1
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Pan Y, Jia X, Ding R, Xia S, Zhu X. Interference of two typical polycyclic aromatic hydrocarbons on the induced anti-grazing defense of Tetradesmus obliquus. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2024; 275:116263. [PMID: 38547727 DOI: 10.1016/j.ecoenv.2024.116263] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2023] [Revised: 03/19/2024] [Accepted: 03/24/2024] [Indexed: 04/12/2024]
Abstract
Anthropogenic emissions of polycyclic aromatic hydrocarbons (PAHs) cause severe ecological impacts by contaminating natural water bodies, affecting various biological groups, and altering interspecies relationships and ecological functions. This study examined the effects of two typical PAHs, phenanthrene (Phe) and naphthalene (Nap), on the anti-grazing defense mechanisms of Tetradesmus obliquus, a primary producer in freshwater food chains. Four non-lethal concentrations (0.01, 0.1, 1, and 10 mg L-1) of Phe and Nap were tested and the population growth, photosynthetic capacity, pigment content, and morphological defense of T. obliquus were analyzed. The results indicated that Phe and Nap inhibited both the growth rate and formation of defensive colonies of T. obliquus induced by Daphnia grazing cues, and the inhibition ratio increased with concentration. Phe and Nap significantly shortened the defense colony formation time of T. obliquus. Phe and Nap significantly suppressed photosynthesis in the early stages; however, the photosynthetic efficiency recovered over time. These findings highlight the high sensitivity of grazing-induced colony formation in T. obliquus to Phe and Nap at non-lethal concentrations, which could affect the interactions between phytoplankton and zooplankton in aquatic ecosystems. Our study underscores the influence of Phe and Nap on the defense mechanisms of phytoplankton and the consequential effects on ecological interactions within freshwater ecosystems, providing insight into the complex impacts of pollutants on phytoplankton-zooplankton relationships. Therefore, it is necessary to consider interspecific interactions when assessing the potential negative effects of environmental pollutants on aquatic ecosystems.
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Affiliation(s)
- Yueqiang Pan
- College of Oceanography, Hohai University, 1 Xikang Road, Nanjing 210098, China
| | - Xuanhe Jia
- College of Oceanography, Hohai University, 1 Xikang Road, Nanjing 210098, China
| | - Ruowen Ding
- College of Oceanography, Hohai University, 1 Xikang Road, Nanjing 210098, China
| | - Siyu Xia
- College of Oceanography, Hohai University, 1 Xikang Road, Nanjing 210098, China
| | - Xuexia Zhu
- College of Oceanography, Hohai University, 1 Xikang Road, Nanjing 210098, China; College of Animal Science and Technology, Yangzhou University, Yangzhou, 225009, China; The First Institute of Oceanography, Ministry of Natural Resources of the People's Republic of China, 6 Xianxialing Road, Qingdao 266061, China.
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2
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Setta SP, Lerch S, Jenkins BD, Dyhrman ST, Rynearson TA. Oligotrophic waters of the Northwest Atlantic support taxonomically diverse diatom communities that are distinct from coastal waters. JOURNAL OF PHYCOLOGY 2023; 59:1202-1216. [PMID: 37737069 DOI: 10.1111/jpy.13388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 07/23/2023] [Accepted: 08/09/2023] [Indexed: 09/23/2023]
Abstract
Diatoms are important components of the marine food web and one of the most species-rich groups of phytoplankton. The diversity and composition of diatoms in eutrophic nearshore habitats have been well documented due to the outsized influence of diatoms on coastal ecosystem functioning. In contrast, patterns of both diatom diversity and community composition in offshore oligotrophic regions where diatom biomass is low have been poorly resolved. To compare the diatom diversity and community composition in oligotrophic and eutrophic waters, diatom communities were sampled along a 1,250 km transect from the oligotrophic Sargasso Sea to the coastal waters of the northeast US shelf. Diatom community composition was determined by amplifying and sequencing the 18S rDNA V4 region. Of the 301 amplicon sequence variants (ASVs) identified along the transect, the majority (70%) were sampled exclusively from oligotrophic waters of the Gulf Stream and Sargasso Sea and included the genera Bacteriastrum, Haslea, Hemiaulus, Pseudo-nitzschia, and Nitzschia. Diatom ASV richness did not vary along the transect, indicating that the oligotrophic Sargasso Sea and Gulf Stream are occupied by a diverse diatom community. Although ASV richness was similar between oligotrophic and coastal waters, diatom community composition in these regions differed significantly and was correlated with temperature and phosphate, two environmental variables known to influence diatom metabolism and geographic distribution. In sum, oligotrophic waters of the western North Atlantic harbor diverse diatom assemblages that are distinct from coastal regions, and these open ocean diatoms warrant additional study, as they may play critical roles in oligotrophic ecosystems.
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Affiliation(s)
- Samantha P Setta
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Sarah Lerch
- College of the Environment and Life Sciences, University of Rhode Island, Kingston, Rhode Island, USA
| | - Bethany D Jenkins
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
- College of the Environment and Life Sciences, University of Rhode Island, Kingston, Rhode Island, USA
| | - Sonya T Dyhrman
- Department of Earth and Environmental Sciences, Columbia University, Palisades, New York, USA
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
| | - Tatiana A Rynearson
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
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3
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Rowlett J, Karlsson CJ, Nursultanov M. Diversity strengthens competing teams. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211916. [PMID: 35958087 PMCID: PMC9363986 DOI: 10.1098/rsos.211916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 07/18/2022] [Indexed: 06/15/2023]
Abstract
How does the composition of a collection of individuals affect its outcome in competition with other collections of individuals? Assuming that individuals can be different, we develop a model to interpolate between individual-level interactions and collective-level consequences. Rooted in theoretical mathematics, the model is not constrained to any specific context. Potential applications include research, education, sports, politics, ecology, agriculture, algorithms and finance. Our first main contribution is a game theoretic model that interpolates between the internal composition of an ensemble of individuals and the repercussions for the ensemble as a whole in competition with others. The second main contribution is the rigorous identification of all equilibrium points and strategies. These equilibria suggest a mechanistic underpinning for biological and physical systems to tend towards increasing diversity due to the strength it imparts to the system in competition with others.
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Affiliation(s)
- J. Rowlett
- Mathematical Sciences, Chalmers University of Technology and the University of Gothenburg, 41296 Gothenburg, Sweden
| | - C. J. Karlsson
- Mathematical Sciences, Chalmers University of Technology and the University of Gothenburg, 41296 Gothenburg, Sweden
| | - M. Nursultanov
- Department of Mathematics and Statistics, University of Helsinki, PO Box 68, Helsinki FI-00014, Finland
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4
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Grujcic V, Taylor GT, Foster RA. One Cell at a Time: Advances in Single-Cell Methods and Instrumentation for Discovery in Aquatic Microbiology. Front Microbiol 2022; 13:881018. [PMID: 35677911 PMCID: PMC9169044 DOI: 10.3389/fmicb.2022.881018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2022] [Accepted: 04/26/2022] [Indexed: 11/13/2022] Open
Abstract
Studying microbes from a single-cell perspective has become a major theme and interest within the field of aquatic microbiology. One emerging trend is the unfailing observation of heterogeneity in activity levels within microbial populations. Wherever researchers have looked, intra-population variability in biochemical composition, growth rates, and responses to varying environmental conditions has been evident and probably reflect coexisting genetically distinct strains of the same species. Such observations of heterogeneity require a shift away from bulk analytical approaches and development of new methods or adaptation of existing techniques, many of which were first pioneered in other, unrelated fields, e.g., material, physical, and biomedical sciences. Many co-opted approaches were initially optimized using model organisms. In a field with so few cultivable models, method development has been challenging but has also contributed tremendous insights, breakthroughs, and stimulated curiosity. In this perspective, we present a subset of methods that have been effectively applied to study aquatic microbes at the single-cell level. Opportunities and challenges for innovation are also discussed. We suggest future directions for aquatic microbiological research that will benefit from open access to sophisticated instruments and highly interdisciplinary collaborations.
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Affiliation(s)
- Vesna Grujcic
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
| | - Gordon T Taylor
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY, United States
| | - Rachel A Foster
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden
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5
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García-Oliva O, Hantzsche FM, Boersma M, Wirtz KW. Phytoplankton and particle size spectra indicate intense mixotrophic dinoflagellates grazing from summer to winter. JOURNAL OF PLANKTON RESEARCH 2022; 44:224-240. [PMID: 35356359 PMCID: PMC8962713 DOI: 10.1093/plankt/fbac013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Accepted: 02/10/2021] [Indexed: 06/14/2023]
Abstract
Mixotrophic dinoflagellates (MTD) are a diverse group of organisms often responsible for the formation of harmful algal blooms. However, the development of dinoflagellate blooms and their effects on the plankton community are still not well explored. Here we relate the species succession of MTD with parallel changes of phytoplankton size spectra during periods of MTD dominance. We used FlowCAM analysis to acquire size spectra in the range 2-200 μm every one or two weeks from July to December 2007 at Helgoland Roads (Southern North Sea). Most size spectra of dinoflagellates were bimodal, whereas for other groups, e.g. diatoms and autotrophic flagellates, the spectra were unimodal, which indicates different resource use strategies of autotrophs and mixotrophs. The biomass lost in the size spectrum correlates with the potential grazing pressure of MTD. Based on size-based analysis of trophic linkages, we suggest that mixotrophy, including detritivory, drives species succession and facilitates the formation of bimodal size spectra. Bimodality in particular indicates niche differentiation through grazing of large MTD on smaller MTD. Phagotrophy of larger MTD may exceed one of the smaller MTD since larger prey was more abundant than smaller prey. Under strong light limitation, a usually overlooked refuge strategy may derive from detritivory. The critical role of trophic links of MTD as a central component of the plankton community may guide future observational and theoretical research.
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Affiliation(s)
| | - Florian M Hantzsche
- Institute of Coastal Systems - Analysis and Modeling, Helmholtz-Zentrum Hereon, Max-Planck-straße 1, Geesthacht 21502, Germany
- Alfred-Wegener-Institute Helmholtz-Zentrum für Polar- und Meeresforschung, Biologischen Anstalt Helgoland, Helgoland 27483, Germany
| | - Maarten Boersma
- Alfred-Wegener-Institute Helmholtz-Zentrum für Polar- und Meeresforschung, Biologischen Anstalt Helgoland, Helgoland 27483, Germany
- FB2, University of Bremen, Leobener-Straße, Bremen 28359, Germany
| | - Kai W Wirtz
- Institute of Coastal Systems - Analysis and Modeling, Helmholtz-Zentrum Hereon, Max-Planck-straße 1, Geesthacht 21502, Germany
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6
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Uchmański J. Can a More Variable Species Win Interspecific Competition? Acta Biotheor 2021; 69:591-628. [PMID: 33576895 PMCID: PMC8594215 DOI: 10.1007/s10441-021-09408-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 01/15/2021] [Indexed: 11/25/2022]
Abstract
An individual-based approach is used to describe population dynamics. Two kinds of models have been constructed with different distributions illustrating individual variability. In both models, the growth rate of an individual and its final body weight at the end of the growth period, which determines the number of offspring, are functions of the amount of resources assimilated by an individual. In the model with a symmetric distribution, the half saturation constant in the Michaelis-Menten function describing the relationship between the growth of individuals and the amount of resources has a normal distribution. In the model with an asymmetric distribution, resources are not equally partitioned among individuals. The individual who acquired more resources in the past, will acquire more resources in the future. A single population comprising identical individuals has a very short extinction time. If individuals differ in the amount of food assimilated, this time significantly increases irrespectively of the type of model describing population dynamics. Individuals of two populations of competing species use common resources. For larger differences in individual variability, the more variable species will have a longer extinction time and will exclude less variable species. Both populations can also coexist when their variabilities are equal or even when they are slightly different, in the latter case under the condition of high variability of both species. These conclusions have a deterministic nature in the case of the model with the asymmetric distribution-repeated simulations give the same results. In the case of the model with the symmetric distribution, these conclusions are of a statistical nature-if we repeat the simulation many times, then the more variable species will have a longer extinction time more frequently, but some results will happen (although less often) when the less variable species has a longer extinction time. Additionally, in the model with the asymmetric distribution, the result of competition will depend on the way of the introduction of variability into the model. If the higher variability is due to an increase in the proportion of individuals with a low assimilation of resources, it can produce a longer extinction time of the less variable species.
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Affiliation(s)
- Janusz Uchmański
- Cardinal Stefan Wyszyński University, Wóycickiego 1/3, 01-938, Warsaw, Poland.
- Tyumen State University, 10 Semakov St., Tyumen, Russia, 625003.
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7
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Menden-Deuer S, Rowlett J, Nursultanov M, Collins S, Rynearson T. Biodiversity of marine microbes is safeguarded by phenotypic heterogeneity in ecological traits. PLoS One 2021; 16:e0254799. [PMID: 34347817 PMCID: PMC8336841 DOI: 10.1371/journal.pone.0254799] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Accepted: 07/05/2021] [Indexed: 11/18/2022] Open
Abstract
Why, contrary to theoretical predictions, do marine microbe communities harbor tremendous phenotypic heterogeneity? How can so many marine microbe species competing in the same niche coexist? We discovered a unifying explanation for both phenomena by investigating a non-cooperative game that interpolates between individual-level competitions and species-level outcomes. We identified all equilibrium strategies of the game. These strategies represent the probability distribution of competitive abilities (e.g. traits) and are characterized by maximal phenotypic heterogeneity. They are also neutral towards each other in the sense that an unlimited number of species can co-exist while competing according to the equilibrium strategies. Whereas prior theory predicts that natural selection would minimize trait variation around an optimum value, here we obtained a mathematical proof that species with maximally variable traits are those that endure. This discrepancy may reflect a disparity between predictions from models developed for larger organisms in contrast to our microbe-centric model. Rigorous mathematics proves that phenotypic heterogeneity is itself a mechanistic underpinning of microbial diversity. This discovery has fundamental ramifications for microbial ecology and may represent an adaptive reservoir sheltering biodiversity in changing environmental conditions.
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Affiliation(s)
- Susanne Menden-Deuer
- Graduate School of Oceanography, University of Rhode Island, Narragansett Bay Campus, Narragansett, RI, United States of America
| | - Julie Rowlett
- Mathematical Sciences, Chalmers University and the University of Gothenburg, Gothenburg, Sweden
- * E-mail:
| | - Medet Nursultanov
- School of Mathematics and Statistics, University of Sydney, Camperdown, Australia
| | - Sinead Collins
- Biological Sciences, Ashworth Laboratories, University of Edinburgh, Edinburgh, United Kingdom
| | - Tatiana Rynearson
- Graduate School of Oceanography, University of Rhode Island, Narragansett Bay Campus, Narragansett, RI, United States of America
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8
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Collins S, Schaum CE. Growth strategies of a model picoplankter depend on social milieu and pCO 2. Proc Biol Sci 2021; 288:20211154. [PMID: 34315257 PMCID: PMC8316809 DOI: 10.1098/rspb.2021.1154] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/07/2021] [Indexed: 11/12/2022] Open
Abstract
Phytoplankton exist in genetically diverse populations, but are often studied as single lineages (single strains), so that interpreting single-lineage studies relies critically on understanding how microbial growth differs with social milieu, defined as the presence or absence of conspecifics. The properties of lineages grown alone often fail to predict the growth of these same lineages in the presence of conspecifics, and this discrepancy points towards an opportunity to improve our understanding of the factors that affect lineage growth rates. We demonstrate that different lineages of a marine picoplankter modulate their maximum lineage growth rate in response to the presence of non-self conspecifics, even when resource competition is effectively absent. This explains why growth rates of lineages in isolation do not reliably predict their growth rates in mixed culture, or the lineage composition of assemblages under conditions of rapid growth. The diversity of growth strategies observed here are consistent with lineage-specific energy allocation that depends on social milieu. Since lineage growth is only one of many traits determining fitness in natural assemblages, we hypothesize that intraspecific variation in growth strategies should be common, with more strategies possible in ameliorated environments that support higher maximum growth rates, such as high CO2 for many marine picoplankton.
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Affiliation(s)
- Sinead Collins
- Institute of Evolutionary Biology, University of Edinburgh, IEB, Ashworth Laboratories, The King's Buildings, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - C. Elisa Schaum
- Institute of Marine Ecosystem and Fishery Science, University of Hamburg, Hamburg, Germany
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9
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Zhong D, Listmann L, Santelia ME, Schaum CE. Functional redundancy in natural pico-phytoplankton communities depends on temperature and biogeography. Biol Lett 2020; 16:20200330. [PMID: 32810430 PMCID: PMC7480144 DOI: 10.1098/rsbl.2020.0330] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Biodiversity affects ecosystem function, and how this relationship will change in a warming world is a major and well-examined question in ecology. Yet, it remains understudied for pico-phytoplankton communities, which contribute to carbon cycles and aquatic food webs year-round. Observational studies show a link between phytoplankton community diversity and ecosystem stability, but there is only scarce causal or empirical evidence. Here, we sampled phytoplankton communities from two geographically related regions with distinct thermal and biological properties in the Southern Baltic Sea and carried out a series of dilution/regrowth experiments across three assay temperatures. This allowed us to investigate the effects of loss of rare taxa and establish causal links in natural communities between species richness and several ecologically relevant traits (e.g. size, biomass production, and oxygen production), depending on sampling location and assay temperature. We found that the samples' biogeographical origin determined whether and how functional redundancy changed as a function of temperature for all traits under investigation. Samples obtained from the slightly warmer and more thermally variable regions showed overall high functional redundancy. Samples from the slightly cooler, less variable, stations showed little functional redundancy, i.e. function decreased when species were lost from the community. The differences between regions were more pronounced at elevated assay temperatures. Our results imply that the importance of rare species and the amount of species required to maintain ecosystem function even under short-term warming may differ drastically even within geographically closely related regions of the same ecosystem.
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Affiliation(s)
- Duyi Zhong
- Institute for Marine Ecosystem and Fisheries Science, University of Hamburg, 22767 Hamburg, Germany
| | - Luisa Listmann
- Institute for Marine Ecosystem and Fisheries Science, University of Hamburg, 22767 Hamburg, Germany.,Centre for Earth System Science and Sustainability, 20146 Hamburg, Germany
| | - Maria-Elisabetta Santelia
- Institute for Marine Ecosystem and Fisheries Science, University of Hamburg, 22767 Hamburg, Germany.,Centre for Earth System Science and Sustainability, 20146 Hamburg, Germany
| | - C-Elisa Schaum
- Institute for Marine Ecosystem and Fisheries Science, University of Hamburg, 22767 Hamburg, Germany.,Centre for Earth System Science and Sustainability, 20146 Hamburg, Germany
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10
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Lin WJ, Ho HC, Chu SC, Chou JY. Effects of auxin derivatives on phenotypic plasticity and stress tolerance in five species of the green alga Desmodesmus (Chlorophyceae, Chlorophyta). PeerJ 2020; 8:e8623. [PMID: 32195045 PMCID: PMC7067201 DOI: 10.7717/peerj.8623] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 01/22/2020] [Indexed: 01/03/2023] Open
Abstract
Green microalgae of the genus Desmodesmus are characterized by a high degree of phenotypic plasticity (i.e. colony morphology), allowing them to be truly cosmopolitan and withstand environmental fluctuations. This flexibility enables Desmodesmus to produce a phenotype–environment match across a range of environments broader compared to algae with more fixed phenotypes. Indoles and their derivatives are a well-known crucial class of heterocyclic compounds and are widespread in different species of plants, animals, and microorganisms. Indole-3-acetic acid (IAA) is the most common, naturally occurring plant hormone of the auxin class. IAA may behave as a signaling molecule in microorganisms, and the physiological cues of IAA may also trigger phenotypic plasticity responses in Desmodesmus. In this study, we demonstrated that the changes in colonial morphs (cells per coenobium) of five species of the green alga Desmodesmus were specific to IAA but not to the chemically more stable synthetic auxins, naphthalene-1-acetic acid and 2,4-dichlorophenoxyacetic acid. Moreover, inhibitors of auxin biosynthesis and polar auxin transport inhibited cell division. Notably, different algal species (even different intraspecific strains) exhibited phenotypic plasticity different to that correlated to IAA. Thus, the plasticity involving individual-level heterogeneity in morphological characteristics may be crucial for microalgae to adapt to changing or novel conditions, and IAA treatment potentially increases the tolerance of Desmodesmus algae to several stress conditions. In summary, our results provide circumstantial evidence for the hypothesized role of IAA as a diffusible signal in the communication between the microalga and microorganisms. This information is crucial for elucidation of the role of plant hormones in plankton ecology.
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Affiliation(s)
- Wei-Jiun Lin
- Department of Biology, National Changhua University of Education, Changhua, Taiwan
| | - Han-Chen Ho
- Department of Anatomy, Tzu Chi University, Hualien, Taiwan
| | - Sheng-Chang Chu
- Department of Biology, National Changhua University of Education, Changhua, Taiwan
| | - Jui-Yu Chou
- Department of Biology, National Changhua University of Education, Changhua, Taiwan
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11
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Abstract
Factors maintaining the populations of diverse species that share limited resources or prey remain important issues in ecology. In the present study, I propose that heritable intraspecific variation in prey, which facilitates natural selection, is a key to solve this issue. A mathematical model reveals that diverse genotypes in a prey promote the coexistence of multiple predator species. When two predators share a prey with multiple genotypes, evolution nearly selects the two prey genotypes. Through analysis, I establish a condition of coexistence of such multiple predator-one prey interaction with two genotypes. If each prey type has high defensive capacity against different predator species, stable coexistence is likely to occur. Particularly, interspecific variations of life-history parameters allow the coexistence equilibrium to be stable. In addition, rapid evolution in a prey allows more than two predator species to coexist. Furthermore, mutation tends to stabilize otherwise unstable systems. These results suggest that intraspecific variation in a prey plays a key role in the maintenance of diverse predator species by driving adaptive evolution.
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Affiliation(s)
- Akihiko Mougi
- Institute of Agricultural and Life Sciences, Academic Assembly, Shimane University, Nishikawatsu-cho, Matsue, Japan
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12
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Beckett SJ, Weitz JS. The Effect of Strain Level Diversity on Robust Inference of Virus-Induced Mortality of Phytoplankton. Front Microbiol 2018; 9:1850. [PMID: 30233501 PMCID: PMC6129610 DOI: 10.3389/fmicb.2018.01850] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 07/24/2018] [Indexed: 11/30/2022] Open
Abstract
Infection and lysis of phytoplankton by viruses affects population dynamics and nutrient cycles within oceanic microbial communities. However, estimating the quantitative rates of viral-induced lysis remains challenging in situ. The modified dilution method is the most commonly utilized empirical approach to estimate virus-induced killing rates of phytoplankton. The lysis rate estimates of the modified dilution method are based on models which assume virus-host interactions can be represented by a single virus and a single host population with homogeneous life-history traits. Here, using modeling approaches, we examine the robustness of the modified dilution method in multi-strain, complex communities. We assume that strains differ in their life history traits, including growth rates (of hosts) and lysis rates (by viruses). We show that trait differences affect resulting experimental dynamics such that lysis rates measured using the modified dilution method may be driven by the fastest replicating strains; which are not necessarily the most abundant in situ. We discuss the implications of using the modified dilution method and alternative dilution-based approaches for estimating viral-induced lysis rates in marine microbial communities.
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Affiliation(s)
- Stephen J. Beckett
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
| | - Joshua S. Weitz
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA, United States
- School of Physics, Georgia Institute of Technology, Atlanta, GA, United States
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13
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14
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Chung TY, Kuo CY, Lin WJ, Wang WL, Chou JY. Indole-3-acetic-acid-induced phenotypic plasticity in Desmodesmus algae. Sci Rep 2018; 8:10270. [PMID: 29980731 PMCID: PMC6035231 DOI: 10.1038/s41598-018-28627-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Accepted: 06/26/2018] [Indexed: 11/09/2022] Open
Abstract
Phenotypic plasticity is the ability of a single genotype of an organism to exhibit variable phenotypes in response to fluctuating environments. It plays a crucial role in their evolutionary success. In natural environments, the importance of interactions between microalgae and other microorganisms is generally well appreciated, but the effects of these interactions on algal phenotypic plasticity has not been investigated. In this study, it revealed that indole-3-acetic acid (IAA), the most common naturally occurring plant hormone, can exert stimulatory at low concentrations and inhibitory effects at high concentrations on the growth of the green alga Desmodesmus. The morphological characteristics of Desmodesmus changed drastically under exposure to IAA compared with the algae in the control environment. The proportion of Desmodesmus unicells in monocultures increased with the IAA concentration, and these unicells exhibited less possibility of sedimentation than large cells. Furthermore, we discovered that lipid droplets accumulated in algal cells grown at a high IAA concentration. Results also demonstrated that the presence of algal competitor further stimulated inducible morphological changes in Desmodesmus populations. The relative abundance of competitors influenced the proportion of induced morphological changes. The results indicate that phenotypic plasticity in microalgae can be a response to fluctuating environments, in which algae optimize the cost–benefit ratio.
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Affiliation(s)
- Tan-Ya Chung
- Department of Biology, National Changhua University of Education, Changhua, 500, Taiwan
| | - Chih-Yen Kuo
- Department of Biology, National Changhua University of Education, Changhua, 500, Taiwan
| | - Wei-Jiun Lin
- Department of Biology, National Changhua University of Education, Changhua, 500, Taiwan
| | - Wei-Lung Wang
- Department of Biology, National Changhua University of Education, Changhua, 500, Taiwan
| | - Jui-Yu Chou
- Department of Biology, National Changhua University of Education, Changhua, 500, Taiwan.
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15
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Godhe A, Rynearson T. The role of intraspecific variation in the ecological and evolutionary success of diatoms in changing environments. Philos Trans R Soc Lond B Biol Sci 2018; 372:rstb.2016.0399. [PMID: 28717025 DOI: 10.1098/rstb.2016.0399] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/12/2017] [Indexed: 01/27/2023] Open
Abstract
Intraspecific variation in diatoms has been shown to play a key role in species' responses to several important environmental factors such as light, salinity, temperature and nutrients. Furthermore, modelling efforts indicate that this variation within species extends bloom periods, and likely provides sufficient variability in competitive interactions between species under hydrographically variable conditions. The intraspecific variation most likely corresponds to optimal fitness in temporary microhabitats and may help to explain the paradox of the plankton. Here, we examine the implications of intraspecific variation for the ecology and success of diatoms in general and emphasize the potential implications for our understanding of carbon metabolism in these important organisms. Additionally, data from palaeoecological studies have the potential for evaluating genetic variation through past climate changes, going thousands of years back in time. We suggest pathways for future research including the adoption of multiple strains of individual species into studies of diatom carbon metabolism, to refine our understanding of the variation within and between species, and the inclusion of experimental evolution as a tool for understanding potential evolutionary responses of diatom carbon metabolism to climate change.This article is part of the themed issue 'The peculiar carbon metabolism in diatoms'.
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Affiliation(s)
- Anna Godhe
- Department of Marine Sciences, University of Gothenburg, Box 461, 405 30 Göteborg, Sweden
| | - Tatiana Rynearson
- Graduate School of Oceanography, The University of Rhode Island, Narragansett, RI 02882, USA
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Hippmann AA, Schuback N, Moon KM, McCrow JP, Allen AE, Foster LJ, Green BR, Maldonado MT. Contrasting effects of copper limitation on the photosynthetic apparatus in two strains of the open ocean diatom Thalassiosira oceanica. PLoS One 2017; 12:e0181753. [PMID: 28837661 PMCID: PMC5570362 DOI: 10.1371/journal.pone.0181753] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2017] [Accepted: 07/06/2017] [Indexed: 11/25/2022] Open
Abstract
There is an intricate interaction between iron (Fe) and copper (Cu) physiology in diatoms. However, strategies to cope with low Cu are largely unknown. This study unveils the comprehensive restructuring of the photosynthetic apparatus in the diatom Thalassiosira oceanica (CCMP1003) in response to low Cu, at the physiological and proteomic level. The restructuring results in a shift from light harvesting for photochemistry—and ultimately for carbon fixation—to photoprotection, reducing carbon fixation and oxygen evolution. The observed decreases in the physiological parameters Fv/Fm, carbon fixation, and oxygen evolution, concomitant with increases in the antennae absorption cross section (σPSII), non-photochemical quenching (NPQ) and the conversion factor (φe:C/ηPSII) are in agreement with well documented cellular responses to low Fe. However, the underlying proteomic changes due to low Cu are very different from those elicited by low Fe. Low Cu induces a significant four-fold reduction in the Cu-containing photosynthetic electron carrier plastocyanin. The decrease in plastocyanin causes a bottleneck within the photosynthetic electron transport chain (ETC), ultimately leading to substantial stoichiometric changes. Namely, 2-fold reduction in both cytochrome b6f complex (cytb6f) and photosystem II (PSII), no change in the Fe-rich PSI and a 40- and 2-fold increase in proteins potentially involved in detoxification of reactive oxygen species (ferredoxin and ferredoxin:NADP+ reductase, respectively). Furthermore, we identify 48 light harvesting complex (LHC) proteins in the publicly available genome of T. oceanica and provide proteomic evidence for 33 of these. The change in the LHC composition within the antennae in response to low Cu underlines the shift from photochemistry to photoprotection in T. oceanica (CCMP1003). Interestingly, we also reveal very significant intra-specific strain differences. Another strain of T. oceanica (CCMP 1005) requires significantly higher Cu concentrations to sustain both its maximal and minimal growth rate compared to CCMP 1003. Under low Cu, CCMP 1005 decreases its growth rate, cell size, Chla and total protein per cell. We argue that the reduction in protein per cell is the main strategy to decrease its cellular Cu requirement, as none of the other parameters tested are affected. Differences between the two strains, as well as differences between the well documented responses to low Fe and those presented here in response to low Cu are discussed.
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Affiliation(s)
- Anna A. Hippmann
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail: (AAH); (MTM)
| | - Nina Schuback
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kyung-Mee Moon
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - John P. McCrow
- Department of Microbial & Environmental Genomics, J. Craig Venter Institute, La Jolla, California, United States of America
| | - Andrew E. Allen
- Department of Microbial & Environmental Genomics, J. Craig Venter Institute, La Jolla, California, United States of America
| | - Leonard J. Foster
- Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Beverley R. Green
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
| | - Maria T. Maldonado
- Department of Earth, Ocean, and Atmospheric Sciences, University of British Columbia, Vancouver, British Columbia, Canada
- * E-mail: (AAH); (MTM)
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Intraspecific variability in Phaeocystis antarctica's response to iron and light stress. PLoS One 2017; 12:e0179751. [PMID: 28692685 PMCID: PMC5503234 DOI: 10.1371/journal.pone.0179751] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2016] [Accepted: 06/02/2017] [Indexed: 12/13/2022] Open
Abstract
Phaeocystis antarctica is an abundant phytoplankton species in the Southern Ocean, where growth is frequently limited by iron and light. Being able to grow under low iron conditions is essential to the species’ success, but there have been hints that this ability differs among clones. Here, we compare the growth, cell size and chlorophyll a concentrations of four P. antarctica clones cultured under different iron and light conditions. Iron was provided either as unchelated iron (Fe′) or bound to the bacterial siderophore desferrioxamine B, representing, respectively, the most and least bioavailable forms of iron which phytoplankton encounter in the marine environment. The growth rate data demonstrate that the clones vary in their ability to grow using organically bound iron, and that this ability is not related to their ability to grow at low inorganic iron concentrations. These results are consistent at low and high light. Physiologically, only three of the four clones shrink or decrease the concentration of chlorophyll a in response to iron limitation, and only one clone decreases colony formation. Together, our data show that P. antarctica clones 1) respond to the same degree of iron limitation using different acclimation strategies, and 2) vary in their ability to grow under the same external iron and light conditions. This physiological diversity is surprisingly large for isolates of a single phytoplankton species.
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Akbar S, Du J, Lin H, Kong X, Sun S, Tian X. Understanding interactive inducible defenses of Daphnia and its phytoplankton prey. HARMFUL ALGAE 2017; 66:47-56. [PMID: 28602253 DOI: 10.1016/j.hal.2017.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/02/2017] [Accepted: 05/06/2017] [Indexed: 06/07/2023]
Abstract
Cyanobacterial and zooplankton inducible defenses are important but understudied process that regulate the trophic interactions of freshwater ecosystem. Daphnia due to its large size is considered an important zooplankton with the high potential to control cyanobacterial blooms. It has been shown that Daphnia through maternal induction transfer tolerance to their next generation against Microcystis toxicity. Maternal induction has been investigated in different Daphnia species without considering phenotypic plasticity of prey. Laboratory experiments were performed to explore cyanobacteria-Daphnia inducible defenses in order to better understand their interactions. Two Daphnia species were fed either with Microcystis aeruginosa PCC7806 (Ma) or Microcystis flos-aquae (Mf) mixed with Chlorella vulgaris (Cv) (exposed Daphnia), and or pure Cv (unexposed Daphnia). Exposed prey cultures were produced by prior exposure to Daphnia infochemicals. Neonates produced by exposed and unexposed Daphnia were fed with mixed diet (Microcystis+Cv) of either exposed and or unexposed prey. Growth parameters and toxin production of exposed prey cultures were significantly different than that of control. Exposed Daphnia fecundity and survival was higher as compared to unexposed Daphnia. Growth and reproduction was reduced in exposed Daphnia when fed with exposed prey as compared to those fed with unexposed prey. This study provides information on the interactive inducible defenses between cyanobacteria and its grazer under laboratory conditions and may increase our understanding of cyanobacteria and Daphnia interactions in the freshwater ecosystem.
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Affiliation(s)
- Siddiq Akbar
- School of Life Sciences, Nanjing University, Nanjing 210093, China.
| | - Jingjing Du
- Henan Collaborative Innovation Center of Environmental Pollution Control and Ecological Restoration, School of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China.
| | - Hong Lin
- School of Life Sciences, Nanjing University, Nanjing 210093, China
| | - Xiangshi Kong
- School of Life Sciences, Nanjing University, Nanjing 210093, China
| | - Shucun Sun
- School of Life Sciences, Nanjing University, Nanjing 210093, China
| | - Xingjun Tian
- School of Life Sciences, Nanjing University, Nanjing 210093, China.
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Harvey EL, Menden-Deuer S, Rynearson TA. Persistent Intra-Specific Variation in Genetic and Behavioral Traits in the Raphidophyte, Heterosigma akashiwo. Front Microbiol 2015; 6:1277. [PMID: 26635748 PMCID: PMC4658419 DOI: 10.3389/fmicb.2015.01277] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 10/31/2015] [Indexed: 01/04/2023] Open
Abstract
Motility is a key trait that phytoplankton utilize to navigate the heterogeneous marine environment. Quantifying both intra- and inter-specific variability in trait distributions is key to utilizing traits to distinguish groups of organisms and assess their ecological function. Because examinations of intra-specific variability are rare, here we measured three-dimensional movement behaviors and distribution patterns of seven genetically distinct strains of the ichthyotoxic raphidophyte, Heterosigma akashiwo. Strains were collected from different ocean basins but geographic distance between isolates was a poor predictor of genetic relatedness among strains. Observed behaviors were significantly different among all strains examined, with swimming speed and turning rate ranging from 33–115 μm s-1 and 41–110° s-1, respectively. Movement behaviors were consistent over at least 12 h, and in one case identical when measured several years apart. Movement behaviors were not associated with a specific cell size, carbon content, genetic relatedness, or geographic distance. These strain-specific behaviors resulted in algal populations that had distinct vertical distributions in the experimental tank. This study demonstrates that the traits of genetic identity and motility can provide resolution to distinguish strains of species, where variations in size or biomass are insufficient characteristics.
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Affiliation(s)
- Elizabeth L Harvey
- Skidaway Institute of Oceanography, University of Georgia, Savannah GA, USA
| | - Susanne Menden-Deuer
- Graduate School of Oceanography, University of Rhode Island, Narragansett RI, USA
| | - Tatiana A Rynearson
- Graduate School of Oceanography, University of Rhode Island, Narragansett RI, USA
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Zhu X, Wang J, Lu Y, Chen Q, Yang Z. Grazer-induced morphological defense in Scenedesmus obliquus is affected by competition against Microcystis aeruginosa. Sci Rep 2015. [PMID: 26224387 PMCID: PMC4649898 DOI: 10.1038/srep12743] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The green alga Scenedesmus is known for its phenotypic plasticity in response to grazing risk. However, the benefits of colony formation induced by infochemicals from zooplankton should come with costs. That is, a tradeoff in benefit-to-cost ratios is likely under complex environmental conditions. In this study, we hypothesized that the coexistence of Scenedesmus and its competitors decreases the formation of anti-grazer colonies in Scenedesmus. Results demonstrated that the presence of a competitor Microcystis aeruginosa inhibited inducible defensive colony formation of Scenedesmus obliquus, and the established defensive colonies negatively affected the competitive ability of S. obliquus. The proportion of induced defensive colonies in cultures was dependent on the relative abundance of competitors. Under low competition intensity, large amount of eight-celled colonies were formed but at the cost of decreased competitive inhibition on M. aeruginosa. By contrast, defensive colony formation of S. obliquus slacked in the presence of high competition intensity to maintain a high displacement rate (competitive ability). In conclusion, S. obliquus exhibited different responses to potential grazing pressure under different intensities of competition, i.e., Scenedesmus morphological response to grazing infochemicals was affected by competition against Microcystis.
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Affiliation(s)
- Xuexia Zhu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Jun Wang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Yichun Lu
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Qinwen Chen
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
| | - Zhou Yang
- Jiangsu Key Laboratory for Biodiversity and Biotechnology, School of Biological Sciences, Nanjing Normal University, 1 Wenyuan Road, Nanjing 210023, China
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Metatranscriptome analyses indicate resource partitioning between diatoms in the field. Proc Natl Acad Sci U S A 2015; 112:E2182-90. [PMID: 25870299 DOI: 10.1073/pnas.1421993112] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Diverse communities of marine phytoplankton carry out half of global primary production. The vast diversity of the phytoplankton has long perplexed ecologists because these organisms coexist in an isotropic environment while competing for the same basic resources (e.g., inorganic nutrients). Differential niche partitioning of resources is one hypothesis to explain this "paradox of the plankton," but it is difficult to quantify and track variation in phytoplankton metabolism in situ. Here, we use quantitative metatranscriptome analyses to examine pathways of nitrogen (N) and phosphorus (P) metabolism in diatoms that cooccur regularly in an estuary on the east coast of the United States (Narragansett Bay). Expression of known N and P metabolic pathways varied between diatoms, indicating apparent differences in resource utilization capacity that may prevent direct competition. Nutrient amendment incubations skewed N/P ratios, elucidating nutrient-responsive patterns of expression and facilitating a quantitative comparison between diatoms. The resource-responsive (RR) gene sets deviated in composition from the metabolic profile of the organism, being enriched in genes associated with N and P metabolism. Expression of the RR gene set varied over time and differed significantly between diatoms, resulting in opposite transcriptional responses to the same environment. Apparent differences in metabolic capacity and the expression of that capacity in the environment suggest that diatom-specific resource partitioning was occurring in Narragansett Bay. This high-resolution approach highlights the molecular underpinnings of diatom resource utilization and how cooccurring diatoms adjust their cellular physiology to partition their niche space.
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