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Zotz G, Andrade JL, Einzmann HJR. CAM plants: their importance in epiphyte communities and prospects with global change. ANNALS OF BOTANY 2023; 132:685-698. [PMID: 36617243 PMCID: PMC10799991 DOI: 10.1093/aob/mcac158] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 12/08/2022] [Accepted: 12/15/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND AND SCOPE The epiphytic life form characterizes almost 10 % of all vascular plants. Defined by structural dependence throughout their life and their non-parasitic relationship with the host, the term epiphyte describes a heterogeneous and taxonomically diverse group of plants. This article reviews the importance of crassulacean acid metabolism (CAM) among epiphytes in current climatic conditions and explores the prospects under global change. RESULTS AND CONCLUSIONS We question the view of a disproportionate importance of CAM among epiphytes and its role as a 'key innovation' for epiphytism but do identify ecological conditions in which epiphytic existence seems to be contingent on the presence of this photosynthetic pathway. Possibly divergent responses of CAM and C3 epiphytes to future changes in climate and land use are discussed with the help of experimental evidence, current distributional patterns and the results of several long-term descriptive community studies. The results and their interpretation aim to stimulate a fruitful discussion on the role of CAM in epiphytes in current climatic conditions and in altered climatic conditions in the future.
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Affiliation(s)
- Gerhard Zotz
- Functional Ecology Group, Institute of Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Box 5634, D-26046 Oldenburg, Germany
- Smithsonian Tropical Research Institute, Box 0843-03092, Panama, Republic of Panama
| | - José Luis Andrade
- Unidad de Recursos Naturales, Centro de Investigación Científica de Yucatán, Calle 43 No. 130, Chuburná de Hidalgo, Mérida, Yucatán, Mexico
| | - Helena J R Einzmann
- Functional Ecology Group, Institute of Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, Box 5634, D-26046 Oldenburg, Germany
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2
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Young SNR, Dunning LT, Liu H, Stevens CJ, Lundgren MR. C4 trees have a broader niche than their close C3 relatives. JOURNAL OF EXPERIMENTAL BOTANY 2022; 73:3189-3204. [PMID: 35293994 PMCID: PMC9126736 DOI: 10.1093/jxb/erac113] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Accepted: 03/12/2022] [Indexed: 06/14/2023]
Abstract
Previous studies have demonstrated the ecological sorting of herbaceous C3 and C4 species along gradients of precipitation and temperature: C4 herbaceous species typically occupy drier and warmer environments than their C3 relatives. However, it is unclear if this pattern holds true for C4 tree species, which are unique to Euphorbiaceae and found only on the Hawaiian Islands. Here, we combine occurrence data with local environmental and soil datasets to, for the first time, distinguish the ecological factors associated with photosynthetic diversification in the tree life form. These data are presented within a phylogenetic framework. We show that C3 and C4 trees inhabit similar environments, but that C4 photosynthesis expands the ecological niche in trees relative to that of C3 tree species. In particular, when compared with C3 trees, C4 trees moved into higher elevation habitats with characteristically sparse vegetation (and thus greater sunlight) and cooler temperatures, a pattern which contrasts with that of herbaceous species. Understanding the relationship between C4 photosynthesis and ecological niche in tree species has implications for establishing how C4 photosynthesis has, in this rare instance, evolved in trees, and whether this unique combination of traits could be exploited from an engineering perspective.
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Affiliation(s)
- Sophie N R Young
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
| | - Luke T Dunning
- Ecology and Evolutionary Biology, School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Hui Liu
- Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, Xingke Road 723, Guangzhou 510650, China
| | - Carly J Stevens
- Lancaster Environment Centre, Lancaster University, Lancaster LA1 4YQ, UK
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3
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Yardeni G, Viruel J, Paris M, Hess J, Groot Crego C, de La Harpe M, Rivera N, Barfuss MHJ, Till W, Guzmán-Jacob V, Krömer T, Lexer C, Paun O, Leroy T. Taxon-specific or universal? Using target capture to study the evolutionary history of rapid radiations. Mol Ecol Resour 2021; 22:927-945. [PMID: 34606683 PMCID: PMC9292372 DOI: 10.1111/1755-0998.13523] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 09/09/2021] [Accepted: 09/22/2021] [Indexed: 12/20/2022]
Abstract
Target capture has emerged as an important tool for phylogenetics and population genetics in nonmodel taxa. Whereas developing taxon‐specific capture probes requires sustained efforts, available universal kits may have a lower power to reconstruct relationships at shallow phylogenetic scales and within rapidly radiating clades. We present here a newly developed target capture set for Bromeliaceae, a large and ecologically diverse plant family with highly variable diversification rates. The set targets 1776 coding regions, including genes putatively involved in key innovations, with the aim to empower testing of a wide range of evolutionary hypotheses. We compare the relative power of this taxon‐specific set, Bromeliad1776, to the universal Angiosperms353 kit. The taxon‐specific set results in higher enrichment success across the entire family; however, the overall performance of both kits to reconstruct phylogenetic trees is relatively comparable, highlighting the vast potential of universal kits for resolving evolutionary relationships. For more detailed phylogenetic or population genetic analyses, for example the exploration of gene tree concordance, nucleotide diversity or population structure, the taxon‐specific capture set presents clear benefits. We discuss the potential lessons that this comparative study provides for future phylogenetic and population genetic investigations, in particular for the study of evolutionary radiations.
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Affiliation(s)
- Gil Yardeni
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | | | - Margot Paris
- Unit of Ecology & Evolution, Department of Biology, University of Fribourg, Fribourg, Switzerland
| | - Jaqueline Hess
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.,Department of Soil Ecology, Helmholtz Centre for Environmental Research, UFZ, Halle (Saale), Germany
| | - Clara Groot Crego
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria.,Vienna Graduate School of Population Genetics, Vienna, Austria
| | - Marylaure de La Harpe
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Norma Rivera
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Michael H J Barfuss
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Walter Till
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Valeria Guzmán-Jacob
- Biodiversity, Macroecology and Biogeography, University of Goettingen, Göttingen, Germany
| | - Thorsten Krömer
- Centro de Investigaciones Tropicales, Universidad Veracruzana, Xalapa, Mexico
| | - Christian Lexer
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Ovidiu Paun
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
| | - Thibault Leroy
- Department of Botany and Biodiversity Research, University of Vienna, Vienna, Austria
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4
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Chang H, Zhang L, Xie H, Liu J, Xi Z, Xu X. The Conservation of Chloroplast Genome Structure and Improved Resolution of Infrafamilial Relationships of Crassulaceae. FRONTIERS IN PLANT SCIENCE 2021; 12:631884. [PMID: 34276716 PMCID: PMC8281817 DOI: 10.3389/fpls.2021.631884] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2020] [Accepted: 06/10/2021] [Indexed: 06/04/2023]
Abstract
Crassulaceae are the largest family in the angiosperm order Saxifragales. Species of this family are characterized by succulent leaves and a unique photosynthetic pathway known as Crassulacean acid metabolism (CAM). Although the inter- and intrageneric relationships have been extensively studied over the last few decades, the infrafamilial relationships of Crassulaceae remain partially obscured. Here, we report nine newly sequenced chloroplast genomes, which comprise several key lineages of Crassulaceae. Our comparative analyses and positive selection analyses of Crassulaceae species indicate that the overall gene organization and function of the chloroplast genome are highly conserved across the family. No positively selected gene was statistically supported in Crassulaceae lineage using likelihood ratio test (LRT) based on branch-site models. Among the three subfamilies of Crassulaceae, our phylogenetic analyses of chloroplast protein-coding genes support Crassuloideae as sister to Kalanchoideae plus Sempervivoideae. Furthermore, within Sempervivoideae, our analyses unambiguously resolved five clades that are successively sister lineages, i.e., Telephium clade, Sempervivum clade, Aeonium clade, Leucosedum clade, and Acre clade. Overall, this study enhances our understanding of the infrafamilial relationships and the conservation of chloroplast genomes within Crassulaceae.
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Affiliation(s)
- Hong Chang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Lei Zhang
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Huanhuan Xie
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Jianquan Liu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
- State Key Laboratory of Grassland Agro-Ecosystems, College of Life Sciences, Lanzhou University, Lanzhou, China
| | - Zhenxiang Xi
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
| | - Xiaoting Xu
- Key Laboratory of Bio-Resource and Eco-Environment of Ministry of Education, College of Life Sciences, Sichuan University, Chengdu, China
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5
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Melo EA, Waechter JL. Beta diversity patterns of Bromeliaceae growing on rocky cliffs within the Atlantic Forest in southern Brazil. BIOTA NEOTROPICA 2020. [DOI: 10.1590/1676-0611-bn-2019-0846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Abstract: In recent years there has been increasing attention in patterns of β-diversity and mechanisms related to variations in species composition. In this study, we evaluated beta diversity patterns of bromeliads growing on cliffs immersed in Atlantic Forest. We hypothesized that the species composition varies according to the spatial scale, inferring that there is a replacement of species influenced mainly by environmental factors. The study was carried out on sandstone cliffs included in contiguous but distinct vegetation formations: Evergreen and Seasonal forests. Twenty-four vertical rocky outcrops were sampled. The spatial variation in species composition was evaluated by two β-diversity components, turnover and nestedness. Multivariate analysis and variation partitioning were performed to distinguish niche and stochastic processes. We recorded 26 bromeliad species and a significantly higher contribution of turnover explaining beta diversity. Environmental factors affect β-diversity patterns of Bromeliaceae. However, individually, the environmental predictors do not explain the data variation. Environmental variations spatially structured, and spatial variables determinate the dissimilarity in the composition of bromeliads on cliffs. Thus, our results revealed that both environmental and spatial effects can act together to define the floristic composition of rock-dwelling bromeliad communities.
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6
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Burress ED, Tan M, Wainwright PC. Head Shape Modulates Diversification of a Classic Cichlid Pharyngeal Jaw Innovation. Am Nat 2019; 194:693-706. [PMID: 31613667 DOI: 10.1086/705392] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Functional innovations are often invoked to explain the uneven distribution of ecological diversity. Innovations may provide access to new adaptive zones by expanding available ecological opportunities and may serve as catalysts of adaptive radiation. However, diversity is often unevenly distributed within clades that share a key innovation, highlighting the possibility that the impact of the innovation is mediated by other traits. Pharyngognathy is a widely recognized innovation of the pharyngeal jaws that enhances the ability to process hard and tough prey in several major radiations of fishes, including marine wrasses and freshwater cichlids. We explored diversification of lower pharyngeal jaw shape, a key feature of pharyngognathy, and the extent to which it is influenced by head shape in Neotropical cichlids. While pharyngeal jaw shape was unaffected by either head length or head depth, its disparity declined dramatically with increasing head width. Head width also predicted the rate of pharyngeal jaw evolution such that higher rates were associated with narrow heads. Wide heads are associated with exploiting prey that require intense processing by pharyngeal jaws that have expanded surfaces for the attachment of enlarged muscles. However, we show that a wide head constrains access to adaptive peaks associated with several trophic roles. A constraint on the independent evolution of pharyngeal jaw and head shape may explain the uneven distribution of ecological diversity within a clade that shares a major functional innovation.
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7
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Niechayev NA, Pereira PN, Cushman JC. Understanding trait diversity associated with crassulacean acid metabolism (CAM). CURRENT OPINION IN PLANT BIOLOGY 2019; 49:74-85. [PMID: 31284077 DOI: 10.1016/j.pbi.2019.06.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 05/30/2019] [Accepted: 06/04/2019] [Indexed: 06/09/2023]
Abstract
Crassulacean acid metabolism (CAM) is a specialized mode of photosynthesis that exploits a temporal CO2 pump with nocturnal CO2 uptake and concentration to reduce photorespiration, improve water-use efficiency (WUE), and optimize the adaptability of plants to climates with seasonal or intermittent water limitations. CAM plants display a plastic continuum in the extent to which species engage in net nocturnal CO2 uptake that ranges from 0 to 100%. CAM plants also display diverse enzyme and organic acid and carbohydrate storage systems, which likely reflect the multiple, independent evolutionary origins of CAM. CAM is often accompanied by a diverse set of anatomical traits, such as tissue succulence and water-storage and water-capture strategies to attenuate drought. Other co-adaptive traits, such as thick cuticles, epicuticular wax, low stomatal density, high stomatal responsiveness, and shallow rectifier-like roots limit water loss under conditions of water deficit. Recommendations for future research efforts to better explore and understand the diversity of traits associated with CAM and CAM Biodesign efforts are presented.
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Affiliation(s)
- Nicholas A Niechayev
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557-0330, United States
| | - Paula N Pereira
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557-0330, United States
| | - John C Cushman
- Department of Biochemistry and Molecular Biology, University of Nevada, Reno, Reno, NV 89557-0330, United States.
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8
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Gianoli E, Torres-Díaz C, Ruiz E, Salgado-Luarte C, Molina-Montenegro MA, Saldaña A, Ríos RS. Woody climbers show greater population genetic differentiation than trees: Insights into the link between ecological traits and diversification. Evolution 2016; 70:2736-2745. [DOI: 10.1111/evo.13073] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Revised: 09/12/2016] [Accepted: 09/12/2016] [Indexed: 11/27/2022]
Affiliation(s)
- Ernesto Gianoli
- Departamento de Biología; Universidad de La Serena; Casilla 554 La Serena Chile
- Departamento de Botánica; Universidad de Concepción; Concepción Chile
| | | | - Eduardo Ruiz
- Departamento de Botánica; Universidad de Concepción; Concepción Chile
| | | | - Marco A. Molina-Montenegro
- Instituto de Ciencias Biológicas; Universidad de Talca; Talca Chile
- Centro de Estudios Avanzados en Zonas Áridas (CEAZA); La Serena Chile
| | - Alfredo Saldaña
- Departamento de Botánica; Universidad de Concepción; Concepción Chile
| | - Rodrigo S. Ríos
- Departamento de Biología; Universidad de La Serena; Casilla 554 La Serena Chile
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9
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Aguirre-Santoro J, Michelangeli FA, Stevenson DW. Molecular phylogenetics of the Ronnbergia Alliance (Bromeliaceae, Bromelioideae) and insights into their morphological evolution. Mol Phylogenet Evol 2016; 100:1-20. [DOI: 10.1016/j.ympev.2016.04.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Revised: 02/29/2016] [Accepted: 04/05/2016] [Indexed: 11/17/2022]
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10
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Donoghue MJ, Sanderson MJ. Confluence, synnovation, and depauperons in plant diversification. THE NEW PHYTOLOGIST 2015; 207:260-274. [PMID: 25778694 DOI: 10.1111/nph.13367] [Citation(s) in RCA: 117] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 01/14/2015] [Indexed: 05/02/2023]
Abstract
We review the empirical phylogenetic literature on plant diversification, highlighting challenges in separating the effects of speciation and extinction, in specifying diversification mechanisms, and in making convincing arguments. In recent discussions of context dependence, key opportunities and landscapes, and indirect effects and lag times, we see a distinct shift away from single-point/single-cause 'key innovation' hypotheses toward more nuanced explanations involving multiple interacting causal agents assembled step-wise through a tree. To help crystalize this emerging perspective we introduce the term 'synnovation' (a hybrid of 'synergy' and 'innovation') for an interacting combination of traits with a particular consequence ('key synnovation' in the case of increased diversification rate), and the term 'confluence' for the sequential coming together of a set of traits (innovations and synnovations), environmental changes, and geographic movements along the branches of a phylogenetic tree. We illustrate these concepts using the radiation of Bromeliaceae. We also highlight the generality of these ideas by considering how rate heterogeneity associated with a confluence relates to the existence of particularly species-poor lineages, or 'depauperons.' Many challenges are posed by this re-purposed research framework, including difficulties associated with partial taxon sampling, uncertainty in divergence time estimation, and extinction.
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Affiliation(s)
- Michael J Donoghue
- Department of Ecology and Evolutionary Biology, Yale University, PO Box 208106, New Haven, CT, 06520, USA
| | - Michael J Sanderson
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
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11
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Quezada IM, Zotz G, Gianoli E. Latitudinal variation in the degree of crassulacean acid metabolism in Puya chilensis. PLANT BIOLOGY (STUTTGART, GERMANY) 2014; 16:848-852. [PMID: 24739103 DOI: 10.1111/plb.12181] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2013] [Accepted: 02/18/2014] [Indexed: 06/03/2023]
Abstract
Crassulacean acid metabolism (CAM) is a photosynthetic pathway found in many plant species from arid and semiarid environments. Few studies aiming to characterise plant species as CAM or C3 account for inter-population differences in photosynthetic pathway, often relying on samples taken from herbarium material and/or a single plant or population. This may be especially problematic for species growing under contrasting climate conditions, as is the case for species with a wide geographic range. We used Puya chilensis, a species previously reported as CAM and C3, to study among-population variation in expression of the CAM pathway within its distribution range, which spans a significant climate gradient. We carried out a wide sampling scheme, including five populations and a combination of analytical methods (quantification of nocturnal acidification and stable isotope measurements). The study populations of P. chilensis encompass the entire latitudinal distribution range, from semi-arid to temperate oceanic climates. Our results indicate that CAM decreased with latitude. However, even in the southern (wetter) populations, where δ13C values were indicative of C3 metabolism, we found some nocturnal acidification. We stress the value of using two methods along with the use of samples from different populations, as this allows more reliable conclusions on the photosynthetic pathway for 'probable' CAM species that face varying climate conditions within their distribution ranges.
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Affiliation(s)
- I M Quezada
- Departamento de Botánica, Universidad de Concepción, Concepción, Chile
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12
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Givnish TJ, Barfuss MH, Ee BV, Riina R, Schulte K, Horres R, Gonsiska PA, Jabaily RS, Crayn DM, Smith JAC, Winter K, Brown GK, Evans TM, Holst BK, Luther H, Till W, Zizka G, Berry PE, Sytsma KJ. Adaptive radiation, correlated and contingent evolution, and net species diversification in Bromeliaceae. Mol Phylogenet Evol 2014; 71:55-78. [DOI: 10.1016/j.ympev.2013.10.010] [Citation(s) in RCA: 254] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 09/18/2013] [Accepted: 10/11/2013] [Indexed: 11/28/2022]
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13
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Silvestro D, Zizka G, Schulte K. DISENTANGLING THE EFFECTS OF KEY INNOVATIONS ON THE DIVERSIFICATION OF BROMELIOIDEAE (BROMELIACEAE). Evolution 2013; 68:163-75. [DOI: 10.1111/evo.12236] [Citation(s) in RCA: 119] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Accepted: 07/25/2013] [Indexed: 01/19/2023]
Affiliation(s)
- Daniele Silvestro
- Biodiversity and Climate Research Centre (BiK-F); Senckenberganlage 25 60325 Frankfurt am Main Germany
- Department of Botany and Molecular Evolution; Senckenberg Research Institute; Senckenberganlage 25 60325 Frankfurt am Main Germany
- Department of Ecology and Evolution, Biophore; University of Lausanne; 1015 Lausanne Switzerland
| | - Georg Zizka
- Biodiversity and Climate Research Centre (BiK-F); Senckenberganlage 25 60325 Frankfurt am Main Germany
- Department of Botany and Molecular Evolution; Senckenberg Research Institute; Senckenberganlage 25 60325 Frankfurt am Main Germany
- Diversity and Evolution of Higher Plants; Institute of Ecology; Evolution and Diversity; Goethe University; Max von Laue Str. 9 60438 Frankfurt am Main Germany
| | - Katharina Schulte
- Australian Tropical Herbarium; James Cook University; P.O. Box 6811 Cairns QLD 4870 Australia
- Centre for Tropical Biodiversity and Climate Change; James Cook University; Townsville QLD 4811 Australia
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14
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Sage RF. Photorespiratory compensation: a driver for biological diversity. PLANT BIOLOGY (STUTTGART, GERMANY) 2013; 15:624-638. [PMID: 23656429 DOI: 10.1111/plb.12024] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 02/07/2013] [Indexed: 06/02/2023]
Abstract
This paper reviews how terrestrial plants reduce photorespiration and thus compensate for its inhibitory effects. As shown in the equation φ = (1/Sc/o )O/C, where φ is the ratio of oxygenation to carboxylation, Sc/o is the relative specificity of Rubisco, O is stromal O2 level and C is the stromal CO2 concentration, plants can reduce photorespiration by increasing Sc/o or C, or by reducing O. By far the most effective means of reducing φ is by concentrating CO2, as occurs in C4 and CAM plants, and to a lesser extent in plants using a glycine shuttle to concentrate CO2 into the bundle sheath. Trapping and refixation of photorespired CO2 by a sheath of chloroplasts around the mesophyll cell periphery in C3 plants also enhances C, particularly at low atmospheric CO2. O2 removal is not practical because high energy and protein investment is needed to have more than a negligible effect. Sc/o enhancement provides for modest reductions in φ, but at the potential cost of limiting the kcat of Rubisco. An effective means of decreasing φ and enhancing carbon gain is to lower leaf temperature by reducing absorbance of solar radiation, or where water is abundant, opening stomata. By using a combination of mechanisms, C3 plants can achieve substantial (>30%) reductions in φ. This may have allowed many C3 species to withstand severe competition from C4 plants in low CO2 atmospheres of recent geological time, thereby preserving some of the Earth's floristic diversity that accumulated over millions of years.
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Affiliation(s)
- R F Sage
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.
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