scholarly journals The Widened Pipe Model of plant hydraulic evolution

2021 ◽  
Vol 118 (22) ◽  
pp. e2100314118
Author(s):  
Loren Koçillari ◽  
Mark E. Olson ◽  
Samir Suweis ◽  
Rodrigo P. Rocha ◽  
Alberto Lovison ◽  
...  
Keyword(s):  
Natural Selection ◽  
Membrane Resistance ◽  
Life Forms ◽  
Carbon Cycles ◽  
Pipe Model ◽  
Pit Membrane ◽  
Water Conduction ◽  
Lower Height ◽  
Xylem Conduits ◽  
Carbon Economy

Shaping global water and carbon cycles, plants lift water from roots to leaves through xylem conduits. The importance of xylem water conduction makes it crucial to understand how natural selection deploys conduit diameters within and across plants. Wider conduits transport more water but are likely more vulnerable to conduction-blocking gas embolisms and cost more for a plant to build, a tension necessarily shaping xylem conduit diameters along plant stems. We build on this expectation to present the Widened Pipe Model (WPM) of plant hydraulic evolution, testing it against a global dataset. The WPM predicts that xylem conduits should be narrowest at the stem tips, widening quickly before plateauing toward the stem base. This universal profile emerges from Pareto modeling of a trade-off between just two competing vectors of natural selection: one favoring rapid widening of conduits tip to base, minimizing hydraulic resistance, and another favoring slow widening of conduits, minimizing carbon cost and embolism risk. Our data spanning terrestrial plant orders, life forms, habitats, and sizes conform closely to WPM predictions. The WPM highlights carbon economy as a powerful vector of natural selection shaping plant function. It further implies that factors that cause resistance in plant conductive systems, such as conduit pit membrane resistance, should scale in exact harmony with tip-to-base conduit widening. Furthermore, the WPM implies that alterations in the environments of individual plants should lead to changes in plant height, for example, shedding terminal branches and resprouting at lower height under drier climates, thus achieving narrower and potentially more embolism-resistant conduits.

scholarly journals Testing for ion-mediated enhancement of the hydraulic conductance of the leaf xylem in diverse angiosperms

2017 ◽  
Vol 4 ◽  
pp. e004 ◽  
Author(s):  
Christine Scoffoni ◽  
Grace John ◽  
Herve Cochard ◽  
Lawren Sack
Keyword(s):  
Water Solution ◽  
Pure Water ◽  
Xylem Sap ◽  
Hydraulic Conductance ◽  
Membrane Pores ◽  
Whole Plant ◽  
Pit Membrane ◽  
Major Bottleneck ◽  
The Difference ◽  
Xylem Conduits

Replacing ultra-pure water solution with ion solution closer to the composition of natural xylem sap increases stem hydraulic conductance by up to 58%, likely due to changes in electroviscosity in the pit membrane pores. This effect has been proposed to contribute to the control of plant hydraulic and stomatal conductance and potentially to influence on carbon balance during dehydration. However, this effect has never been directly tested for leaf xylem, which constitutes a major bottleneck in the whole plant. We tested for an ion-mediated increase in the hydraulic conductance of the leaf xylem (Kx) for seven species diverse in phylogeny and drought tolerance. Across species, no significant changes in Kx were observed between 0 and 15 mM KCl. We further tested for an effect of ion solution during measurements of Kx vulnerability to dehydration in Quercus agrifolia and found no significant impact. These results for leaf xylem contrast with the often strong ion effect reported for stems, and we suggest several hypotheses to account for the difference, relating to the structure of xylem conduits across vein orders, and the ultrastructure of leaf xylem pores. A negligible ion response in leaves would weaken xylem sap ion-mediated control of plant hydraulic conductance, facilitating modeling of whole plant hydraulic behavior and its influence on productivity.

An Evolutionary Approach to Synthetic Biology: Zen and the Art of Creating Life

1993 ◽  
Vol 1 (1_2) ◽  
pp. 179-209 ◽  
Author(s):  
Thomas S. Ray
Keyword(s):  
Natural Selection ◽  
Synthetic Biology ◽  
Evolutionary Biology ◽  
Evolutionary Process ◽  
Life Forms ◽  
Evolutionary Approach ◽  
Artificial Medium ◽  
Natural Form ◽  
Evolution By Natural Selection ◽  
Physical Laws

Our concepts of biology, evolution, and complexity are constrained by having observed only a single instance of life, life on earth. A truly comparative biology is needed to extend these concepts. Because we cannot observe life on other planets, we are left with the alternative of creating Artificial Life forms on earth. I will discuss the approach of inoculating evolution by natural selection into the medium of the digital computer. This is not a physical/chemical medium; it is a logical/informational medium. Thus, these new instances of evolution are not subject to the same physical laws as organic evolution (e.g., the laws of thermodynamics) and exist in what amounts to another universe, governed by the “physical laws” of the logic of the computer. This exercise gives us a broader perspective on what evolution is and what it does. An evolutionary approach to synthetic biology consists of inoculating the process of evolution by natural selection into an artificial medium. Evolution is then allowed to find the natural forms of living organisms in the artificial medium. These are not models of life, but independent instances of life. This essay is intended to communicate a way of thinking about synthetic biology that leads to a particular approach: to understand and respect the natural form of the artificial medium, to facilitate the process of evolution in generating forms that are adapted to the medium, and to let evolution find forms and processes that naturally exploit the possibilities inherent in the medium. Examples are cited of synthetic biology embedded in the computational medium, where in addition to being an exercise in experimental comparative evolutionary biology, it is also a possible means of harnessing the evolutionary process for the production of complex computer software.

BIODIVERSITY AND INTERSLOPE DIVERGENCE OF VASCULAR PLANTS CAUSED BY MICROCLIMATIC DIFFERENCES AT “EVOLUTION CANYON”, LOWER NAHAL OREN, MOUNT CARMEL, ISRAEL

1999 ◽  
Vol 47 (1) ◽  
pp. 49-59 ◽  
Author(s):  
Eviatar Nevo ◽  
Ori Fragman ◽  
Amots Dafni ◽  
Avigdor Beiles
Keyword(s):  
Natural Selection ◽  
Species Diversity ◽  
Vascular Plants ◽  
Vascular Plant ◽  
Plant Cover ◽  
Life Forms ◽  
Valley Bottom ◽  
Content Sharing ◽  
The North ◽  
Evolution Canyon

Species diversity of plants was recorded in 1992 and 1993 at seven stations of the “Evolution Canyon” microsite. Higher solar radiation on the South-Facing Slope (SFS) causes warm, xeric savannoid formation versus temperate, cool, mesic, dense maquis on the North-Facing Slope (NFS), and riverine, segetal plant formations on the Valley Bottom (VB). In an area of 7000 m2, we recorded 320 vascular plant species in 217 genera and 59 families. Plant cover varied from 35% (SFS) to 150% (NFS). Annuals predominated among all life forms (61.3% of all species). SFS and NFS varied in species content, sharing only 31–18% of species. Phytogeographical types varied among the two slopes and valley bottom. Inter-and intraslope species composition varied drastically due to differential microclimatic stresses, thereby demonstrating at a microscale natural selection in action.

Artifactual lipid coatings on intervessel pit membranes in dried xylem tissues of some angiosperms

IAWA Journal ◽  
2021 ◽  
pp. 1-19
Author(s):  
Shohei Yamagishi ◽  
Kengo Shigetomi ◽  
Syunya Fujiyasu ◽  
Dan Aoki ◽  
Tetsuro Uno ◽  
...  
Keyword(s):  
Room Temperature ◽  
Secondary Ion Mass Spectrometry ◽  
Plant Cell Walls ◽  
Tof Sims ◽  
Pit Membrane ◽  
Water Conduction ◽  
Wood Extracts ◽  
Xylem Tissue ◽  
Embolism Resistance ◽  
Secondary Ion

Abstract Intervessel pit membranes are recognized as key structures for influencing water flow/embolism resistance. The mechanisms remain largely unclear owing to difficulties in examining them intact in nature. This study investigates ethanol-extractable pit membrane incrustations (PMIs), which were previously reported in certain angiosperms and may affect their water conduction. The presence of PMIs was determined for 40 angiosperms by field-emission scanning electron microscopy (FE-SEM). Candidate components of PMIs were determined by chemical analyses of wood extracts, and their distributions in the xylem were examined by time-of-flight secondary ion mass spectrometry (TOF-SIMS). Cryo-TOF-SIMS and cryo-FE-SEM were also performed to clarify the native distribution of PMIs. PMIs were observed in 11 species. Some of them were categorized as fat trees, which are known to store abundant lipids. Tilia japonica sapwood displaying PMIs contained large amounts of lipids, which were distributed in the dried xylem tissue, consistent with the distribution of the PMIs. In the frozen samples of T. japonica, however, the distributions were restricted to the parenchyma. In conclusion, PMIs consist of an artifactual coating of lipids originated from the parenchyma in dried samples at room temperature. Researchers performing surface analyses of plant cell walls should take strong precautions against such self-coating by these intrinsic chemicals.

scholarly journals The natural selection of metabolism explains curvature in fossil body mass evolution

2016 ◽  
Author(s):  
Lars Witting
Keyword(s):  
Natural Selection ◽  
Body Mass ◽  
Full Range ◽  
Life Forms ◽  
Maximum Mass ◽  
Niche Evolution ◽  
Major Life ◽  
Terrestrial Mammals ◽  
Predicted Values ◽  
Selection Of

AbstractThe natural selection of metabolism and mass can explain inter-specific allometries from prokaryotes to mammals (Witting 2017a), with exponents that depend on the selected metabolism and the spatial dimensionality (2D/3D) of intra-specific behaviour. The predicted 2D-exponent for total metabolism increases from 3/4 to 7/4 when the fraction of the inter-specific body mass variation that follows from primary variation in metabolism increases from zero to one.A 7/4 exponent for mammals has not been reported from inter-specific comparisons, but I detect the full range of allometries for evolution in the fossil record. There are no fossil data for allometric correlations between metabolism and mass, but I estimate life history allometries from the allometry for the rate of evolution in mass (w) in physical time (t).The exponent describes the curvature of body mass evolution, with predicted values being: 3/2 (2D) for within niche evolution in small horses over 54 million years. 5/4 (2D) and 9/8 (3D) for across niche evolution of maximum mass in four mammalian clades. 3/4 (2D) for fast evolution in large horses, and maximum mass in trunked and terrestrial mammals. 1 for maximum mass across major life-forms during 3.5 billion years of evolution along a metabolic bound.

Evolution, theory of

2018 ◽  
Author(s):  
Elisabeth A. Lloyd
Keyword(s):  
Natural Selection ◽  
Evolutionary Theory ◽  
Life Forms ◽  
Genetic Mutation ◽  
Theory Of Evolution ◽  
Selection Processes ◽  
Wide Range ◽  
In The Wild ◽  
Forms Of Life ◽  
The Public Sphere

The biological theory of evolution advances the view that the variety and forms of life on earth are the result of descent with modification from the earliest forms of life. Evolutionary theory does not attempt to explain the origin of life itself, that is, how the earliest forms of life came to exist, nor does it apply to the history of changes of the non-biological parts of the universe, which are also often described as ’evolutionary’. The mechanisms of natural selection, mutation and speciation are used in evolutionary theory to explain the relations and characteristics of all life forms. Modern evolutionary theory explains a wide range of natural phenomena, including the deep resemblances among organisms, the diversity of life forms, organisms’ possession of vestigial organs and the good fit or ’adaptedness’ between organisms and their environment. Often summarized as ’survival of the fittest’, the mechanism of natural selection actually includes several distinct processes. There must be variation in traits among the members of a population; these traits must be passed on from parents to offspring; and the different traits must confer differential advantage for reproducing successfully in that environment. Because evidence for each of these processes can be gathered independently of the evolutionary claim, natural selection scenarios are robustly testable. When a trait in a population has arisen because it was directly selected in this fashion, it is called an adaptation. Genetic mutation is the originating source of variation, and selection processes shape that variation into adaptive forms; random genetic drift and various levels and forms of selection dynamic developed by geneticists have been integrated into a general theory of evolutionary change that encompasses natural selection and genetic mutation as complementary processes. Detailed ecological studies are used to provide evidence for selection scenarios involving the evolution of species in the wild. Evolutionary theory is supported by an unusually wide range of scientific evidence, gaining its support from fields as diverse as geology, embryology, molecular genetics, palaeontology, climatology and functional morphology. Because of tensions between an evolutionary view of homo sapiens and some religious beliefs, evolutionary theory has remained controversial in the public sphere far longer than no less well-supported scientific theories from other sciences.

Hydraulic conductance and tracheid anatomy in six species of extant seed plants

1988 ◽  
Vol 66 (6) ◽  
pp. 1073-1079 ◽  
Author(s):  
Paul J. Schulte ◽  
Arthur C. Gibson
Keyword(s):  
Capillary Flow ◽  
Large Diameter ◽  
Membrane Resistance ◽  
Hydraulic Conductance ◽  
Linear Increase ◽  
Biophysical Model ◽  
Lumen Diameter ◽  
Seed Plants ◽  
Pit Membrane ◽  
Conductance Increase

Hydraulic conductance of tracheids was studied in either petioles or young stems of six species of seed plants having various types of intertracheid pitting. Measured conductances were compared with estimates based on Hagen–Poiseuille flow through ideal capillaries and with predictions from a biophysical model incorporating observed anatomical characteristics of tracheids and intertracheid pits. Conductance of the xylem, expressed as a percentage of the ideal capillary flow prediction, varied from an average of 88% for a species containing only very narrow tracheids to less than 35% for species with large-diameter tracheids. The biophysical model allowed fairly close predictions of conductance for all species except one, where an estimate of the pit membrane resistance could not be experimentally obtained. For individual tracheids, conductance was largely a function of lumen diameter, pit membrane resistivity, and the exposed area of the pit membranes, as determined by pit shape, size, and frequency. For wide tracheids, scalariform-pitted elements showed a linear increase in conductance with an increase in lumen diameter; however, for tracheids with large circular pits, the conductance increase afforded by a wider lumen declines as lumen diameter increases. These model simulations demonstrate the increasing significance of intertracheid pitting in obstructing flow as lumen diameter increases.

7. The geographic and ecological advance of humanity

2020 ◽  
pp. 129-138
Author(s):  
Mark V. Lomolino
Keyword(s):  
Natural Selection ◽  
Endemic Species ◽  
Life Forms ◽  
Indigenous Populations ◽  
Human Species ◽  
Tropical Regions ◽  
Global Expansion ◽  
Biological Communities

“The geographic and ecological advance of humanity” argues that the global expansion of the human species was influenced by the same factors that shaped the expansions of other life forms. Our indigenous populations were also strongly influenced by the forces of natural selection, driving human micro-evolution across the geographic template, such as larger size in higher latitudes and darker skin in tropical regions. Unfortunately, the expansion of our species has simultaneously homogenized biological communities across the globe—driving unique, locally endemic species to extinction and introducing a redundant set of species into even the most isolated regions of the planet. It is therefore imperative that we now apply the lessons on the geography of life to conserve the Earth’s remaining species.

6. Macroecology and the geography of micro-evolution

2020 ◽  
pp. 117-128
Author(s):  
Mark V. Lomolino
Keyword(s):  
Species Richness ◽  
Natural Selection ◽  
Life Forms ◽  
Ecological Traits ◽  
Environmental Characteristics ◽  
Evolutionary Patterns ◽  
Commensal Species

“Macroecology and the geography of micro-evolution” shifts the focus from macroevolutionary patterns in species richness to micro-evolutionary patterns of biogeographic variation within species. These patterns are driven by natural selection and adaptation, which in turn are driven by variation in environmental characteristics among regions and across the geographic template. How do physiological, behavioral, and ecological traits of species vary across their regional populations? Exotic, insular life forms, shaped by their island homelands void of mammalian competitors and predators, often suffered extinctions after colonization by humans and their many commensal species.

Form, Function, Agency: Sources of Natural Purpose in Animal Evolution

2022 ◽  
Author(s):  
Stuart A. Newman
Keyword(s):  
Natural Selection ◽  
Life Forms ◽  
Ecological Niches ◽  
Animal Evolution ◽  
Gene Variation ◽  
Form And Function ◽  
Extant Species ◽  
History Of ◽  
Muscle Nerve ◽  
And Function

The origination and evolution of multicellular form and function is generally thought to be based on gene-based variation, with natural selection changing the populational composition in the respective variants over time. The criterion for evolutionary success is differential fitness, the relative capacity to leave progeny in the next generation. Theoretical considerations show that this model implies that phenotypic evolution will generally be gradual, based on variations of small effect. But the fossil record of early phylogenesis, notably for the metazoans, or animals, does not support the gradualist scenario. Moreover, discordances of phenotype and genotype in extant species, along with the existence of a pan-metazoan developmental genetic toolkit, does not support the gene-variation-based evolutionary mechanism, at least at the level of phyla. Most importantly, all life-forms, including the cells that constitute animal embryos, exhibit agency, and associations of cells (even constructed ones with no history of natural selection) exhibit novel kinds of agency. This strongly suggests that new multicellular forms can invent new ways of life (e.g., ecological niches) and can persist without supplanting their populational cohorts. This chapter describes how anatomical (e.g., segments, appendages) and functional (e.g., muscle, nerve) phenotypes can emerge without cycles of gradual selection from inherent properties of metazoan cells and their aggregates. While such phenotypic “add-ons” could provide enablements for exploration of new niches, it is implausible that they arose as adaptations to external challenges. Reproductive fitness, which is essential for understanding biogeography and ecology, is unlikely to have played a role in phylum-level evolution.

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