rennan G Moreira
- Laboratorio Multiusuário de Genômica, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Glória R Franco
- Departamento de Bioquímica e Imunologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
| | - Marc-André Lachance
- Department of Biology, University of Western Ontario, London, Ontario, Canada
| | - Carlos A Rosa
- Departamento de Microbiologia, ICB, C.P. 486, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil
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2
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Murphy HA. Harnessing the power of digital droplet PCR to conduct real-world microbial competitions. Mol Ecol Resour 2019; 17:353-355. [PMID: 28497651 DOI: 10.1111/1755-0998.12611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 09/08/2016] [Indexed: 11/29/2022]
Abstract
The budding yeast, Saccharomyces cerevisiae, has a long and storied history as a model organism for genetic, cellular and molecular biological research. More recently, researchers have sought to understand the ecology and evolution of its sister species, Saccharomyces paradoxus, in part to put our vast knowledge of the model yeast into its natural context (Replansky et al. ). However, the research tools have been limited, and most investigations into natural populations have either been descriptions of patterns of biogeography or taken the organism back into the laboratory for mating, growth and competition assays (Kuehne et al. ; Miller & Greig ; Murphy & Zeyl ; Samani et al. ). The link between what occurs out in the real world and what is measured in the laboratory has not yet been made, as so much is still unknown about the natural history of these yeasts. In this issue of Molecular Ecology Resources, Boynton et al. () take a major step towards bridging laboratory studies with field ecological research. By isolating a panel of S. paradoxus strains from a wooded area, culturing them in the laboratory, reintroducing pairs back into their habitat on natural substrate and monitoring the frequency of individual strains using digital droplet PCR, the researchers were able to use the framework of laboratory-based microbial competitions, but conduct them in a natural setting. While there is still more to learn about how to optimize this approach, it represents an exciting step in microbial ecological research and should prove an important tool for other species and numerous ecological questions.
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Affiliation(s)
- Helen A Murphy
- Department of Biology, The College of William and Mary, PO Box 8795, Williamsburg, VA, 23187-8795, USA
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3
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Bleuven C, Dubé AK, Nguyen GQ, Gagnon‐Arsenault I, Martin H, Landry CR. A collection of barcoded natural isolates of Saccharomyces paradoxus to study microbial evolutionary ecology. Microbiologyopen 2018; 8:e00773. [PMID: 30569485 PMCID: PMC6612553 DOI: 10.1002/mbo3.773] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Revised: 11/05/2018] [Accepted: 11/06/2018] [Indexed: 01/24/2023] Open
Abstract
While the use of barcoded collections of laboratory microorganisms and the development of barcode-based cell tracking are rapidly developing in genetics and genomics research, tools to track natural populations are still lacking. The yeast Saccharomyces paradoxus is an emergent microbial model in ecology and evolution. More than five allopatric and sympatric lineages have been identified and hundreds of strains have been isolated for this species, allowing to assess the impact of natural diversity on complex traits. We constructed a collection of 550 barcoded and traceable strains of S. paradoxus, including all three North American lineages SpB, SpC, and SpC*. These strains are diploid, many have their genome fully sequenced and are barcoded with a unique 20 bp sequence that allows their identification and quantification. This yeast collection is functional for competitive experiments in pools as the barcodes allow to measure each lineage's and individual strains' fitness in common conditions. We used this tool to demonstrate that in the tested conditions, there are extensive genotype-by-environment interactions for fitness among S. paradoxus strains, which reveals complex evolutionary potential in variable environments. This barcoded collection provides a valuable resource for ecological genomics studies that will allow gaining a better understanding of S. paradoxus evolution and fitness-related traits.
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Affiliation(s)
- Clara Bleuven
- Département de BiologieUniversité LavalQuébecQuébecCanada,Institut de Biologie Intégrative et des Systèmes (IBIS)Université LavalQuébecQuébecCanada,Big Data Research CenterUniversité LavalQuébecQuébecCanada,PROTEO, The Quebec Network for Research on Protein Function, Engineering, and ApplicationsQuébecQuébecCanada
| | - Alexandre K. Dubé
- Département de BiologieUniversité LavalQuébecQuébecCanada,Institut de Biologie Intégrative et des Systèmes (IBIS)Université LavalQuébecQuébecCanada,Big Data Research CenterUniversité LavalQuébecQuébecCanada,PROTEO, The Quebec Network for Research on Protein Function, Engineering, and ApplicationsQuébecQuébecCanada,Département de Biochimiede Microbiologie et de Bio‐informatique, Université LavalQuébecQuébecCanada
| | - Guillaume Q. Nguyen
- Département de BiologieUniversité LavalQuébecQuébecCanada,Institut de Biologie Intégrative et des Systèmes (IBIS)Université LavalQuébecQuébecCanada,Big Data Research CenterUniversité LavalQuébecQuébecCanada,PROTEO, The Quebec Network for Research on Protein Function, Engineering, and ApplicationsQuébecQuébecCanada,Département des Sciences des aliments, Institut sur la nutrition et les aliments fonctionnels (INAF)Université LavalQuébecQuébecCanada
| | - Isabelle Gagnon‐Arsenault
- Département de BiologieUniversité LavalQuébecQuébecCanada,Institut de Biologie Intégrative et des Systèmes (IBIS)Université LavalQuébecQuébecCanada,Big Data Research CenterUniversité LavalQuébecQuébecCanada,PROTEO, The Quebec Network for Research on Protein Function, Engineering, and ApplicationsQuébecQuébecCanada,Département de Biochimiede Microbiologie et de Bio‐informatique, Université LavalQuébecQuébecCanada
| | - Hélène Martin
- Département de BiologieUniversité LavalQuébecQuébecCanada,Institut de Biologie Intégrative et des Systèmes (IBIS)Université LavalQuébecQuébecCanada,Big Data Research CenterUniversité LavalQuébecQuébecCanada,PROTEO, The Quebec Network for Research on Protein Function, Engineering, and ApplicationsQuébecQuébecCanada,Département de Biochimiede Microbiologie et de Bio‐informatique, Université LavalQuébecQuébecCanada
| | - Christian R. Landry
- Département de BiologieUniversité LavalQuébecQuébecCanada,Institut de Biologie Intégrative et des Systèmes (IBIS)Université LavalQuébecQuébecCanada,Big Data Research CenterUniversité LavalQuébecQuébecCanada,PROTEO, The Quebec Network for Research on Protein Function, Engineering, and ApplicationsQuébecQuébecCanada,Département de Biochimiede Microbiologie et de Bio‐informatique, Université LavalQuébecQuébecCanada
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Persistence of Resident and Transplanted Genotypes of the Undomesticated Yeast Saccharomyces paradoxus in Forest Soil. mSphere 2018; 3:3/3/e00211-18. [PMID: 29925673 PMCID: PMC6010622 DOI: 10.1128/msphere.00211-18] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Accepted: 05/29/2018] [Indexed: 02/06/2023] Open
Abstract
Saccharomyces yeasts are intensively studied in biological research and in their domesticated roles in brewing and baking, and yet, remarkably little is known about their mode of life in forest soils. We report here that resident genotypes of the yeast S. paradoxus are persistent on a time scale of years in their microhabitats in forest soils. We also show that resident genotypes can be replaced by transplanted yeast genotypes. The high inoculum levels in experimental transplantations rapidly decreased over time, but the transplanted genotypes persisted at low abundance. We conclude that, in forest soils, Saccharomyces yeasts exist at very low abundance and that dispersal events are rare. One might expect yeasts in soil to be highly dispersed via water or insects, forming ephemeral, genetically heterogeneous populations subject to competition and environmental stochasticity. Here, we report persistence of genotypes of the yeast Saccharomyces paradoxus in space and time. Within 1 km2 in a mixed hardwood forest on scales from centimeters to tens of meters, we detected persistence over 3 years of native genotypes, identified by single nucleotide polymorphisms (SNPs) genome-wide, of the wild yeast Saccharomyces paradoxus growing around Quercus rubra and Quercus alba. Yeasts were recovered by enrichment in ethanol-containing medium, which measures only presence or absence, not abundance. Additional transplantation experiments employed strains marked with spontaneous defects in the URA3 gene, which also confer resistance to 5-fluoroorotic acid (5FOA). Plating soil suspensions from transplant sites on 5FOA-containing medium permitted one-step quantification of yeast CFU, with no interference from other unmarked yeasts or microorganisms. After an initial steep decrease in abundance, the yeast densities fluctuated over time, increasing in association with rainfall and decreasing in association with drought. After 18 months, the transplanted yeasts remained in place on the nine sites. In vitro transplantation experiments into nonsterile soil in petri dishes showed similar patterns of persistence and response to moisture and drought. To determine whether Saccharomyces cerevisiae, not previously recovered from soils regionally, can persist in our cold climate sites, we transplanted marked S. cerevisiae alone and in mixture with S. paradoxus in the fall of 2017. Five months later, S. cerevisiae persisted to the same extent as S. paradoxus. IMPORTANCESaccharomyces yeasts are intensively studied in biological research and in their domesticated roles in brewing and baking, and yet, remarkably little is known about their mode of life in forest soils. We report here that resident genotypes of the yeast S. paradoxus are persistent on a time scale of years in their microhabitats in forest soils. We also show that resident genotypes can be replaced by transplanted yeast genotypes. The high inoculum levels in experimental transplantations rapidly decreased over time, but the transplanted genotypes persisted at low abundance. We conclude that, in forest soils, Saccharomyces yeasts exist at very low abundance and that dispersal events are rare.
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5
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Eberlein C, Nielly-Thibault L, Maaroufi H, Dubé AK, Leducq JB, Charron G, Landry CR. The Rapid Evolution of an Ohnolog Contributes to the Ecological Specialization of Incipient Yeast Species. Mol Biol Evol 2017; 34:2173-2186. [PMID: 28482005 DOI: 10.1093/molbev/msx153] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Identifying the molecular changes that lead to ecological specialization during speciation is one of the major goals of molecular evolution. One question that remains to be thoroughly investigated is whether ecological specialization derives strictly from adaptive changes and their associated trade-offs, or from conditionally neutral mutations that accumulate under relaxed selection. We used whole-genome sequencing, genome annotation and computational analyses to identify genes that have rapidly diverged between two incipient species of Saccharomyces paradoxus that occupy different climatic regions along a south-west to north-east gradient. As candidate loci for ecological specialization, we identified genes that show signatures of adaptation and accelerated rates of amino acid substitutions, causing asymmetric evolution between lineages. This set of genes includes a glycyl-tRNA-synthetase, GRS2, which is known to be transcriptionally induced under heat stress in the model and sister species S. cerevisiae. Molecular modelling, expression analysis and fitness assays suggest that the accelerated evolution of this gene in the Northern lineage may be caused by relaxed selection. GRS2 arose during the whole-genome duplication (WGD) that occurred 100 million years ago in the yeast lineage. While its ohnolog GRS1 has been preserved in all post-WGD species, GRS2 has frequently been lost and is evolving rapidly, suggesting that the fate of this ohnolog is still to be resolved. Our results suggest that the asymmetric evolution of GRS2 between the two incipient S. paradoxus species contributes to their restricted climatic distributions and thus that ecological specialization derives at least partly from relaxed selection rather than a molecular trade-off resulting from adaptive evolution.
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Affiliation(s)
- Chris Eberlein
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada
| | - Lou Nielly-Thibault
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada.,Big Data Research Center (CRDM), Université Laval, Québec, QC, Canada
| | - Halim Maaroufi
- Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada
| | - Alexandre K Dubé
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada
| | - Jean-Baptiste Leducq
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada
| | - Guillaume Charron
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada
| | - Christian R Landry
- Département de Biologie, Université Laval, Québec, QC, Canada.,Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, QC, Canada.,PROTEO, The Quebec Network for Research on Protein Function, Engineering and Applications, Québec, QC, Canada.,Big Data Research Center (CRDM), Université Laval, Québec, QC, Canada
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6
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Filteau M, Charron G, Landry CR. Identification of the fitness determinants of budding yeast on a natural substrate. THE ISME JOURNAL 2017; 11:959-971. [PMID: 27935595 PMCID: PMC5364353 DOI: 10.1038/ismej.2016.170] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/15/2016] [Accepted: 10/20/2016] [Indexed: 12/21/2022]
Abstract
The budding yeasts are prime models in genomics and cell biology, but the ecological factors that determine their success in non-human-associated habitats is poorly understood. In North America Saccharomyces yeasts are present on the bark of deciduous trees, where they feed on bark and sap exudates. In the North East, Saccharomyces paradoxus is found on maples, which makes maple sap a natural substrate for this species. We measured growth rates of S. paradoxus natural isolates on maple sap and found variation along a geographical gradient not explained by the inherent variation observed under optimal laboratory conditions. We used a functional genomic screen to reveal the ecologically relevant genes and conditions required for optimal growth in this substrate. We found that the allantoin degradation pathway is required for optimal growth in maple sap, in particular genes necessary for allantoate utilization, which we demonstrate is the major nitrogen source available to yeast in this environment. Growth with allantoin or allantoate as the sole nitrogen source recapitulated the variation in growth rates in maple sap among strains. We also show that two lineages of S. paradoxus display different life-history traits on allantoin and allantoate media, highlighting the ecological relevance of this pathway.
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Affiliation(s)
- Marie Filteau
- Département de Biologie, PROTEO, Big Data Research Center and Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
- Département des Sciences des aliments, Institut sur la nutrition et les aliments fonctionnels (INAF), Université Laval, Québec, Québec, Canada
| | - Guillaume Charron
- Département de Biologie, PROTEO, Big Data Research Center and Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
| | - Christian R Landry
- Département de Biologie, PROTEO, Big Data Research Center and Institut de Biologie Intégrative et des Systèmes (IBIS), Université Laval, Québec, Québec, Canada
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7
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Xia W, Nielly-Thibault L, Charron G, Landry CR, Kasimer D, Anderson JB, Kohn LM. Population genomics reveals structure at the individual, host-tree scale and persistence of genotypic variants of the undomesticated yeast Saccharomyces paradoxus in a natural woodland. Mol Ecol 2017; 26:995-1007. [PMID: 27988980 DOI: 10.1111/mec.13954] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 11/28/2016] [Indexed: 12/23/2022]
Abstract
Genetic diversity in experimental, domesticated and wild populations of the related yeasts, Saccharomyces cerevisiae and Saccharomyces paradoxus, has been well described at the global scale. We investigated the population genomics of a local population on a small spatial scale to address two main questions. First, is there genomic variation in a S. paradoxus population at a spatial scale spanning centimetres (microsites) to tens of metres? Second, does the distribution of genomic variants persist over time? Our sample consisted of 42 S. paradoxus strains from 2014 and 43 strains from 2015 collected from the same 72 microsites around four host trees (Quercus rubra and Quercus alba) within 1 km2 in a mixed hardwood forest in southern Ontario. Six additional S. paradoxus strains recovered from adjacent maple and beech trees in 2015 are also included in the sample. Whole-genome sequencing and genomic SNP analysis revealed five differentiated groups (clades) within the sampled area. The signal of persistence of genotypes in their microsites from 2014 to 2015 was highly significant. Isolates from the same tree tended to be more related than strains from different trees, with limited evidence of dispersal between trees. In growth assays, one genotype had a significantly longer lag phase than the other strains. Our results indicate that different clades coexist at fine spatial scale and that population structure persists over at least a one-year interval in these wild yeasts, suggesting the efficacy of yearly sampling to follow longer term genetic dynamics in future studies.
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Affiliation(s)
- Wenjing Xia
- Departments of Ecology and Evolutionary Biology and Cell and Systems Biology, University of Toronto Mississauga, 3359 Mississauga Rd, Mississauga, ON, L5L 1C6, Canada
| | - Lou Nielly-Thibault
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes, PROTEO, Pavillon Charles-Eugène-Marchand, Université Laval, 1030 avenue de la Médecine, Québec, QC, G1V 0A6, Canada
| | - Guillaume Charron
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes, PROTEO, Pavillon Charles-Eugène-Marchand, Université Laval, 1030 avenue de la Médecine, Québec, QC, G1V 0A6, Canada
| | - Christian R Landry
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes, PROTEO, Pavillon Charles-Eugène-Marchand, Université Laval, 1030 avenue de la Médecine, Québec, QC, G1V 0A6, Canada
| | - Dahlia Kasimer
- Departments of Ecology and Evolutionary Biology and Cell and Systems Biology, University of Toronto Mississauga, 3359 Mississauga Rd, Mississauga, ON, L5L 1C6, Canada
| | - James B Anderson
- Departments of Ecology and Evolutionary Biology and Cell and Systems Biology, University of Toronto Mississauga, 3359 Mississauga Rd, Mississauga, ON, L5L 1C6, Canada
| | - Linda M Kohn
- Departments of Ecology and Evolutionary Biology and Cell and Systems Biology, University of Toronto Mississauga, 3359 Mississauga Rd, Mississauga, ON, L5L 1C6, Canada
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8
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Yeast Population Genomics Goes Wild: The Case of Saccharomyces paradoxus. POPULATION GENOMICS: MICROORGANISMS 2017. [DOI: 10.1007/13836_2017_4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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9
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Samani P, Bell G. Experimental evolution of the grain of metabolic specialization in yeast. Ecol Evol 2016; 6:3912-22. [PMID: 27516854 PMCID: PMC4972220 DOI: 10.1002/ece3.2151] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2016] [Accepted: 04/04/2016] [Indexed: 12/27/2022] Open
Abstract
Adaptation to any given environment may be accompanied by a cost in terms of reduced growth in the ancestral or some alternative environment. Ecologists explain the cost of adaptation through the concept of a trade‐off, by which gaining a new trait involves losing another trait. Two mechanisms have been invoked to explain the evolution of trade‐offs in ecological systems, mutational degradation, and functional interference. Mutational degradation occurs when a gene coding a specific trait is not under selection in the resident environment; therefore, it may be degraded through the accumulation of mutations that are neutral in the resident environment but deleterious in an alternative environment. Functional interference evolves if the gene or a set of genes have antagonistic effects in two or more ecologically different traits. Both mechanisms pertain to a situation where the selection and the alternative environments are ecologically different. To test this hypothesis, we conducted an experiment in which 12 experimental populations of wild yeast were each grown in a minimal medium supplemented with a single substrate. We chose 12 different carbon substrates that were metabolized through similar and different pathways in order to represent a wide range of ecological conditions. We found no evidence for trade‐offs between substrates on the same pathway. The indirect response of substrates on other pathways, however, was consistently negative, with little correlation between the direct and indirect responses. We conclude that the grain of specialization in this case is the metabolic pathway and that specialization appears to evolve through mutational degradation.
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Affiliation(s)
- Pedram Samani
- Biology Department McGill University Montreal QCH3A 1B1 Canada; University of Montana 32 Campus Drive Missoula 59812 Montana
| | - Graham Bell
- Biology Department McGill University Montreal QC H3A 1B1 Canada
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10
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Speciation driven by hybridization and chromosomal plasticity in a wild yeast. Nat Microbiol 2016; 1:15003. [PMID: 27571751 DOI: 10.1038/nmicrobiol.2015.3] [Citation(s) in RCA: 123] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 09/18/2015] [Indexed: 02/07/2023]
Abstract
Hybridization is recognized as a powerful mechanism of speciation and a driving force in generating biodiversity. However, only few multicellular species, limited to a handful of plants and animals, have been shown to fulfil all the criteria of homoploid hybrid speciation. This lack of evidence could lead to the interpretation that speciation by hybridization has a limited role in eukaryotes, particularly in single-celled organisms. Laboratory experiments have revealed that fungi such as budding yeasts can rapidly develop reproductive isolation and novel phenotypes through hybridization, showing that in principle homoploid speciation could occur in nature. Here, we report a case of homoploid hybrid speciation in natural populations of the budding yeast Saccharomyces paradoxus inhabiting the North American forests. We show that the rapid evolution of chromosome architecture and an ecological context that led to secondary contact between nascent species drove the formation of an incipient hybrid species with a potentially unique ecological niche.
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11
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Marques WL, Raghavendran V, Stambuk BU, Gombert AK. Sucrose and Saccharomyces cerevisiae: a relationship most sweet. FEMS Yeast Res 2015; 16:fov107. [PMID: 26658003 DOI: 10.1093/femsyr/fov107] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2015] [Indexed: 12/16/2022] Open
Abstract
Sucrose is an abundant, readily available and inexpensive substrate for industrial biotechnology processes and its use is demonstrated with much success in the production of fuel ethanol in Brazil. Saccharomyces cerevisiae, which naturally evolved to efficiently consume sugars such as sucrose, is one of the most important cell factories due to its robustness, stress tolerance, genetic accessibility, simple nutrient requirements and long history as an industrial workhorse. This minireview is focused on sucrose metabolism in S. cerevisiae, a rather unexplored subject in the scientific literature. An analysis of sucrose availability in nature and yeast sugar metabolism was performed, in order to understand the molecular background that makes S. cerevisiae consume this sugar efficiently. A historical overview on the use of sucrose and S. cerevisiae by humans is also presented considering sugarcane and sugarbeet as the main sources of this carbohydrate. Physiological aspects of sucrose consumption are compared with those concerning other economically relevant sugars. Also, metabolic engineering efforts to alter sucrose catabolism are presented in a chronological manner. In spite of its extensive use in yeast-based industries, a lot of basic and applied research on sucrose metabolism is imperative, mainly in fields such as genetics, physiology and metabolic engineering.
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Affiliation(s)
- Wesley Leoricy Marques
- Department of Chemical Engineering, University of São Paulo, São Paulo-SP, 05424-970, Brazil School of Food Engineering, University of Campinas, Campinas-SP, 13083-862, Brazil
| | | | - Boris Ugarte Stambuk
- Department of Biochemistry, Federal University of Santa Catarina, Florianópolis-SC, 88040-900, Brazil
| | - Andreas Karoly Gombert
- Department of Chemical Engineering, University of São Paulo, São Paulo-SP, 05424-970, Brazil School of Food Engineering, University of Campinas, Campinas-SP, 13083-862, Brazil
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Murphy HA, Zeyl CW. A Potential Case of Reinforcement in a Facultatively Sexual Unicellular Eukaryote. Am Nat 2015; 186:312-9. [PMID: 26655159 DOI: 10.1086/682071] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The origin of a new species requires a mechanism to prevent divergent populations from interbreeding. In the classic allopatric model, divided populations evolve independently and accumulate genetic differences. If contact is restored, hybrids suffer reduced fitness and selection may favor traits that prevent mistakes in mating, a process known as reinforcement. This decisive but transient phase is challenging to document and has been reported mostly in macroorganisms. Very little is known about the processes through which new microbial species originate. In particular, it is unclear whether microbial eukaryotes, many of which can reproduce sexually during complex life cycles, speciate in much the same way as do well-studied plants and animals. Using individual cellular mate choice trials, we investigated the mating behavior of sympatric and allopatric woodland populations of the yeast Saccharomyces paradoxus. We find evidence consistent with reinforcement, potentially representing an example of microbial speciation in progress.
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Affiliation(s)
- Helen A Murphy
- Department of Biology, Wake Forest University, Box 7325 Reynolda Station, Winston-Salem, North Carolina 27109
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