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Power JF, Carere CR, Welford HE, Hudson DT, Lee KC, Moreau JW, Ettema TJG, Reysenbach AL, Lee CK, Colman DR, Boyd ES, Morgan XC, McDonald IR, Craig Cary S, Stott MB. A genus in the bacterial phylum Aquificota appears to be endemic to Aotearoa-New Zealand. Nat Commun 2024; 15:179. [PMID: 38167814 PMCID: PMC10762115 DOI: 10.1038/s41467-023-43960-2] [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: 04/18/2023] [Accepted: 11/24/2023] [Indexed: 01/05/2024] Open
Abstract
Allopatric speciation has been difficult to examine among microorganisms, with prior reports of endemism restricted to sub-genus level taxa. Previous microbial community analysis via 16S rRNA gene sequencing of 925 geothermal springs from the Taupō Volcanic Zone (TVZ), Aotearoa-New Zealand, revealed widespread distribution and abundance of a single bacterial genus across 686 of these ecosystems (pH 1.2-9.6 and 17.4-99.8 °C). Here, we present evidence to suggest that this genus, Venenivibrio (phylum Aquificota), is endemic to Aotearoa-New Zealand. A specific environmental niche that increases habitat isolation was identified, with maximal read abundance of Venenivibrio occurring at pH 4-6, 50-70 °C, and low oxidation-reduction potentials. This was further highlighted by genomic and culture-based analyses of the only characterised species for the genus, Venenivibrio stagnispumantis CP.B2T, which confirmed a chemolithoautotrophic metabolism dependent on hydrogen oxidation. While similarity between Venenivibrio populations illustrated that dispersal is not limited across the TVZ, extensive amplicon, metagenomic, and phylogenomic analyses of global microbial communities from DNA sequence databases indicates Venenivibrio is geographically restricted to the Aotearoa-New Zealand archipelago. We conclude that geographic isolation, complemented by physicochemical constraints, has resulted in the establishment of an endemic bacterial genus.
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Affiliation(s)
- Jean F Power
- Thermophile Research Unit, Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, 3240, Aotearoa New Zealand
| | - Carlo R Carere
- Te Tari Pūhanga Tukanga Matū | Department of Chemical and Process Engineering, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, 8140, Aotearoa New Zealand
| | - Holly E Welford
- Te Kura Pūtaiao Koiora | School of Biological Sciences, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, 8140, Aotearoa New Zealand
| | - Daniel T Hudson
- Te Tari Moromoroiti me te Ārai Mate | Department of Microbiology and Immunology, Te Whare Wānanga o Ōtākou | University of Otago, Dunedin, 9054, Aotearoa New Zealand
| | - Kevin C Lee
- Te Kura Pūtaiao | School of Science, Te Wānanga Aronui o Tāmaki Makau Rau | Auckland University of Technology, Auckland, 1010, Aotearoa New Zealand
| | - John W Moreau
- School of Geographical & Earth Sciences, University of Glasgow, Glasgow, G12 8RZ, UK
| | - Thijs J G Ettema
- Laboratory of Microbiology, Wageningen University & Research, 6708, WE, Wageningen, the Netherlands
| | | | - Charles K Lee
- Thermophile Research Unit, Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, 3240, Aotearoa New Zealand
| | - Daniel R Colman
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, 59717, USA
| | - Eric S Boyd
- Department of Microbiology and Cell Biology, Montana State University, Bozeman, MT, 59717, USA
| | - Xochitl C Morgan
- Te Tari Moromoroiti me te Ārai Mate | Department of Microbiology and Immunology, Te Whare Wānanga o Ōtākou | University of Otago, Dunedin, 9054, Aotearoa New Zealand
- Department of Biostatistics, Harvard T. H. Chan School of Public Health, Boston, MA, 02115, USA
| | - Ian R McDonald
- Thermophile Research Unit, Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, 3240, Aotearoa New Zealand
| | - S Craig Cary
- Thermophile Research Unit, Te Aka Mātuatua | School of Science, Te Whare Wānanga o Waikato | University of Waikato, Hamilton, 3240, Aotearoa New Zealand.
| | - Matthew B Stott
- Te Kura Pūtaiao Koiora | School of Biological Sciences, Te Whare Wānanga o Waitaha | University of Canterbury, Christchurch, 8140, Aotearoa New Zealand.
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Loewen CJG, Jackson DA, Gilbert B. Biodiversity patterns diverge along geographic temperature gradients. GLOBAL CHANGE BIOLOGY 2023; 29:603-617. [PMID: 36169599 PMCID: PMC10100522 DOI: 10.1111/gcb.16457] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 09/06/2022] [Indexed: 06/16/2023]
Abstract
Models applying space-for-time substitution, including those projecting ecological responses to climate change, generally assume an elevational and latitudinal equivalence that is rarely tested. However, a mismatch may lead to different capacities for providing climatic refuge to dispersing species. We compiled community data on zooplankton, ectothermic animals that form the consumer basis of most aquatic food webs, from over 1200 mountain lakes and ponds across western North America to assess biodiversity along geographic temperature gradients spanning nearly 3750 m elevation and 30° latitude. Species richness, phylogenetic relationships, and functional diversity all showed contrasting responses across gradients, with richness metrics plateauing at low elevations but exhibiting intermediate latitudinal maxima. The nonmonotonic/hump-shaped diversity trends with latitude emerged from geographic interactions, including weaker latitudinal relationships at higher elevations (i.e. in alpine lakes) linked to different underlying drivers. Here, divergent patterns of phylogenetic and functional trait dispersion indicate shifting roles of environmental filters and limiting similarity in the assembly of communities with increasing elevation and latitude. We further tested whether gradients showed common responses to warmer temperatures and found that mean annual (but not seasonal) temperatures predicted elevational richness patterns but failed to capture consistent trends with latitude, meaning that predictions of how climate change will influence diversity also differ between gradients. Contrasting responses to elevation- and latitude-driven warming suggest different limits on climatic refugia and likely greater barriers to northward range expansion.
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Affiliation(s)
- Charlie J. G. Loewen
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoOntarioCanada
- Department of Ecology, Evolution, and Organismal BiologyIowa State UniversityAmesIowaUSA
| | - Donald A. Jackson
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoOntarioCanada
| | - Benjamin Gilbert
- Department of Ecology and Evolutionary BiologyUniversity of TorontoTorontoOntarioCanada
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3
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Jasser I, Panou M, Khomutovska N, Sandzewicz M, Panteris E, Niyatbekov T, Łach Ł, Kwiatowski J, Kokociński M, Gkelis S. Cyanobacteria in hot pursuit: Characterization of cyanobacteria strains, including novel taxa, isolated from geothermal habitats from different ecoregions of the world. Mol Phylogenet Evol 2022; 170:107454. [PMID: 35341965 DOI: 10.1016/j.ympev.2022.107454] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Revised: 01/18/2022] [Accepted: 03/04/2022] [Indexed: 10/18/2022]
Abstract
Well-studied thermal spring microbial mat systems continue to serve as excellent models from which to make discoveries of general importance to microbial community ecology in order to address comprehensively the question of "who is there" in a microbial community. Cyanobacteria are highly adaptable and an integral part of many ecosystems including thermal springs. In this context, we sampled disparate thermal springs, spanning from Iceland and Poland to Greece and Tajikistan. Thirteen (13) strains were isolated and characterised with taxonomic indices and molecular markers (16S-23S rRNA region and cpcBA gene), whilst their thermotolerance was evaluated. Screening for the presence of genes encoding three heat shock proteins, as well as non-ribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs) was performed. This approach resulted in the description of two new genera (Hillbrichtia and Amphirytos) and their type species (Hillbrichtia pamiria and Amphirytos necridicus) representing Oscillatoriales and Synechococcales orders, respectively. We also found unique lineages inside the genus Thermoleptolyngbya, describing a novel species (T. hindakiae). We described the presence of sub-cosmopolitan taxa (such as Calothrix, Desertifilum, and Trichormus). Strains were diverse concerning their thermophilic ability with the strains well adapted to high temperatures possessing all three investigated genes encoding heat shock proteins as well as studied PKS and NRPS genes. In this work, we show novel cyanobacteria diversity from thermal springs from disparate environments, possible correlation of thermotolerance and their genetic background, which may have implications on strategic focusing of screening programs on underexploited taxa in these habitats.
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Affiliation(s)
- Iwona Jasser
- Institute of Environmental Biology, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Manthos Panou
- Department of Botany, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Nataliia Khomutovska
- Institute of Environmental Biology, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Małgorzata Sandzewicz
- Institute of Environmental Biology, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Emmanuel Panteris
- Department of Botany, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece
| | - Toirbek Niyatbekov
- Institute of Botany, Plant Physiology and Genetics, Academy Science Republic of Tajikistan, 27 Karamov Str., Dushanbe 734017, Tajikistan
| | - Łukasz Łach
- Institute of Environmental Biology, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Jan Kwiatowski
- Institute of Environmental Biology, Faculty of Biology, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland
| | - Mikołaj Kokociński
- Department of Hydrobiology, Institute of Environmental Biology, Faculty of Biology, Adam Mickiewicz University in Poznań, Uniwersytetu Poznańskiego 6, 61-614 Poznań, Poland
| | - Spyros Gkelis
- Department of Botany, School of Biology, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.
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Habitat Adaptation Drives Speciation of a Streptomyces Species with Distinct Habitats and Disparate Geographic Origins. mBio 2022; 13:e0278121. [PMID: 35012331 PMCID: PMC8749437 DOI: 10.1128/mbio.02781-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Microbial diversification is driven by geographic and ecological factors, but how the relative importance of these factors varies among species, geographic scales, and habitats remains unclear. Streptomyces, a genus of antibiotic-producing, spore-forming, and widespread bacteria, offers a robust model for identifying the processes underlying population differentiation. We examined the population structure of 37 Streptomyces olivaceus strains isolated from various sources, showing that they diverged into two habitat-associated (free-living and insect-associated) and geographically disparate lineages. More frequent gene flow within than between the lineages confirmed genetic isolation in S. olivaceus. Geographic isolation could not explain the genetic isolation; instead, habitat type was a strong predictor of genetic distance when controlling for geographic distance. The identification of habitat-specific genetic variations, including genes involved in regulation, resource use, and secondary metabolism, suggested a significant role of habitat adaptation in the diversification process. Physiological assays revealed fitness trade-offs under different environmental conditions in the two lineages. Notably, insect-associated isolates could outcompete free-living isolates in a free-iron-deficient environment. Furthermore, substrate (e.g., sialic acid and glycogen) utilization but not thermal traits differentiated the two lineages. Overall, our results argue that adaptive processes drove ecological divergence among closely related streptomycetes, eventually leading to dispersal limitation and gene flow barriers between the lineages. S. olivaceus may best be considered a species complex consisting of two cryptic species. IMPORTANCE Both isolation by distance and isolation by environment occur in bacteria, and different diversification patterns may apply to different species. Streptomyces species, typified by producing useful natural products, are widespread in nature and possess high genetic diversity. However, the ecological processes and evolutionary mechanisms that shape their distribution are not well understood. Here, we show that the population structure of a ubiquitous Streptomyces species complex matches its habitat distribution and can be defined by gene flow discontinuities. Using comparative genomics and physiological assays, we reveal that gains and losses of specific genomic traits play a significant role in the transition between free-living and host-associated lifestyles, driving speciation of the species. These results provide new insights into the evolutionary trajectory of Streptomyces and the notion of species.
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5
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Stevenson DS, Wallace R. Biogeographical Modeling of Alien Worlds. ASTROBIOLOGY 2021; 21:831-844. [PMID: 33904766 DOI: 10.1089/ast.2020.2304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
In this article, we partially quantify the biological potential of an exoplanet. We employ a variety of biogeographical analyses, placing biological evolution in the context of the geological evolution of the planet as a whole. Terrestrial (as in Earthly) biodiversity is tightly constrained in terms of species richness by its environment. An organism's habitable environment may be considered its niche space or hypervolume in terms of the physical characteristics in which that organism can survive and reproduce. This fundamental niche forms the broader space in which the organism realizes its true niche in terms of its interactions with other species. Many of the physical characteristics can be determined from astrophysical constraints and are thus amenable for dissection. However, the geographical space that organisms occupy is driven by the geological evolution of a sizable telluric planet. In turn, this is driven by the progressive differentiation of its interior to produce increasingly felsic crust. Using a variety of available models, we can then constrain the available space that species can inhabit using species-area relationships. By considering a combination of astrophysical constraints and geographical space, we partially quantify the numbers of species that can inhabit the landscape that geology provides. Finally, we also identify a correlation between geomorphological scale and speciation, which, if validated, will allow further dissection of species diversity on alien worlds.
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Affiliation(s)
- David S Stevenson
- Science Department, Carlton le Willows Academy, Nottingham, United Kingdom
| | - Rodrick Wallace
- Division of Epidemiology, The New York State Psychiatric Institute at Columbia University, New York Psychiatric Institute, New York, USA
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6
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Harrow GL, Lees JA, Hanage WP, Lipsitch M, Corander J, Colijn C, Croucher NJ. Negative frequency-dependent selection and asymmetrical transformation stabilise multi-strain bacterial population structures. THE ISME JOURNAL 2021; 15:1523-1538. [PMID: 33408365 PMCID: PMC8115253 DOI: 10.1038/s41396-020-00867-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 12/01/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023]
Abstract
Streptococcus pneumoniae can be divided into many strains, each a distinct set of isolates sharing similar core and accessory genomes, which co-circulate within the same hosts. Previous analyses suggested the short-term vaccine-associated dynamics of S. pneumoniae strains may be mediated through multi-locus negative frequency-dependent selection (NFDS), which maintains accessory loci at equilibrium frequencies. Long-term simulations demonstrated NFDS stabilised clonally-evolving multi-strain populations through preventing the loss of variation through drift, based on polymorphism frequencies, pairwise genetic distances and phylogenies. However, allowing symmetrical recombination between isolates evolving under multi-locus NFDS generated unstructured populations of diverse genotypes. Replication of the observed data improved when multi-locus NFDS was combined with recombination that was instead asymmetrical, favouring deletion of accessory loci over insertion. This combination separated populations into strains through outbreeding depression, resulting from recombinants with reduced accessory genomes having lower fitness than their parental genotypes. Although simplistic modelling of recombination likely limited these simulations' ability to maintain some properties of genomic data as accurately as those lacking recombination, the combination of asymmetrical recombination and multi-locus NFDS could restore multi-strain population structures from randomised initial populations. As many bacteria inhibit insertions into their chromosomes, this combination may commonly underlie the co-existence of strains within a niche.
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Affiliation(s)
- Gabrielle L Harrow
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - John A Lees
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK
| | - William P Hanage
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA, 02115, USA
| | - Marc Lipsitch
- Center for Communicable Disease Dynamics, Department of Epidemiology, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA, 02115, USA
| | - Jukka Corander
- Department of Biostatistics, University of Oslo, Oslo, Norway
- Helsinki Institute of Information Technology, Department of Mathematics and Statistics, University of Helsinki, Helsinki, Finland
- Parasites & Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
| | - Caroline Colijn
- Parasites & Microbes Programme, Wellcome Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridge, UK
- Department of Mathematics, Simon Fraser University, Burnaby, BC, Canada
| | - Nicholas J Croucher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, W2 1PG, UK.
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7
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Hernández-Hernández T, Miller EC, Román-Palacios C, Wiens JJ. Speciation across the Tree of Life. Biol Rev Camb Philos Soc 2021; 96:1205-1242. [PMID: 33768723 DOI: 10.1111/brv.12698] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Revised: 02/13/2021] [Accepted: 02/16/2021] [Indexed: 01/04/2023]
Abstract
Much of what we know about speciation comes from detailed studies of well-known model systems. Although there have been several important syntheses on speciation, few (if any) have explicitly compared speciation among major groups across the Tree of Life. Here, we synthesize and compare what is known about key aspects of speciation across taxa, including bacteria, protists, fungi, plants, and major animal groups. We focus on three main questions. Is allopatric speciation predominant across groups? How common is ecological divergence of sister species (a requirement for ecological speciation), and on what niche axes do species diverge in each group? What are the reproductive isolating barriers in each group? Our review suggests the following patterns. (i) Based on our survey and projected species numbers, the most frequent speciation process across the Tree of Life may be co-speciation between endosymbiotic bacteria and their insect hosts. (ii) Allopatric speciation appears to be present in all major groups, and may be the most common mode in both animals and plants, based on non-overlapping ranges of sister species. (iii) Full sympatry of sister species is also widespread, and may be more common in fungi than allopatry. (iv) Full sympatry of sister species is more common in some marine animals than in terrestrial and freshwater ones. (v) Ecological divergence of sister species is widespread in all groups, including ~70% of surveyed species pairs of plants and insects. (vi) Major axes of ecological divergence involve species interactions (e.g. host-switching) and habitat divergence. (vii) Prezygotic isolation appears to be generally more widespread and important than postzygotic isolation. (viii) Rates of diversification (and presumably speciation) are strikingly different across groups, with the fastest rates in plants, and successively slower rates in animals, fungi, and protists, with the slowest rates in prokaryotes. Overall, our study represents an initial step towards understanding general patterns in speciation across all organisms.
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Affiliation(s)
- Tania Hernández-Hernández
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A.,Catedrática CONACYT asignada a LANGEBIO-UGA Cinvestav, Libramiento Norte Carretera León Km 9.6, 36821, Irapuato, Guanajuato, Mexico
| | - Elizabeth C Miller
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - Cristian Román-Palacios
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
| | - John J Wiens
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721-0088, U.S.A
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8
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Baquero F, Coque TM, Galán JC, Martinez JL. The Origin of Niches and Species in the Bacterial World. Front Microbiol 2021; 12:657986. [PMID: 33815348 PMCID: PMC8010147 DOI: 10.3389/fmicb.2021.657986] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2021] [Accepted: 02/23/2021] [Indexed: 12/15/2022] Open
Abstract
Niches are spaces for the biological units of selection, from cells to complex communities. In a broad sense, "species" are biological units of individuation. Niches do not exist without individual organisms, and every organism has a niche. We use "niche" in the Hutchinsonian sense as an abstraction of a multidimensional environmental space characterized by a variety of conditions, both biotic and abiotic, whose quantitative ranges determine the positive or negative growth rates of the microbial individual, typically a species, but also parts of the communities of species contained in this space. Microbial organisms ("species") constantly diversify, and such diversification (radiation) depends on the possibility of opening up unexploited or insufficiently exploited niches. Niche exploitation frequently implies "niche construction," as the colonized niche evolves with time, giving rise to new potential subniches, thereby influencing the selection of a series of new variants in the progeny. The evolution of niches and organisms is the result of reciprocal interacting processes that form a single unified process. Centrifugal microbial diversification expands the limits of the species' niches while a centripetal or cohesive process occurs simultaneously, mediated by horizontal gene transfers and recombinatorial events, condensing all of the information recovered during the diversifying specialization into "novel organisms" (possible future species), thereby creating a more complex niche, where the selfishness of the new organism(s) establishes a "homeostatic power" limiting the niche's variation. Once the niche's full carrying capacity has been reached, reproductive isolation occurs, as no foreign organisms can outcompete the established population/community, thereby facilitating speciation. In the case of individualization-speciation of the microbiota, its contribution to the animal' gut structure is a type of "niche construction," the result of crosstalk between the niche (host) and microorganism(s). Lastly, there is a parallelism between the hierarchy of niches and that of microbial individuals. The increasing anthropogenic effects on the biosphere (such as globalization) might reduce the diversity of niches and bacterial individuals, with the potential emergence of highly transmissible multispecialists (which are eventually deleterious) resulting from the homogenization of the microbiosphere, a possibility that should be explored and prevented.
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Affiliation(s)
- Fernando Baquero
- Division of Biology and Evolution of Microorganisms, Department of Microbiology, Ramón y Cajal Institute for Health Research (IRYCIS), Ramón y Cajal University Hospital, Madrid, Spain
| | - Teresa M Coque
- Division of Biology and Evolution of Microorganisms, Department of Microbiology, Ramón y Cajal Institute for Health Research (IRYCIS), Ramón y Cajal University Hospital, Madrid, Spain
| | - Juan Carlos Galán
- Division of Biology and Evolution of Microorganisms, Department of Microbiology, Ramón y Cajal Institute for Health Research (IRYCIS), Ramón y Cajal University Hospital, Madrid, Spain
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9
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Hoetzinger M, Pitt A, Huemer A, Hahn MW. Continental-Scale Gene Flow Prevents Allopatric Divergence of Pelagic Freshwater Bacteria. Genome Biol Evol 2021; 13:6126423. [PMID: 33674852 PMCID: PMC7936036 DOI: 10.1093/gbe/evab019] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/25/2021] [Indexed: 12/24/2022] Open
Abstract
Allopatric divergence is one of the principal mechanisms for speciation of macro-organisms. Microbes by comparison are assumed to disperse more freely and to be less limited by dispersal barriers. However, thermophilic prokaryotes restricted to geothermal springs have shown clear signals of geographic isolation, but robust studies on this topic for microbes with less strict habitat requirements are scarce. Furthermore, it has only recently been recognized that homologous recombination among conspecific individuals provides species coherence in a wide range of prokaryotes. Recombination barriers thus may define prokaryotic species boundaries, yet, the extent to which geographic distance between populations gives rise to such barriers is an open question. Here, we investigated gene flow and population structure in a widespread species of pelagic freshwater bacteria, Polynucleobacter paneuropaeus. Through comparative genomics of 113 conspecific strains isolated from freshwater lakes and ponds located across a North–South range of more than 3,000 km, we were able to reconstruct past gene flow events. The species turned out to be highly recombinogenic as indicated by significant signs of gene transfer and extensive genome mosaicism. Although genomic differences increased with spatial distance on a regional scale (<170 km), such correlations were mostly absent on larger scales up to 3,400 km. We conclude that allopatric divergence in European P. paneuropaeus is minor, and that effective gene flow across the sampled geographic range in combination with a high recombination efficacy maintains species coherence.
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Affiliation(s)
- Matthias Hoetzinger
- Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria.,Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences, Uppsala SE-75651, Sweden
| | - Alexandra Pitt
- Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria
| | - Andrea Huemer
- Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria
| | - Martin W Hahn
- Research Department for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310 Mondsee, Austria
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10
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Becraft ED, Wood JM, Cohan FM, Ward DM. Biogeography of American Northwest Hot Spring A/B '-Lineage Synechococcus Populations. Front Microbiol 2020; 11:77. [PMID: 32153516 PMCID: PMC7050468 DOI: 10.3389/fmicb.2020.00077] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 01/15/2020] [Indexed: 12/17/2022] Open
Abstract
Previous analyses have shown how diversity among unicellular cyanobacteria inhabiting island-like hot springs is structured relative to physical separation and physiochemical differences among springs, especially at local to regional scales. However, these studies have been limited by the low resolution provided by the molecular markers surveyed. We analyzed large datasets obtained by high-throughput sequencing of a segment of the photosynthesis gene psaA from samples collected in hot springs from geothermal basins in Yellowstone National Park, Montana, and Oregon, all known from previous studies to contain populations of A/B'-lineage Synechococcus. The fraction of identical sequences was greater among springs separated by <50 km than among springs separated by >50 km, and springs separated by >800 km shared sequence variants only rarely. Phylogenetic analyses provided evidence for endemic lineages that could be related to geographic isolation and/or geochemical differences on regional scales. Ecotype Simulation 2 was used to predict putative ecotypes (ecologically distinct populations), and their membership, and canonical correspondence analysis was used to examine the geographical and geochemical bases for variation in their distribution. Across the range of Oregon and Yellowstone, geographical separation explained the largest percentage of the differences in distribution of ecotypes (9.5% correlated to longitude; 9.4% to latitude), with geochemical differences explaining the largest percentage of the remaining differences in distribution (7.4-9.3% correlated to magnesium, sulfate, and sulfide). Among samples within the Greater Yellowstone Ecosystem, geochemical differences significantly explained the distribution of ecotypes (6.5-9.3% correlated to magnesium, boron, sulfate, silicon dioxide, chloride, and pH). Nevertheless, differences in the abundance and membership of ecotypes in Yellowstone springs with similar chemistry suggested that allopatry may be involved even at local scales. Synechococcus populations have diverged both by physical isolation and physiochemical differences, and populations on surprisingly local scales have been evolving independently.
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Affiliation(s)
- Eric D Becraft
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States.,Department of Biology, University of North Alabama, Florence, AL, United States
| | - Jason M Wood
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States.,Biotechnology and Planetary Protection Group, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
| | - Frederick M Cohan
- Department of Biology, Wesleyan University, Middletown, CT, United States
| | - David M Ward
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, United States
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Iranzo J, Wolf YI, Koonin EV, Sela I. Gene gain and loss push prokaryotes beyond the homologous recombination barrier and accelerate genome sequence divergence. Nat Commun 2019; 10:5376. [PMID: 31772262 PMCID: PMC6879757 DOI: 10.1038/s41467-019-13429-2] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2019] [Accepted: 11/07/2019] [Indexed: 02/05/2023] Open
Abstract
Bacterial and archaeal evolution involve extensive gene gain and loss. Thus, phylogenetic trees of prokaryotes can be constructed both by traditional sequence-based methods (gene trees) and by comparison of gene compositions (genome trees). Comparing the branch lengths in gene and genome trees with identical topologies for 34 clusters of closely related bacterial and archaeal genomes, we show here that terminal branches of gene trees are systematically compressed compared to those of genome trees. Thus, sequence evolution is delayed compared to genome evolution by gene gain and loss. The extent of this delay differs widely among bacteria and archaea. Mathematical modeling shows that the divergence delay can result from sequence homogenization by homologous recombination. The model explains how homologous recombination maintains the cohesiveness of the core genome of a species while allowing extensive gene gain and loss within the accessory genome. Once evolving genomes become isolated by barriers impeding homologous recombination, gene and genome evolution processes settle into parallel trajectories, and genomes diverge, resulting in speciation. A significant proportion of the molecular evolution of bacteria and archaea occurs through gene gain and loss. Here Iranzo et al. develop a mathematical model that explains observed differential patterns of sequence evolution vs. gene content evolution as a consequence of homologous recombination.
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Affiliation(s)
- Jaime Iranzo
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA.,Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid (UPM)-Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), Campus de Montegancedo-UPM, Pozuelo de Alarcón, 28223, Madrid, Spain
| | - Yuri I Wolf
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA
| | - Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA.
| | - Itamar Sela
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, 20894, USA.
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12
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A Reverse Ecology Framework for Bacteria and Archaea. POPULATION GENOMICS: MICROORGANISMS 2018. [DOI: 10.1007/13836_2018_46] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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13
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Hoetzinger M, Hahn MW. Genomic divergence and cohesion in a species of pelagic freshwater bacteria. BMC Genomics 2017; 18:794. [PMID: 29037158 PMCID: PMC5644125 DOI: 10.1186/s12864-017-4199-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 10/08/2017] [Indexed: 11/15/2022] Open
Abstract
Background In many prokaryotic genera a clustered phylogeny is observed, akin to the occurrence of species in sexually reproducing organisms. For some taxa, homologous recombination has been invoked as the underlying mechanism providing genomic cohesion among conspecific individuals. Whether this mechanism is applicable to prokaryotes in freshwaters with low habitat connectivity – i.e. elevated geographic barriers to gene flow – is unclear. To investigate further we studied genomic trends within the globally abundant PnecC cluster (genus Polynucleobacter, Betaproteobacteria) and analyzed homologous recombination within the affiliated species P. asymbioticus. Results Comparisons among 20 PnecC genomes revealed a clearly discontinuous distribution of nucleotide sequence similarities. Among the nine conspecific individuals (P. asymbioticus) all average nucleotide identity (ANI) values were greater than 97%, whereas all other comparisons exhibited ANI values lower than 85%. The reconstruction of recombination and mutation events for the P. asymbioticus core genomes yielded an r/m ratio of 7.4, which is clearly above estimated thresholds for recombination to act as a cohesive force. Hotspots of recombination were found to be located in the flanking regions of genomic islands. Even between geographically separated habitats a high flux of recombination was evident. While a biogeographic population structure was suggested from MLST data targeting rather conserved loci, such a structure was barely visible when whole genome data was considered. However, both MLST and whole genome data showed evidence of differentiation between two lineages of P. asymbioticus. The ratios of non-synonymous to synonymous substitution rates as well as growth rates in transplantation experiments suggested that this divergence was not selectively neutral. Conclusions The high extent of homologous recombination among P. asymbioticus bacteria can act as a cohesive force that effectively counteracts genetic divergence. At least on a regional scale, homologous recombination can act across geographically separated ecosystems and therefore plays an important role in the evolution and consistency of bacterial freshwater species. A species model akin to the biological species concept may be applicable for P. asymbioticus. Nonetheless, two genetically distinct lineages have emerged and further research may clarify if their divergence has been initiated by reinforced geographical barriers or has been evolving in sympatry. Electronic supplementary material The online version of this article (10.1186/s12864-017-4199-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Matthias Hoetzinger
- Research Institute for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310, Mondsee, Austria.
| | - Martin W Hahn
- Research Institute for Limnology, University of Innsbruck, Mondseestrasse 9, A-5310, Mondsee, Austria
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Pérez Carrascal OM, VanInsberghe D, Juárez S, Polz MF, Vinuesa P, González V. Population genomics of the symbiotic plasmids of sympatric nitrogen-fixing Rhizobium species associated with Phaseolus vulgaris. Environ Microbiol 2016; 18:2660-76. [PMID: 27312778 DOI: 10.1111/1462-2920.13415] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2016] [Accepted: 06/13/2016] [Indexed: 11/28/2022]
Abstract
Cultivated common beans are the primary protein source for millions of people around the world who subsist on low-input agriculture, enabled by the symbiotic N2 -fixation these legumes perform in association with rhizobia. Within a single agricultural plot, multiple Rhizobium species can nodulate bean roots, but it is unclear how genetically isolated these species remain in sympatry. To better understand this issue, we sequenced and compared the genomes of 33 strains isolated from the rhizosphere and root nodules of a particular bean variety grown in the same agricultural plot. We found that the Rhizobium species we observed coexist with low genetic recombination across their core genomes. Accessory plasmids thought to be necessary for the saprophytic lifestyle in soil show similar levels of genetic isolation, but with higher rates of recombination than the chromosomes. However, the symbiotic plasmids are extremely similar, with high rates of recombination and do not appear to have co-evolved with the chromosome or accessory plasmids. Therefore, while Rhizobium species are genetically isolated units within the microbial community, a common symbiotic plasmid allows all Rhizobium species to engage in symbiosis with the same host in a single agricultural plot.
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Affiliation(s)
- Olga M Pérez Carrascal
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, México
| | - David VanInsberghe
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Soledad Juárez
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, México
| | - Martin F Polz
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Pablo Vinuesa
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, México
| | - Víctor González
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, 62210, México
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15
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Biogeography of sulfur-oxidizing Acidithiobacillus populations in extremely acidic cave biofilms. ISME JOURNAL 2016; 10:2879-2891. [PMID: 27187796 PMCID: PMC5148195 DOI: 10.1038/ismej.2016.74] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 03/17/2016] [Accepted: 03/24/2016] [Indexed: 02/01/2023]
Abstract
Extremely acidic (pH 0–1.5) Acidithiobacillus-dominated biofilms known as snottites are found in sulfide-rich caves around the world. Given the extreme geochemistry and subsurface location of the biofilms, we hypothesized that snottite Acidithiobacillus populations would be genetically isolated. We therefore investigated biogeographic relationships among snottite Acidithiobacillus spp. separated by geographic distances ranging from meters to 1000s of kilometers. We determined genetic relationships among the populations using techniques with three levels of resolution: (i) 16S rRNA gene sequencing, (ii) 16S–23S intergenic transcribed spacer (ITS) region sequencing and (iii) multi-locus sequencing typing (MLST). We also used metagenomics to compare functional gene characteristics of select populations. Based on 16S rRNA genes, snottites in Italy and Mexico are dominated by different sulfur-oxidizing Acidithiobacillus spp. Based on ITS sequences, Acidithiobacillus thiooxidans strains from different cave systems in Italy are genetically distinct. Based on MLST of isolates from Italy, genetic distance is positively correlated with geographic distance both among and within caves. However, metagenomics revealed that At. thiooxidans populations from different cave systems in Italy have different sulfur oxidation pathways and potentially other significant differences in metabolic capabilities. In light of those genomic differences, we argue that the observed correlation between genetic and geographic distance among snottite Acidithiobacillus populations is partially explained by an evolutionary model in which separate cave systems were stochastically colonized by different ancestral surface populations, which then continued to diverge and adapt in situ.
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Ben-Jacob E, Finkelshtein A, Ariel G, Ingham C. Multispecies Swarms of Social Microorganisms as Moving Ecosystems. Trends Microbiol 2016; 24:257-269. [DOI: 10.1016/j.tim.2015.12.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2015] [Revised: 12/16/2015] [Accepted: 12/21/2015] [Indexed: 10/22/2022]
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17
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Ryšánek D, Elster J, Kováčik L, Škaloud P. Diversity and dispersal capacities of a terrestrial algal genusKlebsormidium(Streptophyta) in polar regions. FEMS Microbiol Ecol 2016; 92:fnw039. [DOI: 10.1093/femsec/fiw039] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/18/2016] [Indexed: 11/13/2022] Open
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18
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Price MT, Fullerton H, Moyer CL. Biogeography and evolution of Thermococcus isolates from hydrothermal vent systems of the Pacific. Front Microbiol 2015; 6:968. [PMID: 26441901 PMCID: PMC4585236 DOI: 10.3389/fmicb.2015.00968] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Accepted: 09/01/2015] [Indexed: 11/13/2022] Open
Abstract
Thermococcus is a genus of hyperthermophilic archaea that is ubiquitous in marine hydrothermal environments growing in anaerobic subsurface habitats but able to survive in cold oxygenated seawater. DNA analyses of Thermococcus isolates were applied to determine the relationship between geographic distribution and relatedness focusing primarily on isolates from the Juan de Fuca Ridge and South East Pacific Rise. Amplified fragment length polymorphism (AFLP) analysis and multilocus sequence typing (MLST) were used to resolve genomic differences in 90 isolates of Thermococcus, making biogeographic patterns and evolutionary relationships apparent. Isolates were differentiated into regionally endemic populations however there was also evidence in some lineages of cosmopolitan distribution. The biodiversity identified in Thermococcus isolates and presence of distinct lineages within the same vent site suggests the utilization of varying ecological niches in this genus. In addition to resolving biogeographic patterns in Thermococcus, this study has raised new questions about the closely related Pyrococcus genus. The phylogenetic placement of Pyrococcus type strains shows the close relationship between Thermococcus and Pyrococcus and the unresolved divergence of these two genera.
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Affiliation(s)
- Mark T Price
- Department of Biology, Western Washington University Bellingham, WA, USA
| | - Heather Fullerton
- Department of Biology, Western Washington University Bellingham, WA, USA
| | - Craig L Moyer
- Department of Biology, Western Washington University Bellingham, WA, USA
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19
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Krause DJ, Whitaker RJ. Inferring Speciation Processes from Patterns of Natural Variation in Microbial Genomes. Syst Biol 2015; 64:926-35. [PMID: 26316424 PMCID: PMC4604833 DOI: 10.1093/sysbio/syv050] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2014] [Accepted: 06/09/2015] [Indexed: 01/22/2023] Open
Abstract
Microbial species concepts have long been the focus of contentious debate, fueled by technological limitations to the genetic resolution of species, by the daunting task of investigating phenotypic variation among individual microscopic organisms, and by a lack of understanding of gene flow in reproductively asexual organisms that are prone to promiscuous horizontal gene transfer. Population genomics, the emerging approach of analyzing the complete genomes of a multitude of closely related organisms, is poised to overcome these limitations by providing a window into patterns of genome variation revealing the evolutionary processes through which species diverge. This new approach is more than just an extension of previous multilocus sequencing technologies, in that it provides a comprehensive view of interacting evolutionary processes. Here we argue that the application of population genomic tools in a rigorous population genetic framework will help to identify the processes of microbial speciation and ultimately lead to a general species concept based on the unique biology and ecology of microorganisms.
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Affiliation(s)
- David J Krause
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | - Rachel J Whitaker
- Department of Microbiology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
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20
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Fahy A, Giloteaux L, Bertin P, Le Paslier D, Médigue C, Weissenbach J, Duran R, Lauga B. 16S rRNA and As-Related Functional Diversity: Contrasting Fingerprints in Arsenic-Rich Sediments from an Acid Mine Drainage. MICROBIAL ECOLOGY 2015; 70:154-167. [PMID: 25592635 DOI: 10.1007/s00248-014-0558-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 12/16/2014] [Indexed: 06/04/2023]
Abstract
To gain an in-depth insight into the diversity and the distribution of genes under the particular evolutionary pressure of an arsenic-rich acid mine drainage (AMD), the genes involved in bacterial arsenic detoxification (arsB, ACR3) and arsenite oxidation (aioA) were investigated in sediment from Carnoulès (France), in parallel to the diversity and global distribution of the metabolically active bacteria. The metabolically active bacteria were affiliated mainly to AMD specialists, i.e., organisms detected in or isolated from AMDs throughout the world. They included mainly Acidobacteria and the non-affiliated "Candidatus Fodinabacter communificans," as well as Thiomonas and Acidithiobacillus spp., Actinobacteria, and unclassified Gammaproteobacteria. The distribution range of these organisms suggested that they show niche conservatism. Sixteen types of deduced protein sequences of arsenite transporters (5 ArsB and 11 Acr3p) were detected, whereas a single type of arsenite oxidase (AioA) was found. Our data suggested that at Carnoulès, the aioA gene was more recent than those encoding arsenite transporters and subjected to a different molecular evolution. In contrast to the 16S ribosomal RNA (16S rRNA) genes associated with AMD environments worldwide, the functional genes aioA, ACR3, and to a lesser extent arsB, were either novel or specific to Carnoulès, raising the question as to whether these functional genes are specific to high concentrations of arsenic, AMD-specific, or site-specific.
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Affiliation(s)
- Anne Fahy
- Équipe Environnement et Microbiologie, EEM, UMR 5254 (IPREM, CNRS), Université de Pau et des Pays de l'Adour, IBEAS, BP 1155, 64013, Pau Cedex, France
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21
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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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22
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Hu S, Jin D, Lu S, Liu S, Zhang J, Wang Y, Bai X, Xiong Y, Huang Y, Xu H, Wang Y, Du X, Ye C, Hänninen ML, Xu J. Helicobacter himalayensis sp. nov. isolated from gastric mucosa of Marmota himalayana. Int J Syst Evol Microbiol 2015; 65:1719-1725. [PMID: 25736414 DOI: 10.1099/ijs.0.000163] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A Gram-stain-negative, microaerophilic strain, 80(YS1)T, with a spiral-shaped morphology and 1-2 sheathed flagella at each end of the cells was isolated from the gastric mucosa of Marmota himalayana, the animal reservoir of Yersinia pestis in China, on the Qinghai-Tibet Plateau. The strain grew at 30, 35 and 42 °C, but not at 25 °C. Growth was in the form of a thinly spreading film on brain heart infusion agar containing 8 % sheep blood under microaerobic conditions. The strain did not hydrolyse urea or hippurate, and did not grow on media containing 1 % glycine. It reduced nitrate to nitrite, and was catalase- and alkaline-phosphatase-positive, susceptible to nalidixic acid and resistant to cefalotin. It was positive for genus-specific PCR for the genus Helicobacter, but could not be classified to any recognized species according biochemical tests results. Therefore, a phylogenetic study based on 16S rRNA, 23S rRNA, 60 kDa heat-shock protein (hsp60) and gyrase subunit B (gyrB) genes was conducted. The 16S rRNA gene sequence (1468 bp) analysis showed that strain 80(YS1)T was most closely related to Helicobacter marmotae (96.7 % similarity). The 23S rRNA gene sequence (2879 bp) analysis showed that the strain was most closely related to Helicobacter canis (96 % similarity). The complete gyrB gene sequence (2325 bp) analysis showed that it was related phylogenetically to Helicobacter cinaedi (79.4 % similarity) and H. marmotae (79.1 % similarity). Analysis of the partial sequence of the hsp60 gene of strain 80(YS1)T showed closest similarity to the sequences of Helicobacter equorum (82 %) and H. cinaedi (81 %), respectively. However, there was no hsp60 sequence of H. marmotae available for analysis. The data of morphological, biochemical and phylogenetic characteristics all supported that this strain represents a novel species. The name Helicobacter himalayensis sp. nov. is proposed for this novel species with the type strain 80(YS1)T ( = CGMCC 1.12864T = DSM 28742T).
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Affiliation(s)
- Shoukui Hu
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Dong Jin
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Shan Lu
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Sha Liu
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Ji Zhang
- Department of Food Hygiene and Environmental Health, Helsinki University, Finland
| | - Yiting Wang
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Xiangning Bai
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Yanwen Xiong
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Ying Huang
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Huaqing Xu
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Yi Wang
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Xiaoli Du
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Changyun Ye
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
| | - Marja-Liisa Hänninen
- Department of Food Hygiene and Environmental Health, Helsinki University, Finland
| | - Jianguo Xu
- State Key Laboratory for Infectious Disease Prevention and Control, and National Institute for Communicable Disease Control and Prevention, China CDC, Beijing, PR China
- Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Beijing, PR China
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Yurkov A, Inácio J, Chernov IY, Fonseca Á. Yeast Biogeography and the Effects of Species Recognition Approaches: The Case Study of Widespread Basidiomycetous Species from Birch Forests in Russia. Curr Microbiol 2014; 70:587-601. [DOI: 10.1007/s00284-014-0755-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 12/06/2014] [Indexed: 11/25/2022]
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24
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Banks JC, Cary SC, Hogg ID. Isolated faecal bacterial communities found for Weddell seals, Leptonychotes weddellii, at White Island, McMurdo Sound, Antarctica. Polar Biol 2014. [DOI: 10.1007/s00300-014-1567-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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25
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Feng S, Powell SM, Wilson R, Bowman JP. Extensive gene acquisition in the extremely psychrophilic bacterial species Psychroflexus torquis and the link to sea-ice ecosystem specialism. Genome Biol Evol 2014; 6:133-48. [PMID: 24391155 PMCID: PMC3914696 DOI: 10.1093/gbe/evt209] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Sea ice is a highly dynamic and productive environment that includes a diverse array of psychrophilic prokaryotic and eukaryotic taxa distinct from the underlying water column. Because sea ice has only been extensive on Earth since the mid-Eocene, it has been hypothesized that bacteria highly adapted to inhabit sea ice have traits that have been acquired through horizontal gene transfer (HGT). Here we compared the genomes of the psychrophilic bacterium Psychroflexus torquis ATCC 700755T, associated with both Antarctic and Arctic sea ice, and its closely related nonpsychrophilic sister species, P. gondwanensis ACAM 44T. Results show that HGT has occurred much more extensively in P. torquis in comparison to P. gondwanensis. Genetic features that can be linked to the psychrophilic and sea ice-specific lifestyle of P. torquis include genes for exopolysaccharide (EPS) and polyunsaturated fatty acid (PUFA) biosynthesis, numerous specific modes of nutrient acquisition, and proteins putatively associated with ice-binding, light-sensing (bacteriophytochromes), and programmed cell death (metacaspases). Proteomic analysis showed that several genes associated with these traits are highly translated, especially those involved with EPS and PUFA production. Because most of the genes relating to the ability of P. torquis to dwell in sea-ice ecosystems occur on genomic islands that are absent in closely related P. gondwanensis, its adaptation to the sea-ice environment appears driven mainly by HGT. The genomic islands are rich in pseudogenes, insertional elements, and addiction modules, suggesting that gene acquisition is being followed by a process of genome reduction potentially indicative of evolving ecosystem specialism.
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Affiliation(s)
- Shi Feng
- Food Safety Centre, Tasmanian Institute of Agriculture, University of Tasmania, Australia
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26
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Barberán A, Casamayor EO, Fierer N. The microbial contribution to macroecology. Front Microbiol 2014; 5:203. [PMID: 24829564 PMCID: PMC4017162 DOI: 10.3389/fmicb.2014.00203] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2014] [Accepted: 04/16/2014] [Indexed: 01/11/2023] Open
Abstract
There has been a recent explosion of research within the field of microbial ecology that has been fueled, in part, by methodological improvements that make it feasible to characterize microbial communities to an extent that was inconceivable only a few years ago. Furthermore, there is increasing recognition within the field of ecology that microorganisms play a critical role in the health of organisms and ecosystems. Despite these developments, an important gap still persists between the theoretical framework of macroecology and microbial ecology. We highlight two idiosyncrasies of microorganisms that are fundamental to understanding macroecological patterns and their mechanistic drivers. First, high dispersal rates provide novel opportunities to test the relative importance of niche, stochastic, and historical processes in structuring biological communities. Second, high speciation rates potentially lead to the convergence of ecological and evolutionary time scales. After reviewing these unique aspects, we discuss strategies for improving the conceptual integration of microbes into macroecology. As examples, we discuss the use of phylogenetic ecology as an integrative approach to explore patterns across the tree of life. Then we demonstrate how two general theories of biodiversity (i.e., the recently developed theory of stochastic geometry and the neutral theory) can be adapted to microorganisms. We demonstrate how conceptual models that integrate evolutionary and ecological mechanisms can contribute to the unification of microbial ecology and macroecology.
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Affiliation(s)
- Albert Barberán
- Cooperative Institute for Research in Environmental Sciences, University of ColoradoBoulder, CO, USA
| | - Emilio O. Casamayor
- Biogeodynamics and Biodiversity Group, Department of Continental Ecology, Center for Advanced Studies of Blanes – Spanish Council for Research (CSIC)Blanes, Spain
| | - Noah Fierer
- Cooperative Institute for Research in Environmental Sciences, University of ColoradoBoulder, CO, USA
- Department of Ecology and Evolutionary Biology, University of ColoradoBoulder, CO, USA
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Cordero OX, Polz MF. Explaining microbial genomic diversity in light of evolutionary ecology. Nat Rev Microbiol 2014; 12:263-73. [PMID: 24590245 DOI: 10.1038/nrmicro3218] [Citation(s) in RCA: 218] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Comparisons of closely related microorganisms have shown that individual genomes can be highly diverse in terms of gene content. In this Review, we discuss several studies showing that much of this variation is associated with social and ecological interactions, which have an important role in the population biology of wild populations of bacteria and archaea. These interactions create frequency-dependent selective pressures that can either stabilize gene frequencies at intermediate levels in populations or promote fast gene turnover, which presents as low gene frequencies in genome surveys. Thus, interpretation of gene-content diversity requires the delineation of populations according to cohesive gene flow and ecology, as micro-evolutionary changes arise in response to local selection pressures and population dynamics.
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Affiliation(s)
- Otto X Cordero
- Department of Environmental Systems Science, Swiss Federal Institute of Technology Zurich (ETH-Zürich), CH-8092 Zürich, Switzerland
| | - Martin F Polz
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology (MIT), Cambridge, Massachusetts 02139-4307, USA
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A mechanistic explanation linking adaptive mutation, niche change, and fitness advantage for the wrinkly spreader. INTERNATIONAL JOURNAL OF EVOLUTIONARY BIOLOGY 2014; 2014:675432. [PMID: 24551477 PMCID: PMC3914426 DOI: 10.1155/2014/675432] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 11/08/2013] [Indexed: 11/17/2022]
Abstract
Experimental evolution studies have investigated adaptive radiation in static liquid microcosms using the environmental bacterium Pseudomonas fluorescens SBW25. In evolving populations a novel adaptive mutant known as the Wrinkly Spreader arises within days having significant fitness advantage over the ancestral strain. A molecular investigation of the Wrinkly Spreader has provided a mechanistic explanation linking mutation with fitness improvement through the production of a cellulose-based biofilm at the air-liquid interface. Colonisation of this niche provides greater access to oxygen, allowing faster growth than that possible for non-biofilm-forming competitors located in the lower anoxic region of the microcosm. Cellulose is probably normally used for attachment to plant and soil aggregate surfaces and to provide protection in dehydrating conditions. However, the evolutionary innovation of the Wrinkly Spreader in static microcosms is the use of cellulose as the matrix of a robust biofilm, and is achieved through mutations that deregulate multiple diguanylate cyclases leading to the over-production of cyclic-di-GMP and the stimulation of cellulose expression. The mechanistic explanation of the Wrinkly Spreader success is an exemplar of the modern evolutionary synthesis, linking molecular biology with evolutionary ecology, and provides an insight into the phenomenal ability of bacteria to adapt to novel environments.
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Leducq JB, Charron G, Samani P, Dubé AK, Sylvester K, James B, Almeida P, Sampaio JP, Hittinger CT, Bell G, Landry CR. Local climatic adaptation in a widespread microorganism. Proc Biol Sci 2014; 281:20132472. [PMID: 24403328 DOI: 10.1098/rspb.2013.2472] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Exploring the ability of organisms to locally adapt is critical for determining the outcome of rapid climate changes, yet few studies have addressed this question in microorganisms. We investigated the role of a heterogeneous climate on adaptation of North American populations of the wild yeast Saccharomyces paradoxus. We found abundant among-strain variation for fitness components across a range of temperatures, but this variation was only partially explained by climatic variation in the distribution area. Most of fitness variation was explained by the divergence of genetically distinct groups, distributed along a north-south cline, suggesting that these groups have adapted to distinct climatic conditions. Within-group fitness components were correlated with climatic conditions, illustrating that even ubiquitous microorganisms locally adapt and harbour standing genetic variation for climate-related traits. Our results suggest that global climatic changes could lead to adaptation to new conditions within groups, or changes in their geographical distributions.
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Affiliation(s)
- Jean-Baptiste Leducq
- Département de Biologie, Institut de Biologie Intégrative et des Systèmes, PROTEO, Pavillon Charles-Eugène-Marchand, , 1030 avenue de la Médecine - Université Laval, Québec, Quebec, Canada , G1V 0A6, Department of Biology, McGill University, , 1205 ave Docteur Penfield, Montreal, Quebec, Canada , H3A 1B1, Laboratory of Genetics, Genome Center of Wisconsin, DOE Great Lakes Bioenergy Research Center, Wisconsin Energy Institute, , 425-G Henry Mall, 2434 Genetics/Biotechnology Center, Madison, WI 53706-1580, USA, Centro de Recursos Microbiológicos, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, , Caparica 2829-516, Portugal
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Lachance MA, Perri AM, Farahbakhsh AS, Starmer WT. Genetic structure ofKurtzmaniella cleridarum, a cactus flower beetle yeast of the Sonoran and Mojave Deserts: speciation by distance? FEMS Yeast Res 2013; 13:674-81. [DOI: 10.1111/1567-1364.12066] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2013] [Revised: 07/09/2013] [Accepted: 07/09/2013] [Indexed: 11/30/2022] Open
Affiliation(s)
| | - Ami M. Perri
- Department of Biology; University of Western Ontario; London; ON; Canada
| | - Amy S. Farahbakhsh
- Department of Biology; University of Western Ontario; London; ON; Canada
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31
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Macalady JL, Hamilton TL, Grettenberger CL, Jones DS, Tsao LE, Burgos WD. Energy, ecology and the distribution of microbial life. Philos Trans R Soc Lond B Biol Sci 2013; 368:20120383. [PMID: 23754819 PMCID: PMC3685468 DOI: 10.1098/rstb.2012.0383] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Mechanisms that govern the coexistence of multiple biological species have been studied intensively by ecologists since the turn of the nineteenth century. Microbial ecologists in the meantime have faced many fundamental challenges, such as the lack of an ecologically coherent species definition, lack of adequate methods for evaluating population sizes and community composition in nature, and enormous taxonomic and functional diversity. The accessibility of powerful, culture-independent molecular microbiology methods offers an opportunity to close the gap between microbial science and the main stream of ecological theory, with the promise of new insights and tools needed to meet the grand challenges humans face as planetary engineers and galactic explorers. We focus specifically on resources related to energy metabolism because of their direct links to elemental cycling in the Earth's history, engineering applications and astrobiology. To what extent does the availability of energy resources structure microbial communities in nature? Our recent work on sulfur- and iron-oxidizing autotrophs suggests that apparently subtle variations in the concentration ratios of external electron donors and acceptors select for different microbial populations. We show that quantitative knowledge of microbial energy niches (population-specific patterns of energy resource use) can be used to predict variations in the abundance of specific taxa in microbial communities. Furthermore, we propose that resource ratio theory applied to micro-organisms will provide a useful framework for identifying how environmental communities are organized in space and time.
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Affiliation(s)
- Jennifer L Macalady
- Department of Geosciences, Penn State University, University Park, PA 16802, USA.
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Wagner ID, Varghese LB, Hemme CL, Wiegel J. Multilocus sequence analysis of Thermoanaerobacter isolates reveals recombining, but differentiated, populations from geothermal springs of the Uzon Caldera, Kamchatka, Russia. Front Microbiol 2013; 4:169. [PMID: 23801987 PMCID: PMC3689144 DOI: 10.3389/fmicb.2013.00169] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Accepted: 06/04/2013] [Indexed: 01/15/2023] Open
Abstract
Thermal environments have island-like characteristics and provide a unique opportunity to study population structure and diversity patterns of microbial taxa inhabiting these sites. Strains having ≥98% 16S rRNA gene sequence similarity to the obligately anaerobic Firmicutes Thermoanaerobacter uzonensis were isolated from seven geothermal springs, separated by up to 1600 m, within the Uzon Caldera (Kamchatka, Russian Far East). The intraspecies variation and spatial patterns of diversity for this taxon were assessed by multilocus sequence analysis (MLSA) of 106 strains. Analysis of eight protein-coding loci (gyrB, lepA, leuS, pyrG, recA, recG, rplB, and rpoB) revealed that all loci were polymorphic and that nucleotide substitutions were mostly synonymous. There were 148 variable nucleotide sites across 8003 bp concatenates of the protein-coding loci. While pairwise FST values indicated a small but significant level of genetic differentiation between most subpopulations, there was a negligible relationship between genetic divergence and spatial separation. Strains with the same allelic profile were only isolated from the same hot spring, occasionally from consecutive years, and single locus variant (SLV) sequence types were usually derived from the same spring. While recombination occurred, there was an “epidemic” population structure in which a particular T. uzonensis sequence type rose in frequency relative to the rest of the population. These results demonstrate spatial diversity patterns for an anaerobic bacterial species in a relative small geographic location and reinforce the view that terrestrial geothermal springs are excellent places to look for biogeographic diversity patterns regardless of the involved distances.
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Affiliation(s)
- Isaac D Wagner
- Department of Microbiology, University of Georgia Athens, GA, USA
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Comparative genomics of Wolbachia and the bacterial species concept. PLoS Genet 2013; 9:e1003381. [PMID: 23593012 PMCID: PMC3616963 DOI: 10.1371/journal.pgen.1003381] [Citation(s) in RCA: 136] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2012] [Accepted: 01/30/2013] [Indexed: 02/04/2023] Open
Abstract
The importance of host-specialization to speciation processes in obligate host-associated bacteria is well known, as is also the ability of recombination to generate cohesion in bacterial populations. However, whether divergent strains of highly recombining intracellular bacteria, such as Wolbachia, can maintain their genetic distinctness when infecting the same host is not known. We first developed a protocol for the genome sequencing of uncultivable endosymbionts. Using this method, we have sequenced the complete genomes of the Wolbachia strains wHa and wNo, which occur as natural double infections in Drosophila simulans populations on the Seychelles and in New Caledonia. Taxonomically, wHa belong to supergroup A and wNo to supergroup B. A comparative genomics study including additional strains supported the supergroup classification scheme and revealed 24 and 33 group-specific genes, putatively involved in host-adaptation processes. Recombination frequencies were high for strains of the same supergroup despite different host-preference patterns, leading to genomic cohesion. The inferred recombination fragments for strains of different supergroups were of short sizes, and the genomes of the co-infecting Wolbachia strains wHa and wNo were not more similar to each other and did not share more genes than other A- and B-group strains that infect different hosts. We conclude that Wolbachia strains of supergroup A and B represent genetically distinct clades, and that strains of different supergroups can co-exist in the same arthropod host without converging into the same species. This suggests that the supergroups are irreversibly separated and that barriers other than host-specialization are able to maintain distinct clades in recombining endosymbiont populations. Acquiring a good knowledge of the barriers to genetic exchange in Wolbachia will advance our understanding of how endosymbiont communities are constructed from vertically and horizontally transmitted genes. Speciation in sexual organisms is defined as the inability of two populations to get viable offspring. Speciation in asexual, obligate endosymbionts is thought to be an indirect consequence of host-specialization. An important question is if divergent endosymbionts would start blending if the host barrier isolating them were removed. Here, we have studied Wolbachia, an abundant group of bacteria in the insect world. Wolbachia is classified into supergroups based on multi-locus sequence typing. We have sequenced the genomes from the Wolbachia strains wNo and wHa. These are particularly interesting since they belong to different supergroups yet co-occur as a double-infection in natural populations of Drosophila simulans. A comparative genomics study showed that wHa and wNo contain no uniquely shared genes. Instead, each strain shares unique gene functions with members of the same supergroup that infect other hosts. This unexpected finding suggests an alternative means of ecological speciation, indicating that speciation is not restricted to host-specialization but rather that related endosymbionts can coexist as separate species in the same host. Our study sheds light on the genomic divergence between different partners inhabiting the intracellular niche of the same host organism.
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Polz MF, Alm EJ, Hanage WP. Horizontal gene transfer and the evolution of bacterial and archaeal population structure. Trends Genet 2013; 29:170-5. [PMID: 23332119 PMCID: PMC3760709 DOI: 10.1016/j.tig.2012.12.006] [Citation(s) in RCA: 262] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 11/29/2012] [Accepted: 12/18/2012] [Indexed: 12/28/2022]
Abstract
Many bacterial and archaeal lineages have a history of extensive and ongoing horizontal gene transfer and loss, as evidenced by the large differences in genome content even among otherwise closely related isolates. How ecologically cohesive populations might evolve and be maintained under such conditions of rapid gene turnover has remained controversial. Here we synthesize recent literature demonstrating the importance of habitat and niche in structuring horizontal gene transfer. This leads to a model of ecological speciation via gradual genetic isolation triggered by differential habitat-association of nascent populations. Further, we hypothesize that subpopulations can evolve through local gene-exchange networks by tapping into a gene pool that is adaptive towards local, continuously changing organismic interactions and is, to a large degree, responsible for the observed rapid gene turnover. Overall, these insights help to explain how bacteria and archaea form populations that display both ecological cohesion and high genomic diversity.
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Affiliation(s)
- Martin F Polz
- Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
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35
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Sul WJ, Oliver TA, Ducklow HW, Amaral-Zettler LA, Sogin ML. Marine bacteria exhibit a bipolar distribution. Proc Natl Acad Sci U S A 2013; 110:2342-7. [PMID: 23324742 PMCID: PMC3568360 DOI: 10.1073/pnas.1212424110] [Citation(s) in RCA: 150] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The microbial cosmopolitan dispersion hypothesis often invoked to explain distribution patterns driven by high connectivity of oceanographic water masses and widespread dispersal ability has never been rigorously tested. By using a global marine bacterial dataset and iterative matrix randomization simulation, we show that marine bacteria exhibit a significantly greater dispersal limitation than predicted by our null model using the "everything is everywhere" tenet with no dispersal limitation scenario. Specifically, marine bacteria displayed bipolar distributions (i.e., species occurring exclusively at both poles and nowhere else) significantly less often than in the null model. Furthermore, we observed fewer taxa present in both hemispheres but more taxa present only in a single hemisphere than expected under the null model. Each of these trends diverged further from the null expectation as the compared habitats became more geographically distant but more environmentally similar. Our meta-analysis supported a latitudinal gradient in bacterial diversity with higher richness at lower latitudes, but decreased richness toward the poles. Bacteria in the tropics also demonstrated narrower latitudinal ranges at lower latitudes and relatively larger ranges in higher latitudes, conforming to the controversial macroecological pattern of the "Rapoport rule." Collectively, our findings suggest that bacteria follow biogeographic patterns more typical of macroscopic organisms, and that dispersal limitation, not just environmental selection, likely plays an important role. Distributions of microbes that deliver critical ecosystem services, particularly those in polar regions, may be vulnerable to the same impacts that environmental stressors, climate warming, and degradation in habitat quality are having on biodiversity in animal and plant species.
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Affiliation(s)
- Woo Jun Sul
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543
| | - Thomas A. Oliver
- Hawai’i Institute of Marine Biology, University of Hawaii, Kaneohe, HI 96744
| | - Hugh W. Ducklow
- Ecosystems Center, Marine Biological Laboratory, Woods Hole, MA 02543; and
| | - Linda A. Amaral-Zettler
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543
- Department of Geological Sciences, Brown University, Providence, RI 02912
| | - Mitchell L. Sogin
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543
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Pole-to-pole biogeography of surface and deep marine bacterial communities. Proc Natl Acad Sci U S A 2012; 109:17633-8. [PMID: 23045668 DOI: 10.1073/pnas.1208160109] [Citation(s) in RCA: 181] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The Antarctic and Arctic regions offer a unique opportunity to test factors shaping biogeography of marine microbial communities because these regions are geographically far apart, yet share similar selection pressures. Here, we report a comprehensive comparison of bacterioplankton diversity between polar oceans, using standardized methods for pyrosequencing the V6 region of the small subunit ribosomal (SSU) rRNA gene. Bacterial communities from lower latitude oceans were included, providing a global perspective. A clear difference between Southern and Arctic Ocean surface communities was evident, with 78% of operational taxonomic units (OTUs) unique to the Southern Ocean and 70% unique to the Arctic Ocean. Although polar ocean bacterial communities were more similar to each other than to lower latitude pelagic communities, analyses of depths, seasons, and coastal vs. open waters, the Southern and Arctic Ocean bacterioplankton communities consistently clustered separately from each other. Coastal surface Southern and Arctic Ocean communities were more dissimilar from their respective open ocean communities. In contrast, deep ocean communities differed less between poles and lower latitude deep waters and displayed different diversity patterns compared with the surface. In addition, estimated diversity (Chao1) for surface and deep communities did not correlate significantly with latitude or temperature. Our results suggest differences in environmental conditions at the poles and different selection mechanisms controlling surface and deep ocean community structure and diversity. Surface bacterioplankton may be subjected to more short-term, variable conditions, whereas deep communities appear to be structured by longer water-mass residence time and connectivity through ocean circulation.
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Souza V, Eguiarte LE, Travisano M, Elser JJ, Rooks C, Siefert JL. Travel, sex, and food: what's speciation got to do with it? ASTROBIOLOGY 2012; 12:634-640. [PMID: 22920513 PMCID: PMC3426884 DOI: 10.1089/ast.2011.0768] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 06/29/2012] [Indexed: 06/01/2023]
Abstract
We discuss the potential interactions among travel (dispersal and gene flow), bacterial "sex" (mainly as horizontal gene transfer), and food (metabolic plasticity and responses to nutrient availability) in shaping microbial communities. With regard to our work at a unique desert oasis, the Cuatro Ciénegas Basin in Coahuila, Mexico, we propose that diversification and low phosphorus availability, in combination with mechanisms for nutrient recycling and community cohesion, result in enhanced speciation through reproductive as well as geographic isolation. We also discuss these mechanisms in the broader sense of ecology and evolution. Of special relevance to astrobiology and central to evolutionary biology, we ask why there are so many species on Earth and provide a working hypothesis and a conceptual framework within which to consider the question. Key Words: Microbial ecology-Microbial mats-Evolution-Horizontal gene transfer-Metabolism.
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Affiliation(s)
- Valeria Souza
- Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Coyoacán, México D.F., México.
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Dvořák P, Hašler P, Poulíčková A. Phylogeography of the Microcoleus vaginatus (Cyanobacteria) from three continents--a spatial and temporal characterization. PLoS One 2012; 7:e40153. [PMID: 22761955 PMCID: PMC3384635 DOI: 10.1371/journal.pone.0040153] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2012] [Accepted: 06/01/2012] [Indexed: 11/18/2022] Open
Abstract
It has long been assumed that cyanobacteria have, as with other free-living microorganisms, a ubiquitous occurrence. Neither the geographical dispersal barriers nor allopatric speciation has been taken into account. We endeavoured to examine the spatial and temporal patterns of global distribution within populations of the cyanobacterium Microcoleus vaginatus, originated from three continents, and to evaluate the role of dispersal barriers in the evolution of free-living cyanobacteria. Complex phylogeographical approach was applied to assess the dispersal and evolutionary patterns in the cyanobacterium Microcoleus vaginatus (Oscillatoriales). We compared the 16S rRNA and 16S-23S ITS sequences of strains which had originated from three continents (North America, Europe, and Asia). The spatial distribution was investigated using a phylogenetic tree, network, as well as principal coordinate analysis (PCoA). A temporal characterization was inferred using molecular clocks, calibrated from fossil DNA. Data analysis revealed broad genetic diversity within M. vaginatus. Based on the phylogenetic tree, network, and PCoA analysis, the strains isolated in Europe were spatially separated from those which originated from Asia and North America. A chronogram showed a temporal limitation of dispersal barriers on the continental scale. Dispersal barriers and allopatric speciation had an important role in the evolution of M. vaginatus. However, these dispersal barriers did not have a permanent character; therefore, the genetic flow among populations on a continental scale was only temporarily present. Furthermore, M. vaginatus is a recently evolved species, which has been going through substantial evolutionary changes.
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Affiliation(s)
- Petr Dvořák
- Department of Botany, Palacký University Olomouc, Olomouc, Czech Republic
| | - Petr Hašler
- Department of Botany, Palacký University Olomouc, Olomouc, Czech Republic
| | - Aloisie Poulíčková
- Department of Botany, Palacký University Olomouc, Olomouc, Czech Republic
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Ragon M, Fontaine MC, Moreira D, López-García P. Different biogeographic patterns of prokaryotes and microbial eukaryotes in epilithic biofilms. Mol Ecol 2012; 21:3852-68. [PMID: 22686398 DOI: 10.1111/j.1365-294x.2012.05659.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Microbial biogeography studies expend much effort in determining whether environmental selection or stochastic processes related to dispersal are more important in shaping community composition. While both types of factors are possibly influential, it is tacitly assumed that protists, or microbial eukaryotes in general, behave biogeographically as prokaryotes because of their small physical size. However, direct evidence for this in exactly the same environment and at the same phylogenetic depth is lacking. In this study, we compared the structure of both prokaryotic and eukaryotic components of microbial communities forming biofilms on mineral substrates in different geographic locations at the level of small-subunit (SSU) rRNA-based operational taxonomic units (OTUs). These microbial communities are subjected to strong environmental selection and contain significant proportions of extremophilic microorganisms adapted to desiccation and UV radiation. We find that the nature of the substrate as well as climatic variables and geography influences microbial community structure. However, constrained correspondence analyses and distance-decay curves showed that, whereas the substrate type was the most significant factor structuring bacterial communities, geographic location was the most influential factor for microbial eukaryote communities. Biological explanations implying a higher dispersal success for bacteria combined with more mobile lifestyles for predatory protists may underlie these different prokaryote versus microbial eukaryote biogeographic patterns.
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Affiliation(s)
- Marie Ragon
- Unité d'Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, Orsay, France
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40
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Manrique JM, Calvo AY, Jones LR. Phylogenetic analysis of Ostreococcus virus sequences from the Patagonian Coast. Virus Genes 2012; 45:316-26. [PMID: 22674355 DOI: 10.1007/s11262-012-0762-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2012] [Accepted: 05/11/2012] [Indexed: 11/29/2022]
Affiliation(s)
- Julieta M Manrique
- Division of Molecular Biology, Estación de Fotobiología Playa Unión, CC 15 (9103), Playa Unión, Rawson, Chubut, Argentina
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41
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Rebollar EA, Avitia M, Eguiarte LE, González-González A, Mora L, Bonilla-Rosso G, Souza V. Water-sediment niche differentiation in ancient marine lineages of Exiguobacterium endemic to the Cuatro Cienegas Basin. Environ Microbiol 2012; 14:2323-33. [PMID: 22639906 DOI: 10.1111/j.1462-2920.2012.02784.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The evolutionary history and ecological differentiation of the genus Exiguobacterium was characterized within natural communities from the Cuatro Cienegas Basin, Mexico. Exiguobacterium comprises both halophilic and alkaliphilic bacteria that are abundant among the aquatic systems of the Cuatro Cienegas Basin. We obtained complete sequences of the 16srRNA gene and partial sequences of four housekeeping genes (citC, rpoB, recA and hsp70) in 183 Exiguobacterium isolates retrieved from distinct aquatic systems. We defined three main phylogroups that are closely related to marine and thermophilic species of the genus. These phylogroups were neither specific to a given aquatic system nor to a particular salinity. Phylogenetic reconstruction indicated the presence of several small clusters within the phylogroups. These clusters consisted of isolates predominantly retrieved from sediment or water. Unifrac and AdaptML analyses confirmed this observation, pointing towards a clear pattern of differentiation linked to either sediment or water habitats. Our results are in line with the concept that niche differentiation is one of the main factors shaping prokaryotic populations and leading to evolutionary divergence.
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Affiliation(s)
- Eria A Rebollar
- Laboratorio de Evolución Molecular y Experimental, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Flores GE, Wagner ID, Liu Y, Reysenbach AL. Distribution, abundance, and diversity patterns of the thermoacidophilic "deep-sea hydrothermal vent euryarchaeota 2". Front Microbiol 2012; 3:47. [PMID: 22363325 PMCID: PMC3282477 DOI: 10.3389/fmicb.2012.00047] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2011] [Accepted: 01/30/2012] [Indexed: 11/23/2022] Open
Abstract
Cultivation-independent studies have shown that taxa belonging to the “deep-sea hydrothermal vent euryarchaeota 2” (DHVE2) lineage are widespread at deep-sea hydrothermal vents. While this lineage appears to be a common and important member of the microbial community at vent environments, relatively little is known about their overall distribution and phylogenetic diversity. In this study, we examined the distribution, relative abundance, co-occurrence patterns, and phylogenetic diversity of cultivable thermoacidophilic DHVE2 in deposits from globally distributed vent fields. Results of quantitative polymerase chain reaction assays with primers specific for the DHVE2 and Archaea demonstrate the ubiquity of the DHVE2 at deep-sea vents and suggest that they are significant members of the archaeal communities of established vent deposit communities. Local similarity analysis of pyrosequencing data revealed that the distribution of the DHVE2 was positively correlated with 10 other Euryarchaeota phylotypes and negatively correlated with mostly Crenarchaeota phylotypes. Targeted cultivation efforts resulted in the isolation of 12 axenic strains from six different vent fields, expanding the cultivable diversity of this lineage to vents along the East Pacific Rise and Mid-Atlantic Ridge. Eleven of these isolates shared greater than 97% 16S rRNA gene sequence similarity with one another and the only described isolate of the DHVE2, Aciduliprofundum boonei T469T. Sequencing and phylogenetic analysis of five protein-coding loci, atpA, EF-2, radA, rpoB, and secY, revealed clustering of isolates according to geographic region of isolation. Overall, this study increases our understanding of the distribution, abundance, and phylogenetic diversity of the DHVE2.
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Affiliation(s)
- Gilberto E Flores
- Department of Biology, Center for Life in Extreme Environments, Portland State University Portland, OR, USA
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Kachalkin AV, Yurkov AM. Yeast communities in Sphagnum phyllosphere along the temperature-moisture ecocline in the boreal forest-swamp ecosystem and description of Candida sphagnicola sp. nov. Antonie van Leeuwenhoek 2012; 102:29-43. [PMID: 22331450 DOI: 10.1007/s10482-012-9710-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2011] [Accepted: 02/03/2012] [Indexed: 11/30/2022]
Abstract
The effects of the temperature-moisture factors on the phylloplane yeast communities inhabiting Sphagnum mosses were studied along the transition from a boreal forest to a swamp biotope at the Central Forest State Biosphere Reserve (Tver region, Russia). We tested the hypothesis that microclimatic parameters affect yeast community composition and structure even on a rather small spatial scale. Using a conventional plating technique we isolated and identified by molecular methods a total of 15 species of yeasts. Total yeast counts and species richness values did not depend on environmental factors, although yeast community composition and structure did. On average, Sphagnum in the swamp biotope supported a more evenly structured yeast community. Relative abundance of ascomycetous yeasts was significantly higher on swamp moss. Rhodotorula mucilaginosa dominated in the spruce forest and Cryptococcus magnus was more abundant in the swamp. Our study confirmed the low occurrence of tremellaceous yeasts in the Sphagnum phyllosphere. Of the few isolated ascomycetous yeast and yeast-like species, some were differentiated from hitherto known species in physiological tests and phylogenetic analyses. We describe one of them as Candida sphagnicola and designate KBP Y-3887(T) (=CBS 11774(T) = VKPM Y-3566(T) = MUCL 53590(T)) as the type strain. The new species was registered in MycoBank under MB 563443.
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Affiliation(s)
- Aleksey V Kachalkin
- Faculty of Soil Science, Lomonosov Moscow State University, Leninskie Gory, 119991, Moscow, Russia.
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Yurkov A, Kemler M, Begerow D. Assessment of yeast diversity in soils under different management regimes. FUNGAL ECOL 2012. [DOI: 10.1016/j.funeco.2011.07.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Weisse T, Berendonk T, Kamjunke N, Moser M, Scheffel U, Stadler P, Weithoff G. Significant habitat effects influence protist fitness: evidence for local adaptation from acidic mining lakes. Ecosphere 2011. [DOI: 10.1890/es11-00157.1] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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Doroghazi JR, Buckley DH. A model for the effect of homologous recombination on microbial diversification. Genome Biol Evol 2011; 3:1349-56. [PMID: 22071790 PMCID: PMC3240962 DOI: 10.1093/gbe/evr110] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The effect of homologous recombination (HR) on the evolution of microbial genomes remains contentious as competing hypotheses seek to explain the evolutionary dynamics of microbial species. Evidence for HR between microbial genomes is widespread, and this process has been proposed to act as a cohesive force that can constrain the diversification of microbial lineages. We seek to characterize the evolutionary dynamics of sympatric populations to explore the impact of HR on microbial speciation. We describe a simple equation for quantifying the cohesive effect of HR on microbial populations as a function of their nucleotide divergence, μ/ρ = πg10 − 20 πg. The model was verified using a forward-time microbial population simulator that can explore the evolutionary dynamics of sympatric populations in nonoverlapping niche space. The model was also evaluated using multilocus sequence data from a range of microbial species, providing criteria for dividing them into either cohesively recombining or clonally diverging lineages. We conclude that models of microbial diversification that appear contradictory can be explained in a unified manner as the natural and predictable consequence of variation in a small number of population parameters.
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Affiliation(s)
- James R Doroghazi
- Department of Microbiology, Cornell University, Ithaca, New York, USA
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van Gremberghe I, Leliaert F, Mergeay J, Vanormelingen P, Van der Gucht K, Debeer AE, Lacerot G, De Meester L, Vyverman W. Lack of phylogeographic structure in the freshwater cyanobacterium Microcystis aeruginosa suggests global dispersal. PLoS One 2011; 6:e19561. [PMID: 21573169 PMCID: PMC3088681 DOI: 10.1371/journal.pone.0019561] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2010] [Accepted: 04/11/2011] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Free-living microorganisms have long been assumed to have ubiquitous distributions with little biogeographic signature because they typically exhibit high dispersal potential and large population sizes. However, molecular data provide contrasting results and it is far from clear to what extent dispersal limitation determines geographic structuring of microbial populations. We aimed to determine biogeographical patterns of the bloom-forming freshwater cyanobacterium Microcystis aeruginosa. Being widely distributed on a global scale but patchily on a regional scale, this prokaryote is an ideal model organism to study microbial dispersal and biogeography. METHODOLOGY/PRINCIPAL FINDINGS The phylogeography of M. aeruginosa was studied based on a dataset of 311 rDNA internal transcribed spacer (ITS) sequences sampled from six continents. Richness of ITS sequences was high (239 ITS types were detected). Genetic divergence among ITS types averaged 4% (maximum pairwise divergence was 13%). Preliminary analyses revealed nearly completely unresolved phylogenetic relationships and a lack of genetic structure among all sequences due to extensive homoplasy at multiple hypervariable sites. After correcting for this, still no clear phylogeographic structure was detected, and no pattern of isolation by distance was found on a global scale. Concomitantly, genetic differentiation among continents was marginal, whereas variation within continents was high and was mostly shared with all other continents. Similarly, no genetic structure across climate zones was detected. CONCLUSIONS/SIGNIFICANCE The high overall diversity and wide global distribution of common ITS types in combination with the lack of phylogeographic structure suggest that intercontinental dispersal of M. aeruginosa ITS types is not rare, and that this species might have a truly cosmopolitan distribution.
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Affiliation(s)
- Ineke van Gremberghe
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Ghent, Belgium
| | | | - Joachim Mergeay
- Laboratory of Aquatic Ecology and Evolutionary Biology, Katholieke Universiteit Leuven, Leuven, Belgium
- Research Institute for Nature and Forest, Geraardsbergen, Belgium
| | - Pieter Vanormelingen
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Ghent, Belgium
| | | | - Ann-Eline Debeer
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Ghent, Belgium
| | - Gissell Lacerot
- Department of Aquatic Ecology and Water Quality Management, Wageningen University, Wageningen, The Netherlands
- Facultad de Ciencias, Sección Limnología, Universidad de la República, Montevideo, Uruguay
| | - Luc De Meester
- Laboratory of Aquatic Ecology and Evolutionary Biology, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Wim Vyverman
- Laboratory of Protistology and Aquatic Ecology, Ghent University, Ghent, Belgium
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Zeglin LH, Dahm CN, Barrett JE, Gooseff MN, Fitpatrick SK, Takacs-Vesbach CD. Bacterial community structure along moisture gradients in the parafluvial sediments of two ephemeral desert streams. MICROBIAL ECOLOGY 2011; 61:543-556. [PMID: 21153024 DOI: 10.1007/s00248-010-9782-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2010] [Accepted: 11/18/2010] [Indexed: 05/30/2023]
Abstract
Microorganisms inhabiting stream sediments mediate biogeochemical processes of importance to both aquatic and terrestrial ecosystems. In deserts, the lateral margins of ephemeral stream channels (parafluvial sediments) are dried and rewetted, creating periodically wet conditions that typically enhance microbial activity. However, the influence of water content on microbial community composition and diversity in desert stream sediments is unclear. We sampled stream margins along gradients of wet to dry sediments, measuring geochemistry and bacterial 16S rRNA gene composition, at streams in both a cold (McMurdo Dry Valleys, Antarctica) and hot (Chihuahuan Desert, New Mexico, USA) desert. Across the gradients, sediment water content spanned a wide range (1.6-37.9% w/w), and conductivity was highly variable (12.3-1,380 μS cm(-2)). Bacterial diversity (at 97% sequence similarity) was high and variable, but did not differ significantly between the hot and cold desert and was not correlated with sediment water content. Instead, conductivity was most strongly related to diversity. Water content was strongly related to bacterial 16S rRNA gene community composition, though samples were distributed in wet and dry clusters rather than as assemblages shifting along a gradient. Phylogenetic analyses showed that many taxa from wet sediments at the hot and cold desert site were related to, respectively, halotolerant Gammaproteobacteria, and one family within the Sphingobacteriales (Bacteroidetes), while dry sediments at both sites contained a high proportion of taxa related to the Acidobacteria. These results suggest that bacterial diversity and composition in desert stream sediments is more strongly affected by hydrology and conductivity than temperature.
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Affiliation(s)
- Lydia H Zeglin
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
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Barberán A, Casamayor EO. Euxinic freshwater hypolimnia promote bacterial endemicity in continental areas. MICROBIAL ECOLOGY 2011; 61:465-472. [PMID: 21107832 DOI: 10.1007/s00248-010-9775-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2010] [Accepted: 11/05/2010] [Indexed: 05/30/2023]
Abstract
Bacteria and archaea represent the vast majority of biodiversity on Earth. The ways that dynamic ecological and evolutionary processes interact in the microbial world are, however, poorly known. Here, we have explored community patterns of planktonic freshwater bacteria inhabiting stratified lakes with oxic/anoxic interfaces and euxinic (anoxic and sulfurous) water masses. The interface separates a well-oxygenated upper water mass (epilimnion) from a lower anoxic water compartment (hypolimnion). We assessed whether or not the vertical zonation of lakes promoted endemism in deeper layers by analyzing bacterial 16S rRNA gene sequences from the water column of worldwide distributed stratified lakes and applying a community ecology approach. Community similarity based on the phylogenetic relatedness showed that bacterial assemblages from the same water layer were more similar across lakes than to communities from different layer within lakes and that anoxic hypolimnia presented greater β-diversity than oxic epilimnia. Higher β-diversity values are attributable to low dispersal and small connectivity between community patches. In addition, surface waters had significant spatial but non-significant environmental components controlling phylogenetic β-diversity patterns, respectively. Conversely, the bottom layers were significantly correlated with environment but not with geographic distance. Thus, we observed different ecological mechanisms simultaneously acting on the same water body. Overall, bacterial endemicity is probably more common than previously thought, particularly in isolated and environmentally heterogeneous freshwater habitats. We argue for a microbial diversity conservation perspective still lacking in the global and local biodiversity preservation policies.
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Affiliation(s)
- Albert Barberán
- Department of Continental Ecology-Limnology, Centre d'Estudis Avançats de Blanes, CSIC, Accés Cala St. Francesc 14, 17300 Blanes, Spain
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