scholarly journals Macroevolución en plantas vasculares.

2003 ◽  
Vol 28 ◽  
pp. 155-177
Author(s):  
José S. Carrión ◽  
Juan Guerra
Keyword(s):  
Vascular Plants ◽  
Evolutionary Model ◽  
Plant Evolution ◽  
Model Systems ◽  
Mass Extinctions ◽  
Terrestrial Plants ◽  
Geological Time ◽  
Living Fossils

RESUMEN. Macroevolución en plantas vasculares. Se revisan los sistemas jerarquizados de evolución vegetal, desde una perspectiva paleoecológica y con énfasis en los controles del nivel superior para las plantas vasculares. Este nivel supone la existencia de breves episodios de intensa radiación, seguidos por largas fases de estabilización y declive taxonómico. El registro fósil sugiere que no han existido extinciones masivas entre las plantas terrestres, en el sentido en que ésta expresión se emplea para la evolución de animales, es decir, la existencia de fuertes pérdidas de biodiversidacl en períodos breves de tiempo geológico comparados con la vida media de las especies. Durante los episodios de estrés ambiental, las plantas han reaccionado haciendo valer sus capacidades de migración, recolonización, desplazamiento competitivo y, en suma, reorganizando la estructura ecológica o fitogeográfica. A un nivel taxonómico elevado, la mayoría de los grandes grupos exhiben un importante componente de supervivencia (fósiles vivientes). El único estrés al que no han podido escapar parece haber sido el de tipo abiótico y extrínseco que supone el incremento atmosférico del dióxido de carbono durante los eventos de superpluma asociados a las pulsaciones tectónicas. De entre estas, aquellas constatables para el Ordovícico Medio-Silúrico (460- 430 Ma), Devónico Medio-Carbonífero Inferior (375-350 Ma), Jurásico (150 Ma) y Cretácico Inferior (120-80 Ma), se correlacionan con fases de incremento rápido en la especiación y con la aparición de nuevos proyectos reproductores, a saber embriófitos, espermatófitos, gimnospermas actuales y angiospermas respectivamente. El artículo concluye considerando las opciones dialécticas de la radiación difusiva frente a la hipótesis adaptacionista, el papel de la preadaptación y la evolución de la complejidad.Palabras clave. Evolución, paleobottinica, paleoecología, plantas terrestres, extinciones masivas, preadaptación, pulsaciones tectónicas.ABSTRACT. Macroevolution in vascular plants. Here we review hierarchical, evolutionary model systems for vascular plants from a palaeoecological perspective, with emphasis in the controls for the highest tier.This involves the existence of rapid events of radiation, followed by enduring phases of stabilization and taxonomic declining. The fossil record fails to recognize mass extinctions among terrestrial plants, at least in the sense adopted for the evolution of animals, namely, short periods of geological time involving strong losses of biodiversity if compared with average lifetimes of the extinct species. During stages of environmental stress, the vascular plants have exploted their capabilities to migration, recolonization, and competitive displacement; shortly, reorganization of the ecological and fitogeographic structure. At high taxonomic levels, most groups exhibit persistence, inertia, and survival rather than extinction, demonstrably through the existence of a number of living fossils among the main clades. The only environmental factor to which plants could not escape was extrinsic abiotic stress in the form of increasing atmospheric CO, during superplumes associated to tectonics pulsations. In fact, those dated at the Mid-Ordovician u; Silurian (460- 430 Ma), Mid-Devonian to Lower Carboniferous (375-350 Ma), Jurassic (150 Ma), and Lower Cretaceous (120-80 Ma), correlate with phases of rapid speciation within the principal reproductive groups, namely embriophytes, seed plants, gymnosperms, and angiosperms respectively. We conclude discussing related issues of palaeoecological concern, such as diffusive versus adaptive hypotheses of radiation, the role of preadaptation in plant evolution, and the long-term patterns of complexity.-Key words. Evolution, palaeobotany, palaeoecology, land plants, mass extinctions, preadaptation, pulsation tectonics.

scholarly journals Origin of horsetails and the role of whole-genome duplication in plant macroevolution

2019 ◽  
Vol 286 (1914) ◽  
pp. 20191662 ◽  
Author(s):  
James W. Clark ◽  
Mark N. Puttick ◽  
Philip C. J. Donoghue
Keyword(s):  
Whole Genome Duplication ◽  
Genome Duplication ◽  
Morphological Evolution ◽  
Land Plant ◽  
Plant Evolution ◽  
Whole Genome ◽  
Geological Time ◽  
Term Survival

Whole-genome duplication (WGD) has occurred commonly in land plant evolution and it is often invoked as a causal agent in diversification, phenotypic and developmental innovation, as well as conferring extinction resistance. The ancient and iconic lineage of Equisetum is no exception, where WGD has been inferred to have occurred prior to the Cretaceous–Palaeogene (K–Pg) boundary, coincident with WGD events in angiosperms. In the absence of high species diversity, WGD in Equisetum is interpreted to have facilitated the long-term survival of the lineage. However, this characterization remains uncertain as these analyses of the Equisetum WGD event have not accounted for fossil diversity. Here, we analyse additional available transcriptomes and summarize the fossil record. Our results confirm support for at least one WGD event shared among the majority of extant Equisetum species. Furthermore, we use improved dating methods to constrain the age of gene duplication in geological time and identify two successive Equisetum WGD events. The two WGD events occurred during the Carboniferous and Triassic, respectively, rather than in association with the K–Pg boundary. WGD events are believed to drive high rates of trait evolution and innovations, but analysed trends of morphological evolution across the historical diversity of Equisetum provide little evidence for further macroevolutionary consequences following WGD. WGD events cannot have conferred extinction resistance to the Equisetum lineage through the K–Pg boundary since the ploidy events occurred hundreds of millions of years before this mass extinction and we find evidence of extinction among fossil polyploid Equisetum lineages. Our findings precipitate the need for a review of the proposed roles of WGDs in biological innovation and extinction survival in angiosperm and non-angiosperm lineages alike.

scholarly journals Conserving evolutionary history does not result in greater diversity over geological time scales

2019 ◽  
Vol 286 (1904) ◽  
pp. 20182896 ◽  
Author(s):  
J. L. Cantalapiedra ◽  
T. Aze ◽  
M. W. Cadotte ◽  
G. V. Dalla Riva ◽  
D. Huang ◽  
...  
Keyword(s):  
Time Scales ◽  
Phylogenetic Trees ◽  
Evolutionary History ◽  
Phylogenetic Diversity ◽  
Random Sets ◽  
Geological Time ◽  
The Future ◽  
Species Production

Alternative prioritization strategies have been proposed to safeguard biodiversity over macroevolutionary time scales. The first prioritizes the most distantly related species—maximizing phylogenetic diversity (PD)—in the hopes of capturing at least some lineages that will successfully diversify into the future. The second prioritizes lineages that are currently speciating, in the hopes that successful lineages will continue to generate species into the future. These contrasting schemes also map onto contrasting predictions about the role of slow diversifiers in the production of biodiversity over palaeontological time scales. We consider the performance of the two schemes across 10 dated species-level palaeo-phylogenetic trees ranging from Foraminifera to dinosaurs. We find that prioritizing PD for conservation generally led to fewer subsequent lineages, while prioritizing diversifiers led to modestly more subsequent diversity, compared with random sets of lineages. Importantly for conservation, the tree shape when decisions are made cannot predict which scheme will be most successful. These patterns are inconsistent with the notion that long-lived lineages are the source of new species. While there may be sound reasons for prioritizing PD for conservation, long-term species production might not be one of them.

The effect of low concentrations of sodium on potassium uptake and growth of wheat

2000 ◽  
Vol 27 (2) ◽  
pp. 175 ◽  
Author(s):  
Sally Box ◽  
Daniel P. Schachtman
Keyword(s):  
Plant Biomass ◽  
Wheat Root ◽  
Terrestrial Plants ◽  
Short Term ◽  
Root Cells ◽  
Light Levels ◽  
Low Concentrations ◽  
Na Uptake

Sodium is a beneficial mineral for some plant species when external concentrations are low. The role of Na+ in energising K+ acquisition in terrestrial plants has recently been suggested because of evidence demonstrating that wheat root cells express a high-affinity Na+-energised K+ symporter. To determine whether low concentrations of Na+ improve the K+ nutrition and growth of wheat, long-term growth and short-term tracer flux experiments were conducted. Long-term growth experiments were conducted over a range of K+ concentrations, at acidic and alkaline pH, with and without 500 µM NaCl. Plant biomass and tissue Na+ and K+ content was measured. Short-term experi-ments were conducted using tracers to determine whether low concentrations of Na+ or K+ stimulate Rb+ or Na+ uptake, respectively. Sodium stimulated the growth of wheat only at low (20 µM) external K+ in one of the long-term experiments, but not in two other experiments. Na+ did not stimulate Rb+ uptake, but K+ stimulated Na+ uptake in short-term tracer flux experiments. The results suggest that low concentrations of Na+ do not increase K+ uptake to a large extent, and only when light levels are low does Na+ have a beneficial effect on the growth of wheat.

Role of Lipid in Sulfite-dependent Propofol Dimerization

2004 ◽  
Vol 100 (5) ◽  
pp. 1235-1241 ◽  
Author(s):  
Max T. Baker ◽  
Marc S. Gregerson ◽  
Mohamed Naguib
Keyword(s):  
Fatty Acids ◽  
Soybean Oil ◽  
Reversed Phase ◽  
Model Systems ◽  
Unsaturated Lipid ◽  
Oil Emulsion ◽  
Peroxide Content ◽  
Peroxide Values

Background During long-term intravenous infusions, sulfite in sulfite-containing propofol emulsions can cause the peroxidation of lipid and dimerization of propofol. This study evaluated the role of lipid in sulfite-dependent propofol dimerization by determining the effects of individual fatty acids in soybean oil emulsion and peroxidized lipids in a model system. Methods Individual fatty acids, stearic (18:0), oleic (18:1), linoleic (18:2), linolenic (18:3), and arachidonic (20:4), were added to sulfite-containing propofol emulsion and incubated for 90 min at 37 degrees C. Model systems containing soybean oil (100 microl), water (900 microl), propofol (10 mg/ml), and sulfite (0.25 mg/ml) composed of oils with different peroxide values were allowed to react for 60 min at room temperature. After the reactions, propofol dimer and propofol dimer quinone were analyzed by reversed-phase high-pressure liquid chromatography. Results Propofol did not dimerize when added to aqueous sulfite unless soybean oil was also included. The addition of the polyunsaturated fatty acids (linoleic, linolenic, arachidonic) to sulfite-containing propofol emulsion resulted in large increases of propofol dimerization compared with stearic or oleic acid. Using biphasic mixtures of soybean oil and aqueous sulfite, propofol dimerization increased with increasing peroxide content of the oil. In propofol emulsion, lipoxidase and ferrous iron in the absence of sulfite also caused the dimerization of propofol. Conclusions These results show that lipid can play a significant role in sulfite-dependent propofol dimerization. The relation of dimerization to polyunsaturated fatty acid and soybean oil peroxide content suggests that sulfite reacts with unsaturated lipid or peroxide-modified lipid to facilitate propofol dimerization.

Review Lecture - Ore-deposition through geological time

1978 ◽  
Vol 362 (1710) ◽  
pp. 305-328 ◽  
Keyword(s):  
Mineral Deposits ◽  
Banded Iron Formations ◽  
Geological Time ◽  
The Earth ◽  
Recent Developments ◽  
Changing Role ◽  
Iron Formations ◽  
Ore Deposition

Economic mineral deposits represent abnormal concentrations of metals which must be regarded as records of unusual geological events. The recognition of any long-term changes in styles of mineralization must depend on the identification of anomalies within the geological régimes characteristic of successive stages of the Earth’s history. This question will be discussed in relation to recent developments in the Earth sciences. The recognition of structural and chemical inhomogeneities in the lithospheric mantle suggests that mapping of mantle age-provinces may become possible; such studies bear on the significance of certain metallogenic provinces. Coordinated geochemical, structural and palaeomagnetic studies which are throwing light on the evolution of early tectonic systems should help to illuminate the significance of changes in style of mineralization at the Archaean/Proterozoic boundary, as well as the distribution of some types of Proterozoic deposits. Geochemical evidence concerning the changing rôle of organic processes in sedimentation and diagenesis has a bearing on the origin of sedimentary ores, especially over the controversial period characterized by accumulation of banded iron-formations.

scholarly journals Mutations in Glucan, Water Dikinase Affect Starch Degradation and Gametophore Development in the Moss Physcomitrella patens

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ntombizanele T. Mdodana ◽  
Jonathan F. Jewell ◽  
Ethel E. Phiri ◽  
Marthinus L. Smith ◽  
Kenneth Oberlander ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Growth Medium ◽  
Vascular Plants ◽  
Physcomitrella Patens ◽  
Early Stage ◽  
Plant Evolution ◽  
The Other ◽  
Starch Degradation ◽  
Glucose Supplementation

Abstract The role of starch degradation in non-vascular plants is poorly understood. To expand our knowledge of this area, we have studied this process in Physcomitrella patens. This has been achieved through examination of the step known to initiate starch degradation in angiosperms, glucan phosphorylation, catalysed by glucan, water dikinase (GWD) enzymes. Phylogenetic analysis indicates that GWD isoforms can be divided into two clades, one of which contains GWD1/GWD2 and the other GWD3 isoforms. These clades split at a very early stage within plant evolution, as distinct sequences that cluster within each were identified in all major plant lineages. Of the five genes we identified within the Physcomitrella genome that encode GWD-like enzymes, two group within the GWD1/GWD2 clade and the others within the GWD3 clade. Proteins encoded by both loci in the GWD1/GWD2 clade, named PpGWDa and PpGWDb, are localised in plastids. Mutations of either PpGWDa or PpGWDb reduce starch phosphate abundance, however, a mutation at the PpGWDa locus had a much greater influence than one at PpGWDb. Only mutations affecting PpGWDa inhibited starch degradation. Mutants lacking this enzyme also failed to develop gametophores, a phenotype that could be chemically complemented using glucose supplementation within the growth medium.

scholarly journals Ancient Plant Genomics in Archaeology, Herbaria, and the Environment

2020 ◽  
Vol 71 (1) ◽  
pp. 605-629 ◽  
Author(s):  
Logan Kistler ◽  
Vanessa C. Bieker ◽  
Michael D. Martin ◽  
Mikkel Winther Pedersen ◽  
Jazmín Ramos Madrigal ◽  
...  
Keyword(s):  
Ancient Dna ◽  
Plant Evolution ◽  
Genomic Research ◽  
Degraded Dna ◽  
Plant Domestication ◽  
Plant Genomics ◽  
Dna Recovery ◽  
Plant Research

The ancient DNA revolution of the past 35 years has driven an explosion in the breadth, nuance, and diversity of questions that are approachable using ancient biomolecules, and plant research has been a constant, indispensable facet of these developments. Using archaeological, paleontological, and herbarium plant tissues, researchers have probed plant domestication and dispersal, plant evolution and ecology, paleoenvironmental composition and dynamics, and other topics across related disciplines. Here, we review the development of the ancient DNA discipline and the role of plant research in its progress and refinement. We summarize our understanding of long-term plant DNA preservation and the characteristics of degraded DNA. In addition, we discuss challenges in ancient DNA recovery and analysis and the laboratory and bioinformatic strategies used to mitigate them. Finally, we review recent applications of ancient plant genomic research.

Weathering of soil minerals by angiosperm and gymnosperm trees

2008 ◽  
Vol 72 (1) ◽  
pp. 11-14 ◽  
Author(s):  
M. Y. Andrews ◽  
J. J. Ague ◽  
R. A. Berner
Keyword(s):  
Carbon Cycle ◽  
Vascular Plants ◽  
Mineral Weathering ◽  
Large Role ◽  
Geological Time ◽  
Weathering Rates ◽  
Element Fluxes ◽  
Ecological Dominance ◽  
Field Setting

AbstractWeathering of terrestrial Ca- and Mg-bearing silicate minerals is an important control on atmospheric CO2 on geological time scales. It has been determined that vascular plants can accelerate mineral weathering as compared to non-vascular plants or non-vegetated surfaces. This indicates that the evolution of vascular plants, particularly the deep-rooted trees, may play a large role in the long-term carbon cycle and its regulation of the atmosphere. The weathering impact of the separate evolutionary appearances of the gymnosperms in the Palaeozoic and the angiosperms in the Mesozoic, and the shifting ecological dominance from the former to the latter, is currently poorly understood. This study aims to contribute to our understanding of the quantitative weathering rates of the angiosperms and gymnosperms by examining plant-mineral interactions of the two tree types in a temperate field setting underlain by granodiorite. Results include determinations of soil element fluxes and etching of minerals. The observed root-mineral interactions resulted in only slightly more weathering of Ca-bearing minerals by the angiosperms. However, we observed significantly more weathering of the Mg-bearing minerals by the gymnosperms. These results suggest that increasing dominance of the angiosperms in forests in the Mesozoic may have had a small or neutral impact on accelerating overall mineral weathering and regulating CO2, but that this impact may be lithology-dependent.

scholarly journals The folding space of protein β2-microglobulin is modulated by a single disulfide bond

2021 ◽  
Author(s):  
Jules Morand ◽  
Ana Nunes ◽  
Patricia FN Faisca
Keyword(s):  
Intermediate State ◽  
Disulfide Bridge ◽  
Intramolecular Interactions ◽  
Model Systems ◽  
Discrete Molecular Dynamics ◽  
Beta 2 Microglobulin ◽  
Dynamics Simulations ◽  
Folding Space

Protein beta-2-microglobulin (β2m) is classically considered the causative agent of dialysis related amyloidosis (DRA), a conformational disorder that affects patients undergoing long-term hemodialysis. Together with the wild type form, the ΔN6 structural variant, and the D76N mutant, have been extensively used as model systems of β2m aggregation. In all of them, the native structure is stabilized by a disulfide bridge between the sulphur atoms of the cysteine residues 25 (at B strand) and 80 (at F strand), which has been considered fundamental in β2m fibrillogenesis. Here, we use extensive Discrete Molecular Dynamics simulations of a full atomistic structure-based model to explore the role of this disulfide bridge as a modulator of the folding space of β2m. In particular, by considering different models for the disulfide bridge, we explore the thermodynamics of the folding transition, and the formation of intermediate states that may have the potential to trigger the aggregation cascade. Our results show that the dissulfide bridge affects folding transition and folding thermodynamics of the considered model systems, although to different extents. In particular, when the interaction between the sulphur atoms is stabilized relative to the other intramolecular interactions, or even locked (i.e. permanently established), the WT form populates an intermediate state featuring a well preserved core, and two unstructured termini, which was previously detected only for the D76N mutant. The formation of this intermediate state may have important implications in our understanding of β2m fibrillogenesis.

scholarly journals Mesozoic mass extinctions and angiosperm radiation: does the molecular clock tell something new?

Geologos ◽  
2012 ◽  
Vol 18 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Dmitry Ruban
Keyword(s):  
Molecular Clock ◽  
Global Scale ◽  
Flowering Plants ◽  
Mass Extinctions ◽  
Geological Time ◽  
Late Mesozoic ◽  
Environmental Perturbation ◽  
History Of

Mesozoic mass extinctions and angiosperm radiation: does the molecular clock tell something new?Angiosperms evolved rapidly in the late Mesozoic. Data from the genetic-based approach called ‘molecular clock’ permit an evaluation of the radiation of flowering plants through geological time and of the possible influences of Mesozoic mass extinctions. A total of 261 divergence ages of angiosperm families are considered. The radiation of flowering plants peaked in the Albian, early Campanian, and Maastrichtian. From the three late Mesozoic mass extinctions (Jurassic/Cretaceous, Cenomanian/Turonian, and Cretaceous/Palaeogene), only the Cretaceous/Palaeogene event coincided with a significant, abrupt, and long-term decline in angiosperm radiation. If their link will be further proven, this means that global-scale environmental perturbation precluded from many innovations in the development of plants. This decline was, however, not unprecedented in the history of the angiosperms. The implication of data from the molecular clock for evolutionary reconstructions is limited, primarily because this approach deals with only extant lineages.

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