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McElwain JC, Matthaeus WJ, Barbosa C, Chondrogiannis C, O' Dea K, Jackson B, Knetge AB, Kwasniewska K, Nair R, White JD, Wilson JP, Montañez IP, Buckley YM, Belcher CM, Nogué S. Functional traits of fossil plants. New Phytol 2024; 242:392-423. [PMID: 38409806 DOI: 10.1111/nph.19622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2023] [Accepted: 12/19/2023] [Indexed: 02/28/2024]
Abstract
A minuscule fraction of the Earth's paleobiological diversity is preserved in the geological record as fossils. What plant remnants have withstood taphonomic filtering, fragmentation, and alteration in their journey to become part of the fossil record provide unique information on how plants functioned in paleo-ecosystems through their traits. Plant traits are measurable morphological, anatomical, physiological, biochemical, or phenological characteristics that potentially affect their environment and fitness. Here, we review the rich literature of paleobotany, through the lens of contemporary trait-based ecology, to evaluate which well-established extant plant traits hold the greatest promise for application to fossils. In particular, we focus on fossil plant functional traits, those measurable properties of leaf, stem, reproductive, or whole plant fossils that offer insights into the functioning of the plant when alive. The limitations of a trait-based approach in paleobotany are considerable. However, in our critical assessment of over 30 extant traits we present an initial, semi-quantitative ranking of 26 paleo-functional traits based on taphonomic and methodological criteria on the potential of those traits to impact Earth system processes, and for that impact to be quantifiable. We demonstrate how valuable inferences on paleo-ecosystem processes (pollination biology, herbivory), past nutrient cycles, paleobiogeography, paleo-demography (life history), and Earth system history can be derived through the application of paleo-functional traits to fossil plants.
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Affiliation(s)
- Jennifer C McElwain
- School of Natural Sciences, Botany, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - William J Matthaeus
- School of Natural Sciences, Botany, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Catarina Barbosa
- School of Natural Sciences, Botany, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | | | - Katie O' Dea
- School of Natural Sciences, Botany, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Bea Jackson
- School of Natural Sciences, Botany, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Antonietta B Knetge
- School of Natural Sciences, Botany, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Kamila Kwasniewska
- School of Natural Sciences, Botany, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Richard Nair
- School of Natural Sciences, Botany, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | - Joseph D White
- Department of Biology, Baylor University, Waco, 76798-7388, TX, USA
| | - Jonathan P Wilson
- Department of Environmental Studies, Haverford College, Haverford, Pennsylvania, 19041, PA, USA
| | - Isabel P Montañez
- UC Davis Institute of the Environment, University of California, Davis, CA, 95616, USA
- Department of Earth and Planetary Sciences, University of California, Davis, CA, 95616, USA
| | - Yvonne M Buckley
- School of Natural Sciences, Zoology, Trinity College Dublin, Dublin, D02 PN40, Ireland
| | | | - Sandra Nogué
- Universitat Autònoma de Barcelona, Bellaterra (Cerdanyola del Vallès), 08193, Catalonia, Spain
- CREAF, Bellaterra (Cerdanyola del Vallès), 08193, Catalonia, Spain
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Kipp MA, Stüeken EE, Strömberg CAE, Brightly WH, Arbour VM, Erdei B, Hill RS, Johnson KR, Kvaček J, McElwain JC, Miller IM, Slodownik M, Vajda V, Buick R. Nitrogen isotopes reveal independent origins of N 2-fixing symbiosis in extant cycad lineages. Nat Ecol Evol 2024; 8:57-69. [PMID: 37974002 DOI: 10.1038/s41559-023-02251-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2023] [Accepted: 10/17/2023] [Indexed: 11/19/2023]
Abstract
Cycads are ancient seed plants (gymnosperms) that emerged by the early Permian. Although they were common understory flora and food for dinosaurs in the Mesozoic, their abundance declined markedly in the Cenozoic. Extant cycads persist in restricted populations in tropical and subtropical habitats and, with their conserved morphology, are often called 'living fossils.' All surviving taxa receive nitrogen from symbiotic N2-fixing cyanobacteria living in modified roots, suggesting an ancestral origin of this symbiosis. However, such an ancient acquisition is discordant with the abundance of cycads in Mesozoic fossil assemblages, as modern N2-fixing symbioses typically occur only in nutrient-poor habitats where advantageous for survival. Here, we use foliar nitrogen isotope ratios-a proxy for N2 fixation in modern plants-to probe the antiquity of the cycad-cyanobacterial symbiosis. We find that fossilized cycad leaves from two Cenozoic representatives of extant genera have nitrogen isotopic compositions consistent with microbial N2 fixation. In contrast, all extinct cycad genera have nitrogen isotope ratios that are indistinguishable from co-existing non-cycad plants and generally inconsistent with microbial N2 fixation, pointing to nitrogen assimilation from soils and not through symbiosis. This pattern indicates that, rather than being ancestral within cycads, N2-fixing symbiosis arose independently in the lineages leading to living cycads during or after the Jurassic. The preferential survival of these lineages may therefore reflect the effects of competition with angiosperms and Cenozoic climatic change.
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Affiliation(s)
- Michael A Kipp
- Department of Earth & Space Sciences, University of Washington, Seattle, WA, USA.
- Virtual Planetary Laboratory, NASA Astrobiology Institute, Seattle, WA, USA.
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA.
- Division of Earth and Climate Sciences, Nicholas School of the Environment, Duke University, Durham, NC, USA.
| | - Eva E Stüeken
- Virtual Planetary Laboratory, NASA Astrobiology Institute, Seattle, WA, USA
- School of Earth & Environmental Sciences, University of St. Andrews, St. Andrews, UK
| | - Caroline A E Strömberg
- Department of Biology, University of Washington, Seattle, WA, USA
- Burke Museum of Natural History and Culture, Seattle, WA, USA
| | | | - Victoria M Arbour
- Department of Knowledge, Royal BC Museum, Victoria, British Columbia, Canada
| | - Boglárka Erdei
- Botanical Department, Hungarian Natural History Museum, Budapest, Hungary
| | - Robert S Hill
- School of Biological Sciences and the Environment Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Kirk R Johnson
- Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
| | - Jiří Kvaček
- Department of Palaeontology, National Museum, Prague, Czech Republic
| | - Jennifer C McElwain
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Ian M Miller
- National Geographic Society, Washington, DC, USA
| | - Miriam Slodownik
- School of Biological Sciences and the Environment Institute, University of Adelaide, Adelaide, South Australia, Australia
| | - Vivi Vajda
- Research Division, Swedish Museum of Natural History, Stockholm, Sweden
- Department of Geology, Lund University, Lund, Sweden
| | - Roger Buick
- Department of Earth & Space Sciences, University of Washington, Seattle, WA, USA
- Virtual Planetary Laboratory, NASA Astrobiology Institute, Seattle, WA, USA
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3
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Baker SJ, Dewhirst RA, McElwain JC, Haworth M, Belcher CM. CO 2 -induced biochemical changes in leaf volatiles decreased fire-intensity in the run-up to the Triassic-Jurassic boundary. New Phytol 2022; 235:1442-1454. [PMID: 35672945 PMCID: PMC9545750 DOI: 10.1111/nph.18299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 04/22/2022] [Indexed: 06/15/2023]
Abstract
The Triassic-Jurassic boundary marks the third largest mass extinction event in the Phanerozoic, characterized by a rise in CO2 -concentrations from c. 600 ppm to c. 2100-2400 ppm, coupled with a c. 3.0-4.0°C temperature rise. This is hypothesized to have induced major floral turnover, altering vegetation structure, composition and leaf morphology, which in turn are hypothesized to have driven changes in wildfire. However, the effects of elevated CO2 on fuel properties, such as chemical composition of leaves, are also important in influencing fire behaviour, but yet have not been considered. We test this by selecting three Triassic analogue species grown experimentally in different atmospheric compositions, and analyse variations in leaf chemistry, and leaf level flammability. These data were used to inform a fire behaviour model. We find that all three species tested showed a reduction in their volatile component, leading to lower flammability. Accounting for these variations in a model, our results suggest that leaf intrinsic flammability has a measurable impact on modelled fire behaviour. If scaled up to ecosystem level, periods of elevated CO2 may therefore be capable of inducing both biochemical and morphological changes in fuel properties, and thus may be capable of influencing fire behaviour.
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Affiliation(s)
| | | | - Jennifer C. McElwain
- Botany Department, School of Natural SciencesTrinity College DublinDublinD02 PN40Ireland
| | - Matthew Haworth
- Institute for Sustainable Plant ProtectionNational Research Council (CNR‐IPSP)Via Madonna del Piano 10 Sesto FiorentinoFlorenceFirenze50019Italy
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4
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Yiotis C, McElwain JC, Osborne BA. Enhancing the productivity of ryegrass at elevated CO2 is dependent on tillering and leaf area development rather than leaf-level photosynthesis. J Exp Bot 2021; 72:1962-1977. [PMID: 33315099 PMCID: PMC7921301 DOI: 10.1093/jxb/eraa584] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 12/10/2020] [Indexed: 05/29/2023]
Abstract
Whilst a range of strategies have been proposed for enhancing crop productivity, many recent studies have focused primarily on enhancing leaf photosynthesis under current atmospheric CO2 concentrations. Given that the atmospheric CO2 concentration is likely to increase significantly in the foreseeable future, an alternative/complementary strategy might be to exploit any variability in the enhancement of growth/yield and photosynthesis at higher CO2 concentrations. To explore this, we investigated the responses of a diverse range of wild and cultivated ryegrass genotypes, with contrasting geographical origins, to ambient and elevated CO2 concentrations and examined what genetically tractable plant trait(s) might be targeted by plant breeders for future yield enhancements. We found substantial ~7-fold intraspecific variations in biomass productivity among the different genotypes at both CO2 levels, which were related primarily to differences in tillering/leaf area, with only small differences due to leaf photosynthesis. Interestingly, the ranking of genotypes in terms of their response to both CO2 concentrations was similar. However, as expected, estimates of whole-plant photosynthesis were strongly correlated with plant productivity. Our results suggest that greater yield gains under elevated CO2 are likely through the exploitation of genetic differences in tillering and leaf area rather than focusing solely on improving leaf photosynthesis.
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Affiliation(s)
- Charilaos Yiotis
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin, Ireland
- UCD Earth Institute, University College Dublin, Belfield, Dublin, Ireland
- Department of Botany, School of Natural Sciences, Trinity College Dublin, College Green, Dublin, Ireland
| | - Jennifer C McElwain
- Department of Botany, School of Natural Sciences, Trinity College Dublin, College Green, Dublin, Ireland
| | - Bruce A Osborne
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin, Ireland
- UCD Earth Institute, University College Dublin, Belfield, Dublin, Ireland
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5
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Tierney JE, Poulsen CJ, Montañez IP, Bhattacharya T, Feng R, Ford HL, Hönisch B, Inglis GN, Petersen SV, Sagoo N, Tabor CR, Thirumalai K, Zhu J, Burls NJ, Foster GL, Goddéris Y, Huber BT, Ivany LC, Kirtland Turner S, Lunt DJ, McElwain JC, Mills BJW, Otto-Bliesner BL, Ridgwell A, Zhang YG. Past climates inform our future. Science 2020; 370:370/6517/eaay3701. [DOI: 10.1126/science.aay3701] [Citation(s) in RCA: 111] [Impact Index Per Article: 27.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
| | - Christopher J. Poulsen
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Isabel P. Montañez
- Department of Earth and Planetary Sciences, University of California, Davis, Davis, CA, USA
| | - Tripti Bhattacharya
- Department of Earth and Environmental Sciences, Syracuse University, Syracuse, NY, USA
| | - Ran Feng
- Department of Geosciences, University of Connecticut, Storrs, CT, USA
| | - Heather L. Ford
- School of Geography, Queen Mary University of London, London, UK
| | - Bärbel Hönisch
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY, USA
| | - Gordon N. Inglis
- Department of Earth and Environmental Sciences, Columbia University, Palisades, NY, USA
| | - Sierra V. Petersen
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Navjit Sagoo
- Department of Meteorology, University of Stockholm, Stockholm, Sweden
| | - Clay R. Tabor
- Department of Geosciences, University of Connecticut, Storrs, CT, USA
| | | | - Jiang Zhu
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, USA
| | - Natalie J. Burls
- Department of Atmospheric, Oceanic, and Earth Sciences, George Mason University, Fairfax, VA, USA
| | - Gavin L. Foster
- Department of Earth and Environmental Sciences, Columbia University, Palisades, NY, USA
| | - Yves Goddéris
- Centre National de la Recherche Scientifique, Géosciences Environnement Toulouse, Toulouse, France
| | - Brian T. Huber
- Department of Paleobiology, Smithsonian National Museum of Natural History, Washington, DC, USA
| | - Linda C. Ivany
- Department of Earth and Environmental Sciences, Syracuse University, Syracuse, NY, USA
| | | | - Daniel J. Lunt
- School of Geographical Sciences, University of Bristol, Bristol, UK
| | | | | | | | - Andy Ridgwell
- Department of Earth Science, University of California, Riverside, Riverside, CA, USA
| | - Yi Ge Zhang
- Department of Oceanography, Texas A&M University, College Station, TX, USA
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6
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Devaney JL, Marone D, McElwain JC. Impact of soil salinity on mangrove restoration in a semiarid region: a case study from the Saloum Delta, Senegal. Restor Ecol 2020. [DOI: 10.1111/rec.13186] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- John L. Devaney
- Botany Department, Trinity College Dublin The University of Dublin Dublin 2 Ireland
- Smithsonian Environmental Research Center Edgewater MD USA
| | - Diatta Marone
- Institut Sénégalais de Recherches Agricoles, Centre de recherche agricole de Saint‐Louis BP 240, Saint‐Louis Senegal
| | - Jennifer C. McElwain
- Botany Department, Trinity College Dublin The University of Dublin Dublin 2 Ireland
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7
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Wilson JP, White JD, Montañez IP, DiMichele WA, McElwain JC, Poulsen CJ, Hren MT. Carboniferous plant physiology breaks the mold. New Phytol 2020; 227:667-679. [PMID: 32267976 DOI: 10.1111/nph.16460] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Accepted: 11/17/2019] [Indexed: 06/11/2023]
Abstract
How plants have shaped Earth surface feedbacks over geologic time is a key question in botanical and geological inquiry. Recent work has suggested that biomes during the Carboniferous Period contained plants with extraordinary physiological capacity to shape their environment, contradicting the previously dominant view that plants only began to actively moderate the Earth's surface with the rise of angiosperms during the Mesozoic Era. A recently published Viewpoint disputes this recent work, thus here, we document in detail, the mechanistic underpinnings of our modeling and illustrate the extraordinary ecophysiological nature of Carboniferous plants.
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Affiliation(s)
- Jonathan P Wilson
- Department of Environmental Studies, Haverford College, Haverford, PA, 19041, USA
| | - Joseph D White
- Department of Biology, Baylor University, Waco, TX, 76798, USA
| | - Isabel P Montañez
- Department of Earth and Planetary Sciences, University of California, Davis, CA, 95616, USA
| | - William A DiMichele
- Department of Paleobiology, Smithsonian Museum of Natural History, Washington, DC, 20560, USA
| | - Jennifer C McElwain
- Department of Botany, School of Natural Sciences, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland
| | - Christopher J Poulsen
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Michael T Hren
- Center for Integrative Geosciences, University of Connecticut, Storrs, CT, 06269, USA
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8
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Soh WK, Yiotis C, Murray M, Parnell A, Wright IJ, Spicer RA, Lawson T, Caballero R, McElwain JC. Rising CO 2 drives divergence in water use efficiency of evergreen and deciduous plants. Sci Adv 2019; 5:eaax7906. [PMID: 31844666 PMCID: PMC6905860 DOI: 10.1126/sciadv.aax7906] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Accepted: 10/31/2019] [Indexed: 05/08/2023]
Abstract
Intrinsic water use efficiency (iWUE), defined as the ratio of photosynthesis to stomatal conductance, is a key variable in plant physiology and ecology. Yet, how rising atmospheric CO2 concentration affects iWUE at broad species and ecosystem scales is poorly understood. In a field-based study of 244 woody angiosperm species across eight biomes over the past 25 years of increasing atmospheric CO2 (~45 ppm), we show that iWUE in evergreen species has increased more rapidly than in deciduous species. Specifically, the difference in iWUE gain between evergreen and deciduous taxa diverges along a mean annual temperature gradient from tropical to boreal forests and follows similar observed trends in leaf functional traits such as leaf mass per area. Synthesis of multiple lines of evidence supports our findings. This study provides timely insights into the impact of Anthropocene climate change on forest ecosystems and will aid the development of next-generation trait-based vegetation models.
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Affiliation(s)
- Wuu Kuang Soh
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
- Corresponding author.
| | - Charilaos Yiotis
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
| | - Michelle Murray
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
| | - Andrew Parnell
- Hamilton Institute, Insight Centre for Data Analytics, Maynooth University, Kildare, Ireland
| | - Ian J. Wright
- Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia
| | - Robert A. Spicer
- CAS Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Mengla 666303, China
- School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes MK7 6AA, UK
| | - Tracy Lawson
- School of Life Sciences, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, Essex, UK
| | - Rodrigo Caballero
- Department of Meteorology, Stockholm University, 10691 Stockholm, Sweden
| | - Jennifer C. McElwain
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin 2, Ireland
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Yiotis C, McElwain JC. A Novel Hypothesis for the Role of Photosynthetic Physiology in Shaping Macroevolutionary Patterns. Plant Physiol 2019; 181:1148-1162. [PMID: 31484680 PMCID: PMC6836816 DOI: 10.1104/pp.19.00749] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Accepted: 08/25/2019] [Indexed: 05/08/2023]
Abstract
The fossil record and models of atmospheric concentrations of O2 and CO2 suggest that past shifts in plant ecological dominance often coincided with dramatic changes in Earth's atmospheric composition. This study tested the effects of past changes in atmospheric composition on the photosynthetic physiology of a limited range of early-diverging angiosperms (eight), gymnosperms (three), and ferns (two). We performed physiological measurements on all species and used the results to parameterize simulations of their photosynthetic paleophysiology using three independent modeling approaches. Unique physiological attributes were identified for the three evolutionary groups: angiosperm taxa displayed significantly higher mesophyll conductance (g m), yet their stomatal conductance (g s) was lower than that of ferns. Gymnosperm taxa displayed low g s and g m, but they partially offset their significant diffusional limitations on photosynthesis through their higher maximum Rubisco carboxylation rate. Despite their high total conductance to CO2, fern taxa lacked an optimized control of g s, which was reflected in their low intrinsic water use efficiency. Simulations of the photosynthetic physiology of ferns, angiosperms, and gymnosperms through Earth's history demonstrated that past fluctuations in O2 and CO2 concentrations may have resulted in significant shifts in the relative competitiveness of the three evolutionary groups. Although preliminary because of limited species sampling, these findings hint at a potential mechanistic basis for the observed broad temporal correlation between atmospheric change and shifts in plant evolutionary group-level richness observed in the fossil record and are presented as a framework to be tested with paleophotosynthetic proxies and through increased species sampling.
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Affiliation(s)
- Charilaos Yiotis
- Botany Department, School of Natural Sciences, Trinity College, Dublin 2, Ireland
| | - Jennifer C McElwain
- Botany Department, School of Natural Sciences, Trinity College, Dublin 2, Ireland
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10
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Murray M, Soh WK, Yiotis C, Batke S, Parnell AC, Spicer RA, Lawson T, Caballero R, Wright IJ, Purcell C, McElwain JC. Convergence in Maximum Stomatal Conductance of C 3 Woody Angiosperms in Natural Ecosystems Across Bioclimatic Zones. Front Plant Sci 2019; 10:558. [PMID: 31134112 PMCID: PMC6514322 DOI: 10.3389/fpls.2019.00558] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2018] [Accepted: 04/12/2019] [Indexed: 05/26/2023]
Abstract
Stomatal conductance (g s) in terrestrial vegetation regulates the uptake of atmospheric carbon dioxide for photosynthesis and water loss through transpiration, closely linking the biosphere and atmosphere and influencing climate. Yet, the range and pattern of g s in plants from natural ecosystems across broad geographic, climatic, and taxonomic ranges remains poorly quantified. Furthermore, attempts to characterize g s on such scales have predominantly relied upon meta-analyses compiling data from many different studies. This approach may be inherently problematic as it combines data collected using unstandardized protocols, sometimes over decadal time spans, and from different habitat groups. Using a standardized protocol, we measured leaf-level g s using porometry in 218 C3 woody angiosperm species in natural ecosystems representing seven bioclimatic zones. The resulting dataset of 4273 g s measurements, which we call STraits (Stomatal Traits), was used to determine patterns in maximum g s (g smax) across bioclimatic zones and whether there was similarity in the mean g smax of C3 woody angiosperms across ecosystem types. We also tested for differential g smax in two broadly defined habitat groups - open-canopy and understory-subcanopy - within and across bioclimatic zones. We found strong convergence in mean g smax of C3 woody angiosperms in the understory-subcanopy habitats across six bioclimatic zones, but not in open-canopy habitats. Mean g smax in open-canopy habitats (266 ± 100 mmol m-2 s-1) was significantly higher than in understory-subcanopy habitats (233 ± 86 mmol m-2 s-1). There was also a central tendency in the overall dataset to operate toward a g smax of ∼250 mmol m-2 s-1. We suggest that the observed convergence in mean g smax of C3 woody angiosperms in the understory-subcanopy is due to a buffering of g smax against macroclimate effects which will lead to differential response of C3 woody angiosperm vegetation in these two habitats to future global change. Therefore, it will be important for future studies of g smax to categorize vegetation according to habitat group.
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Affiliation(s)
- Michelle Murray
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Wuu Kuang Soh
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Charilaos Yiotis
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Sven Batke
- Department of Biology, Edge Hill University, Ormskirk, United Kingdom
| | | | - Robert A. Spicer
- Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun, China
- School of Environment, Earth and Ecosystem Sciences, The Open University, Milton Keynes, United Kingdom
| | - Tracy Lawson
- School of Biological Sciences, University of Essex, Colchester, United Kingdom
| | | | - Ian J. Wright
- Department of Biological Sciences, Faculty of Science, Macquarie University, Sydney, NSW, Australia
| | - Conor Purcell
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
| | - Jennifer C. McElwain
- Department of Botany, School of Natural Sciences, Trinity College Dublin, Dublin, Ireland
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11
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Purcell C, Batke SP, Yiotis C, Caballero R, Soh WK, Murray M, McElwain JC. Increasing stomatal conductance in response to rising atmospheric CO2. Ann Bot 2018; 121:1427. [PMID: 29471375 PMCID: PMC6007760 DOI: 10.1093/aob/mcy023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
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Purcell C, Batke SP, Yiotis C, Caballero R, Soh WK, Murray M, McElwain JC. Increasing stomatal conductance in response to rising atmospheric CO2. Ann Bot 2018; 121:1137-1149. [PMID: 29394303 PMCID: PMC5946907 DOI: 10.1093/aob/mcx208] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2017] [Accepted: 12/16/2017] [Indexed: 05/19/2023]
Abstract
Background and Aims Studies have indicated that plant stomatal conductance (gs) decreases in response to elevated atmospheric CO2, a phenomenon of significance for the global hydrological cycle. However, gs increases across certain CO2 ranges have been predicted by optimization models. The aim of this work was to demonstrate that under certain environmental conditions, gs can increase in response to elevated CO2. Methods Using (1) an extensive, up-to-date synthesis of gs responses in free air CO2 enrichment (FACE)experiments, (2) in situ measurements across four biomes showing dynamic gs responses to a CO2 rise of ~50 ppm (characterizing the change in this greenhouse gas over the past three decades) and (3) a photosynthesis-stomatal conductance model, it is demonstrated that gs can in some cases increase in response to increasing atmospheric CO2. Key Results Field observations are corroborated by an extensive synthesis of gs responses in FACE experiments showing that 11.8 % of gs responses under experimentally elevated CO2 are positive. They are further supported by a strong data-model fit (r2 = 0.607) using a stomatal optimization model applied to the field gs dataset. A parameter space identified in the Farquhar-Ball-Berry photosynthesis-stomatal conductance model confirms field observations of increasing gs under elevated CO2 in hot dry conditions. Contrary to the general assumption, positive gs responses to elevated CO2, although relatively rare, are a feature of woody taxa adapted to warm, low-humidity conditions, and this response is also demonstrated in global simulations using the Community Land Model (CLM4). Conclusions The results contradict the over-simplistic notion that global vegetation always responds with decreasing gs to elevated CO2, a finding that has important implications for predicting future vegetation feedbacks on the hydrological cycle at the regional level.
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Affiliation(s)
- C Purcell
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Belfield, Dublin, Ireland
| | - S P Batke
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Belfield, Dublin, Ireland
- Department of Biology, Edge Hill University, St. Helens Road, Ormskirk, UK
| | - C Yiotis
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Belfield, Dublin, Ireland
| | - R Caballero
- Department of Meteorology and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
| | - W K Soh
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Belfield, Dublin, Ireland
| | - M Murray
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Belfield, Dublin, Ireland
| | - J C McElwain
- Botany Department, Trinity College Dublin, College Green, Dublin, Ireland
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Abstract
Human carbon use during the next century will lead to atmospheric carbon dioxide concentrations (pCO2) that have been unprecedented for the past 50-100+ million years according to fossil plant-based CO2 estimates. The paleobotanical record of plants offers key insights into vegetation responses to past global change, including suitable analogs for Earth's climatic future. Past global warming events have resulted in transient poleward migration at rates that are equivalent to the lowest climate velocities required for current taxa to keep pace with climate change. Paleobiome reconstructions suggest that the current tundra biome is the biome most threatened by global warming. The common occurrence of paleoforests at high polar latitudes when pCO2 was above 500 ppm suggests that the advance of woody shrub and tree taxa into tundra environments may be inevitable. Fossil pollen studies demonstrate the resilience of wet tropical forests to global change up to 700 ppm CO2, contrary to modeled predictions of the future. The paleobotanical record also demonstrates a high capacity for functional trait evolution as an additional strategy to migration and maintenance of a species' climate envelope in response to global change.
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Affiliation(s)
- Jennifer C McElwain
- Botany Department, Trinity College Dublin, The University of Dublin, Dublin 2, Ireland;
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14
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Wilson JP, Montañez IP, White JD, DiMichele WA, McElwain JC, Poulsen CJ, Hren MT. Dynamic Carboniferous tropical forests: new views of plant function and potential for physiological forcing of climate. New Phytol 2017; 215:1333-1353. [PMID: 28742257 DOI: 10.1111/nph.14700] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/22/2017] [Indexed: 05/05/2023]
Abstract
Contents 1333 I. 1334 II. 1335 III. 1339 IV. 1344 V. 1347 VI. 1347 1348 1348 References 1348 SUMMARY: The Carboniferous, the time of Earth's penultimate icehouse and widespread coal formation, was dominated by extinct lineages of early-diverging vascular plants. Studies of nearest living relatives of key Carboniferous plants suggest that their physiologies and growth forms differed substantially from most types of modern vegetation, particularly forests. It remains a matter of debate precisely how differently and to what degree these long-extinct plants influenced the environment. Integrating biophysical analysis of stomatal and vascular conductivity with geochemical analysis of fossilized tissues and process-based ecosystem-scale modeling yields a dynamic and unique perspective on these paleoforests. This integrated approach indicates that key Carboniferous plants were capable of growth and transpiration rates that approach values found in extant crown-group angiosperms, differing greatly from comparatively modest rates found in their closest living relatives. Ecosystem modeling suggests that divergent stomatal conductance, leaf sizes and stem life span between dominant clades would have shifted the balance of soil-atmosphere water fluxes, and thus surface runoff flux, during repeated, climate-driven, vegetation turnovers. This synthesis highlights the importance of 'whole plant' physiological reconstruction of extinct plants and the potential of vascular plants to have influenced the Earth system hundreds of millions of years ago through vegetation-climate feedbacks.
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Affiliation(s)
| | - Isabel P Montañez
- Department of Earth and Planetary Sciences, University of California, Davis, CA, 95616, USA
| | - Joseph D White
- Department of Biology, Baylor University, Waco, TX, 76798, USA
| | - William A DiMichele
- Department of Paleobiology, Smithsonian Museum of Natural History, Washington, DC, 20560, USA
| | - Jennifer C McElwain
- Earth Institute, School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Christopher J Poulsen
- Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Michael T Hren
- Center for Integrative Geosciences, University of Connecticut, Storrs, CT, 06269, USA
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15
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McElwain JC. Palaeobotany: New ways with old fossils. Nat Plants 2017; 3:17121. [PMID: 28758993 DOI: 10.1038/nplants.2017.121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Affiliation(s)
- Jennifer C McElwain
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Ireland
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16
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Soh WK, Wright IJ, Bacon KL, Lenz TI, Steinthorsdottir M, Parnell AC, McElwain JC. Corrigendum: Palaeo leaf economics reveal a shift in ecosystem function associated with the end-Triassic mass extinction event. Nat Plants 2017; 3:17126. [PMID: 28758989 DOI: 10.1038/nplants.2017.126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
This corrects the article DOI: 10.1038/nplants.2017.104.
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17
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Soh WK, Wright IJ, Bacon KL, Lenz TI, Steinthorsdottir M, Parnell AC, McElwain JC. Palaeo leaf economics reveal a shift in ecosystem function associated with the end-Triassic mass extinction event. Nat Plants 2017; 3:17104. [PMID: 28714942 DOI: 10.1038/nplants.2017.104] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2016] [Accepted: 06/09/2017] [Indexed: 06/07/2023]
Abstract
Climate change is likely to have altered the ecological functioning of past ecosystems, and is likely to alter functioning in the future; however, the magnitude and direction of such changes are difficult to predict. Here we use a deep-time case study to evaluate the impact of a well-constrained CO2-induced global warming event on the ecological functioning of dominant plant communities. We use leaf mass per area (LMA), a widely used trait in modern plant ecology, to infer the palaeoecological strategy of fossil plant taxa. We show that palaeo-LMA can be inferred from fossil leaf cuticles based on a tight relationship between LMA and cuticle thickness observed among extant gymnosperms. Application of this new palaeo-LMA proxy to fossil gymnosperms from East Greenland reveals significant shifts in the dominant ecological strategies of vegetation found across the Triassic-Jurassic transition. Late Triassic forests, dominated by low-LMA taxa with inferred high transpiration rates and short leaf lifespans, were replaced in the Early Jurassic by forests dominated by high-LMA taxa that were likely to have slower metabolic rates. We suggest that extreme CO2-induced global warming selected for taxa with high LMA associated with a stress-tolerant strategy and that adaptive plasticity in leaf functional traits such as LMA contributed to post-warming ecological success.
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Affiliation(s)
- W K Soh
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - I J Wright
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - K L Bacon
- School of Geography, University of Leeds, Leeds LS2 9JT, UK
| | - T I Lenz
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
| | - M Steinthorsdottir
- Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, SE-109 61 Stockholm, Sweden
- Department of Paleobiology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden
| | - A C Parnell
- School of Mathematics &Statistics, Insight Centre for Data Analytics, University College Dublin, Belfield, Dublin 4, Ireland
| | - J C McElwain
- School of Biology and Environmental Science, Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
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McElwain JC, Steinthorsdottir M. Paleoecology, Ploidy, Paleoatmospheric Composition, and Developmental Biology: A Review of the Multiple Uses of Fossil Stomata. Plant Physiol 2017; 174:650-664. [PMID: 28495890 PMCID: PMC5462064 DOI: 10.1104/pp.17.00204] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 05/10/2017] [Indexed: 05/05/2023]
Affiliation(s)
- Jennifer C McElwain
- Earth Institute, O'Brien Centre for Science, and School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland (J.C.M.);
- Department of Palaeobiology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden (M.S.); and
- Bolin Centre for Climate Research, Stockholm University, SE-104 05 Stockholm, Sweden (M.S.)
| | - Margret Steinthorsdottir
- Earth Institute, O'Brien Centre for Science, and School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland (J.C.M.)
- Department of Palaeobiology, Swedish Museum of Natural History, SE-104 05 Stockholm, Sweden (M.S.); and
- Bolin Centre for Climate Research, Stockholm University, SE-104 05 Stockholm, Sweden (M.S.)
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Evans-Fitz.Gerald C, Porter AS, Yiotis C, Elliott-Kingston C, McElwain JC. Co-ordination in Morphological Leaf Traits of Early Diverging Angiosperms Is Maintained Following Exposure to Experimental Palaeo-atmospheric Conditions of Sub-ambient O 2 and Elevated CO 2. Front Plant Sci 2016; 7:1368. [PMID: 27695464 PMCID: PMC5023689 DOI: 10.3389/fpls.2016.01368] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 08/29/2016] [Indexed: 05/27/2023]
Abstract
In order to be successful in a given environment a plant should invest in a vein network and stomatal distribution that ensures balance between both water supply and demand. Vein density (Dv) and stomatal density (SD) have been shown to be strongly positively correlated in response to a range of environmental variables in more recently evolved plant species, but the extent of this relationship has not been confirmed in earlier diverging plant lineages. In order to examine the effect of a changing atmosphere on the relationship between Dv and SD, five early-diverging plant species representing two different reproductive plant grades were grown for 7 months in a palaeo-treatment comprising an O2:CO2 ratio that has occurred multiple times throughout plant evolutionary history. Results show a range of species-specific Dv and SD responses to the palaeo-treatment, however, we show that the strong relationship between Dv and SD under modern ambient atmospheric composition is maintained following exposure to the palaeo-treatment. This suggests strong inter-specific co-ordination between vein and stomatal traits for our study species even under relatively extreme environmental change. This co-ordination supports existing plant function proxies that use the distance between vein endings and stomata (Dm) to infer plant palaeo-physiology.
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Affiliation(s)
- Christiana Evans-Fitz.Gerald
- Earth Institute, O’Brien Centre for Science, University College DublinDublin, Ireland
- School of Biology and Environmental Science, University College DublinDublin, Ireland
| | - Amanda S. Porter
- Earth Institute, O’Brien Centre for Science, University College DublinDublin, Ireland
- School of Biology and Environmental Science, University College DublinDublin, Ireland
| | - Charilaos Yiotis
- Earth Institute, O’Brien Centre for Science, University College DublinDublin, Ireland
- School of Biology and Environmental Science, University College DublinDublin, Ireland
| | | | - Jennifer C. McElwain
- Earth Institute, O’Brien Centre for Science, University College DublinDublin, Ireland
- School of Biology and Environmental Science, University College DublinDublin, Ireland
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Elliott-Kingston C, Haworth M, Yearsley JM, Batke SP, Lawson T, McElwain JC. Does Size Matter? Atmospheric CO2 May Be a Stronger Driver of Stomatal Closing Rate Than Stomatal Size in Taxa That Diversified under Low CO2. Front Plant Sci 2016; 7:1253. [PMID: 27605929 PMCID: PMC4996050 DOI: 10.3389/fpls.2016.01253] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 08/08/2016] [Indexed: 05/02/2023]
Abstract
One strategy for plants to optimize stomatal function is to open and close their stomata quickly in response to environmental signals. It is generally assumed that small stomata can alter aperture faster than large stomata. We tested the hypothesis that species with small stomata close faster than species with larger stomata in response to darkness by comparing rate of stomatal closure across an evolutionary range of species including ferns, cycads, conifers, and angiosperms under controlled ambient conditions (380 ppm CO2; 20.9% O2). The two species with fastest half-closure time and the two species with slowest half-closure time had large stomata while the remaining three species had small stomata, implying that closing rate was not correlated with stomatal size in these species. Neither was response time correlated with stomatal density, phylogeny, functional group, or life strategy. Our results suggest that past atmospheric CO2 concentration during time of taxa diversification may influence stomatal response time. We show that species which last diversified under low or declining atmospheric CO2 concentration close stomata faster than species that last diversified in a high CO2 world. Low atmospheric [CO2] during taxa diversification may have placed a selection pressure on plants to accelerate stomatal closing to maintain adequate internal CO2 and optimize water use efficiency.
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Affiliation(s)
| | - Matthew Haworth
- Italian National Research Council, Institute of Tree and Timber IVALSARome, Italy
| | - Jon M. Yearsley
- Earth Institute, Science Centre East, School of Biology and Environmental Science, University College DublinDublin, Ireland
| | - Sven P. Batke
- Earth Institute, Science Centre East, School of Biology and Environmental Science, University College DublinDublin, Ireland
| | - Tracy Lawson
- School of Biological Science, University of EssexColchester, UK
| | - Jennifer C. McElwain
- Earth Institute, Science Centre East, School of Biology and Environmental Science, University College DublinDublin, Ireland
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21
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Affiliation(s)
- Tracy Lawson
- School of Biological Sciences, University of Essex, Colchester, CO4 3SQ, UK
| | - Jennifer C McElwain
- School of Biology and Environmental Science, The Earth Institute, O'Brien Centre for Science, University College Dublin, Belfield, Dublin 4, Ireland
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22
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McElwain JC, Yiotis C, Lawson T. Using modern plant trait relationships between observed and theoretical maximum stomatal conductance and vein density to examine patterns of plant macroevolution. New Phytol 2016; 209:94-103. [PMID: 26230251 PMCID: PMC5014202 DOI: 10.1111/nph.13579] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 06/27/2015] [Indexed: 05/04/2023]
Abstract
Understanding the drivers of geological-scale patterns in plant macroevolution is limited by a hesitancy to use measurable traits of fossils to infer palaeoecophysiological function. Here, scaling relationships between morphological traits including maximum theoretical stomatal conductance (gmax ) and leaf vein density (Dv ) and physiological measurements including operational stomatal conductance (gop ), saturated (Asat ) and maximum (Amax ) assimilation rates were investigated for 18 extant taxa in order to improve understanding of angiosperm diversification in the Cretaceous. Our study demonstrated significant relationships between gop , gmax and Dv that together can be used to estimate gas exchange and the photosynthetic capacities of fossils. We showed that acquisition of high gmax in angiosperms conferred a competitive advantage over gymnosperms by increasing the dynamic range (plasticity) of their gas exchange and expanding their ecophysiological niche space. We suggest that species with a high gmax (> 1400 mmol m(-2) s(-1) ) would have been capable of maintaining a high Amax as the atmospheric CO2 declined through the Cretaceous, whereas gymnosperms with a low gmax would experience severe photosynthetic penalty. Expansion of the ecophysiological niche space in angiosperms, afforded by coordinated evolution of high gmax , Dv and increased plasticity in gop , adds further functional insights into the mechanisms driving angiosperm speciation.
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Affiliation(s)
- Jennifer C. McElwain
- Earth InstituteO'Brien Centre for ScienceUniversity College DublinBelfieldIreland
- School of Biology and Environmental ScienceUniversity College DublinBelfieldIreland
| | - Charilaos Yiotis
- Earth InstituteO'Brien Centre for ScienceUniversity College DublinBelfieldIreland
- School of Biology and Environmental ScienceUniversity College DublinBelfieldIreland
| | - Tracy Lawson
- School of Biological ScienceUniversity of EssexColchesterCO4 3SQUK
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23
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Shinde S, Behpouri A, McElwain JC, Ng CKY. Genome-wide transcriptomic analysis of the effects of sub-ambient atmospheric oxygen and elevated atmospheric carbon dioxide levels on gametophytes of the moss, Physcomitrella patens. J Exp Bot 2015; 66:4001-12. [PMID: 25948702 PMCID: PMC4473992 DOI: 10.1093/jxb/erv197] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
It is widely accepted that atmospheric O2 has played a key role in the development of life on Earth, as evident from the coincidence between the rise of atmospheric O2 concentrations in the Precambrian and biological evolution. Additionally, it has also been suggested that low atmospheric O2 is one of the major drivers for at least two of the five mass-extinction events in the Phanerozoic. At the molecular level, our understanding of the responses of plants to sub-ambient O2 concentrations is largely confined to studies of the responses of underground organs, e.g. roots to hypoxic conditions. Oxygen deprivation often results in elevated CO2 levels, particularly under waterlogged conditions, due to slower gas diffusion in water compared to air. In this study, changes in the transcriptome of gametophytes of the moss Physcomitrella patens arising from exposure to sub-ambient O2 of 13% (oxygen deprivation) and elevated CO2 (1500 ppmV) were examined to further our understanding of the responses of lower plants to changes in atmospheric gaseous composition. Microarray analyses revealed that the expression of a large number of genes was affected under elevated CO2 (814 genes) and sub-ambient O2 conditions (576 genes). Intriguingly, the expression of comparatively fewer numbers of genes (411 genes) was affected under a combination of both sub-ambient O2 and elevated CO2 condition (low O2-high CO2). Overall, the results point towards the effects of atmospheric changes in CO2 and O2 on transcriptional reprogramming, photosynthetic regulation, carbon metabolism, and stress responses.
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Affiliation(s)
- Suhas Shinde
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Ali Behpouri
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Jennifer C McElwain
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
| | - Carl K-Y Ng
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland UCD Earth Institute, University College Dublin, Belfield, Dublin 4, Ireland
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Váry Z, Mullins E, McElwain JC, Doohan FM. The severity of wheat diseases increases when plants and pathogens are acclimatized to elevated carbon dioxide. Glob Chang Biol 2015; 21:2661-2669. [PMID: 25899718 DOI: 10.1111/gcb.12899] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Revised: 01/30/2015] [Accepted: 02/03/2015] [Indexed: 05/21/2023]
Abstract
Wheat diseases present a constant and evolving threat to food security. We have little understanding as to how increased atmospheric carbon dioxide levels will affect wheat diseases and thus the security of grain supply. Atmospheric CO2 exceeded the 400 ppmv benchmark in 2013 and is predicted to double or even treble by the end of the century. This study investigated the impact of both pathogen and wheat acclimation to elevated CO2 on the development of Fusarium head blight (FHB) and Septoria tritici blotch (STB) disease of wheat. Here, plants and pathogens were cultivated under either 390 or 780 ppmv CO2 for a period (two wheat generations, multiple pathogen subcultures) prior to standard disease trials. Acclimation of pathogens and the wheat cultivar Remus to elevated CO2 increased the severity of both STB and FHB diseases, relative to ambient conditions. The effect of CO2 on disease development was greater for FHB than for STB. The highest FHB disease levels and associated yield losses were recorded for elevated CO2 -acclimated pathogen on elevated CO2 -acclimated wheat. When similar FHB experiments were conducted using the disease-resistant cultivar CM82036, pathogen acclimation significantly enhanced disease levels and yield loss under elevated CO2 conditions, thereby indicating a reduction in the effectiveness of the defence pathways innate to this wheat cultivar. We conclude that acclimation to elevated CO2 over the coming decades will have a significant influence on the outcome of plant-pathogen interactions and the durability of disease resistance.
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Affiliation(s)
- Zsolt Váry
- UCD Earth Institute and School of Biology and Environmental Science, College of Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Ewen Mullins
- Teagasc Crops Research Centre, Oakpark, Co., Carlow, Ireland
| | - Jennifer C McElwain
- UCD Earth Institute and School of Biology and Environmental Science, College of Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Fiona M Doohan
- UCD Earth Institute and School of Biology and Environmental Science, College of Science, University College Dublin, Belfield, Dublin 4, Ireland
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Porter AS, Evans-Fitz.Gerald C, McElwain JC, Yiotis C, Elliott-Kingston C. How well do you know your growth chambers? Testing for chamber effect using plant traits. Plant Methods 2015; 11:44. [PMID: 26396588 PMCID: PMC4578792 DOI: 10.1186/s13007-015-0088-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 09/10/2015] [Indexed: 05/05/2023]
Abstract
BACKGROUND Plant growth chambers provide a controlled environment to analyse the effects of environmental parameters (light, temperature, atmospheric gas composition etc.) on plant function. However, it has been shown that a 'chamber effect' may exist whereby results observed are not due to an experimental treatment but to inconspicuous differences in supposedly identical chambers. In this study, Vicia faba L. 'Aquadulce Claudia' (broad bean) plants were grown in eight walk-in chambers to establish if a chamber effect existed, and if so, what plant traits are best for detecting such an effect. A range of techniques were used to measure differences between chamber plants, including chlorophyll fluorescence measurements, gas exchange analysis, biomass, reproductive yield, anatomical traits and leaf stable carbon isotopes. RESULTS AND DISCUSSION Four of the eight chambers exhibited a chamber effect. In particular, we identified two types of chamber effect which we term 'resolvable' or 'unresolved'; a resolvable chamber effect is caused by malfunctioning components of a chamber and an unresolved chamber effect is caused by unknown factors that can only be mitigated by appropriate experimental design and sufficient replication. Not all measured plant traits were able to detect a chamber effect and no single trait was capable of detecting all chamber effects. Fresh weight and flower count detected a chamber effect in three chambers, stable carbon isotopes (δ(13)C) and net rate CO2 assimilation (An) identified a chamber effect in two chambers, stomatal conductance (gs) and total performance index detected an effect only in one chamber. CONCLUSION (1) Chamber effects can be adequately detected by fresh weight measurements and flower counts on Vicia faba plants. These methods were the most effective in terms of detection and most efficient in terms of time. (2) δ(13)C, gs and An measurements help distinguish between resolvable and unresolved chamber effects. (3) Unresolved chamber effects require experimental unit replication while resolvable chamber effects require investigation, repair and retesting in advance of initiating further experiments.
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Affiliation(s)
- Amanda S. Porter
- School of Biology and Environmental Science, Earth Institute, O’Brien Centre for Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Christiana Evans-Fitz.Gerald
- School of Biology and Environmental Science, Earth Institute, O’Brien Centre for Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Jennifer C. McElwain
- School of Biology and Environmental Science, Earth Institute, O’Brien Centre for Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Charilaos Yiotis
- School of Biology and Environmental Science, Earth Institute, O’Brien Centre for Science, University College Dublin, Belfield, Dublin 4, Ireland
| | - Caroline Elliott-Kingston
- School of Biology and Environmental Science, Earth Institute, O’Brien Centre for Science, University College Dublin, Belfield, Dublin 4, Ireland
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Barclay RS, McElwain JC, Duckett JG, van Es MH, Mostaert AS, Pressel S, Sageman BB. New methods reveal oldest known fossil epiphyllous moss: Bryiidites utahensis gen. et sp. nov. (Bryidae). Am J Bot 2013; 100:2450-2457. [PMID: 24302691 DOI: 10.3732/ajb.1300209] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
PREMISE OF THE STUDY Epiphyllous bryophytes are a highly characteristic feature of many humid tropical forest ecosystems. In contrast to the extensive fossil record for the leaves of their host plants, the record is virtually nonexistent for the epiphylls themselves, despite a fossil record for mosses that begins in the Middle Carboniferous Period, 330 million years ago. METHODS Epifluorescence optical microscopy, scanning electron microscopy, and atomic force microscopy were employed to investigate an intimate association between a newly discovered epiphyllous moss and a Lauraceae plant host from the middle Cretaceous. KEY RESULTS We describe the oldest fossil specimen of an epiphyllous moss, Bryiidites utahensis gen. et sp. nov., identified from an individual specimen only 450 µm long, situated on an approximately one millimeter square fossil leaf fragment. The moss epiphyll is exquisitely preserved as germinating spores and short-celled protonemata with transverse and oblique cross-walls closely matching those of extant epiphyllous mosses on the surface of the plant-leaf hosts. CONCLUSIONS The extension of the epiphyll record back to the middle Cretaceous provides fossil evidence for the appearance of epiphyllous mosses during the diversification of flowering plants, at least 95 million years ago. It also provides substantive evidence for a tropical maritime climate in central North America during the middle Cretaceous.
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Affiliation(s)
- Richard S Barclay
- Northwestern University, Department of Earth & Planetary Sciences, Technological Institute, 2145 Sheridan Road, Evanston, Illinois 60208-3130 USA
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Haworth M, Elliott-Kingston C, McElwain JC. Co-ordination of physiological and morphological responses of stomata to elevated [CO2] in vascular plants. Oecologia 2013. [PMID: 22810089 DOI: 10.1007/s00442-012-24069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Plant stomata display a wide range of short-term behavioural and long-term morphological responses to atmospheric carbon dioxide concentration ([CO(2)]). The diversity of responses suggests that plants may have different strategies for controlling gas exchange, yet it is not known whether these strategies are co-ordinated in some way. Here, we test the hypothesis that there is co-ordination of physiological (via aperture change) and morphological (via stomatal density change) control of gas exchange by plants. We examined the response of stomatal conductance (G(s)) to instantaneous changes in external [CO(2)] (C(a)) in an evolutionary cross-section of vascular plants grown in atmospheres of elevated [CO(2)] (1,500 ppm) and sub-ambient [O(2)] (13.0 %) compared to control conditions (380 ppm CO(2), 20.9 % O(2)). We found that active control of stomatal aperture to [CO(2)] above current ambient levels was not restricted to angiosperms, occurring in the gymnosperms Lepidozamia peroffskyana and Nageia nagi. The angiosperm species analysed appeared to possess a greater respiratory demand for stomatal movement than gymnosperm species displaying active stomatal control. Those species with little or no control of stomatal aperture (termed passive) to C(a) were more likely to exhibit a reduction in stomatal density than species with active stomatal control when grown in atmospheres of elevated [CO(2)]. The relationship between the degree of stomatal aperture control to C(a) above ambient and the extent of any reduction in stomatal density may suggest the co-ordination of physiological and morphological responses of stomata to [CO(2)] in the optimisation of water use efficiency. This trade-off between stomatal control strategies may have developed due to selective pressures exerted by the costs associated with passive and active stomatal control.
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Mander L, Wesseln CJ, McElwain JC, Punyasena SW. Tracking taphonomic regimes using chemical and mechanical damage of pollen and spores: an example from the Triassic-Jurassic mass extinction. PLoS One 2012; 7:e49153. [PMID: 23145104 PMCID: PMC3492321 DOI: 10.1371/journal.pone.0049153] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2012] [Accepted: 10/09/2012] [Indexed: 11/18/2022] Open
Abstract
The interpretation of biotic changes in the geological past relies on the assumption that samples from different time intervals represent an equivalent suite of natural sampling conditions. As a result, detailed investigations of taphonomic regimes during intervals of major biotic upheaval, such as mass extinctions, are crucial. In this paper, we have used variations in the frequency of chemical and mechanical sporomorph (pollen and spore) damage as a guide to taphonomic regimes across the Triassic-Jurassic mass extinction (Tr-J; ∼201.3 Ma) at a boundary section at Astartekløft, East Greenland. We find that the frequency of sporomorph damage is extremely variable in samples from this locality. This likely reflects a combination of taxon-specific susceptibility to damage and the mixing of sporomorphs from a mosaic of environments and taphonomic regimes. The stratigraphic interval containing evidence of plant extinction and compositional change in the source vegetation at Astartekløft is not marked by a consistent rise or fall in the frequency of sporomorph damage. This indicates that natural taphonomic regimes did not shift radically during this critical interval. We find no evidence of a consistent relationship between the taxonomic richness of sporomorph assemblages and the frequency of damage among sporomorphs at Astartekløft. This indicates that previously reported patterns of sporomorph richness across the Tr-J at this locality are likely to be robust. Taken together, our results suggest that the patterns of vegetation change at Astartekløft represent a real biological response to environmental change at the Tr-J.
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Affiliation(s)
- Luke Mander
- Department of Plant Biology, University of Illinois, Urbana, Illinois, United States of America.
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Haworth M, Elliott-Kingston C, McElwain JC. Co-ordination of physiological and morphological responses of stomata to elevated [CO2] in vascular plants. Oecologia 2012; 171:71-82. [PMID: 22810089 DOI: 10.1007/s00442-012-2406-9] [Citation(s) in RCA: 74] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Accepted: 06/19/2012] [Indexed: 10/28/2022]
Abstract
Plant stomata display a wide range of short-term behavioural and long-term morphological responses to atmospheric carbon dioxide concentration ([CO(2)]). The diversity of responses suggests that plants may have different strategies for controlling gas exchange, yet it is not known whether these strategies are co-ordinated in some way. Here, we test the hypothesis that there is co-ordination of physiological (via aperture change) and morphological (via stomatal density change) control of gas exchange by plants. We examined the response of stomatal conductance (G(s)) to instantaneous changes in external [CO(2)] (C(a)) in an evolutionary cross-section of vascular plants grown in atmospheres of elevated [CO(2)] (1,500 ppm) and sub-ambient [O(2)] (13.0 %) compared to control conditions (380 ppm CO(2), 20.9 % O(2)). We found that active control of stomatal aperture to [CO(2)] above current ambient levels was not restricted to angiosperms, occurring in the gymnosperms Lepidozamia peroffskyana and Nageia nagi. The angiosperm species analysed appeared to possess a greater respiratory demand for stomatal movement than gymnosperm species displaying active stomatal control. Those species with little or no control of stomatal aperture (termed passive) to C(a) were more likely to exhibit a reduction in stomatal density than species with active stomatal control when grown in atmospheres of elevated [CO(2)]. The relationship between the degree of stomatal aperture control to C(a) above ambient and the extent of any reduction in stomatal density may suggest the co-ordination of physiological and morphological responses of stomata to [CO(2)] in the optimisation of water use efficiency. This trade-off between stomatal control strategies may have developed due to selective pressures exerted by the costs associated with passive and active stomatal control.
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Affiliation(s)
- Jennifer C McElwain
- School of Biology and Environmental Science, University College Dublin, Ireland.
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Affiliation(s)
- Matthew Haworth
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland.
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Haworth M, Elliott-Kingston C, McElwain JC. The stomatal CO2 proxy does not saturate at high atmospheric CO2 concentrations: evidence from stomatal index responses of Araucariaceae conifers. Oecologia 2011; 167:11-9. [DOI: 10.1007/s00442-011-1969-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Accepted: 03/08/2011] [Indexed: 10/18/2022]
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Abstract
Metazoan diversification occurred during a time when atmospheric oxygen levels fluctuated between 15 and 30%. The hypoxia-inducible factor (HIF) is a primary regulator of the adaptive transcriptional response to hypoxia. Although the HIF pathway is highly conserved, its complexity increased during periods when atmospheric oxygen concentrations were increasing. Thus atmospheric oxygen levels may have provided a selection force on the development of cellular oxygen-sensing pathways.
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Affiliation(s)
- Cormac T Taylor
- UCD Conway Institute, Systems Biology Ireland and School of Medicine and Medical Science, University College Dublin, Belfield, Dublin, Ireland.
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Haworth M, Gallagher A, Elliott-Kingston C, Raschi A, Marandola D, McElwain JC. Stomatal index responses of Agrostis canina to CO2 and sulphur dioxide: implications for palaeo-[CO2] using the stomatal proxy. New Phytol 2010; 188:845-855. [PMID: 20704659 DOI: 10.1111/j.1469-8137.2010.03403.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
• Stomatal index values of fossil plants are widely used in reconstructing palaeo-[CO(2)]. This depends upon the assumption that the stomatal index is determined by the atmospheric concentration of CO(2) ([CO(2)]). This study investigates whether fumigation with, and resistance to, sulphur dioxide (SO(2)) induces a reduction in the stomatal index that may affect stomatal reconstructions of palaeo-[CO(2)] coinciding with episodes of global-scale volcanism. • Agrostis canina from Mefite di Ansanto, Italy, grow in atmospheres of elevated-[CO(2)], SO(2) and hydrogen sulphide (H(2)S). Mefite A. canina were compared with a control population in a 'common-garden' experiment and a controlled-environment study under elevated-[CO(2)] and SO(2) fumigation. • In A. canina, resistance to toxic volcanic gases is not associated with reduced stomatal index, and fumigation with SO(2) does not cause a decrease in stomatal initiation. The two populations of A. canina analyzed in this study exhibit different stomatal index-[CO(2)] 'responses', with control plants showing a reduction in stomatal index and Mefite plants showing no response. • Stomatal reconstructions of palaeo-[CO(2)] during past episodes of global-scale volcanism probably reflect atmospheric [CO(2)] and not [SO(2)]. The lack of a reduction in the stomatal index in response to elevated [CO(2)] in the Mefite plants, suggests that resistance to toxic gases and/or long-term growth at high [CO(2)] reduces, or negates, sensitivity of the stomatal index-[CO(2)] relationship, or that stomatal index-[CO(2)] in the Mefite plants is attuned to [CO(2)] fluctuations at much higher concentrations.
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Affiliation(s)
- Matthew Haworth
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland.
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Belcher CM, Mander L, Rein G, Jervis FX, Haworth M, Hesselbo SP, Glasspool IJ, McElwain JC. Increased fire activity at the Triassic/Jurassic boundary in Greenland due to climate-driven floral change. Nature Geosci 2010. [PMID: 0 DOI: 10.1038/ngeo871] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
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Haworth M, Heath J, McElwain JC. Differences in the response sensitivity of stomatal index to atmospheric CO2 among four genera of Cupressaceae conifers. Ann Bot 2010; 105:411-8. [PMID: 20089556 PMCID: PMC2826259 DOI: 10.1093/aob/mcp309] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2009] [Revised: 11/05/2009] [Accepted: 12/03/2009] [Indexed: 05/07/2023]
Abstract
BACKGROUND AND AIMS The inverse relationship between stomatal density (SD: number of stomata per mm(2) leaf area) and atmospheric concentration of CO2 ([CO2]) permits the use of plants as proxies of palaeo-atmospheric CO2. Many stomatal reconstructions of palaeo-[CO2] are based upon multiple fossil species. However, it is unclear how plants respond to [CO2] across genus, family or ecotype in terms of SD or stomatal index (SI: ratio of stomata to epidermal cells). This study analysed the stomatal numbers of conifers from the ancient family Cupressaceae, in order to examine the nature of the SI-[CO2] relationship, and potential implications for stomatal reconstructions of palaeo-[CO2]. Methods Stomatal frequency measurements were taken from historical herbarium specimens of Athrotaxis cupressoides, Tetraclinis articulata and four Callitris species, and live A. cupressoides grown under CO2-enrichment (370, 470, 570 and 670 p.p.m. CO2). KEY RESULTS T. articulata, C. columnaris and C. rhomboidea displayed significant reductions in SI with rising [CO2]; by contrast, A. cupressoides, C. preissii and C. oblonga show no response in SI. However, A. cupressoides does reduce SI to increases in [CO2] above current ambient (approx. 380 p.p.m. CO2). This dataset suggests that a shared consistent SI-[CO2] relationship is not apparent across the genus Callitris. Conclusions The present findings suggest that it is not possible to generalize how conifer species respond to fluctuations in [CO2] based upon taxonomic relatedness or habitat. This apparent lack of a consistent response, in conjunction with high variability in SI, indicates that reconstructions of absolute palaeo-[CO2] based at the genus level, or upon multiple species for discrete intervals of time are not as reliable as those based on a single or multiple temporally overlapping species.
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Affiliation(s)
- Matthew Haworth
- School of Biology & Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland.
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Affiliation(s)
- Jennifer C McElwain
- UCD School of Biology and Environmental Science, University College Dublin, National University of Ireland, Belfield, Dublin 4, Ireland.
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McElwain JC. 70 MILLION YEARS OF VEGETATION DYNAMICS. DIVERS DISTRIB 2008. [DOI: 10.1111/j.1472-4642.2000.00073.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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Abstract
* Variation in the size and shape (physiognomy) of leaves has long been correlated to climate, and paleobotanists have used these correlations to reconstruct paleo-climate. Most studies focus on site-level means of largely nonoverlapping species sets. The sensitivity of leaf shape to climate within species is poorly known, which limits our general understanding of leaf-climate relationships and the value of intraspecific patterns for paleoclimate reconstructions. * The leaf physiognomy of two species whose native North American ranges span large climatic gradients (Acer rubrum and Quercus kelloggii) was quantified and correlated to mean annual temperature (MAT). Quercus kelloggii was sampled across a wide elevation range, but A. rubrum was sampled in strictly lowland areas. * Within A. rubrum, leaf shape correlates with MAT in a manner that is largely consistent with previous site-level studies; leaves from cold climates are toothier and more highly dissected. By contrast, Q. kelloggii is largely insensitive to MAT; instead, windy conditions with ample plant-available water may explain the preponderance of small teeth at high elevation sites, independent of MAT. * This study highlights the strong correspondence between leaf form and climate within some species, and demonstrates that intraspecific patterns may contribute useful information towards reconstructing paleoclimate.
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Affiliation(s)
- Dana L Royer
- Department of Earth and Environmental Sciences, Wesleyan University, Middletown, CT 06459, USA
| | - Jennifer C McElwain
- UCD School of Biology and Environmental Science, University College Dublin, Belfield Dublin 4, Ireland
| | - Jonathan M Adams
- Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA
| | - Peter Wilf
- Department of Geosciences, Pennsylvania State University, University Park, PA 16802, USA
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McElwain JC, Punyasena SW. Mass extinction events and the plant fossil record. Trends Ecol Evol 2007; 22:548-57. [PMID: 17919771 DOI: 10.1016/j.tree.2007.09.003] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2006] [Revised: 07/13/2007] [Accepted: 09/25/2007] [Indexed: 11/26/2022]
Abstract
Five mass extinction events have punctuated the geological record of marine invertebrate life. They are characterized by faunal extinction rates and magnitudes that far exceed those observed elsewhere in the geological record. Despite compelling evidence that these extinction events were probably driven by dramatic global environmental change, they were originally thought to have little macroecological or evolutionary consequence for terrestrial plants. New high-resolution regional palaeoecological studies are beginning to challenge this orthodoxy, providing evidence for extensive ecological upheaval, high species-level turnover and recovery intervals lasting millions of years. The challenge ahead is to establish the geographical extent of the ecological upheaval, because reconstructing the vegetation dynamics associated with these events will elucidate the role of floral change in faunal mass extinction and provide a better understanding of how plants have historically responded to global environmental change similar to that anticipated for our future.
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Affiliation(s)
- Jennifer C McElwain
- School of Biology and Environmental Science, University College Dublin, Belfield, Dublin 4, Ireland.
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McElwain JC, Wade-Murphy J, Hesselbo SP. Changes in carbon dioxide during an oceanic anoxic event linked to intrusion into Gondwana coals. Nature 2005; 435:479-82. [PMID: 15917805 DOI: 10.1038/nature03618] [Citation(s) in RCA: 354] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Accepted: 03/24/2005] [Indexed: 11/09/2022]
Abstract
The marine sedimentary record exhibits evidence for episodes of enhanced organic carbon burial known as 'oceanic anoxic events' (OAEs). They are characterized by carbon-isotope excursions in marine and terrestrial reservoirs and mass extinction of marine faunas. Causal mechanisms for the enhancement of organic carbon burial during OAEs are still debated, but it is thought that such events should draw down significant quantities of atmospheric carbon dioxide. In the case of the Toarcian OAE (approximately 183 million years ago), a short-lived negative carbon-isotope excursion in oceanic and terrestrial reservoirs has been interpreted to indicate raised atmospheric carbon dioxide caused by oxidation of methane catastrophically released from either marine gas hydrates or magma-intruded organic-rich rocks. Here we test these two leading hypotheses for a negative carbon isotopic excursion marking the initiation of the Toarcian OAE using a high-resolution atmospheric carbon dioxide record obtained from fossil leaf stomatal frequency. We find that coincident with the negative carbon-isotope excursion carbon dioxide is first drawn down by 350 +/- 100 p.p.m.v. and then abruptly elevated by 1,200 +/- 400 p.p.m.v, and infer a global cooling and greenhouse warming of 2.5 +/- 0.1 degrees C and 6.5 +/- 1 degrees C, respectively. The pattern and magnitude of carbon dioxide change are difficult to reconcile with catastrophic input of isotopically light methane from hydrates as the cause of the negative isotopic signal. Our carbon dioxide record better supports a magma-intrusion hypothesis, and suggests that injection of isotopically light carbon from the release of thermogenic methane occurred owing to the intrusion of Gondwana coals by Toarcian-aged Karoo-Ferrar dolerites.
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Affiliation(s)
- Jennifer C McElwain
- Department of Geology, The Field Museum, 1400 S. Lake Shore Drive, Chicago, Illinois 60605-2496, USA
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Kouwenberg LLR, McElwain JC, Kürschner WM, Wagner F, Beerling DJ, Mayle FE, Visscher H. Stomatal frequency adjustment of four conifer species to historical changes in atmospheric CO2. Am J Bot 2003; 90:610-619. [PMID: 21659156 DOI: 10.3732/ajb.90.4.610] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The species-specific inverse relation between atmospheric CO(2) concentration and stomatal frequency for many woody angiosperm species is being used increasingly with fossil leaves to reconstruct past atmospheric CO(2) levels. To extend our limited knowledge of the responsiveness of conifer needles to CO(2) fluctuations, the stomatal frequency response of four native North American conifer species (Tsuga heterophylla, Picea glauca, Picea mariana, and Larix laricina) to a range of historical CO(2) mixing ratios (290 to 370 ppmV) was analyzed. Because of the specific mode of leaf development and the subsequent stomatal patterning in conifer needles, the stomatal index of these species was not affected by CO(2). In contrast, a new measure of stomatal frequency, based on the number of stomata per millimeter of needle length, decreased significantly with increasing CO(2). For Tsuga heterophylla, the stomatal frequency response to CO(2) changes in the last century is validated through assessment of the influence of other biological and environmental variables. Because of their sensitive response to CO(2), combined with a high preservation capacity, fossil needles of Tsuga heterophylla, Picea glauca, P. mariana, and Larix laricina have great potential for detecting and quantifying past atmospheric CO(2) fluctuations.
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Affiliation(s)
- Lenny L R Kouwenberg
- Laboratory of Palaeobotany and Palynology, Utrecht University, 3584 CD Utrecht, Netherlands
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Abstract
The Triassic-Jurassic boundary marks a major faunal mass extinction, but records of accompanying environmental changes are limited. Paleobotanical evidence indicates a fourfold increase in atmospheric carbon dioxide concentration and suggests an associated 3 degrees to 4 degrees C "greenhouse" warming across the boundary. These environmental conditions are calculated to have raised leaf temperatures above a highly conserved lethal limit, perhaps contributing to the >95 percent species-level turnover of Triassic-Jurassic megaflora.
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Affiliation(s)
- JC McElwain
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK
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