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Singhal S, Balitactac AK, Nayagam AG, Pour Bahrami P, Nayeem S, Turner PE. Experimental Evolution Studies in Φ6 Cystovirus. Viruses 2024; 16:977. [PMID: 38932268 PMCID: PMC11209170 DOI: 10.3390/v16060977] [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: 04/27/2024] [Revised: 06/05/2024] [Accepted: 06/08/2024] [Indexed: 06/28/2024] Open
Abstract
Experimental evolution studies, in which biological populations are evolved in a specific environment over time, can address questions about the nature of spontaneous mutations, responses to selection, and the origins and maintenance of novel traits. Here, we review more than 30 years of experimental evolution studies using the bacteriophage (phage) Φ6 cystovirus. Similar to many lab-studied bacteriophages, Φ6 has a high mutation rate, large population size, fast generation time, and can be genetically engineered or cryogenically frozen, which facilitates its rapid evolution in the laboratory and the subsequent characterization of the effects of its mutations. Moreover, its segmented RNA genome, outer membrane, and capacity for multiple phages to coinfect a single host cell make Φ6 a good non-pathogenic model for investigating the evolution of RNA viruses that infect humans. We describe experiments that used Φ6 to address the fitness effects of spontaneous mutations, the consequences of evolution in the presence of coinfection, the evolution of host ranges, and mechanisms and consequences of the evolution of thermostability. We highlight open areas of inquiry where further experimentation on Φ6 could inform predictions for pathogenic viruses.
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Affiliation(s)
- Sonia Singhal
- Department of Biological Sciences, San José State University, San José, CA 95192, USA; (A.K.B.); (A.G.N.); (P.P.B.); (S.N.)
| | - Akiko K. Balitactac
- Department of Biological Sciences, San José State University, San José, CA 95192, USA; (A.K.B.); (A.G.N.); (P.P.B.); (S.N.)
| | - Aruna G. Nayagam
- Department of Biological Sciences, San José State University, San José, CA 95192, USA; (A.K.B.); (A.G.N.); (P.P.B.); (S.N.)
| | - Parnian Pour Bahrami
- Department of Biological Sciences, San José State University, San José, CA 95192, USA; (A.K.B.); (A.G.N.); (P.P.B.); (S.N.)
| | - Sara Nayeem
- Department of Biological Sciences, San José State University, San José, CA 95192, USA; (A.K.B.); (A.G.N.); (P.P.B.); (S.N.)
| | - Paul E. Turner
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, USA;
- Program in Microbiology, Yale School of Medicine, New Haven, CT 06520, USA
- Center for Phage Biology and Therapy, Yale University, New Haven, CT 06511, USA
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2
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Bisesi AT, Möbius W, Nadell CD, Hansen EG, Bowden SD, Harcombe WR. Bacteriophage specificity is impacted by interactions between bacteria. mSystems 2024; 9:e0117723. [PMID: 38376179 PMCID: PMC11237722 DOI: 10.1128/msystems.01177-23] [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: 11/07/2023] [Accepted: 01/20/2024] [Indexed: 02/21/2024] Open
Abstract
Predators play a central role in shaping community structure, function, and stability. The degree to which bacteriophage predators (viruses that infect bacteria) evolve to be specialists with a single bacterial prey species versus generalists able to consume multiple types of prey has implications for their effect on microbial communities. The presence and abundance of multiple bacterial prey types can alter selection for phage generalists, but less is known about how interactions between prey shape predator specificity in microbial systems. Using a phenomenological mathematical model of phage and bacterial populations, we find that the dominant phage strategy depends on prey ecology. Given a fitness cost for generalism, generalist predators maintain an advantage when prey species compete, while specialists dominate when prey are obligately engaged in cross-feeding interactions. We test these predictions in a synthetic microbial community with interacting strains of Escherichia coli and Salmonella enterica by competing a generalist T5-like phage able to infect both prey against P22vir, an S. enterica-specific phage. Our experimental data conform to our modeling expectations when prey species are competing or obligately mutualistic, although our results suggest that the in vitro cost of generalism is caused by a combination of biological mechanisms not anticipated in our model. Our work demonstrates that interactions between bacteria play a role in shaping ecological selection on predator specificity in obligately lytic bacteriophages and emphasizes the diversity of ways in which fitness trade-offs can manifest. IMPORTANCE There is significant natural diversity in how many different types of bacteria a bacteriophage can infect, but the mechanisms driving this diversity are unclear. This study uses a combination of mathematical modeling and an in vitro system consisting of Escherichia coli, Salmonella enterica, a T5-like generalist phage, and the specialist phage P22vir to highlight the connection between bacteriophage specificity and interactions between their potential microbial prey. Mathematical modeling suggests that competing bacteria tend to favor generalist bacteriophage, while bacteria that benefit each other tend to favor specialist bacteriophage. Experimental results support this general finding. The experiments also show that the optimal phage strategy is impacted by phage degradation and bacterial physiology. These findings enhance our understanding of how complex microbial communities shape selection on bacteriophage specificity, which may improve our ability to use phage to manage antibiotic-resistant microbial infections.
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Affiliation(s)
- Ave T. Bisesi
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota, USA
| | - Wolfram Möbius
- Living Systems Institute, University of Exeter, Exeter, United Kingdom
- Department of Physics and Astronomy, University of Exeter, Exeter, United Kingdom
| | - Carey D. Nadell
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Eleanore G. Hansen
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA
| | - Steven D. Bowden
- Department of Food Science and Nutrition, University of Minnesota, St. Paul, Minnesota, USA
| | - William R. Harcombe
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, Minnesota, USA
- BioTechnology Institute, University of Minnesota, St. Paul, Minnesota, USA
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3
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Chavhan Y, Malusare S, Dey S. Population size shapes trade-off dilution and adaptation to a marginal niche unconstrained by sympatric habitual conditions. Evolution 2024; 78:342-354. [PMID: 38038256 DOI: 10.1093/evolut/qpad212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 11/06/2023] [Accepted: 11/29/2023] [Indexed: 12/02/2023]
Abstract
How does niche expansion occur when the habitual (high-productivity) and marginal (low-productivity) niches are simultaneously available? Without spatial structuring, such conditions should impose fitness maintenance in the former while adapting to the latter. Hence, adaptation to a given marginal niche should be influenced by the identity of the simultaneously available habitual niche. This hypothesis remains untested. Similarly, it is unknown if larger populations, which can access greater variation and undergo more efficient selection, are generally better at niche expansion. We tested these hypotheses using a large-scale evolution experiment with Escherichia coli. While we observed widespread niche expansion, larger populations consistently adapted to a greater extent to both marginal and habitual niches. Owing to diverse selection pressures in different habitual niches (constant vs. fluctuating environments; environmental fluctuations varying in both predictability and speed), fitness in habitual niches was significantly shaped by their identities. Surprisingly, despite this diversity in habitual selection pressures, adaptation to the marginal niche was unconstrained by the habitual niche's identity. We show that in terms of fitness, two negatively correlated habitual niches can still have positive correlations with the marginal niche. This allows the marginal niche to dilute fitness trade-offs across habitual niches, thereby allowing costless niche expansion. Our results provide fundamental insights into the sympatric niche expansion.
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Affiliation(s)
- Yashraj Chavhan
- Biology Division, Indian Institute of Science Education and Research (IISER) Pune, Pune, Maharashtra, India
| | - Sarthak Malusare
- Biology Division, Indian Institute of Science Education and Research (IISER) Pune, Pune, Maharashtra, India
| | - Sutirth Dey
- Biology Division, Indian Institute of Science Education and Research (IISER) Pune, Pune, Maharashtra, India
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4
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Houpt NSB, Kassen R. On the De Novo Emergence of Ecological Interactions during Evolutionary Diversification: A Conceptual Framework and Experimental Test. Am Nat 2023; 202:800-817. [PMID: 38033179 DOI: 10.1086/726895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
AbstractEcological interactions are crucial to the structure and function of biological communities, but we lack a causal understanding of the forces shaping their emergence during evolutionary diversification. Here we provide a conceptual framework linking different modes of diversification (e.g., ecological diversification), which depend on environmental characteristics, to the evolution of different forms of ecological interactions (e.g., resource partitioning) in asexual lineages. We tested the framework by examining the net interactions in communities of Pseudomonas aeruginosa produced via experimental evolution in nutritionally simple (SIM) or complex (COM) environments by contrasting the productivity and competitive fitness of whole evolved communities relative to their component isolates. As expected, we found that nutritional complexity drove the evolution of communities with net positive interactions whereas SIM communities had similar performance as their component isolates. A follow-up experiment revealed that high fitness in two COM communities was driven by rare variants (frequency <0.1%) that antagonized PA14, the ancestral strain and common competitor used in fitness assays. Our study suggests that the evolution of de novo ecological interactions in asexual lineages is predictable at a broad scale from environmental conditions. Further, our work demonstrates that rare variants can disproportionately impact the function of relatively simple microbial communities.
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5
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Yang Y, Zhang W, Liu W, He D, Wan W. Irreversible community difference between bacterioplankton generalists and specialists in response to lake dredging. WATER RESEARCH 2023; 243:120344. [PMID: 37482008 DOI: 10.1016/j.watres.2023.120344] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 07/10/2023] [Accepted: 07/11/2023] [Indexed: 07/25/2023]
Abstract
Understanding response of bacterioplankton community responsible for maintaining ecological functions of aquatic ecosystems to environmental disturbance is an important subject. However, it remains largely unclear how bacterioplankton generalists and specialists respond to dredging disturbance. Illumina MiSeq sequencing and statistical analyses were used to evaluate landscape patterns, evolutionary potentials, environmental adaptability, and community assembly processes of generalists and specialists in response to dredging in eutrophic Lake Nanhu. The Proteobacteria and Actinobacteria dominated bacterioplankton communities of generalists and specialists, and abundances of Proteobacteria decreased and Actinobacteria increased after dredging. The generalists displayed higher phylogenetic distance, richness difference, speciation rate, extinction rate, and diversification rate as well as stronger environmental adaptation than that of specialists. In contrast, the specialists rather than generalists showed higher community diversity, taxonomic distance, and species replacement as well as closer phylogenetic clustering. Stochastic processes dominated community assemblies of generalists and specialists, and stochasticity exhibited a larger effect on community assembly of generalists rather than specialists. Our results emphasized that lake dredging could change landscape patterns of bacterioplankton generalists and specialists, whereas the short-term dredging conducted within one year was unable to reverse community difference between generalists and specialists. Our findings extend our understanding of how bacterioplankton generalists and specialists responding to dredging disturbance, and these findings might in turn call on long-term dredging for better ecological restoration of eutrophic lakes.
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Affiliation(s)
- Yuyi Yang
- Key Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430070, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430070, China
| | - Weihong Zhang
- Key Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430070, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430070, China
| | - Wenzhi Liu
- Key Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430070, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430070, China
| | - Donglan He
- College of Life Science, South-Central Minzu University, Wuhan 430070, China
| | - Wenjie Wan
- Key Laboratory of Aquatic Botany and Watershed Ecology Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430070, China; Danjiangkou Wetland Ecosystem Field Scientific Observation and Research Station, Chinese Academy of Sciences & Hubei Province, Wuhan 430070, China.
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6
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Bono LM, Mao S, Done RE, Okamoto KW, Chan BK, Turner PE. Advancing phage therapy through the lens of virus host-breadth and emergence potential. Adv Virus Res 2021; 111:63-110. [PMID: 34663499 DOI: 10.1016/bs.aivir.2021.07.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Phages are viruses that specifically infect bacteria, and their biodiversity contributes to historical and current development of phage therapy to treat myriad bacterial infections. Phage therapy holds promise as an alternative to failing chemical antibiotics, but there are benefits and costs of this technology. Here, we review the rich history of phage therapy, highlighting reasons (often political) why it was widely rejected by Western medicine until recently. One longstanding idea involves mixing different phages together in cocktails, to increase the probability of killing target pathogenic bacteria without pre-screening for phage susceptibility. By challenging 30 lytic phages to infect 14 strains of the bacteria Pseudomonas aeruginosa, we showed that some phages were "generalists" with broad host-ranges, emphasizing that extreme host-specificity of phages was not necessarily a liability. Using a "greedy algorithm" analysis, we identified the best cocktail mixture of phages to achieve broad bacteria killing. Additionally, we review how virus host-range can evolve and connect lessons learned from virus emergence-including contributions of elevated virus mutation rates in promoting emergence and virus evolutionary transitions from specialized to generalized host-use-as cautionary tales for avoiding risk of "off-target" phage emergence on commensal bacteria in microbiomes. Throughout, we highlight how fundamental understanding of virus ecology and evolution is vital for developing phage therapy; heeding these principles should help in designing therapeutic strategies that do not recapitulate consequences of virus selection to emerge on novel hosts.
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Affiliation(s)
- Lisa M Bono
- Department of Biology, Emory University, Atlanta, GA, United States.
| | - Stephanie Mao
- Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Rachel E Done
- Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Laney Graduate School, Emory University, Atlanta, GA, United States; Division of Pulmonary, Allergy and Immunology, Cystic Fibrosis, and Sleep, Department of Pediatrics, Emory University School of Medicine, Atlanta, GA, United States
| | - Kenichi W Okamoto
- Department of Biology, University of St. Thomas, St. Paul, MN, United States
| | - Benjamin K Chan
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States
| | - Paul E Turner
- Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT, United States; Microbiology Program, Yale School of Medicine, New Haven, CT, United States
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7
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Host diversity slows bacteriophage adaptation by selecting generalists over specialists. Nat Ecol Evol 2021; 5:350-359. [PMID: 33432132 DOI: 10.1038/s41559-020-01364-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 11/12/2020] [Indexed: 01/28/2023]
Abstract
Most viruses can infect multiple hosts, yet the selective mechanisms that maintain multi-host generalists over single-host specialists remain an open question. Here we propagate populations of the newly identified bacteriophage øJB01 in coculture with many host genotypes and find that while phage can adapt to infect any of the new hosts, increasing the number of hosts slows the rate of adaptation. We quantify trade-offs in the capacity for individual phage to infect different hosts and find that phage from evolved populations with more hosts are more likely to be generalists. Sequencing of evolved phage reveals strong selection and the genetic basis of adaptation, supporting a model that shows how the addition of more potential hosts to a community can select for low-fitness generalists over high-fitness specialists. Our results show how evolution with multiple hosts alters the rate of viral adaptation and provides empirical support for an evolutionary mechanism that promotes generalists over specialists.
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8
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Lievens EJP, Michalakis Y, Lenormand T. Trait‐specific trade‐offs prevent niche expansion in two parasites. J Evol Biol 2020; 33:1704-1714. [DOI: 10.1111/jeb.13708] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 09/08/2020] [Accepted: 09/10/2020] [Indexed: 12/31/2022]
Affiliation(s)
- Eva J. P. Lievens
- CEFE, CNRS Univ MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
- UMR 5290 MIVEGEC Univ MontpellierCNRSIRD Montpellier Cedex 5 France
| | - Yannis Michalakis
- UMR 5290 MIVEGEC Univ MontpellierCNRSIRD Montpellier Cedex 5 France
- Centre of Research in Ecology and Evolution of Diseases (CREES) Montpellier France
| | - Thomas Lenormand
- CEFE, CNRS Univ MontpellierUniv Paul Valéry Montpellier 3EPHEIRD Montpellier France
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9
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Visher E, Boots M. The problem of mediocre generalists: population genetics and eco-evolutionary perspectives on host breadth evolution in pathogens. Proc Biol Sci 2020; 287:20201230. [PMID: 32811306 PMCID: PMC7482275 DOI: 10.1098/rspb.2020.1230] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Accepted: 07/22/2020] [Indexed: 01/29/2023] Open
Abstract
Many of our theories for the generation and maintenance of diversity in nature depend on the existence of specialist biotic interactions which, in host-pathogen systems, also shape cross-species disease emergence. As such, niche breadth evolution, especially in host-parasite systems, remains a central focus in ecology and evolution. The predominant explanation for the existence of specialization in the literature is that niche breadth is constrained by trade-offs, such that a generalist is less fit on any particular environment than a given specialist. This trade-off theory has been used to predict niche breadth (co)evolution in both population genetics and eco-evolutionary models, with the different modelling methods providing separate, complementary insights. However, trade-offs may be far from universal, so population genetics theory has also proposed alternate mechanisms for costly generalism, including mutation accumulation. However, these mechanisms have yet to be integrated into eco-evolutionary models in order to understand how the mechanism of costly generalism alters the biological and ecological circumstances predicted to maintain specialism. In this review, we outline how population genetics and eco-evolutionary models based on trade-offs have provided insights for parasite niche breadth evolution and argue that the population genetics-derived mutation accumulation theory needs to be better integrated into eco-evolutionary theory.
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Affiliation(s)
- Elisa Visher
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
| | - Mike Boots
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA, USA
- College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Ringgold Standard Institution, Penryn, Cornwall, UK
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10
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Kennedy PG, Gagne J, Perez-Pazos E, Lofgren LA, Nguyen NH. Does fungal competitive ability explain host specificity or rarity in ectomycorrhizal symbioses? PLoS One 2020; 15:e0234099. [PMID: 32810132 PMCID: PMC7433872 DOI: 10.1371/journal.pone.0234099] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 06/09/2020] [Indexed: 11/28/2022] Open
Abstract
Two common ecological assumptions are that host generalist and rare species are poorer competitors relative to host specialist and more abundant counterparts. While these assumptions have received considerable study in both plant and animals, how they apply to ectomycorrhizal fungi remains largely unknown. To investigate how interspecific competition may influence the anomalous host associations of the rare ectomycorrhizal generalist fungus, Suillus subaureus, we conducted a seedling bioassay. Pinus strobus seedlings were inoculated in single- or two-species treatments of three Suillus species: S. subaureus, S. americanus, and S. spraguei. After 4 and 8 months of growth, seedlings were harvested and scored for mycorrhizal colonization as well as dry biomass. At both time points, we found a clear competitive hierarchy among the three ectomycorrhizal fungal species: S. americanus > S. subaureus > S. spraguei, with the competitive inferior, S. spraguei, having significantly delayed colonization relative to S. americanus and S. subaureus. In the single-species treatments, we found no significant differences in the dry biomasses of P. strobus seedlings colonized by each Suillus species, suggesting none was a more effective plant symbiont. Taken together, these results indicate that the rarity and anomalous host associations exhibited by S. subaureus in natural settings are not driven by inherently poor competitive ability or host growth promotion, but that the timing of colonization is a key factor determining the outcome of ectomycorrhizal fungal competitive interactions.
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Affiliation(s)
- Peter G. Kennedy
- Department of Plant and Microbial Biology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Joe Gagne
- Department of Plant and Microbial Biology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Eduardo Perez-Pazos
- Department of Plant and Microbial Biology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Lotus A. Lofgren
- Department of Microbiology and Plant Pathology, University of California, Riverside, Riverside, California, United States of America
| | - Nhu H. Nguyen
- Department of Tropical Plant & Soil Sciences, University of Hawai’i, Manoa, Manoa, Honolulu, Hawai’i, United States of America
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11
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Tomasini M, Peischl S. When does gene flow facilitate evolutionary rescue? Evolution 2020; 74:1640-1653. [DOI: 10.1111/evo.14038] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 06/03/2020] [Accepted: 06/06/2020] [Indexed: 12/28/2022]
Affiliation(s)
- Matteo Tomasini
- Interfaculty Bioinformatics UnitUniversity of Bern Bern 3012 Switzerland
- Computational and Molecular Population Genetics Laboratory, Institute of Ecology and EvolutionUniversity of Bern Bern 3012 Switzerland
- Swiss Institute for Bioinformatics Lausanne 1015 Switzerland
- Current Address: Department of Integrative BiologyMichigan State University East Lansing Michigan 48824
| | - Stephan Peischl
- Interfaculty Bioinformatics UnitUniversity of Bern Bern 3012 Switzerland
- Swiss Institute for Bioinformatics Lausanne 1015 Switzerland
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12
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Gibson AK, Baffoe-Bonnie H, Penley MJ, Lin J, Owens R, Khalid A, Morran LT. The evolution of parasite host range in heterogeneous host populations. J Evol Biol 2020; 33:773-782. [PMID: 32086852 PMCID: PMC7275899 DOI: 10.1111/jeb.13608] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 01/24/2020] [Accepted: 02/11/2020] [Indexed: 01/07/2023]
Abstract
Theory on the evolution of niche width argues that resource heterogeneity selects for niche breadth. For parasites, this theory predicts that parasite populations will evolve, or maintain, broader host ranges when selected in genetically diverse host populations relative to homogeneous host populations. To test this prediction, we selected the bacterial parasite Serratia marcescens to kill Caenorhabditis elegans in populations that were genetically heterogeneous (50% mix of two experimental genotypes) or homogeneous (100% of either genotype). After 20 rounds of selection, we compared the host range of selected parasites by measuring parasite fitness (i.e. virulence, the selected fitness trait) on the two focal host genotypes and on a novel host genotype. As predicted, heterogeneous host populations selected for parasites with a broader host range: these parasite populations gained or maintained virulence on all host genotypes. This result contrasted with selection in homogeneous populations of one host genotype. Here, host range contracted, with parasite populations gaining virulence on the focal host genotype and losing virulence on the novel host genotype. This pattern was not, however, repeated with selection in homogeneous populations of the second host genotype: these parasite populations did not gain virulence on the focal host genotype, nor did they lose virulence on the novel host genotype. Our results indicate that host heterogeneity can maintain broader host ranges in parasite populations. Individual host genotypes, however, vary in the degree to which they select for specialization in parasite populations.
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Affiliation(s)
- Amanda K Gibson
- Department of Biology, Emory University, Atlanta, GA 30322
- Department of Biology, University of Virginia, Virginia 22902, USA
| | | | | | - Julie Lin
- Department of Biology, Emory University, Atlanta, GA 30322
| | - Raythe Owens
- Department of Biology, Emory University, Atlanta, GA 30322
| | - Arooj Khalid
- Department of Biology, Emory University, Atlanta, GA 30322
| | - Levi T. Morran
- Department of Biology, Emory University, Atlanta, GA 30322
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13
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Bono LM, Draghi JA, Turner PE. Evolvability Costs of Niche Expansion. Trends Genet 2019; 36:14-23. [PMID: 31699305 DOI: 10.1016/j.tig.2019.10.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 08/22/2019] [Accepted: 10/07/2019] [Indexed: 01/31/2023]
Abstract
What prevents generalists from displacing specialists, despite obvious competitive advantages of utilizing a broad niche? The classic genetic explanation is antagonistic pleiotropy: genes underlying the generalism produce 'jacks-of-all-trades' that are masters of none. However, experiments challenge this assumption that mutations enabling niche expansion must reduce fitness in other environments. Theory suggests an alternative cost of generalism: decreased evolvability, or the reduced capacity to adapt. Generalists using multiple environments experience relaxed selection in any one environment, producing greater relative lag load. Additionally, mutations fixed by generalist lineages early during their evolution that avoid or compensate for antagonistic pleiotropy may limit access to certain future evolutionary trajectories. Hypothesized evolvability costs of generalism warrant further exploration, and we suggest outstanding questions meriting attention.
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Affiliation(s)
- Lisa M Bono
- Department of Ecology, Evolution, and Natural Resources, Rutgers, the State University of New Jersey, New Brunswick, NJ 08901, USA
| | - Jeremy A Draghi
- Department of Biological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA; Department of Biology, Brooklyn College, City University of New York, Brooklyn, NY 11210, USA; Program in Ecology, Evolutionary Biology and Behavior, Graduate Center, City University of New York, New York, NY 10016, USA
| | - Paul E Turner
- Microbiology Program, Yale School of Medicine, New Haven, CT 06510, USA; Yale University, Department of Ecology and Evolutionary Biology, New Haven, CT 06511, USA.
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14
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Broeker NK, Roske Y, Valleriani A, Stephan MS, Andres D, Koetz J, Heinemann U, Barbirz S. Time-resolved DNA release from an O-antigen-specific Salmonella bacteriophage with a contractile tail. J Biol Chem 2019; 294:11751-11761. [PMID: 31189652 PMCID: PMC6682738 DOI: 10.1074/jbc.ra119.008133] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 06/11/2019] [Indexed: 12/20/2022] Open
Abstract
Myoviruses, bacteriophages with T4-like architecture, must contract their tails prior to DNA release. However, quantitative kinetic data on myovirus particle opening are lacking, although they are promising tools in bacteriophage-based antimicrobial strategies directed against Gram-negative hosts. For the first time, we show time-resolved DNA ejection from a bacteriophage with a contractile tail, the multi-O-antigen-specific Salmonella myovirus Det7. DNA release from Det7 was triggered by lipopolysaccharide (LPS) O-antigen receptors and notably slower than in noncontractile-tailed siphoviruses. Det7 showed two individual kinetic steps for tail contraction and particle opening. Our in vitro studies showed that highly specialized tailspike proteins (TSPs) are necessary to attach the particle to LPS. A P22-like TSP confers specificity for the Salmonella Typhimurium O-antigen. Moreover, crystal structure analysis at 1.63 Å resolution confirmed that Det7 recognized the Salmonella Anatum O-antigen via an ϵ15-like TSP, DettilonTSP. DNA ejection triggered by LPS from either host showed similar velocities, so particle opening is thus a process independent of O-antigen composition and the recognizing TSP. In Det7, at permissive temperatures TSPs mediate O-antigen cleavage and couple cell surface binding with DNA ejection, but no irreversible adsorption occurred at low temperatures. This finding was in contrast to short-tailed Salmonella podoviruses, illustrating that tailed phages use common particle-opening mechanisms but have specialized into different infection niches.
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Affiliation(s)
- Nina K Broeker
- Department of Physikalische Biochemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
| | - Yvette Roske
- Max-Delbrück-Centrum für Molekulare Medizin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
| | - Angelo Valleriani
- Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany
| | - Mareike S Stephan
- Department of Physikalische Biochemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
| | - Dorothee Andres
- Department of Physikalische Biochemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
| | - Joachim Koetz
- Kolloidchemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
| | - Udo Heinemann
- Max-Delbrück-Centrum für Molekulare Medizin, Robert-Rössle-Strasse 10, 13125 Berlin, Germany
- Institut für Chemie und Biochemie, Freie Universität, Takustrasse 6, 14195 Berlin, Germany
| | - Stefanie Barbirz
- Department of Physikalische Biochemie, Universität Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
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15
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Zhao L, Duffy S. Gauging genetic diversity of generalists: A test of genetic and ecological generalism with RNA virus experimental evolution. Virus Evol 2019; 5:vez019. [PMID: 31275611 PMCID: PMC6599687 DOI: 10.1093/ve/vez019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Generalist viruses, those with a comparatively larger host range, are considered more likely to emerge on new hosts. The potential to emerge in new hosts has been linked to viral genetic diversity, a measure of evolvability. However, there is no consensus on whether infecting a larger number of hosts leads to higher genetic diversity, or whether diversity is better maintained in a homogeneous environment, similar to the lifestyle of a specialist virus. Using experimental evolution with the RNA bacteriophage phi6, we directly tested whether genetic generalism (carrying an expanded host range mutation) or environmental generalism (growing on heterogeneous hosts) leads to viral populations with more genetic variation. Sixteen evolved viral lineages were deep sequenced to provide genetic evidence for population diversity. When evolved on a single host, specialist and generalist genotypes both maintained the same level of diversity (measured by the number of single nucleotide polymorphisms (SNPs) above 1%, P = 0.81). However, the generalist genotype evolved on a single host had higher SNP levels than generalist lineages under two heterogeneous host passaging schemes (P = 0.001, P < 0.001). RNA viruses’ response to selection in alternating hosts reduces standing genetic diversity compared to those evolving in a single host to which the virus is already well-adapted.
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Affiliation(s)
- Lele Zhao
- Department of Ecology, Evolution and Natural Resources, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, NJ, USA
| | - Siobain Duffy
- Department of Ecology, Evolution and Natural Resources, School of Environmental and Biological Sciences, Rutgers, The State University of New Jersey, 14 College Farm Road, New Brunswick, NJ, USA
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16
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Raffini F, Fruciano C, Meyer A. Gene(s) and individual feeding behavior: Exploring eco-evolutionary dynamics underlying left-right asymmetry in the scale-eating cichlid fish Perissodus microlepis. Ecol Evol 2018; 8:5495-5507. [PMID: 29938068 PMCID: PMC6010907 DOI: 10.1002/ece3.4070] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 03/22/2018] [Accepted: 03/26/2018] [Indexed: 01/09/2023] Open
Abstract
The scale‐eating cichlid fish Perissodus microlepis is a textbook example of bilateral asymmetry due to its left or right‐bending heads and of negative frequency‐dependent selection, which is proposed to maintain this stable polymorphism. The mechanisms that underlie this asymmetry remain elusive. Several studies had initially postulated a simple genetic basis for this trait, but this explanation has been questioned, particularly by reports observing a unimodal distribution of mouth shapes. We hypothesize that this unimodal distribution might be due to a combination of genetic and phenotypically plastic components. Here, we expanded on previous work by investigating a formerly identified candidate SNP associated to mouth laterality, documenting inter‐individual variation in feeding preference using stable isotope analyses, and testing their association with mouth asymmetry. Our results suggest that this polymorphism is influenced by both a polygenic basis and inter‐individual non‐genetic variation, possibly due to feeding experience, individual specialization, and intraspecific competition. We introduce a hypothesis potentially explaining the simultaneous maintenance of left, right, asymmetric and symmetric mouth phenotypes due to the interaction between diverse eco‐evolutionary dynamics including niche construction and balancing selection. Future studies will have to further tease apart the relative contribution of genetic and environmental factors and their interactions in an integrated fashion.
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Affiliation(s)
- Francesca Raffini
- Lehrstuhl für Zoologie und Evolutionsbiologie Department of Biology University of Konstanz Konstanz Germany.,International Max Planck Research School (IMPRS) for Organismal Biology University of Konstanz Konstanz Germany
| | - Carmelo Fruciano
- Lehrstuhl für Zoologie und Evolutionsbiologie Department of Biology University of Konstanz Konstanz Germany.,School of Earth, Environmental & Biological Sciences Queensland University of Technology Brisbane QLD Australia.,Institut de biologie de l'Ecole normale supérieure (IBENS) Ecole normale supérieure, CNRS, INSERM PSL Université, Paris France
| | - Axel Meyer
- Lehrstuhl für Zoologie und Evolutionsbiologie Department of Biology University of Konstanz Konstanz Germany.,International Max Planck Research School (IMPRS) for Organismal Biology University of Konstanz Konstanz Germany.,Radcliffe Institute for Advanced Study Harvard University Cambridge Massachusetts
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17
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Schillewaert S, Vantaux A, Van den Ende W, Wenseleers T. The effect of host plants on genotype variability in fitness and honeydew composition of Aphis fabae. INSECT SCIENCE 2017; 24:781-788. [PMID: 27226343 DOI: 10.1111/1744-7917.12360] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/03/2016] [Indexed: 06/05/2023]
Abstract
Aphid species can be polyphagous, feeding on multiple host plants across genera. As host plant species can have large variation in their phloem composition, this can affect aphid fitness and honeydew composition. Previous research showed significant intraspecific genotype variation in the composition of the honeydew carbohydrates of the black bean aphid Aphis fabae, with the ant attractant trisaccharide melezitose showing especially large variation across different genotypes. In this study, we test if variation in melezitose and carbohydrate composition of aphid honeydew could be linked to the adaptation of specific aphid genotypes to particular host plants. To this end, 4 high and 5 low melezitose secreting genotypes of the black bean aphid Aphis fabae were reared on 4 common host plants: broad bean, goosefoot, beet, and poppy. The carbohydrate composition, and in particular melezitose secretion, showed important aphid genotype and host plant interactions, with some genotypes being high melezitose secreting on 1 host plant but not on another. However, the interaction effects were not paralleled in the fitness measurements, even though there were significant differences in the average fitness across the different host plants. On the whole, this study demonstrates that aphid honeydew composition is influenced by complex herbivore-plant interactions. We discuss the relevance of these findings in the context of ant-aphid mutualisms and adaptive specialization in aphids.
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Affiliation(s)
- Sharon Schillewaert
- Laboratory of Socioecology and Social Evolution, Biology Department, Zoological Institute, University of Leuven, Leuven, Belgium
| | - Amélie Vantaux
- Laboratory of Socioecology and Social Evolution, Biology Department, Zoological Institute, University of Leuven, Leuven, Belgium
- Institut Pasteur du Cambodge, Unité d'Epidémiologie Moléculaire du Paludisme, Phnom Penh, Cambodia
| | - Wim Van den Ende
- Laboratory of Molecular Plant Biology, Biology Department, University of Leuven, Leuven, Belgium
| | - Tom Wenseleers
- Laboratory of Socioecology and Social Evolution, Biology Department, Zoological Institute, University of Leuven, Leuven, Belgium
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18
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Bono LM, Smith LB, Pfennig DW, Burch CL. The emergence of performance trade‐offs during local adaptation: insights from experimental evolution. Mol Ecol 2017; 26:1720-1733. [DOI: 10.1111/mec.13979] [Citation(s) in RCA: 84] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 12/15/2016] [Accepted: 12/19/2016] [Indexed: 01/05/2023]
Affiliation(s)
- Lisa M. Bono
- Department of Biology University of North Carolina at Chapel Hill CB# 3280 Chapel Hill NC 27599 USA
| | - Leno B. Smith
- Department of Biology University of North Carolina at Chapel Hill CB# 3280 Chapel Hill NC 27599 USA
| | - David W. Pfennig
- Department of Biology University of North Carolina at Chapel Hill CB# 3280 Chapel Hill NC 27599 USA
| | - Christina L. Burch
- Department of Biology University of North Carolina at Chapel Hill CB# 3280 Chapel Hill NC 27599 USA
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19
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Parnell JJ, Berka R, Young HA, Sturino JM, Kang Y, Barnhart DM, DiLeo MV. From the Lab to the Farm: An Industrial Perspective of Plant Beneficial Microorganisms. FRONTIERS IN PLANT SCIENCE 2016; 7:1110. [PMID: 27540383 PMCID: PMC4973397 DOI: 10.3389/fpls.2016.01110] [Citation(s) in RCA: 149] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 07/12/2016] [Indexed: 05/18/2023]
Abstract
Any successful strategy aimed at enhancing crop productivity with microbial products ultimately relies on the ability to scale at regional to global levels. Microorganisms that show promise in the lab may lack key characteristics for widespread adoption in sustainable and productive agricultural systems. This paper provides an overview of critical considerations involved with taking a strain from discovery to the farmer's field. In addition, we review some of the most effective microbial products on the market today, explore the reasons for their success and outline some of the major challenges involved in industrial production and commercialization of beneficial strains for widespread agricultural application. General processes associated with commercializing viable microbial products are discussed in two broad categories, biofertility inoculants and biocontrol products. Specifically, we address what farmers desire in potential microbial products, how mode of action informs decisions on product applications, the influence of variation in laboratory and field study data, challenges with scaling for mass production, and the importance of consistent efficacy, product stability and quality. In order to make a significant impact on global sustainable agriculture, the implementation of plant beneficial microorganisms will require a more seamless transition between laboratory and farm application. Early attention to the challenges presented here will improve the likelihood of developing effective microbial products to improve crop yields, decrease disease severity, and help to feed an increasingly hungry planet.
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